Missing Photons that Count: Galaxy Evolution via Absorbing Gas (and a little bit of fundamental physics to boot) Chris Churchill (Penn State)

To Earth CIV SiIVCIISiII Ly  em Ly  forest Lyman limit NV em SiIV em CIV em Ly  em Ly  SiII quasar Quasars: physics laboratories in the early universe Ly 

Damped Lyman-  Absorbers (DLAs): N(HI) > 2 x cm -2 Lyman Limit Systems (LLSs): N(HI) > 2 x cm -2 Lyman-  Forest N(HI) < 6 x cm -2 Categories by Neutral Hydrogen Compact Star forming objects Galaxy centers Metal lines, low ionization dominate Proto-galaxy structures Galaxy outskirts (extended halos, disks) Metal lines, low, intermediate, and high ionization Cosmic Web Sheets and Filaments Metal lines, weak to non-existent

“The Lyman Alpha Forest” Piercing the Cosmic Web Tracing Structure Growth Constraining Ionization Evolution Ly  forest N(HI) < cm -2

Great Insights are gained from simulations of structure growth, but these simulations are starved for hard data to constrain the physics… Note structure growth is rapid at for z>5 (a short cosmological time frame), and then evolution is slower, especially from z<1 (majority of time)… (courtesy M. Haehnelt)

The Power of Simply Counting Lines The redshift path density, dN/dz, places constraints on simulations of structure growth as a function of redshift… (Dave’ etal 1999)

The Power of Simply Counting Lines The redshift path density, dN/dz, places constraints on simulations of structure growth as a function of redshift… (Dave’ etal 1999)

The Power of Simply Counting Lines The redshift path density, dN/dz, places constraints on simulations of structure growth as a function of redshift… (Dave’ etal 1999)

The Power of Simply Counting Lines The redshift path density, dN/dz, places constraints on simulations of structure growth as a function of redshift… (Dave’ etal 1999) or

The Power of Simply Counting Lines (Dave’ etal 1999) (Weymann’ etal 1999)

“C IV Systems” Proto-galactic clumps Tracing Pre-galactic Structure Growth Constraining Kinematic/Dynamic Evolution Metal Lines N(HI) ~ 2 x cm -2

Efforts have been made to include ionization feedback, both in terms of spectral energy distributions, photon transport, and mechanical stirring of the gas… QSO Absorption Lines: Anatonomy of a Simulation (courtesy M. Steinmetz)

Technology and innovation is quickly outpacing observational data… QSO Absorption Lines: Anatonomy of a Simulation (courtesy M. Steinmetz) Ly-  C IV Velocity

The Power of Simply Counting Lines Mg II shows no evolution (co-moving), but nothing in known above z=2.2 Lyman Limit systems (LLS) show no evolution, measured from continuum “break” at 916 A in the rest frame, N(HI)> cm -2 C IV systems evolve rapidly! They increase with cosmic time until z=1.5 and then show no evolution Structure, Ionization, or Chemical Evolution? Evolution measures product of: number size ionization fraction Is this an increase in number, in ionization level, or in the chemical abundance of carbon? We need low ionization data. Mg II.

Motivations and Astrophysical Context Mg II arises in environments ranging over five decades of N(H I) Damped Lyman-  Absorbers (DLAs): N(HI) > 2 x cm -2 Lyman Limit Systems (LLSs): N(HI) > 2 x cm -2 sub-LLSs: (low redshift forest!) N(HI) < 6 x cm -2 eg. Biosse’ etal (1998); Rao & Turnshek (2000); Churchill etal (2000b) eg. Steidel & Sargent (1992); Churchill etal (2000a) eg. Churchill & Le Brun (1998); Churchill etal (1999); Rigby etal (2001) Mg II selection probes a wide range of astrophysical sites where star formation has enriched gas; these sites can be traced from redshift 0 to 5 Mg II  -process ion – Type II SNe – enrichment from first stars (<1 Myr) Fe II iron-group ion – Type Ia SNe – late stellar evolution (>few Gyr)

Present Day Coverage and Astrophysical Context

Simple Kinematic Models of Absorbing Gas from Galaxies Absorption kinematics is symmetric about the galaxy’s systemic velocity Absorption kinematics is offset in the direction of stellar rotation compared to the galaxy’s systemic velocity Halo/infall + Rotating/disk produces both signatures in single profile (Charlton & Churchill 1998)

Mg II 2796 Absorption Profiles from HIRES/Keck Galaxy redshifts can be matched to the absorbers… (Churchill 2001)

Mg II 2796 Absorption Profiles from HIRES/Keck (Churchill & Vogt 2001)

