Lifeontheedge: Braneworld cosmology observationalsignatures - - PowerPoint PPT Presentation

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 1/23

Lifeontheedge:

• bservationalsignatures
• f braneworldmodels

SanjeevS.Seahra

DepartmentofMathematics&Statistics UniversityofNewBrunswick,Canada

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 2/23

Current status of gravitational theory

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 3/23

Quick history of gravitation

■ 1605: Kepler used observations by Tycho Brahe to find his

three empirical laws of planetary motion

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 3/23

Quick history of gravitation

■ 1605: Kepler used observations by Tycho Brahe to find his

three empirical laws of planetary motion

■ 1677: Newton proposed inverse-square law of gravitation

from which he derived Kepler’s laws

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 3/23

Quick history of gravitation

■ 1605: Kepler used observations by Tycho Brahe to find his

three empirical laws of planetary motion

■ 1677: Newton proposed inverse-square law of gravitation

from which he derived Kepler’s laws

■ 1800s: observations of orbit of Mercury were found to be

inconsistent with Kepler’s laws

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 3/23

Quick history of gravitation

■ 1605: Kepler used observations by Tycho Brahe to find his

three empirical laws of planetary motion

■ 1677: Newton proposed inverse-square law of gravitation

from which he derived Kepler’s laws

■ 1800s: observations of orbit of Mercury were found to be

inconsistent with Kepler’s laws

◆ the “dark planet” Vulcan was proposed to explain the

discrepancy

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 3/23

Quick history of gravitation

■ 1605: Kepler used observations by Tycho Brahe to find his

three empirical laws of planetary motion

■ 1677: Newton proposed inverse-square law of gravitation

from which he derived Kepler’s laws

■ 1800s: observations of orbit of Mercury were found to be

inconsistent with Kepler’s laws

◆ the “dark planet” Vulcan was proposed to explain the

discrepancy

■ 1915: Einstein put forth the theory of general relativity (GR)

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 3/23

Quick history of gravitation

■ 1605: Kepler used observations by Tycho Brahe to find his

three empirical laws of planetary motion

■ 1677: Newton proposed inverse-square law of gravitation

from which he derived Kepler’s laws

■ 1800s: observations of orbit of Mercury were found to be

inconsistent with Kepler’s laws

◆ the “dark planet” Vulcan was proposed to explain the

discrepancy

■ 1915: Einstein put forth the theory of general relativity (GR) ◆ explained Mercury’s orbit without the “dark planet”

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:photontrajectories deflectedbymassive bodies

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:photontrajectories deflectedbymassive bodies

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:photontrajectories deflectedbymassive bodies Newtoniantrajectory

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:photontrajectories deflectedbymassive bodies Newtoniantrajectory G R

• p

r e d i c t i

• n

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:photontrajectories deflectedbymassive bodies Newtoniantrajectory G R

• p

r e d i c t i

• n

effectobservedby Eddingtonin1919

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:radarsignalsare delayedwhentheytravel nearmassivebodies

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:radarsignalsare delayedwhentheytravel nearmassivebodies Cassini spacecraft

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:radarsignalsare delayedwhentheytravel nearmassivebodies Cassini spacecraft

r a d a r

• s

i g n a l

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions Sun Earth e.g.:radarsignalsare delayedwhentheytravel nearmassivebodies Cassini spacecraft

r a d a r

• s

i g n a l

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:binarypulsarsemit gravitationalwaves(GWs)

PSR1913+16

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:binarypulsarsemit gravitationalwaves(GWs)

PSR1913+16

GWs(wavelikefluctuations ingeometryof spacetime)

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:binarypulsarsemit gravitationalwaves(GWs)

PSR1913+16

GWs(wavelikefluctuations ingeometryof spacetime)

(sameeffectasinMaxwell’s theory:acceleratingcharges produceEMradiation)

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:binarypulsarsemit gravitationalwaves(GWs)

(sameeffectasinMaxwell’s theory:acceleratingcharges produceEMradiation) GWstakeenergyoutof thesystemandcause starstospiraltogether

PSR1913+16

GWs

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions e.g.:binarypulsarsemit gravitationalwaves(GWs)

(sameeffectasinMaxwell’s theory:acceleratingcharges produceEMradiation) GWstakeenergyoutof thesystemandcause starstospiraltogether

PSR1913+16

GWs

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions canalsotestGRinthelabby measuringgravitational attractiondirectly

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 4/23

Testing general relativity

GRhasmanyother testablepredictions canalsotestGRinthelabby measuringgravitational attractiondirectly

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... e.g.:galacticrotation curves

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... e.g.:galacticrotation curves galaxy star

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

velocity distancefromcenter

• bserved

GRprediction

e.g.:galacticrotation curves galaxy star

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

velocity distancefromcenter

• bserved

GRprediction

e.g.:galacticrotation curves galaxy star discrepancyusually explainedbytheexistence

• f “darkmatter”haloes

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

• neof thekeypredictions
• f GRistheexpansionof

theuniverse...

