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A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E : S T U DY I N G T H E G L OW I N G C G M I N D E N S E E N V I R O N M E N T S M O I R E P R E S C OT T ( N E W M E X I C O S TAT E U N I V E R S I T Y )


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SLIDE 1

A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E : S T U DY I N G T H E G L OW I N G C G M I N D E N S E E N V I R O N M E N T S

M O I R E P R E S C OT T ( N E W M E X I C O S TAT E U N I V E R S I T Y )

G A B R I E L B R A M M E R ( S T S C I ) , A R J U N D E Y ( N OAO ) , J O H A N F Y N B O ( DA R K C O S M O L O G Y C E N T R E ) , AG NA R H A L L ( N M S U ) , C RY S TA L M A RT I N ( U C S B ) , I VA M O M C H E VA ( S T S C I ) , PA L L E M Ø L L E R ( E S O )

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SLIDE 2

LY M A N - A L P H A N E B U L A E — T H E O P P O RT U N I T Y

  • Ly𝛽 nebulae are a unique

window into:

  • the CGM in emission
  • ver 10s or 100s of kpc
  • an active phase of

galaxy formation (precursors to galaxy groups/clusters)

  • To leverage this
  • pportunity, need to know

what is lighting them up — not always obvious!

Credit: M. Prescott &

  • A. Dey 2010

40 kpc

Credit: NASA/CXC/SAO

80 kpc

Q2) What are the morphological and physical properties

  • f the CGM?

Q3) What are the physical processes that shape the CGM

  • n both large (kpc)

and small (pc) scales?

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SLIDE 3

Millennium Simulation, Springel et al. 2005

LY M A N - A L P H A N E B U L A E — T H E C H A L L E N G E

  • Ly𝛽 nebulae are

challenging to interpret:

  • in massive halos,

messy, energetic regions

  • many processes at

work — shock-heating, gravitational cooling, resonant scattering, and AGN/SF photoionization

  • difficult to disentangle,

given uncertainties in both data and models

Mori+2004

Shock-heating

Faucher-Giguere+2010

Gravitational Cooling

Zheng et al. 2010

Resonant Scattering

Cantalupo+2005

AGN

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SLIDE 4

A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E

  • Using multi-wavelength data on individual Ly𝛽 nebulae as

a window into the CGM in dense regions:

  • Environment — census of nearby galaxies (& AGN)
  • Kinematics — map out how the gas is moving
  • Physical conditions — metallicity, density, source of

ionization

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SLIDE 5

A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E

  • Using multi-wavelength data on individual Ly𝛽 nebulae

reveals a more complete picture of the CGM in dense regions:

  • Environment — census of nearby galaxies (& AGN)
  • Kinematics — map out how the gas is moving
  • Physical conditions — metallicity, density, source of

ionization

galaxy redshifts, multi-wavelength coverage to find AGN

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SLIDE 6

E N V I R O N M E N T: LY M A N - A L P H A N E B U L A E L I V E I N OV E R D E N S E R E G I O N S

  • Environments of Ly𝛽 nebulae
  • verdense on large (~50 Mpc) scales
  • Early circumstantial evidence: first

examples found in surveys of dense regions (Francis+1999, Steidel+2000)

  • Subsequent follow-up showed Ly𝛽

nebulae:

  • live in overdense regions (Matsuda

+2004,2005, Prescott+2008)

  • are strongly clustered (Yang+2009)
  • have low space densities (Saito

+2006, Prescott 2009, Yang+2010)

Steidel et al. 2000

80 kpc Prescott et al. 2008

Ly𝜷 Nebula

(also see Cai+2016, 2017)

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SLIDE 7
  • On smaller scales, the local environment is overdense

Prescott+2012b

z=2.656 LABd05 x4 Ly𝜷

  • Large population
  • f associated

galaxies and a nearby obscured AGN

  • Factor of ~4

galaxy overdensity

  • n ~50-100 kpc

scales

Found a similar situation even in a Ly𝛽 nebula that was previously thought to be alone…

E N V I R O N M E N T: LY M A N - A L P H A N E B U L A E L I V E I N OV E R D E N S E R E G I O N S

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SLIDE 8

A “ C O O L I N G ” LY M A N - A L P H A N E B U L A ?

