Joseph F. Hennawi UC Berkeley &

1. Xavier Prochaska (UCSC) Quasars Probing Quasars Joseph F. Hennawi UC Berkeley & OSU October 3, 2007

2. A Simple Observation Spectrum from Wallace Sargent

3. The Basic Picture Transverse Line-of-Sight b/g QSO QSO R R|| f/g QSO HI cloud HI cloud • Ly absorption can probe 8 decades in NHI (Ly is large!). • Neighboring sightline provides a another view of the QSO. • Redshift space distortions from kT motions (~ 20 km/s ) smooth with Gaussian of Rprop ~ 60 kpc = 10” @ z = 2. • Need projected QSO pairs to study small scales!

4. Physics of IGM well understood no sub-grid physics or semi-analytical recipes! What Can Proximity Effects Teach Us? • How is HI distributed around quasars? • What is the quasar duty cycle tQSO/tH ? • What is the obscured fraction (1- Ω/4)? • Can we constrain episodic QSO variability, tburst? • Directly observe impact of AGN feedback on the IGM?

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 • About 50 Keck & Gemni nights. Ly Forest Correlations Normalized Flux CIV Metal Line Correlations Keck 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 from • 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

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 M31 (Andromeda) M33 VLA 21cm map 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. Ionized Gas Proximity Effects Isolated QSO Projected QSO Pair Neutral Gas • Proximity Effect  Decrease in Ly forest absorption due to large ionizing flux near a quasar • Transverse Proximity Effect  Decrease in absorption in background QSO spectrum due to transverse ionizing flux of a foreground quasar • Geometry of quasar radiation field (obscuration?) • Quasar lifetime/variability • Measure distribution of HI in quasar environments Are there similar effects for optically thick absorbers?

11. Transverse Optically Thick zbg = 2.53; zfg= 2.43; R = 78 kpc/h; logNHI = 19.7 zbg = 3.13; zfg= 2.29; R = 22 kpc/h; logNHI = 20.5 zbg = 2.17; zfg= 2.11; R = 97 kpc/h; logNHI = 20.3 zbg = 2.07; zfg= 1.98; R = 139 kpc/h; logNHI = 19.0 zbg = 2.35; zfg= 2.28; R = 37 kpc/h; logNHI = 18.9 zbg = 2.21; zfg= 2.18; R = 61 kpc/h; logNHI = 18.5 Hennawi, Prochaska, et al. (2007)

12. Transverse Optically Thick Clustering Hennawi, Prochaska et al. (2007); Hennawi & Prochaska (2007) Enhancement over UVB • 29 new QSO-LLSs with R < 2 Mpc/h • High covering factor for R < 100 kpc/h • For T(r) = (r/rT)-,  = 1.6, log NHI > 19 rT = 9  1.7 Mpc/h (3  QSO-LBG)  = 2.0  = 1.6 QSO-LBG z (redshift) = SDSS = Keck = Gemini = has absorber = no absorber

13. Line-of-Sight Clustering Proximate DLA  DLA within v < 3000 km/s Line-of-Sight Clustering Strength Transverse prediction 1 + ||(∆v) Extrapolation of trans. predictions Line-of-sight measurements z Prochaska, Hennawi, & Herbert-Fort (2007) • Factor 5-10 fewer PDLAs then expected from transverse clustering. • Transverse clustering strength at z = 2.5 predicts that ~ 90% ofQSO’s should have an absorber with NHI > 1019 cm-2 along the LOS?? • Rapid redshift evolution of QSO clustering compared to paucity of proximate DLAs implies that photoevaporation has to be occurring.

14. Photoevaporation QSO is to DLA . . . as . . . O-star is to interstellar cloud Cloud survives provided b/g QSO f/g QSO R Otherwise it is photoevaporated Bertoldi (1989), Bertodi & McKee (1989) log NHI = 20.3 r = 17 r = 19 r = 21 nH = 0.1 Hennawi & Prochaska (2007a)

15. Episodic Variability b/g QSO Ionization state of gas depends on QSO at time t = t0 - R/c f/g QSO R > 104 yr Absorber t = t0 We observe light emitted at time t = t0 • Episodic Variability  QSO’s vary significantly on timescale t < tcross ~ 4 105 yr @  = 20” (120 kpc/h). Current best limit is tburst > 104 yr. Emission Anisotropy b/g QSO Obscuration/Beaming f/g QSO R Absorber 

16. Proximity Effects: Thick and Thin • Optically Thick LLSs and DLAs (today’s talk) • Nature of absorbers near QSO’s is unclear. • Gas entrained from AGN driven outflow? (AGN feedback!) • Absorption from nearby dwarf galaxies? • To measure tQSO/tH  or (Ω/4) we need to model absorbers and do radiative transfer (hard). • Optically Thin Ly Forest (in progess) • Best for constraining tQSO/tH  and (Ω/4). • Why? Because we can predict the Ly forest fluctuations ab initio from N-body simulations (easy).

17. Optically Thin (Sneak Preview) Hennawi, et al. (2007), in prep Gemini NIRI K-band spectrum Enhancement over UVB Sample • 1.6 < z < 4.5; 20 kpc < R < 10 Mpc • 59 pairs with gUV > 100. • 30 accurate near-IR redshifts. z = 2.4360 z = 44 km/s z (redshift)  (m) , = SDSS , , = Keck = Gemini = accurate z = no accurate z

18. with f/g QSO Transverse Proximity Effect? Spectrum from Keck ESI Gemini NIRI K-band spectrum Real zbg = 4.11, zfg= 3.81  = 34”, R = 175 kpc/h tcross = 5.7107 yr gUV = 626! z = 3.8135 z = 44 km/s Simulated without f/g QSO Hennawi et al. 2007, in prep.

19. Summary • With projected pairs, QSO environments can be probed down to ~ 20 kpc where ionizing flux is ~ 104 times the UVB. • Clustering of optically thick absorbers around QSOs is highly anisotropic. • Paucity of PDLAs implies photoevaporation has to occur. • Physical arguments indicate DLAs < 1 Mpc from a QSO can be photoevaporated. • There is a LOS optically thick proximity effect but no transverse one. • Either QSOs emit anisotropically or are variable on timescales < 106 yr. • The optically thin proximity effect will distinguish between these two possibility and yield new quantitative constraints.