Probing the Universe with QSO Absorption Lines David Turnshek University of Pittsburgh

Outline: Outline: QSO Absorption Line Overview QSO Absorption Line Overview Investigating the Neutral Gas Component Investigating the Neutral Gas Component Future Work with SDSS Data Future Work with SDSS Data Collaborators: Collaborators: Sandhya Rao Sandhya Rao Daniel Nestor Daniel Nestor Brice Menard Brice Menard Eric Monier Eric Monier Michele Belfort-Mihalyi Michele Belfort-Mihalyi Andrew Hopkins Andrew Hopkins Lorenzo Rimoldini Lorenzo Rimoldini Ravi Sheth Ravi Sheth Daniel Vanden Berk Daniel Vanden Berk Stefano Zibetti Stefano Zibetti Anna Quider Anna Quider + new SDSS collaborators … + new SDSS collaborators …

Quasar Absorption Lines: Probing the Gas in the Universe Courtesy John Webb Quasar spectroscopy offers the opportunity to study foreground gas.

Motivation galaxy formation  conversion of gas into stars galaxy formation  conversion of gas into stars probe to large redshift (look back time) without luminosity bias probe to large redshift (look back time) without luminosity bias use QSO absorption lines to study: use QSO absorption lines to study: dark matter dark matter extragalactic UV ionizing background extragalactic UV ionizing background structure formation structure formation physical properties of gas/dust physical properties of gas/dust e.g., gas-phase metallicity, ionization, density, temperature, distribution and extent, W gas e.g., gas-phase metallicity, ionization, density, temperature, distribution and extent, W gas

QSO Absorption-Line Jargon Intrinsic QSO Absorbers (e.g. BALs)  tomorrow Intrinsic QSO Absorbers (e.g. BALs)  tomorrow Ly  ( l1216) forest: Ly  ( l1216) forest: weak systems trace the dark matter weak systems trace the dark matter z>1.65 (optical spectroscopy), z>2.2 (SDSS) z>1.65 (optical spectroscopy), z>2.2 (SDSS) Metal-Line Systems: Metal-Line Systems: OIV – samples high ionizations OIV – samples high ionizations CIV – samples moderate ionizations CIV – samples moderate ionizations MgII - samples a large range in HI column density MgII - samples a large range in HI column density Ly  forest Ly  forest Lyman Limit Lyman Limit Damped Ly  (DLA) Damped Ly  (DLA) DLAs (bulk of neutral gas component!) DLAs (bulk of neutral gas component!)

Some QSO Absorption Line Studies Ly  forest: Ly  forest: ground-based +HST (Weymann et al) ground-based +HST (Weymann et al) Keck/VLT Hi-Res  1.5<z<4, 90% of baryons in forest Keck/VLT Hi-Res  1.5<z<4, 90% of baryons in forest SDSS (Bernardi et al)  near z=3, signature of HeII reionization (temp, opt depth) SDSS (Bernardi et al)  near z=3, signature of HeII reionization (temp, opt depth) SDSS (McDonald, Seljak et al)  clustering, power spectrum, cosmological parameters, neutrino mass SDSS (McDonald, Seljak et al)  clustering, power spectrum, cosmological parameters, neutrino mass Metal-Line Systems: Metal-Line Systems: ground-based CIV + MgII Surveys (Sargent et al; Churchill et al) ground-based CIV + MgII Surveys (Sargent et al; Churchill et al) HST OVI Surveys – warm-hot IGM (Tripp et al) HST OVI Surveys – warm-hot IGM (Tripp et al)

Weymann et al. (1998):

Steidel, Sargent, Boksenberg (1988):

courtesy Chris Churchill:

QSO Absorption-Line Jargon Intrinsic QSO Absorbers (e.g. BALs)  tomorrow Intrinsic QSO Absorbers (e.g. BALs)  tomorrow Ly  ( l1216) forest: Ly  ( l1216) forest: weak systems trace the dark matter weak systems trace the dark matter z>1.65 (optical spectroscopy), z>2.2 (SDSS) z>1.65 (optical spectroscopy), z>2.2 (SDSS) Metal-Line Systems: Metal-Line Systems: OVI – samples high ionizations OVI – samples high ionizations CIV – samples moderate ionizations CIV – samples moderate ionizations MgII - samples a large range in HI column density MgII - samples a large range in HI column density Ly  forest Ly  forest Lyman Limit Lyman Limit Damped Ly  (DLA) Damped Ly  (DLA) DLAs (bulk of neutral gas component!) DLAs (bulk of neutral gas component!)