  • Nilsson+2006 discovered an

unusual Ly𝛽 nebula:

No associated galaxies

No associated AGN

Surface brightness profile similar to early “gravitational cooling” model predictions

  • Became known as the “best

candidate for a Ly𝜷 nebula powered by cold accretion”

Nilsson+2006

…because what else could it be?

LABn06 z=3.157

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SLIDE 9

M U C H H A S C H A N G E D S I N C E T H E D I S C OV E RY

  • New data - 3D-HST spectra,

CANDELS imaging, much improved photo-zs, improved IRAC/MIPS fluxes, Herschel measurements

  • New understanding of AGN

identification using MIR, X-ray

  • New theoretical predictions for

Ly𝛽 nebulae powered by “cold accretion”

Nilsson+2006

Drastically changed our understanding of this system -

  • stensibly the poster child of a

gravitationally powered nebula

LABn06 z=3.157

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SLIDE 10

Ngal(per deg2 per mag)

LY M A N - A L P H A N E B U L A D O E S H AV E A S S O C I AT E D G A L A X I E S

3D-HST photo-z / grism-z

z=3.157

  • 7 photo-z neighbors within

R<10” and dz<0.15

  • 1 has a grism-z with a faint

[OII] detection at the redshift

  • f nebula
  • Still no visible central

galaxy, closest galaxy part of a foreground structure (z=1)

  • Local region (R<10”) is
  • verdense

Prescott+2015b

LABn06 Ly𝜷

NMSU student Agnar Hall finding similar results

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SLIDE 11

T H E R E I S A N E A R B Y O B S C U R E D AG N

  • IRAC/MIPS source

with power-law MIR SED, consistent with being an obscured AGN

  • Lower surface

brightness Ly𝛽 emission encircles

  • bscured AGN
  • AGN redshift poorly

constrained, but highly suggestive of an association

Obscured AGN Prescott+2015b

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SLIDE 12

AG N C O M I N G O U T O F H I D I N G

  • The more carefully

we look, the more AGN we find

  • AGN often offset

from the Ly𝛽 emission

  • Demonstrates

importance of multi- wavelength coverage to get a full census of the local region

Ly𝜷 nebulae

Overzier+2013

~60-80% AGN

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SLIDE 13

A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E

  • Using multi-wavelength data on individual Ly𝛽 nebulae

reveals a more complete picture of the CGM in dense regions:

  • Environment — census of nearby galaxies (& AGN)
  • Kinematics — map out how the gas is moving
  • Physical conditions — metallicity, density, source of

ionization

multiple emission lines, Ly𝛽 vs. less optically thick lines

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SLIDE 14
  • Velocity offsets of

Ly𝛽 vs. non-resonant lines (e.g., H𝛽, [OIII]) encode information about outflow/infall

  • Low velocity offsets

measured for LAEs

  • Low velocity offsets

for embedded galaxies within Ly𝛽 nebulae

Prescott+2015a

(including data from Steidel+2010, Yang+2011, Finkelstein +2011, McLinden+2011,2013, Hashimoto+2013, Guaita+2013; see also Yang+2014)

