Shedding (Quasar) Light on High Redshift Galaxies

Shedding (Quasar) Light on High Redshift Galaxies

Joseph F. HennawiUC Berkeley

Hubble Fellowship SymposiumApril 2, 2007

Suspects

Jason X. Prochaska(UCSC)

Juna Kollmeier (Carnegie) & Zheng Zheng (IAS)

Hubble Fellow Class of 2001

Hubble Fellow Classes of 2006 and 2004

OutlineOutline

• Finding close projected quasar pairs

• IGM Physics Primer

• Fluorescent Ly Emission

Bottom Line: The physical problem of a quasar illuminating a high redshift galaxy is very simple compared to other problems in galaxy formation.

The AGN Unified ModelThe AGN Unified Model

BLAGN Steffen et al. (2003)

unidentified

non-BLAGN

The AGN unified model breaks down at high luminosities.

“Nearly all (~ 90%) luminous quasars are unobscured . . . ”

Barger et al. (2005)

AGN unified model

BLAGN

obscured non-BLAGN

Ω=4πnBLAGN

nhard X-ray

Mining Large SurveysMining Large SurveysApache Point Observatory (APO) • Spectroscopic QSO survey

– 5000 deg2

– 45,000 z < 2.2; i < 19.1– 5,000 z > 3; i < 20.2– Precise (u,g,r, i, z) photometry

• Photometric QSO sample– 8000 deg2

– 500,000 z < 3; i < 21.0– 20,000 z > 3; i < 21.0 – Richards et al. 2004; Hennawi et al. 2006

SDSS 2.5m

ARC 3.5m

Jim Gunn

Follow up QSO pair confirmation

from ARC 3.5m and MMT 6.5m

MMT 6.5m

= 3.7”

2’55”

ExcludedArea

Finding Quasar PairsFinding Quasar Pairs

SDSS QSO @ z =3.13

4.02.0

3.0

2.03.0

3.0

2.04.0

low-zQSOs

f/g QSO z = 2.29

b/g QSO z = 3.13

Keck LRIS spectra (Å)

Cosmology with Quasar PairsCosmology with Quasar PairsClose Quasar Pair Survey

• Discovered > 100 sub-Mpc pairs (z > 2)

• Factor 25 increase in number known

• Moderate & Echelle Resolution Spectra

• Near-IR Foreground QSO Redshifts

• 45 Keck & Gemni nights. 8 MMT nights

= 13.8”, z = 3.00; Beam =79 kpc/h

Spectra from Keck ESI

Keck Gemini-N

Science

• Dark energy at z > 2 from AP test

• Small scale structure of Ly forest

• Thermal history of the Universe

• Topology of metal enrichment

• Transverse proximity effects

Gemini-S MMT

Collaborators: Jason Prochaska, Crystal Martin, Sara Ellison, George Djorgovski, Scott Burles, Michael Strauss

Ly Forest Correlations

CIV Metal Line Correlations

Nor

mal

ized

Flu

x

Quasar Absorption LinesQuasar Absorption Lines

DLA (HST/STIS)

Moller et al. (2003)

LLS

Nobody et al. (200?)

Lyz = 2.96

Lyman Limitz = 2.96

QSO z = 3.0 LLS

Lyz = 2.58

DLA

• Ly Forest– Optically thin diffuse IGM / ~ 1-10; 1014 < NHI < 1017.2

– well studied for R > 1 Mpc/h

• Lyman Limit Systems (LLSs)– Optically thick 912 > 1

– 1017.2 < NHI < 1020.3

– almost totally unexplored

• Damped Ly Systems (DLAs)– NHI > 1020.3 comparable to disks

– sub-L galaxies?

– Dominate HI content of Universe

Self Shielding: A Local ExampleSelf Shielding: A Local Example

Sharp edges of galaxy disks set by ionization equilibrium with the UV background. HI is ‘self-shielded’ from extragalactic UV photons.