Mg II 2796 Absorption Profiles from HIRES/Keck Each Mg II system has several Fe II transitions and Mg I (neutral) The clouds are modeled using Voigt profile decomposition… Obtain number of clouds, temperatures, column densities, ionization conditions (from modeling)…

Build the Database and the Simulations will Follow Ultimately, the simulations need to be driven by the data… as we have seen the great successes in this arena for the Lya forest to z=5, and are seeing the new successes for metal enriched diffuse objects to z=5…. We will begin to see the successes of galaxy evolution in more detail, including structure evolution, kinematics, metallicity, and ionization. The data are lacking. Wholesale inventory of Mg II absorbers is the best approach. (courtesy M. Haehnelt)

Q Q Q (Steidel etal 2002)

Kinematics: Stellar, Mg II 2796, and C IV 1548, 1551 Mg II traces stellar kinematics yet is difficult to explain as extended disk rotation (at 72 kpc impact parameter!). C IV traces Mg II kinematics but has strongest component at galaxy’s systemic velocity, as highlighted in What physical entity is giving rise to this C IV component? (Churchill 2003; Churchill etal, in prep)

Population of Weak Systems: Where do they arise? 1.Their equivalent width distribution follows a power law down to 0.02 A 2.Arise in optically thin H I (Ly  clouds) 25%-100% of all Lya clouds with column densities <N(HI)< cm -2 3.Constrained to not have supersolar metallicity, almost all have z>0.1 solar 4.Many are iron rich, suggesting later stages of star formation 5.90% cannot be associated with galaxies (within 70 kpc) (Churchill etal 1999; Rigby etal 2002)

Equivalent Width Distribution Differential Number Density Distribution Redshift Path Density Using HIRES/Keck, we discovered that the EW distribution followed a power law, with no observable cut off down to W=0.02 A. - these are high metallicity “forest” clouds. 5 papers over 10 years predicted that none of these “weak” systems existed! They outnumber galaxies by 1:10 6. As the lower EW cutoff of the sample, W min, is increased, the number of systems per unit redshift decreases… (As W min increases, the mean redshift increases – ) differential redshift evolution Comoving redshift path density is consistent with no structure/ionization evolution for W min =0.02 A (red) and W min =0.3 A (blue). dN/dz ~ n  (1+z) .

Evolution of Strongest Systems As W min increased – evolution is stronger dN/dz = N 0 (1+z)  What is the nature of the evolution??? Is it related to high velocity clouds, presence of supperbubbles, or superwinds??? REDSHIFTREDSHIFT Scenario of kinematic evolution of gas…

Present Day Coverage and Astrophysical Context The epochs of greatest evolution are un-probed… (Based upon Pei etal 1999)

 (stars)  (gas)  (baryons)  (gas flow)  (IGM metals) No coverage for Mg II for z>2.2 No high resolution coverage for Mg II for z>1.4 Mg II provides metalicity for high-z forest in lower ionization gas- heretofore un-probed Constraints on Global Galaxy Evolution Models (Pei etal 1999)

Some Future Plans High Resolution optical spectra of QSOs to get Mg II kinematics to cover 1.4<z<2.2 High Resolution HST ultraviolet spectra of higher ionization gas Low Resolution infrared spectra of QSOs to get Mg II statistics for 2.2<z<4.0 Moderated Resolution HST ultraviolet spectra of higher ionization gas High Resolution infrared spectra of QSOs to get Mg II kinematics for 2.2<z<4.0 Leading international collaboration: Keck, Subaru, VLT, HET, BLT Student opportunities include observing, echelle data reduction, data analysis --- VP decomposition, statistics, distribution function (DF) evolution Collaborating with N. Kobayashi: Subaru, VLT Student opportunities include observing, UV and IR data reduction, data analysis --- visibility function, sample completeness, statistics, DF evolution This is 5-10 years future:VLT, BLT

“And now… for something completely different.”

Evidence For Cosmological Evolution of the Fine Structure Constant?  = (  z -  0 )/  0  = e 2 /hc

Relativistic shift of the central line in the multiplet Procedure 1. Compare heavy (Z~30) and light (Z<10) atoms, OR 2. Compare s p and d p transitions in heavy atoms. Shifts can be of opposite sign. Illustrative formula: E z=0 is the laboratory frequency. 2 nd term is non-zero only if  has changed. q is derived from relativistic many-body calculations. K is the spin-orbit splitting parameter. Numerical examples: Z=26 (s p) FeII 2383A:   = (2) x Z=12 (s p) MgII 2796A:   = (2) + 120x Z=24 (d p) CrII 2066A:   = (2) x where x =  z  0  MgII “anchor”

 /  = -5×10 -5 High-z Low-z

Uncorrected: Quoted Results