Damped Lyman Alpha lines : N HI > 2 x atoms cm -2 DLA systems are very rare. Yet, they contain about 95% of the neutral gas mass in the universe. They are important because galaxy formation and evolution involves the collapse of neutral gas that eventually forms stars. by tracking DLA systems back in time (redshift), we can study galaxy formation and evolution. Kim et al f is the frequency distribution of H I column densities.

The Lyman-Alpha Absorption Line of Neutral Hydrogen H I Ly a (l1216) The shape of an absorption line depends on the column density of the gas, N, and the thermal velocity of the gas, b. b = 2 v rms 1 cm 2 N = number of atoms per cm 2 along the line of sight “Damped Ly a”” ” The curve of growth

20 Years of Searching for DLAs 20 Years of Searching for DLAs interested in selecting galaxies by gas cross- section (e.g., sightline through MWG  DLA) interested in selecting galaxies by gas cross- section (e.g., sightline through MWG  DLA) Wolfe, Turnshek, Smith, Cohen (1986) probed redshifts z = 1.7  3.3 from the ground Wolfe, Turnshek, Smith, Cohen (1986) probed redshifts z = 1.7  3.3 from the ground found excess in gas cross-sections times number of absorbers (compared to expectations at z=0) found excess in gas cross-sections times number of absorbers (compared to expectations at z=0) found W HI (hi-z) approximately equals W * (z=0) found W HI (hi-z) approximately equals W * (z=0) redshifts too high to search for galaxy light in the optical (cosmological dimming) redshifts too high to search for galaxy light in the optical (cosmological dimming)

Courtesy John Webb

H I 21 cm Maps of Some Nearby Galaxies: VLA and WSRT maps courtesy John Hibbard, NRAO

H I 21 cm Maps of Some Nearby Galaxies: VLA and WSRT maps courtesy John Hibbard, NRAO

H I 21 cm Maps of Some Nearby Galaxies: VLA and WSRT maps courtesy John Hibbard, NRAO

Optical Images of Stars in M51: Courtesy NOAO Deep exposureShort exposure

How to Probe to Low-z? Problem: need scarce HST UV spectroscopy time to search at z<1.65 Problem: need scarce HST UV spectroscopy time to search at z<1.65 z<1.65 covers 70% of the age of the Universe! z<1.65 covers 70% of the age of the Universe! Problem: DLAs are rare (0.2 per unit z at hi-z, and more rare at low-z) Problem: DLAs are rare (0.2 per unit z at hi-z, and more rare at low-z) HST QSO AL Key Project found only one DLA during its 4 Cycles of HST observation. HST QSO AL Key Project found only one DLA during its 4 Cycles of HST observation.

How to Probe to Low-z? Solution: use low-z (z>0.13) MgII ll2796,2802 AL systems as tracers for DLAs and measure N HI with HST  Rao, Turnshek, Briggs (1995) Solution: use low-z (z>0.13) MgII ll2796,2802 AL systems as tracers for DLAs and measure N HI with HST  Rao, Turnshek, Briggs (1995) Rao, Turnshek (2000) Rao, Turnshek (2000) Rao, Turnshek, Nestor (2004) Rao, Turnshek, Nestor (2004)

SDSS Spectrum of MgII Absorption z=0.741 MgII absorption system (REW2796 = 2.95Angstroms) z=0.741 MgII absorption system (REW2796 = 2.95Angstroms) Right: Strong MgII doublet and weaker MgI line. Left: Two Strong FeII lines and three weaker MnII lines.