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

• neof thekeypredictions
• f GRistheexpansionof

theuniverse... sizeof universe time GR

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

• neof thekeypredictions
• f GRistheexpansionof

theuniverse... sizeof universe time inGR,gravityisan attractiveforce:so expansionshould decelerate GR

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

• neof thekeypredictions
• f GRistheexpansionof

theuniverse... sizeof universe time inGR,gravityisan attractiveforce:so expansionshould decelerate GR

• bservations

inreality,the expansionis accelerating!

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything...

• neof thekeypredictions
• f GRistheexpansionof

theuniverse... sizeof universe time inGR,gravityisan attractiveforce:so expansionshould decelerate GR

• bservations

inreality,the expansionis accelerating! discrepancy usuallyexplained byexistenceof exotic“dark energy”

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests

differenteffectsprobe gravityatdifferentscales

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests

differenteffectsprobe gravityatdifferentscales

GRworkswell

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests

differenteffectsprobe gravityatdifferentscales

GRworkswell nodataeither way

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests

differenteffectsprobe gravityatdifferentscales

GRworkswell GRneedshelp fromthedarkside nodataeither way

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests

differenteffectsprobe gravityatdifferentscales

GRworkswell GRneedshelp fromthedarkside nodataeither way

...orGRisnotthe correcttheoryof gravityonlarge scales

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 5/23

Shortcomings of GR

however,GRdoesn’t explaineverything... scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests

differenteffectsprobe gravityatdifferentscales

GRworkswell GRneedshelp fromthedarkside nodataeither way

...orGRisnotthe correcttheoryof gravityonlarge scales

isGRtheright theoryonsmall scales?

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

◆ conclusion 1: it is possible to quantize GR, just really

hard (loop quantum gravity)

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

◆ conclusion 1: it is possible to quantize GR, just really

hard (loop quantum gravity)

◆ conclusion 2: GR is an effective theory whose UV

completion has a sensible quantum description (string theory)

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

◆ conclusion 1: it is possible to quantize GR, just really

hard (loop quantum gravity)

◆ conclusion 2: GR is an effective theory whose UV

completion has a sensible quantum description (string theory)

◆ conclusion 3: you can’t quantize gravity (let’s all go

home)

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

◆ conclusion 1: it is possible to quantize GR, just really

hard (loop quantum gravity)

◆ conclusion 2: GR is an effective theory whose UV

completion has a sensible quantum description (string theory)

◆ conclusion 3: you can’t quantize gravity (let’s all go

home)

■ we pursue option 2 here and consider a phenomenological

model inspired by string theory

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

◆ conclusion 1: it is possible to quantize GR, just really

hard (loop quantum gravity)

◆ conclusion 2: GR is an effective theory whose UV

completion has a sensible quantum description (string theory)

◆ conclusion 3: you can’t quantize gravity (let’s all go

home)

■ we pursue option 2 here and consider a phenomenological

model inspired by string theory

◆ it gives classical corrections to GR on small scales

Status of gravity

• Quick history of gravitation
• Testing general relativity
• Shortcomings of GR
• Small scale gravity

Introducing braneworlds Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 6/23

Small scale gravity

■ no direct evidence that GR doesn’t work on small scales ■ however, GR alone is a remarkably difficult theory to

quantize, which implies:

◆ conclusion 1: it is possible to quantize GR, just really

hard (loop quantum gravity)

◆ conclusion 2: GR is an effective theory whose UV

completion has a sensible quantum description (string theory)

◆ conclusion 3: you can’t quantize gravity (let’s all go

home)

■ we pursue option 2 here and consider a phenomenological

model inspired by string theory

◆ it gives classical corrections to GR on small scales ◆ somewhat surprisingly, it can also gives large scale

modifications

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 7/23

Introducing braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

instringtheorythe fundamentalobjects are...strings aclosedstring

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

instringtheorythe fundamentalobjects are...strings aclosedstring themodesof vibrationof thestringareassociated withparticlesandfields; includinggravityandthe standardmodel

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

instringtheorythe fundamentalobjects are...strings aclosedstring thequantumdescriptionof thesevibrationsonly makessenseif thereare10or11dimensions themodesof vibrationof thestringareassociated withparticlesandfields; includinggravityandthe standardmodel

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

aclosedstring themodesof vibrationof thestringareassociated withparticlesandfields; includinggravityandthe standardmodel thequantumdescriptionof thesevibrationsonly makessenseif thereare10or11dimensions whydon’tweseenthe extradimensions? instringtheorythe fundamentalobjects are...strings

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

historically:appealto Klein’soldideaof compactification whydon’tweseenthe extradimensions?

