Dark matter ManojKaplinghat under our - - PowerPoint PPT Presentation

▶
dark matter
SMART_READER_LITE
LIVE PREVIEW

Dark matter ManojKaplinghat under our - - PowerPoint PPT Presentation

Dec 29, 2023 194 likes •576 views

Dark matter ManojKaplinghat under our UniversityofCalifornia,Irvine feet and in the sky Searching for Dark Matter Particles on Earth and in Space photo by Art Rosch Tuesday, June 26, 2012 dark matter searches are

slide-1
SLIDE 1

photo by Art Rosch

Dark matter under our feet and in the sky

Manoj
Kaplinghat University
of
California,
Irvine

Searching for Dark Matter Particles on Earth and in Space

Tuesday, June 26, 2012

slide-2
SLIDE 2
  • dark matter searches are well-motivated
  • the field is changing rapidly and

experiments capable of “seeing” WIMP dark matter are finally operational

  • however, there are indications that we may

have to extend the cold dark matter model

  • if so, then dark matter is not a WIMP

Tuesday, June 26, 2012

slide-3
SLIDE 3

what is the universe made of?

Background: The Hubble Ultra Deep Field

  • Normal matter (makes bacteria, comets, etc)
  • Dark matter (behaves gravitationally like

normal matter but so far we no concrete evidence that it interacts with anything else)

  • More dark stuff (seriously!) dubbed dark

energy (that does not behave gravitationally like normal matter)

Tuesday, June 26, 2012

slide-4
SLIDE 4

is dark matter weird?

  • Doesn’t have to be. In

fact, we would have been wondering why there isn’t any dark matter if all of matter was “normal”!

  • Neutrinos are good dark

matter candidates. Just not heavy enough to make up all of the dark matter we see. Particles of the standard model of particle physics that have been seen in the laboratory

Tuesday, June 26, 2012

slide-5
SLIDE 5

10 kpc

what we see: some length scales

Stellar nurseries Galaxies Clusters of galaxies 10 pc 1 Mpc pc (parsec) is 3 light-years or 30 trillion km or 200,000 AU

Tuesday, June 26, 2012

slide-6
SLIDE 6

Sloan Digital Sky Survey Filaments of structure -- the “cosmic web”

what we see: some length scales

Gigaparsecs

Tuesday, June 26, 2012

slide-7
SLIDE 7

About half gram of dark matter in a cube with side 1000 km in the solar neighborhood T y p i c a l s p e e d

  • f

d a r k m a t t e r p a r t i c l e s i s a b

  • u

t 2 k m / s n e a r t h e s

  • l

a r n e i g h b

  • r

h

  • d

.

Rotation speed Distance from center

dark matter in galaxies

Tuesday, June 26, 2012

slide-8
SLIDE 8

U G C 7 5 2 4 / N G C 4 3 9 5

dark matter in galaxies

Rotation supported by dark matter Close-by and faint

Tuesday, June 26, 2012

slide-9
SLIDE 9

Note the linear rise in rotation speed close to the center.

dark matter in galaxies: rotation speeds

Note the plateau in speed as the distance from the center increases. This universal feature is the primary case for dark matter in galaxies.

Tuesday, June 26, 2012

slide-10
SLIDE 10

Arcs are distorted images of background galaxies: “strong gravitational lensing”

dark matter in clusters of galaxies: gravitational lensing

Tuesday, June 26, 2012

slide-11
SLIDE 11

dark matter in clusters of galaxies: gravitational lensing

Bullet cluster

Composite Credit: X-ray: NASA/CXC/CfA/ M.Markevitch et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/ D.Clowe et al. Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.;

Blue: matter from “weak” gravitational lensing red: gas in x-rays

Tuesday, June 26, 2012

slide-12
SLIDE 12

Bell labs (1964)

2.7 degree Kelvin The Universe is not perfectly smooth -- very small variations are needed to make galaxies.

COBE (1990)

Discovered in 1990s with the COBE satellite

WMAP (2003)

WMAP : (a) universe is close to flat, and (b) about 5 times more dark matter than normal matter

dark matter on horizon scales

Tuesday, June 26, 2012

slide-13
SLIDE 13

story so far

We have looked at some of strongest lines of evidence for dark matter. The next section is about the basic questions we may ask about dark matter particles.

