How Big What? Are IGM Absorbers? Charles Danforth U. Colorado John Stocke Mike Shull Brian Keeney Devin Silvia etc. The Leiden Summer CGM-Galaxy Interface Workshop 20/6/13
The cartoon picture of the Lyα forest There is no IGM! It s all CGM!*
Plenty of evidence that IGM, particularly metal absorbers, is associated with galaxies HI HI+metals Stocke et al. 2012
Tumlinson et al. (2011) O VI probes of galactic halos and CGM Strong O VI absorbers in CGM around star-forming galaxies
Many IGM systems are not associated with galaxies Strong Absorbers IGM Weak Absorbers CGM 45 QSO-galaxy pairs (13 targeted, 32 serendipitous) Stocke, Keeney, Danforth, Penton, Shull 2012
What is actually known? redshift N = n dl temperature (maybe) metallicity (maybe) galaxy relationship (sometimes, maybe)
DM halo! AGN feedback! IGM absorber large-scale structure! all a big conspiracy, man! cooling flow! filament! getting our stories straight is critical
Transverse absorber correlations to the rescue! correlation between absorbers in adjacent sight lines cloud sizes physical density association with galaxies,and/or LSS
The usual method mostly at z>1 Weymann & Foltz 1983 Foltz+ 1984 Crotts 1994, Smette 1992, 95 Dinshaw+ 1997, 98, Lopez+ 2000 Rosenberg+ 2003 etc.
...has limitations pairs of background sources are rare typical cloud size turns out to be ~sight line spacing galaxy information difficult (requires many milli-steidels of Keck time)
Can we use all this COS spectroscopy to say something about IGM absorber scales? low-redshift close pairs not needed galaxy information is easier! UV sources (rare)
COS IGM Survey: Scope 4 years of COS science observations >300 AGN sight lines observed general-purpose database of low-z IGM absorbers baryon census, evolution, galaxy-igm relationship, etc. moderate/weak IGM absorbers only care about the good data. ~70 sight lines, Δz(Lyα)>22, Δz(OVI)>15 (Danforth+++ 2013, in prep) Matt Stevans UT Austin
COS IGM Survey: Results 70 sight lines 5391 IGM lines (z<1) 2591 IGM systems all kinds of cool low-z cosmology results!
Absorber pairs Paired Absorbers Rudie+12 z 2
Two Point Correlation Function ξ( v) N obs( v) N rand ( v) 1 galaxy-galaxy TPCF
Multiple probes of individual objects? Keeney+ 2013
COS multiples sample AGN Pairs+ separation Δzcommon Program RXJ0439.6-5311 / HE0435-5304 / HE0439-5254 1ES1028+511 / 1SAXJ1032.3+5051 TonS210 / B0117-2837/ B0120-28 3C273 / Q1230+0115 ~30 0.24 / 0.42 GTO 9.37 0.17 GTO ~30 0.116 Chris Thom 54 0.117 GTO LBQS0107-0235 pair 1.29 >0.9! Neil Creighton
paired COS sight lines Lyα sensitivity gaps 0.1L* 3C273/Q1230+0115 0.3L* 1.0L* TonS210/B0117 Triple Probe 1SJ1032/1ES1028 filament cluster/group LBQS0107-0235A/B halo
9.4 Correlations seen over small transverse distances R vir 250 kpc (L/L ) 0.2ish
similar absorption seen over 100-200 kpc scale 32.1 23.7 28.2 Keeney+ 2013 Keeney+ 2013
sep=250 kpc
sep=90 kpc
Correlations over large (!) distances
Correlations over large (!) distances
Lyα 1216 nearest galaxy (~4 Mpc away) 1.3 Mpc OVI 1032Å
Looks like a filament. 3.1 Mpc No single galaxy close in D or z
filament?
6.2 Mpc Looks more like a filament. A bit closer in Δz this time.
Maybe they are chance coincidences? dn/dzchance<1
Correlation in absorber quantities?
Correlation in absorber quantities?
Correlation in absorber quantities? Maybe at least a trend?
What about metal absorbers? only three pairs show metals in both sight lines, all at dperp<500 kpc seven show metals in one but not the other
Conclusions First Impressions Lyα TPCF lower, smaller Δv than galaxy TPCF Lyα absorber redshifts correlated over much larger transverse scales than expected. poor correlation in N, b, metallicity no examples of dperp>1 Mpc metal systems One size does not fit all.
Dank u wel!