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 - - PowerPoint PPT Presentation

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 )

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?

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

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

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

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)

• 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

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

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

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

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

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

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

• 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

• 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

• 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

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)

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

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

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)

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

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

• 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