Why do we need a VLST for studying QSO absorption lines? So that we can go deeper…

Brilliant! A Genius!! sublime…. The Critics agree….

QSO absorption lines and a VLST My top-three topics for QAL studies in the UV: {  detailed probing of the `cosmic web’ (Ly , weak metal lines)}  metallicity of nearby galaxies  QSO absorption lines from QSOs (briefly)

What about metallicity? Measurements from QSO absorption lines show little evolution from z=4 to ~1 The lack of evolution appears to be largely independent of column density –from Ly  -forest clouds to Damped Ly  systems (DLAs)

What about metallicity? Pettini (2003) DLAs in particular don’t approach solar at z=0 5.8 – 1.2 Gyr Gyr Kinda surprising…. expect `gas’ in the universe to be getting more enriched with time as galaxies evolve and pollute

Let’s measure metallicities from nearby galaxies… Advantages of looking at nearby galaxies: determine wide range of galaxy properties (21cm, X-ray, etc.) select low luminosity galaxies that are hard to see at higher-z check for fainter interlopers close to any selected galaxy easier to examine the galaxy’s environment (isolated, group, cluster)

QSO absorption lines from nearby galaxies NGC 4319, v=1405 km s -1 Mrk 205, z=0.071

Time for one example… … to show what can be done and how far we’ve got Used HST + STIS to measure abundances towards HS / SBS With: Ed Jenkins, Todd Tripp, Max Pettini

10 ’ HS z=0.807 DSS image SBS

APO 3.5m, R, 15 min QSO HII region, z=0.009 (2700 km s - 1 ) star Reimers & Hagen 98

HST STIS (clear), 800s QSO star

Spectroscopy F (1200) = 2.6x  pretty hard even with first-order gratings; fortunately CVZ object (15 orbits) [S/H] = -0.4 Higher than expected?

Observing at low-z was useful… LSBs can be DLAs Absorbing galaxy would never have been discovered if at higher-z Background spiral would have been id’ed as absorber Surprising the metallicity was quite so high given the fact that the galaxy is an LSB. Known to have many HII regions though

Compare Zs with DLA samples Pettini (2003) HS PG

List of other suitable pairs which can be observed at high spectral resolution with HST: Name of QSOName of f/g galaxy

What could we do with a VLST? There are plenty of QSO-galaxy pairs in the sky! Just too faint! Go deeper, the number of interesting pairs becomes substantial

STIS echelle

What could we do with a VLST? There are plenty of QSO-galaxy pairs in the sky! Just too faint! Go deeper, the number of interesting pairs becomes substantial Already know some QSO intercept large N(H I) from 21cm maps [knowing HI a priori helps choose a target to measure Z] Four examples, just to show what we’re missing out on…. VLA maps from Womble (1993) optical images from DSS

Gal: IC1746 cz = 5201 km/s QSO: sep = 10 kpc V=14.8? F (1220)=3e-15 ==30 STIS orbits Nice edge-on galaxy  probe outer disk

CaII:  N(H I) ~ 7-13 e19 cm/2

Gal: NGC3184 cz = 592 km/s QSO: sep = 11 kpc V=17.7 – 19.1? F (1220)=? chance to probe edge of huge HI envelope… …compare to metallicties from HII regions…

CaII:  N(H I) ~ 4e19 cm/2

Gal: NGC470 cz = 2374 km/s QSO: Q sep = 10 kpc V=18.2 F (1220)=? NGC

CaII:  N(H I) ~ 6-10 e20 cm/2

Gal: NGC3079 cz = 1125 km/s QSO: Q sep = 8 kpc V=17.4 F (1220)=1e-15

2.5 hrs, F658N, WFPC2 Great way to study outflows!

CaII:  N(H I) ~ 3 e20 cm/2

…or multiple QSOs! Arp et al 2002 NGC 3628 (cz=843 km/s) QSOs have ‘O’ mags between 18.7 and X-ray sources near M65

…or multiple multiple QSOs! (narrow metal lines instead of DLAs)

Summary There are plenty of QSO-galaxy pairs known: –though number with 21cm maps and/or CaII/NaI observations is smaller –more behind galaxy disks to appear with GALEX presumably –… and using SDSS photo-z techniques Need UV telescope that can: –reach  10 km/s resolution down to 20 mag factor of 250 in flux over STIS G140M echelle –large wavelength range to cover many lines important for ionization corrections …. and for studying relative abundunace patterns which can be used to infer history of metal production –how about…. a LiF coated mirror and do < 1100A as well? i.e. HST+FUSE Payoff: –detailed inventory of galaxy metallicities in the local universe –for individual galaxies: ability to compare ISM abundances with values from HII regions variations of metallicities as a function of radius if multiple sightlines available kinematics and ionization structure of gas in the outer regions of galaxies –probes of the interface between a galaxy and the IGM

QSO absorption lines from QSOs Suppose instead of probing galaxies, could probe QSOs instead. QSOs are ejecting large amounts of metal-enriched gas into the IGM  might expect: –metallicity of the gas around a QSO to be high –ionization of the gas to be high –absorption to be complex from outflows mixing with the IGM By observing many QSO-QSO pairs, should be able to track the enrichment of the IGM with radius Compare absorption from a f/g QSO with associated absorption (z abs ~ z em ) in the QSO’s spectrum –learn more about associated systems, compare structure, ionization, and metallicity variations over small scales.

Available QSO-QSO pairs SDSS provides a large # of QSO pair candidates with the b/g QSO < 20 th Often require follow-up spectra of one of the pairs from the ground –both from collaborators: Joe Hannawi, Gordon Richards and Michael Strauss

J z=1.71 z= ”, 19 h -1 kpc

J z abs = z QSO = 0.66 in SDSS spec Likely to be a DLA! Probably host galaxy Perhaps high metallicity?

J z bg = 1.52 z fg = 0.79 sep = 6.4” or 32 h -1 kpc 3e-16 - outflowing gas from jet -companion fuelling QSO - unrelated galaxy in QSO cluster

A future project QSOs appear to cause the same kinds of MgII systems that field galaxies cause Will need a VLST to do the kinds of spectroscopy of interest….