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

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

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. The 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

5. Mining Large Surveys Apache Point Observatory (APO) Spectroscopic QSO survey –5000 deg 2 –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 deg 2 –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

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

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  = 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 Normalized Flux

8. Quasar Absorption Lines DLA (HST/STIS) Moller et al. (2003) LLS Nobody et al. (200?) Ly  z = 2.96 Lyman Limit z = 2.96 QSO z = 3.0 LLS Ly  z = 2.58 DLA Ly  Forest –Optically thin diffuse IGM –  /  ~ 1-10; 10 14 < N HI < 10 17.2 –well studied for R > 1 Mpc/h Lyman Limit Systems (LLSs) –Optically thick  912 > 1 –10 17.2 < N HI < 10 20.3 –almost totally unexplored Damped Ly  Systems (DLAs) –N HI > 10 20.3 comparable to disks –sub-L  galaxies? –Dominate HI content of Universe

9. Self 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 M BH = 3  10 7 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

10. Fluorescent Ly  Emission In ionization equilibrium ~ 60% of recombinations yield a Ly  photon Since  1216 > 10 4  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  ~ 10 4 Self-Shielded HI UV Background Only Ly  photons in tail can escape P(x) Escape Probability Resonant Line Emission Profile x

11. Imaging 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!

12. Help From a Nearby Quasar Adelberger et al. (2006) DLA trough 2-d Spectrum of Background Quasar Spatial Along Slit (”) Wavelength 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

13. Transverse Fluorescence? Implied transverse flux g UV = 6370  UVB! f Ly  < 4  10 -18 erg/cm 2 /s Could detect signal to R || < 7.5 R  = 170 kpc/h background 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(  =4  ) = 9% P(  =2  ) = 77%

14. Near-IR Quasar Redshifts

15. Transverse Fluorescence? metals at this z Background 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 g UV = 7870  UVB! f Ly  < 5  10 -18 erg/cm 2 /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(  =4  ) = 5% P(  =2  ) = 76%

16. Punchline With projected QSO pairs, QSO environments can be studied down to ~ 20 kpc where ionizing fluxes are as large as 10 4 times the UVB. QSO-absorber pairs provide new laboratories to study Ly  fluorescent emission without at 30m telescope. RR f/g QSO b/g QSO Absorber Aperture Spectra Ly  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.