Tuesday, June 26, 2012

slide-14
SLIDE 14

Dark matter: Cold and Warm

Cold/Warm:
main
 distinction
is
(of
 course)
temperature Temperature:
 measure
of
random
 (thermal)
motion
 before
dark
matter
 particles
are
bound
 into
halos
(galaxies) As
the
universe
cools,
 this
thermal
motion
 decreases Operational definitions Cold dark matter: thermal motions irrelevant for galaxy formation Warm dark matter: thermal motions (a) cut-off formation of small-galaxies

  • r (b) reduce the amount of

dark matter in the central parts of galaxies

Tuesday, June 26, 2012

slide-15
SLIDE 15

dark matter interactions (other than gravitation) Does it interact with other particles? Does it interact with itself? Is it stable?

Tuesday, June 26, 2012

slide-16
SLIDE 16

Matches data on cosmological scales (CMB) down to scales of order Mega-parsec (Galaxies) Zero-parameter fit (not counting the cosmological parameters) from the astrophysical point of view

Observations Theory

COLD dark matter on “large” scales

Tuesday, June 26, 2012

slide-17
SLIDE 17

extending cold dark matter model?

Should we really expect dark sector to be so simple (so much simpler than the visible sector)? Cold dark matter model is clearly right (on large scales) but will it need modification as we probe smaller scales? If yes, what are the motivations? What sort of modifications? How may we test them? How does computing play into this?

Tuesday, June 26, 2012

slide-18
SLIDE 18

extending cold dark matter model

(i) Warmer

  • r

(ii) Stronger self-interaction Actually... (i) much much ... warmer

  • r

(ii) much much ... stronger self-interaction How does warmness or strong self- interaction manifest itself in astrophysics? Next ...

Tuesday, June 26, 2012

slide-19
SLIDE 19

Milky Way halo simulated (almost...)

Milky Way stars

Via Lactea: Diemand et al 2006

Tuesday, June 26, 2012

slide-20
SLIDE 20

Radius (distance from center of clump or “subhalo”) Density

Milky Way halo simulated (almost...)

Via Lactea Radius (distance from center of clump or “subhalo”) Mass enclosed

Tuesday, June 26, 2012

slide-21
SLIDE 21

Warmness and Self-interactions

Distance from center of halo Halo Density Self-interaction strength is dialed up Number of halos

  • f mass > M

Mass M Warmer

Tuesday, June 26, 2012

slide-22
SLIDE 22

some models of dark matter

LIGHT AXION

Behaves like normal matter except it does not shine. Interacts very weakly with normal matter.

M A C H O Particles from extra-dimensions

SM

Self-annihilating Self-interacting

Hidden sector dark matter

SuperWIMP WIMP (Weakly Interacting Massive Particle) Light Gravitino

warm

Tuesday, June 26, 2012

slide-23
SLIDE 23

WIMP Hidden sector DM

S e l f i n t e r a c t i

  • n

Damping Warmness

Sterile ν SuperWIMP Central density of halos is lowered

Mass of smallest halos H a l

  • s

m

  • r

e s p h e r i c a l a n d b i g g e r c

  • r

e s

Tuesday, June 26, 2012

slide-24
SLIDE 24

Hidden Sector SM Hidden Connector SUSY

if our sector is supersymmetric imagine proton and neutron-like particles here

Tuesday, June 26, 2012

slide-25
SLIDE 25

How is dark matter produced?

  • By freeze-out process : stronger the

self-annihilation smaller the present abundance (e.g., WIMP , x-dim)

  • Through decay process where the

parent particle’s abundance is set via the freeze-out mechanism (e.g., SuperWIMP)

  • By non-thermal process (e.g., axions,

sterile neutrino)

  • Directly during reheating : fine

tuned (e.g., WIMPZILLA)

Weak scale dark matter

Right abundance! Successful cosmological predictions on large scales Hints for new physics at the weak scale (~1000 proton masses)

Tuesday, June 26, 2012

slide-26
SLIDE 26

story so far

  • We have seen that well-motivated dark matter models

are varied and they make differing predictions for:

  • formation of small galaxies
  • for density of dark matter in the central parts of the

galaxy

  • WIMPs are the favored candidates
  • well-motivated
  • provide the most dramatic avenues for seeing dark

matter -- Direct detection, Indirect detection, Direct production. Coming up next...

