SDSS and VLST Probe the IGM-Galaxy ConnectionJason TumlinsonUniversity of Chicago

Very Large Space Telescope WorkshopSTScIFebruary 26, 2004

SDSS 2.5 mARC 3.5 mSDSS PT 1 mNMSU 1.0 mApache Point Observatory

How do baryons get from the IGM into galaxies?

How and when do they return?

Where, and in what phase, do the missing baryons reside?

Do either galaxy feedback or IGM evolution control the global star formation rate?

How are metals transported and distributed?

What are the observable features of these processes?

Good questions! But galaxy-IGM interfaces are hidden, we have not probed the relevant scales . . .

Ne VIIIO VIGalaxiesWHIMIGMDav et al. 1999Most of the baryons are thought to reside in a Warm-hot IGM, with T = 105 107 K (WHIM; Cen et al. 1999; Dav et al. 1999). Only 5 10% of this phase has been found via O VI (Tripp 2002) with FUSE and HST. At high z, most gas that enters galaxies does so via the cold mode (T ~ 104 K). At low z, filaments are larger, and gas is heated to T ~ 106 K before entering galaxies. Does this occur on filament or group scales, and what is its relationship to the WHIM and/or HVCs? To answer, we must probe structures on all these scales.Katz et al. 2002O VI: ll1032,1038; Ne VIII: ll770,780

However, even if local conditions come to be known, we cannot connect them to larger theories of galaxy formation and evolution without statistical evidence currently lacking that other galaxies possess such hot surroundings. The FUSE survey of O VI in the vicinity of the Galaxy found HVC OVI in > 60 % of all extragalactic sightlines. Some probably arises in cooler gas shocked against a hot Galactic halo with R ~ 100 kpc, perhaps a consequence of past galaxy mergers. However, the origins of the local group O VI HVCs is still uncertain, due in large part to the radial viewing geometry that precludes accurate distances. Sembach et al. 2003

Toward PG1211+143, we have usedHST/STIS and FUSE to discover two O VI systems they appear to be associated with galaxy halos at < 150 kpc, but the stronger system also lies in a group and so is ambiguous. Nevertheless, these may be HVC analogs and/or accreting 105 K gas.Tumlinson et al. 2004

FUSE has found H I and O VI in association with O VIII toward PKS2155-304. This appears to be multiphase IGM gas (Shull, Tumlinson, & Giroux 2003; O VIII from Fang et al. 2002). The O VI is thought to arise in a shock interface between infalling photoionized gas and a hot intragroup medium.Shull, Tumlinson, & Giroux 2003Shull et al. 1998

Hot galactic halos?Missing baryons?FUSE O VI SurveyPG1211+143+=Local O VII WHIM?PKS2155-304+=Clear physical originMany cases+=Clues about galaxy formationClear physical originMany cases+=Complete baryon census=O VI in external galaxiesMany close pairs=O VI in group material-Q.E.D.Access to OVI/NeVIII+Many group probes=Access to UV linesGood statistics for galaxies and LSS

SDSS: To date, 1360 deg2 = 53M photometric sources, 186000 spectra (up to DR1).

~17000 QSOs in main sample down to gQSO ~ 20.5. Many more available by photometric screens down to g ~ 22 23 (in blue at right).

Photometric redshifts accurate to z = 0.04 can yield candidates for QSO/galaxy pairs.

Group catalog (z < 0.1) derived from spectroscopic galaxy sample (Berlind 2003).

Clusters and filament-scale structures are identifiable in both photometric and spectroscopic redshift surveys. DR1HST/STISFUSEVLST?www.sdss.orgPhoto-QSO

Access to gQSO = 20 and = 900 1200 , will yield ( < 150 kpc) >102 of pairs (r < 150 kpc) for Ne VIII and >103 of pairs for O VI (HST and FUSE ranges in color).

Large numbers allow careful selection for galaxy properties and more choice cases.

At z < 0.2, there are Npairs = 2 10 pairs per QSO, with = 2. FUSE O VIHST O VIFUSE Ne VIIIHST He VIIII

SDSS provides excellent statistics on color, luminosity, position, and separation.

For example, FUV wavelengths offer access to faint galaxies (dwarfs, LMC/SMC) for study of their feedback on surrounding IGM.

SDSS at z < 0.1 offers full coverage of the r = 150 kpc region near galaxies.

z > 0.1

Close spacing of faint QSOs gives many QSO pairs or multi-QSO asterisms with < 1 Mpc separations, crucial for tests of absorber size and filament growth.

This is an aperture driver for a VLST, as the number of close pairs is a steep function of gQSO for g = 20 23.

At z < 0.1, we will have >1000 groups with 2 10 QSOs per group.

GroupsHalosg < 23g < 22 g < 21 4.5'

D ~ 30 mAccess to O VI and Ne VIII in SDSS redshift rangeEfficiently multiplexed pairs (>2 10/QSO @ z < 0.1)Efficiently multiplexed probes of groups @ z < 0.1Multiple (N = 2 6) QSO probes of individual galaxiesIGM tomography with small QSO/QSO separationsFlexibility for Optimal Samples++> 107 Galaxies=> 105 QSOs+=l1 QSO per group.g < 20g < 19 g < 18

These questions are timely and relevant, as shown by the poster from the 2002 Boulder meeting. I will focus here on the role of hot gas, since it plays a critical role in some pressing theoretical and observational problems.Here we have a particular case widespread HVC material which, if generalized, could lead to important clues about galaxy formation namely, the common presence of hot (107 K) halos resulting from major galaxy mergers.Once again, we have a particular case possible intragroup WHIM which, if confidently generalized, would result in a major result the completion of the baryon census. However, present QSO availability is too sparse for meaningful statistics.These two equations describe two possible scenarios for interpreting and generalizing the foregoing observational results

All problems point in the same direction we need many galaxies and many QSO probes, and access to the right wavelengths.Linearized were going to ignore second order effects

Basic IGM arithmetic

"Let's do a substitution"

"Write down the simple relations that describe a possible scenario for the previous three observational cases"