K I N E M AT I C S - L OW V E L O C I T Y O F F S E T S I N LY M A N - A L P H A N E B U L A E

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SLIDE 15
  • See the same

picture within the nebula gas itself

  • Consistently low

velocity offsets (~100 km/s) between Ly𝛽 and non-resonant HeII

K I N E M AT I C S - L OW V E L O C I T Y O F F S E T S I N LY M A N - A L P H A N E B U L A E

Prescott+2015a Ly𝜷 HeII CIV CIII] 11 arcsec - 94 kpc 7.4 arcsec = 63 kpc

PRG1 z=1.67

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SLIDE 16
  • Low velocity offsets

for LAEs and embedded galaxies in Ly𝛽 nebulae

  • Measure similarly

low velocity offsets within the diffuse gas in Ly𝛽 nebulae

  • Ly𝛽 roughly tracing

the systemic velocity

Prescott+2015a

(including data from Steidel+2010, Yang+2011, Finkelstein +2011, McLinden+2011,2013, Hashimoto+2013, Guaita+2013; see also Yang+2014)

K I N E M AT I C S - L OW V E L O C I T Y O F F S E T S I N LY M A N - A L P H A N E B U L A E

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SLIDE 17

K I N E M AT I C S — S I G N S O F R OTAT I O N I N LY M A N - A L P H A N E B U L A E

  • Large-scale velocity shear

suggestive of rotation

  • Similar to predictions for

recently accreted gas

PRG1

Stewart+2013 Prescott+2015a

(Also see talks by F. Arrigoni-Battaia, D. C. Martin)

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SLIDE 18

A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E

  • Using multi-wavelength data on individual Ly𝛽 nebulae

reveals a more complete picture of the CGM in dense regions:

  • Environment — census of nearby galaxies (& AGN)
  • Kinematics — map out how the gas is moving
  • Physical conditions — metallicity, density, source of

ionization

multiple emission lines, emission line diagnostics, comparisons to photoionization models

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SLIDE 19

z=2.38

B1 South B1 North

Overzier+2013

  • B1 - IFU data, split

nebula into two large apertures

  • — consistent with

AGN photoionization

P H Y S I CA L C O N D I T I O N S — I O N I Z AT I O N

B1

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SLIDE 20

P H Y S I CA L C O N D I T I O N S — I O N I Z AT I O N

AGN models SF models

  • PRG1 — deep spectroscopy

from 2 nights on Keck/LRIS allows us to use many spatial apertures across the nebula

  • — consistent with AGN

photoionization

Ly𝜷 HeII CIV CIII] 11 arcsec - 94 kpc 7.4 arcsec = 63 kpc

PRG1 z=1.67

Prescott, Martin, & Dey in prep. (overplotted on Feltre+2016)

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SLIDE 21

P H Y S I CA L C O N D I T I O N S — M E TA L L I C I T Y, D E N S I T Y, I O N I Z AT I O N

PRG1 PA=52.44o

  • assuming AGN powering, fit

CIV+HeII+CIII] measurements using grid of Cloudy photoionization models

Prescott et al., in prep.

Z ~ 0.03 - 0.1 Zo nH ~ 3 - 10 cm-3 log U ~ -1 to -2

Preliminary

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SLIDE 22

P H Y S I CA L C O N D I T I O N S — M E TA L L I C I T Y, D E N S I T Y, I O N I Z AT I O N

PRG1 PA=146.0o

Z ~ 0.03 - 0.1 Zo nH ~ 3 - 10 cm-3 log U ~ -1 to -2

  • assuming AGN powering, fit

CIV+HeII+CIII] measurements using grid of Cloudy photoionization models

Prescott et al., in prep.

Preliminary

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SLIDE 23
  • Using multi-wavelength data on

individual Ly𝛽 nebulae as a window into the CGM in dense regions:

  • Environment — live in regions that

are overdense in galaxies; the closer we look, the more AGN we find

  • Kinematics — low velocity offsets

and evidence for large-scale rotation

  • Physical conditions — evidence for

AGN powering, constraints on metallicity, density, ionization across central 30-40 kpc

Q2) What are the morphological and physical properties

  • f the CGM?

Q3) What are the physical processes that shape the CGM

  • n both large (kpc)

and small (pc) scales?

A M U LT I - WAV E L E N G T H V I E W O F LY M A N - A L P H A N E B U L A E — S U M M A RY