Tuesday, June 26, 2012

slide-27
SLIDE 27

dark matter is all around us: how do we “see it”?

Tuesday, June 26, 2012

slide-28
SLIDE 28

the WIMP casebook

  • Weakly Interacting Massive Particle
  • Weakly interacting: this is what makes dark matter

effectively “dark”. The weak interactions also endow the dark matter with the right cosmological abundance.

  • “Massive”: has to be or we would have seen it in the lab

despite the weak interactions

  • These particles fall out of theories designed to complete

the standard model of particle physics

Tuesday, June 26, 2012

slide-29
SLIDE 29

Indirect detection

Fermi (gamma-rays) PAMELA (antimatter)

DM anti-q, anti-e q, e DM protons, anti-protons, electrons, anti-electrons, photons

Stay tuned for results from AMS-02

Tuesday, June 26, 2012

slide-30
SLIDE 30

Not all these clumps light up (form stars)! But some have to and we can look towards them.

Sources for indirect detection

Milky Way stars Satellites of the Milky Way Both the center of the Milky Way and satellites of the Milky Way have large concentrations of dark matter. So look towards them for indirect signatures of dark matter (other than gravitational).

Tuesday, June 26, 2012

slide-31
SLIDE 31

Direct detection

DM proton proton DM

Cryogenic Dark Matter Search (Soudan)

Xenon Dark Matter Search Gran Sasso

recoils with energy

  • f order (DMP

mass)(200 km/s)2 number of events depends on: (a) how strongly DMP couples to protons and neutrons, and (b) how many DMPs per meter3 in the solar neighborhood

DAMA COGENT CRESST

Tuesday, June 26, 2012

slide-32
SLIDE 32

Direct production

Large Hadron Collider

DM quarks anti- quarks DM

Make dark matter!

Tuesday, June 26, 2012

slide-33
SLIDE 33

last part of talk now...

  • We have seen various ways to “see” WIMPs

and we have seen why they are (deservingly) the most favored candidates

  • Next we look at two issues for a perfectly

Cold Dark Matter model

  • Density of dark matter in satellites of the

Milky Way

  • Density of dark matter in small spiral

galaxies

Tuesday, June 26, 2012

slide-34
SLIDE 34

Satellites of the Milky Way

Discovered in SDSS Pre-SDSS

CARI DRAC FORN LEO1 LEO2 SCUL SEXT UMIN BOO1 CVN1 CVN2 COMB HERC LEO4 SEG1 UMA1 UMA2

50 100 150 200 250 2 3 4 5 6 7 Distance to dwarf kiloparsec

  • 10

10 10 10 10 10 Luminosity (solar luminosities)

Tuesday, June 26, 2012

slide-35
SLIDE 35

10 10 10 10 10

CARI DRAC FORN LEO1 LEO2 SCUL SEXT UMIN

Lines are satellites in Aquarius simulation Filled circles are observed bright satellites

200 400 600 800 1000 5 6 7 8 9 Radius parsec Masses of bright Milky Way satellites Mass solar masses

subhalos

Tuesday, June 26, 2012

slide-36
SLIDE 36

10 10 10 10 10 Massive
 satellites
 missing! Thousands
more
with
lower
 masses
that
are
not
seen!

CARI DRAC FORN LEO1 LEO2 SCUL SEXT UMIN

Lines are satellites in Aquarius simulation Filled circles are observed bright satellites

200 400 600 800 1000 5 6 7 8 9 Radius parsec Masses of bright Milky Way satellites Mass solar masses

subhalos

Could
be
 solved
by
 self‐ interacting


  • r
warm


dark
matter

Tuesday, June 26, 2012

slide-37
SLIDE 37

dark matter in other galaxies

Distance from center of halo Halo Density Halos with self-interacting dark matter

Linear rise in rotation speed

Rotation speed (km/s) Distance from center (kilo-parsec)

Tuesday, June 26, 2012

slide-38
SLIDE 38
  • dark matter searches are well motivated
  • the field is changing rapidly and

experiments capable of “seeing” WIMP dark matter are finally operational

  • however, there are strong hints that we may

have to extend the cold dark matter model

  • if so, then dark matter is not a WIMP
  • requires investment in supercomputing for

(a) understanding feedback from star formation and (b) simulating alternative dark matter cosmologies

Tuesday, June 26, 2012