Optical MgII AL Surveys z = 0.37  2.27: SDSS spectroscopy of 3700 QSO sightlines (Nestor, Turnshek, Rao 2004) z = 0.37  2.27: SDSS spectroscopy of 3700 QSO sightlines (Nestor, Turnshek, Rao 2004) >1300 MgII systems >1300 MgII systems REW > 0.3 Angstrom REW > 0.3 Angstrom z = 0.14  0.96: MMT spectroscopy of 400 QSO sightlines (Nestor, Turnshek, Rao 2005) z = 0.14  0.96: MMT spectroscopy of 400 QSO sightlines (Nestor, Turnshek, Rao 2005) 141 MgII systems 141 MgII systems REW > 0.1 Angstrom REW > 0.1 Angstrom

Interpretation of Absorption Rest Equivalent Width (REW) Due to “curve-of- growth” saturation effects, MgII REWs mostly measure kinematic spread. Due to “curve-of- growth” saturation effects, MgII REWs mostly measure kinematic spread. REW=1 Angstrom black absorption  > 107 km/s. REW=1 Angstrom black absorption  > 107 km/s.

How to Probe to Low-z? Solution: use low-z (z>0.13) MgII ll2796,2802 AL systems as tracers for DLAs and measure N HI with HST  Rao, Turnshek, Briggs (1995) Solution: use low-z (z>0.13) MgII ll2796,2802 AL systems as tracers for DLAs and measure N HI with HST  Rao, Turnshek, Briggs (1995) Rao, Turnshek (2000) Rao, Turnshek (2000) Rao, Turnshek, Nestor (2004) Rao, Turnshek, Nestor (2004) Infer DLA statistics from MgII statistics Infer DLA statistics from MgII statistics

SDSS Redshift-REW Sightline Coverage Small REWs require high S/N for detection Small REWs require high S/N for detection Large REWs can be detected in most spectra Large REWs can be detected in most spectra

MgII REW Dist N : 0.1  5 Angstroms Left: SDSS and MMT Surveys Left: SDSS and MMT Surveys Right: SDSS Survey alone Right: SDSS Survey alone

MgII REW Dist N : 0.1  1.5 Angstroms Shows details of smaller REWs Shows details of smaller REWs Evidence for two Populations? Evidence for two Populations?

Evolution of MgII REWs: z=0.4  2.2 Dashed: no-evolution curves Dashed: no-evolution curves Stronger systems may evolve away faster Stronger systems may evolve away faster

MgII Effective Absorbing Cross-Sections The incidence, dn/dz, depends on the product of galaxy cross-section times comoving galaxy number density The incidence, dn/dz, depends on the product of galaxy cross-section times comoving galaxy number density Right: constant comoving number density Right: constant comoving number density

How to Probe to Low-z? [Aim: study the neutral gas component] Solution: use low-z (z>0.13) MgII ll2796,2802 AL systems as tracers for DLAs and measure N HI with HST  Rao, Turnshek, Briggs (1995) Solution: use low-z (z>0.13) MgII ll2796,2802 AL systems as tracers for DLAs and measure N HI with HST  Rao, Turnshek, Briggs (1995) Rao, Turnshek (2000) Rao, Turnshek (2000) Rao, Turnshek, Nestor (2004) Rao, Turnshek, Nestor (2004) Infer DLA statistics from MgII statistics Infer DLA statistics from MgII statistics HST DLA Surveys in Cycles 6, 9, 11 HST DLA Surveys in Cycles 6, 9, MgII systems studied  41 DLAs identified 198 MgII systems studied  41 DLAs identified

Some Representative HST DLA Data

HST DLA Data: Detection of Double DLA Turnshek et al z abs =0.945, N(HI)=1.45E21, 2.60E21 atoms cm-2 [Zn/H]=26.5%, 4.7% solar

MgII-FeII-DLA Selection Filled circles  DLAs with N HI > 2 x atoms cm -2 Left: MgII REW versus FeII REWRight: N HI versus MgII REW

Evolution of Incidence of DLAs solid curve: no-evolution solid curve: no-evolution incidence is product of absorber cross-section times absorber number density incidence is product of absorber cross-section times absorber number density

Evolution of HI Cosmological Mass Density from DLAs HI gas mass approximately constant from z=0.5  4.5, but is 3x lower at z=0. HI gas mass approximately constant from z=0.5  4.5, but is 3x lower at z=0.