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

thingschangedwhenit wasdiscoveredthatthere werealsobranesinstring theory

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

thingschangedwhenit wasdiscoveredthatthere werealsobranesinstring theory brane:object

• nwhichtheendsof
• penstringsreside

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

thingschangedwhenit wasdiscoveredthatthere werealsobranesinstring theory closedstrings: carrygravitationalDOFs

• penstrings:carrystandard

modeldegreesof freedom brane:object

• nwhichtheendsof
• penstringsreside

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

closedstrings: carrygravitationalDOFs

• penstrings:carrystandard

modeldegreesof freedom anaturalpictureemergeswhere

• rdinarymatterisconfinedtoabrane

whilegravitypropagatesinthebulk

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 8/23

A brief tour of string theory

closedstrings: carrygravitationalDOFs

• penstrings:carrystandard

modeldegreesof freedom braneworldidea: identifyouruniverse witha4Dbrane anaturalpictureemergeswhere

• rdinarymatterisconfinedtoabrane

whilegravitypropagatesinthebulk

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space ◆ this is too hard to realize in practice

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space ◆ this is too hard to realize in practice ■ phenomenological braneworld models assume 4D brane

embedded in 5D bulk

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space ◆ this is too hard to realize in practice ■ phenomenological braneworld models assume 4D brane

embedded in 5D bulk

■ such models allow us to quantitatively calculate corrections

to GR

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space ◆ this is too hard to realize in practice ■ phenomenological braneworld models assume 4D brane

embedded in 5D bulk

■ such models allow us to quantitatively calculate corrections

to GR

■ there are two principal types of model:

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space ◆ this is too hard to realize in practice ■ phenomenological braneworld models assume 4D brane

embedded in 5D bulk

■ such models allow us to quantitatively calculate corrections

to GR

■ there are two principal types of model: ◆ Randall-Sundrum (RS) model (1999)

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 9/23

Braneworld paradigm

■ don’t need compactification because non-gravitational

physics naturally confined to the 4D brane

■ gravity lives in higher dimensions

⇒ there may be deviations from GR

■ ideally, we want a 4D brane embedded in 11D space ◆ this is too hard to realize in practice ■ phenomenological braneworld models assume 4D brane

embedded in 5D bulk

■ such models allow us to quantitatively calculate corrections

to GR

■ there are two principal types of model: ◆ Randall-Sundrum (RS) model (1999) ◆ Dvali-Gabadadze-Porrati (DGP) model (2000)

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 10/23

Randall-Sundrum braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 11/23

DGP braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 11/23

DGP braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 11/23

DGP braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 11/23

DGP braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 11/23

DGP braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 11/23

DGP braneworlds

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 12/23

Braneworld observational signatures

scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests GRworkswell GRneedshelp nodata

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 12/23

Braneworld observational signatures

scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests GRworkswell GRneedshelp nodata

RSmodel modifiesGR DGPmodel modifiesGR

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 12/23

Braneworld observational signatures

scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests GRworkswell GRneedshelp nodata

RSmodel modifiesGR DGPmodel modifiesGR

wheretolookfor

• bservational

signatures?

Status of gravity Introducing braneworlds

• A brief tour of string theory
• Braneworld paradigm
• RS braneworlds
• DGP braneworlds
• Braneworld signatures

Braneworld cosmology Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 12/23

Braneworld observational signatures

scale

accelerated expansion galacticrot’n curves solarsystem/ binarypulsar laboratory tests GRworkswell GRneedshelp nodata

RSmodel modifiesGR DGPmodel modifiesGR

wheretolookfor

• bservational

signatures?

shortwavelengthGWs

• rearlyuniverse
• bservationsof

nearbycosmology

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 13/23

Braneworld cosmology

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 14/23

Cosmological probes

weobservetheuniverseinanumberof differentways: WMAP Planck SDSS HST+ground telesopes

cosmicmicrowave background(CMB) supernovae typeIa(SNeIa) largescale structure(LSS)

