Shedding (Quasar) Light on High Redshift Galaxies

1. Shedding (Quasar) Light on High Redshift Galaxies Joseph F. Hennawi UC Berkeley Hubble Fellowship Symposium April 2, 2007

2. Suspects Hubble Fellow Class of 2001 Jason X. Prochaska (UCSC) Hubble Fellow Classes of 2006 and 2004 Juna Kollmeier (Carnegie) & Zheng Zheng (IAS)

3. Outline • 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.

4. BLAGN obscured non-BLAGN The AGN Unified Model AGN unified model Barger et al. (2005) unidentified BLAGN Steffen et al. (2003) non-BLAGN The AGN unified model breaks down at high luminosities. “Nearly all (~ 90%) luminous quasars are unobscured . . . ”

5. Mining Large Surveys Apache Point Observatory (APO) ARC 3.5m Jim Gunn • 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 MMT 6.5m Follow up QSO pair confirmation from ARC 3.5m and MMT 6.5m

6.  = 3.7” 55” Excluded Area b/g QSO z = 3.13 f/g QSO z = 2.29  (Å) Keck LRIS spectra Finding Quasar Pairs low-z QSOs 2’ 2.0 2.0 3.0 4.0 3.0 SDSS QSO @ z =3.13 2.0 4.0 3.0

7. Cosmology with Quasar Pairs Close 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 Ly Forest Correlations Normalized Flux CIV Metal Line Correlations Keck MMT Gemini-S 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  = 13.8”, z = 3.00; Beam =79 kpc/h Spectra from Keck ESI Collaborators: Jason Prochaska, Crystal Martin, Sara Ellison, George Djorgovski, Scott Burles, Michael Strauss

8. Lyman Limit z = 2.96 Ly z = 2.96 Ly z = 2.58 LLS DLA (HST/STIS) DLA LLS ? Moller et al. (2003) Nobody et al. (200?) Quasar Absorption Lines • 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 QSO z = 3.0

9. Self Shielding: A Local Example Average HI of Andromeda bump due to M33 LLS Ly forest M33 VLA 21cm map M31 (Andromeda) Braun & Thilker (2004) DLA Sharp edges of galaxy disks set by ionization equilibrium with the UV background. HI is ‘self-shielded’ from extragalactic UV photons. What if the MBH = 3107 Mblack hole at Andromeda’s center started accreting at the Eddington limit? What would M33 look like then?

10. Fluorescent Ly Emission Resonant Line Emission Profile Self-Shielded HI In self shielding skin 912 ~ 1; Ly ~ 104 UV Background Escape Probability P(x) Only Ly photons in tail can escape Zheng & Miralda-Escude (2002) x • 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

11. Imaging Optically Thick Absorbers Column Density Ly Surface Brightness Cantalupo et al. (2005) • Expected surface brightness: • Still not detected. Even after 60h integrations on 10m telescopes! or Sounds pretty hard!

12. Help From a Nearby Quasar Background QSO spectrum 2-d Spectrum of Background Quasar Transverse flux = 5700  UVB! Wavelength DLA trough r = 15.7! 11 kpc 4 kpc f/g QSO extended emission Spatial Along Slit (”) Adelberger et al. (2006) R = 384 kpc Doubled Peaked Resonant Profile?

13. Transverse Fluorescence? 2 hours Keck LRIS-B b/g QSO f/g QSO PSF subtracted 2-d spectrum (Data-Model)/Noise R|| Implied transverse flux gUV = 6370  UVB! R = 22 kpc/h b/g QSO z = 3.13 2-d spectrum f/g QSO z = 2.29 fLy< 410-18 erg/cm2/s Could detect signal to R|| < 7.5 R = 170 kpc/h background QSO spectrum Probability of null detection: P(=4) = 9% P(=2) = 77% Hennawi & Prochaska (2007)

14. Near-IR Quasar Redshifts

15. Transverse Fluorescence? 6 hours Gemini GMOS b/g QSO f/g QSO PSF subtracted 2-d spectrum (Data-Model)/Noise R|| Implied ionizing flux gUV = 7870  UVB! R = 38 kpc/h b/g QSO z = 2.35 2-d spectrum f/g QSO z = 2.27 fLy< 510-18 erg/cm2/s Could detect signal to R|| < 7.8 R = 295 kpc/h metals at this z Background QSO spectrum near-IR f/g z Probability of null detection: P(=4) = 5% P(=2) = 76% Hennawi & Prochaska (2007)

16. Punchline Aperture Spectra Ly Emissivity f/g QSO R b/g QSO • 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. Absorber 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.