Identification of MgII Absorbing Galaxies Hubble Space Telescope image of a field with several quasar absorption line system galaxies identified. A galaxy at the DLA redshift (z=0.656) is not visible. Courtesy Chuck Steidel Quasar 3C336 Sightline

Identification of DLA Absorbing Galaxies Infrared K-band image of the Q sightline with DLAs at z = and z = IDs put the galaxies at 0.08 and 0.1L *, respectively. Turnshek et al. 2001

Identification of DLA Absorbing Galaxies Infrared K-band image of the SDSS QSO sightline with DLAs at z = and z = IDs for G1 and G2 are, conservatively, 0.06 and 0.15 L*. Turnshek et al. 2004

Some Results on DLA Galaxy IDs ?

Evolution of Neutral Gas Metal Abundance Beginning to measure abundances at lower-z, seeing evidence for evolution. Beginning to measure abundances at lower-z, seeing evidence for evolution. Rao et al. 2004

Theory Prochaska & Wolfe (1997) proposed that leading edge asymmetry in hi-z absorption profiles were signatures of thick rotating HI disks. Prochaska & Wolfe (1997) proposed that leading edge asymmetry in hi-z absorption profiles were signatures of thick rotating HI disks. Keck HIRES

Theory Haehnelt, Steinmetz, Rauch (1998) found that merging fragments could also account for profiles. Haehnelt, Steinmetz, Rauch (1998) found that merging fragments could also account for profiles.

Theory Luminous disks as favored by Prochaska & Wolfe (1997) ?  e.g., Eggen, Lynden-Bell, Sandage (1962) scenario of monolithic disk collapse. Luminous disks as favored by Prochaska & Wolfe (1997) ?  e.g., Eggen, Lynden-Bell, Sandage (1962) scenario of monolithic disk collapse. Merging fragments as favored by Haehnelt, Steinmetz, Rauch (1998) ?  e.g., merging hierarchy of CDM halos (White & Rees 1978). Merging fragments as favored by Haehnelt, Steinmetz, Rauch (1998) ?  e.g., merging hierarchy of CDM halos (White & Rees 1978). Great variety  seems to rule possibility that DLAs are exclusively large disks. Great variety  seems to rule possibility that DLAs are exclusively large disks.

Theory Pei, Fall, Hauser (1999): Pei, Fall, Hauser (1999): Right: Models of Cosmic SFLeft: Corresponding Predictions W HI W*W* W bary_gal W bary_flow

Cosmic Star Formation and DLAs Hopkins: DLAs  filled black circles Hopkins: DLAs  filled black circles

Progress on MgIIs and DLAs with SDSS SDSS continues to offer a wealth of knew information SDSS continues to offer a wealth of knew information Summer 2004: have recently-generated catalog of 20,000 MgII Absorbers (about 40% of eventual total) Summer 2004: have recently-generated catalog of 20,000 MgII Absorbers (about 40% of eventual total) Preliminary work in many areas … Preliminary work in many areas …

Current SDSS MgII Plans Current SDSS MgII Plans 1. Statistical Properties of MgII Absorbers 1. Statistical Properties of MgII Absorbers must improve statistics at higher REW must improve statistics at higher REW  Only have analyzed 243 MgII systems with kinematically extreme absorption (REW > 2 Angstroms).  Potentially: ~9000

Current SDSS MgII Plans Current SDSS MgII Plans 2. Neutral Gas-Phase Element Abundances + Dust 2. Neutral Gas-Phase Element Abundances + Dust use HST N HI measurements and SDSS composites use HST N HI measurements and SDSS composites