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 14/23

Cosmological probes

weobservetheuniverseinanumberof differentways: SNeIa’sprovideadirect measureof theexpansion rateof theuniverse sizeof universe time GR

• bservations

HST+ground telesopes

supernovae typeIa(SNeIa)

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 14/23

Cosmological probes

weobservetheuniverseinanumberof differentways: CMBexperiments directlymeasure thermalrelicsof the earlyuniverse

allskymapof temperaturefluctuations incosmicblackbodyradiation

WMAP Planck

cosmicmicrowave background(CMB)

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 14/23

Cosmological probes

weobservetheuniverseinanumberof differentways: probesof LSSmeasure thedistributionof nearbygalaxies SDSS

largescale structure(LSS)

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 14/23

Cosmological probes

weobservetheuniverseinanumberof differentways: homogeneous expansion dynamicsof fluctuatations cosmicmicrowave background(CMB) supernovae typeIa(SNeIa) largescale structure(LSS) (latetime) (earlytime) (latetime)

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 14/23

Cosmological probes

weobservetheuniverseinanumberof differentways: homogeneous expansion dynamicsof fluctuatations cosmicmicrowave background(CMB) supernovae typeIa(SNeIa) largescale structure(LSS) (latetime) (earlytime) (latetime) braneworldmodelsaltertheGR predictionsforboththebackground expansionandgrowthof perturbations

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

extra dimension inbraneworld cosmology,the branemovesinthe extradimension

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

extra dimension inbraneworld cosmology,the branemovesinthe extradimension asthebranemoves, itssizechanges branemotion=cosmologicalexpansion

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

extra dimension inbraneworld cosmology,the branemovesinthe extradimension asthebranemoves, itssizechanges branemotion=cosmologicalexpansion

“if theuniverseis expanding,whatisit expandinginto?”

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

extra dimension branemotion=cosmologicalexpansion

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

extra dimension branemotion=cosmologicalexpansion

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

sizeof universe time GR

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

sizeof universe time GR RS

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

sizeof universe time GR DGP RS

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

sizeof universe time GR DGP RS

supernovae

• bservations

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

sizeof universe time GR DGP RS

supernovae

• bservations

DGPactuallypredicts latetimeacceleration!

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 15/23

Modifications to the expansion

sizeof universe time GR DGP RS

supernovae

• bservations

DGPactuallypredicts latetimeacceleration! RScorrectionsare tooearlytooobserve directly

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

supernovaeobservationsalone arenotenoughtodiscriminate betweenDGPandother“dark energy”models theyalsoshednolight

• nRSscenarios

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

supernovaeobservationsalone arenotenoughtodiscriminate betweenDGPandother“dark energy”models theyalsoshednolight

• nRSscenarios

...looktoperturbationsof themodeltogetmore information

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

inbraneworld model,thereare lotsof different perturbationsto consider

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

inbraneworld model,thereare lotsof different perturbationsto consider bulkspacetime perturbations

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

inbraneworld model,thereare lotsof different perturbationsto consider bulkspacetime perturbations inhomogeneties inbranematter

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

inbraneworld model,thereare lotsof different perturbationsto consider bulkspacetime perturbations inhomogeneties inbranematter fluctuationsin branegeometry

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

inbraneworld model,thereare lotsof different perturbationsto consider bulkspacetime perturbations inhomogeneties inbranematter fluctuationsin branegeometry plusthebraneis moving---complicated problemthatneeds simulations

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

RS:correctionscome inearlyuniverse

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

RS:correctionscome inearlyuniverse inearlyuniverse,

• verdenseregionsare

closetogether

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

RS:correctionscome inearlyuniverse inearlyuniverse,

• verdenseregionsare

closetogether forceof gravityin RSenhancedfor separationsless thancurvaturescale

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

RS:correctionscome inearlyuniverse inearlyuniverse,

• verdenseregionsare

closetogether forceof gravityin RSenhancedfor separationsless thancurvaturescale hence,perturbations shouldgrowfaster thaninGR