Braun & Thilker (2004)M31 (Andromeda) M33 VLA 21cm map

DLA

Ly forest

LLS

What if the MBH = 3107 M black hole at Andromeda’s center started accreting at the Eddington limit? What would M33 look like then?

bump due

to M33

Average HI of Andromeda

Fluorescent Ly EmissionFluorescent Ly Emission

• In ionization equilibrium ~ 60% of recombinations yield a Ly photon

• Since 1216 > 104 912 , Ly photons must ‘diffuse’ out of the cloud

• Photons only escape from tails of velocity distribution where Ly is small

• LLSs ‘reflect’ ~ 60% of UV continuum in a fluorescent double peaked line

Zheng & Miralda-Escude (2002)

In self shielding skin

912 ~ 1; Ly ~ 104

Self-Shielded HI

UV Background

x =ν −ν0

νD

= 0e−(x2 /2)

Only Ly photons in tail can escape

P(x)

Escape Probability

Resonant Line Emission Profile

x

Imaging Optically Thick AbsorbersImaging Optically Thick Absorbers

Cantalupo et al. (2005)

Column Density Ly Surface Brightness

• Expected surface brightness:

• Still not detected. Even after 60h integrations on 10m telescopes!

or

Sounds pretty hard!

SBLy =3.7 ×10−20 J −22

912

4⎛

⎝⎜⎞

⎠⎟1+ z4

⎛⎝⎜

⎞⎠⎟

−4

ergs cm-2s-1W" μLyα = 30 mag/W"

Help From a Nearby QuasarHelp From a Nearby Quasar

Adelberger et al. (2006)

DLAtrough

2-d Spectrum of Background Quasar

Spatial Along Slit (”)W

avel

engt

h

extended emission

r = 15.7!

Doubled Peaked Resonant Profile?

Background QSO spectrum

Transverse flux = 5700 UVB!

f/g QSO

R = 384 kpc

11 kpc

4 kpc

Transverse Fluorescence?Transverse Fluorescence?

Implied transverse flux

gUV = 6370 UVB!

fLy< 410-18 erg/cm2/s

Could detect signal to

R|| < 7.5 R = 170 kpc/hbackground QSO spectrum

2-d spectrum

f/g QSO z = 2.29

PSF subtracted 2-d spectrum

(Data-Model)/Noise

Hennawi & Prochaska (2007)

b/g QSO z = 3.13

2 hours Keck LRIS-B

f/g QSO

R||

b/g QSO

R = 22 kpc/h

Probability of null detection:

P(Ω=4) = 9%

P(Ω=2) = 77%

Near-IR Quasar RedshiftsNear-IR Quasar Redshifts

Transverse Fluorescence?Transverse Fluorescence?

metals at this zBackground QSO spectrum

2-d spectrum

f/g QSO z = 2.27

PSF subtracted 2-d spectrum

(Data-Model)/Noise

Hennawi & Prochaska (2007)

b/g QSO z = 2.35

6 hours Gemini GMOS

Implied ionizing flux

gUV = 7870 UVB!

fLy< 510-18 erg/cm2/s

Could detect signal to

R|| < 7.8 R = 295 kpc/h

f/g QSO

R||

b/g QSO

R = 38 kpc/h

near-IR f/g z

Probability of null detection:

P(Ω=4) = 5%

P(Ω=2) = 76%

PunchlinePunchline

• With projected QSO pairs, QSO environments can be studied down to ~ 20 kpc where ionizing fluxes are as large as 104 times the UVB.

• QSO-absorber pairs provide new laboratories to study Ly fluorescent emission without at 30m telescope.

R

f/g QSO

b/g QSO

Absorber

Aperture SpectraLy Emissivity

Kollmeier et al. (2007); Hennawi, Kollmeier, Prochaska, & Zheng (2007)

• The physics of self-shielding and Ly resonant line radiative transfer are very simple compared to other problems in galaxy formation.