Neutral Gas-Phase Element Abundances + Dust Neutral Gas-Phase Element Abundances + Dust N HI ~ constant for saturated MgII REWs! N HI ~ constant for saturated MgII REWs! find increasing metallicity with increasing kinematic spread find increasing metallicity with increasing kinematic spread Unsaturated ZnII l2026 CrII l2062 Turnshek, Nestor, et al composite:

Current SDSS MgII Plans Current SDSS MgII Plans 3. Gravitational Amplification of Bkgd QSOs 3. Gravitational Amplification of Bkgd QSOs Observed Frame: amplification/reddening (Menard, Nestor, Turnshek 2004) Top 2 rows, fake data Bottom row, real data

Current SDSS MgII Plans Current SDSS MgII Plans 3. Gravitational Amplification of Bkgd QSOs 3. Gravitational Amplification of Bkgd QSOs Observed Frame: amplification/reddening (Menard, Nestor, Turnshek 2004) real data corrected for bias

Current SDSS MgII Plans Current SDSS MgII Plans 4. Mean Reddening and Extinction 4. Mean Reddening and Extinction mean reddening in QSO frame (van den Berk)

Current SDSS MgII Plans Current SDSS MgII Plans 5. Study of Individual Absorbing Galaxies 5. Study of Individual Absorbing Galaxies IRTF H-band image of double DLA sightline (z=1) (Belfort-Mihalyi) z=0.009 DLA dwarf galaxy (Schulte-Ladbeck et al 2004)

Current SDSS MgII Plans Current SDSS MgII Plans 6. Mean Integrated Light of Absorbing Galaxies 6. Mean Integrated Light of Absorbing Galaxies  Can stack images! Right: Putative MgII gas cross-sections of HST UDF galaxies (Rimoldini). For SDSS MgII absorbers, a QSO sightline passes through each circle. Stacking images centered on the QSO will yield mean integrated light of absorbing galaxies.

E.g., Composite Light from Halos of Edge-On Galaxies E.g., Composite Light from Halos of Edge-On Galaxies Zibetti, White, Brinkmann (2004): For SDSS MgII Systems: Use images stacked on the position of the QSO to measure the mean integrated light of absorbing galaxies; then compare to non-absorbed samples of QSOs (Zibetti)

Current SDSS MgII Plans Current SDSS MgII Plans 7. Absorber Kinematics and Clustering 7. Absorber Kinematics and Clustering e.g., 2-pt correlation function e.g., 2-pt correlation function null results on initial (small) sample (Rimoldini) null results on initial (small) sample (Rimoldini) but now 20x bigger but now 20x bigger also, account for velocity substructure (< 500 km/s) also, account for velocity substructure (< 500 km/s) 8. MgII Absorbers and LRGs 8. MgII Absorbers and LRGs Bouche, Murphy, Peroux (2004) claim positive cross- correlation between MgIIs-LRGs, 0.67 times amplitude of LRG-LRG auto-correlation (212 MgIIs, 20,000 LRGs) Bouche, Murphy, Peroux (2004) claim positive cross- correlation between MgIIs-LRGs, 0.67 times amplitude of LRG-LRG auto-correlation (212 MgIIs, 20,000 LRGs) Menard can’t confirm?  but now bigger sample Menard can’t confirm?  but now bigger sample

Summary: Strong MgII Absorbers Summary: Strong MgII Absorbers Mostly Galaxies Selected by Gas Cross-Section Mostly Galaxies Selected by Gas Cross-Section Strong MgII Absorbers  high-N HI DLAs Strong MgII Absorbers  high-N HI DLAs track evolution of the HI mass in the universe track evolution of the HI mass in the universe track absorber cross-section times comoving density track absorber cross-section times comoving density track cosmic neutral-gas phase metallicity + dust track cosmic neutral-gas phase metallicity + dust explore lensing/DM explore lensing/DM expore environment (associated galaxies, clustering) expore environment (associated galaxies, clustering)