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

5Dsimulation effectivetheory GR initialvalue setbyinflation

Cardoso,Hiramatsu,Koyama&SSS;JCAP(2007)

enhancementinamplitudeof perturbationsseeninsimulations

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

generalrelativity effective theory

(assumingscaleinvariant primordialspectrum)

simulationresults

inRSbraneworld: excesspower

• nsmallscales

Cardoso,Hiramatsu,Koyama&SSS;JCAP(2007)

resultsinanamplificationinthepowerspectrum

• f densityperturbationsonsmallscales

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

generalrelativity effective theory

(assumingscaleinvariant primordialspectrum)

simulationresults

inRSbraneworld: excesspower

• nsmallscales

Cardoso,Hiramatsu,Koyama&SSS;JCAP(2007)

resultsinanamplificationinthepowerspectrum

• f densityperturbationsonsmallscales

effectontoosmalla scaletobeseenin CMBorLSS,butdoes affectproductionof primordialblackholes

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect

CMB photon

distantgalaxy (cluster) Earth

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect distantgalaxy (cluster) Earth photonblueshiftedby potentialwell

CMB photon

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect distantgalaxy (cluster) galaxygrowsas photoncrossesit Earth photonblueshiftedby potentialwell

CMB photon

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect distantgalaxy (cluster) Earth photonemerges withdifferent colour photonblueshiftedby potentialwell

CMB photon

galaxygrowsas photoncrossesit

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect CMB LSS correlated

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

DGP:correctionscome inlateuniverse bestseenintheintegrated Sachs-Wolfeeffect CMB LSS correlated theDGPmodelpredictsadifferent evolutionforLSSthanGR,hencethedegree

• f CMB/LSScrosscorrelationchanges

Status of gravity Introducing braneworlds Braneworld cosmology

• Cosmological probes
• Modified expansion
• Modified perturbations

Braneworld black holes Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 16/23

Modifications to perturbations

Cardoso,Koyama,SSS,Silva;arXiv:0711.2563

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 17/23

Braneworld black holes

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs?

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? interferometer

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? interferometer GWs interferometer howdoesone detectGWs? interferometer GWs interferometer

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? interferometer GWs interferometer waveschangearm lengthandhence producefringes

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? interferometer GWs interferometer waveschangearm lengthandhence producefringes

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? interferometer GWs interferometer waveschangearm lengthandhence producefringes

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? interferometer GWs interferometer waveschangearm lengthandhence producefringes theeffectissmall, soyouneedabig interferometer

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? GWs waveschangearm lengthandhence producefringes theeffectissmall, soyouneedabig interferometer LIGO(4kmarms,kHz) (inoperation)

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? GWs waveschangearm lengthandhence producefringes theeffectissmall, soyouneedabig interferometer LISA(Gmarms,10mHz) (launch2018?)

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 18/23

Detecting gravitational waves

howdoesone detectGWs? LISA(Gmarms,10mHz) (launch2018?) LIGO(4kmarms,kHz) (inoperation)

blackholesare importantsources,are thereanybraneworld signatures?

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

Ourbraneworldblackholemodelinvolvesthe two-branevariantoftheRSsetup: extradimension

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

Ourbraneworldblackholemodelinvolvesthe two-branevariantoftheRSsetup: extradimension positivetension “visible”brane(us) negativetension “shadow”brane(them) 5Dcosmological constant:

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

Thegeometryinbetweenthebranesis describedbythe5Dblackstring: extradimension warped horizon linesingularity

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

Thegeometryinbetweenthebranesis describedbythe5Dblackstring: extradimension warped horizon linesingularity geometryonour braneexactlymatches 4DSchwarzschild

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

3typesofperturbationstoconsider:

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

3typesofperturbationstoconsider: matterperturbations

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

3typesofperturbationstoconsider: matterperturbations perturbationof braneshapesand positions

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

3typesofperturbationstoconsider: matterperturbations perturbationof braneshapesand positions perturbationof5Dgeometry (bulkgravitationalwaves)

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

Focusonbulkperturbations...

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

…5Dgravitonislikea wavetrappedinaboxwith discretemodesofpropagation profileofbulkmodes alongextradimension Focusonbulkperturbations...

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

modesarelabeledby numberofzeros in-betweenbranes profileofbulkmodes alongextradimension …5Dgravitonislikea wavetrappedinaboxwith discretemodesofpropagation Focusonbulkperturbations...

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

modesarelabeledby numberofzeros in-betweenbranes profileofbulkmodes alongextradimension zero-modebehavesexactly like4Dmassless(spin-2)graviton …5Dgravitonislikea wavetrappedinaboxwith discretemodesofpropagation Focusonbulkperturbations...

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

modesarelabeledby numberofzeros in-betweenbranes profileofbulkmodes alongextradimension zero-modebehavesexactly like4Dmassless(spin-2)graviton …5Dgravitonislikea wavetrappedinaboxwith discretemodesofpropagation Focusonbulkperturbations...

{

higher-order “Kaluza-Klein” modesactas coupledmassive spin-0,spin-1and spin-2fields effective4Dmass

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

modesarelabeledby numberofzeros in-betweenbranes profileofbulkmodes alongextradimension zero-modebehavesexactly like4Dmassless(spin-2)graviton …5Dgravitonislikea wavetrappedinaboxwith discretemodesofpropagation Focusonbulkperturbations...

KKModes giveDeviations fromGR

{

higher-order “Kaluza-Klein” modesactas coupledmassive spin-0,spin-1and spin-2fields effective4Dmass

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 19/23

The black string braneworld

ToquantifytheKK modes,weneedto worryabouthowall typesofperturbations coupleto/sourceone another

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 20/23

GW signal from the black string

typicalgravitywavesignalfromablackholein4-dimensions:

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 20/23

GW signal from the black string

thegravitywavesignalfromablackstring:

[SSS,Clarkson&Maartens; (2005)] Phys.Rev.Lett.

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 20/23

GW signal from the black string

detectingextradimensionswithgravitywavespectroscopy:

[SSS,Clarkson&Maartens; (2005)] Phys.Rev.Lett.

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 21/23

Detectability of massive modes

■ depending on parameters, massive mode signal are 104 to

1011 Hz

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 21/23

Detectability of massive modes

■ depending on parameters, massive mode signal are 104 to

1011 Hz

■ generally higher frequencies than LIGO or LISA were

designed to detect

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 21/23

Detectability of massive modes

■ depending on parameters, massive mode signal are 104 to

1011 Hz

■ generally higher frequencies than LIGO or LISA were

designed to detect

◆ may need high frequency GW detectors to really get a

handle on the system

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 21/23

Detectability of massive modes

■ depending on parameters, massive mode signal are 104 to

1011 Hz

■ generally higher frequencies than LIGO or LISA were

designed to detect

◆ may need high frequency GW detectors to really get a

handle on the system

■ amplitudes are tiny, several orders of magnitude less than

the GR case

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes

• Detecting GWs
• Black string braneworld
• GW signals
• Detectability

Summary Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 21/23

Detectability of massive modes

■ depending on parameters, massive mode signal are 104 to

1011 Hz

■ generally higher frequencies than LIGO or LISA were

designed to detect

◆ may need high frequency GW detectors to really get a

handle on the system

■ amplitudes are tiny, several orders of magnitude less than

the GR case

■ nevertheless, they are long lived suggesting they may be

detectable with a long integration time

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 22/23

Summary

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity ■ braneworlds are phenomenological realizations of one

candidate quantum theory of gravity (string theory)

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity ■ braneworlds are phenomenological realizations of one

candidate quantum theory of gravity (string theory)

◆ can modify gravity on large and small scales

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity ■ braneworlds are phenomenological realizations of one

candidate quantum theory of gravity (string theory)

◆ can modify gravity on large and small scales ◆ can help get rid of dark energy, not dark matter

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity ■ braneworlds are phenomenological realizations of one

candidate quantum theory of gravity (string theory)

◆ can modify gravity on large and small scales ◆ can help get rid of dark energy, not dark matter ■ to observationally confirm or refute braneworlds, one needs

to observe gravitational phenomena on large and small scales

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity ■ braneworlds are phenomenological realizations of one

candidate quantum theory of gravity (string theory)

◆ can modify gravity on large and small scales ◆ can help get rid of dark energy, not dark matter ■ to observationally confirm or refute braneworlds, one needs

to observe gravitational phenomena on large and small scales

◆ measure cosmological effects at early or late times

Status of gravity Introducing braneworlds Braneworld cosmology Braneworld black holes Summary

• What have we seen?

Sanjeev S. Seahra; 25 January, 2008 Observational signatures of braneworlds - p. 23/23

What have we seen?

■ without the “dark-side”, GR is an adequate description of

gravity on sub-galactic scales

◆ exotic dark matter and energy is one way to bring GR in

line with observations

◆ another is to modify gravity ■ braneworlds are phenomenological realizations of one

candidate quantum theory of gravity (string theory)

◆ can modify gravity on large and small scales ◆ can help get rid of dark energy, not dark matter ■ to observationally confirm or refute braneworlds, one needs

to observe gravitational phenomena on large and small scales

◆ measure cosmological effects at early or late times ◆ observe short wavelength gravitational waves