Jessica L. Rosenberg George Mason University Using the EVLA to Extend Studies of Baryons in the Local Universe to Higher Redshift Jessica L. Rosenberg George Mason University Collaborators: Andrew West, Lisa Horne, Preston Zeh, ALFALFA team lead by Giovanelli and Haynes

Combining SDSS and ALFALFA to Study Baryons in the Local Universe ~4000 deg2 of overlap 30,000+ galaxies in the final sample Samples a wide range of galaxy environment Selecting SDSS galaxies from spectroscopic sample Most ALFALFA galaxies not in the spectroscopic sample will have SDSS photometric information 180 300 60 -30 30 Northern Virgo “Region 2”

Combining SDSS and ALFALFA to Study Baryons in the Local Universe Beginning with 2 small regions for which data are presently available 926 galaxies in total Samples different environments Useful for testing SDSS photometry, ALFALFA upper limits, etc. 180 300 60 -30 30 Northern Virgo “Region 2”

SDSS ALFALFA 2.5m telescope 305m telescope u, g, r, i, z optical bands spectroscopy for >675,000 galaxies >8000 deg2 of sky 120x106 pixels, >600 slits/field 305m telescope spectroscopy for >30,000 galaxies survey limit of cz=18,000 km/s ~7000 deg2 of sky 7 “pixels”

Why study gas and stars in galaxies. i. e Why study gas and stars in galaxies? i.e. Why bother combining SDSS & ALFALFA in a common volume? Most previous studies have selected galaxies by stars OR gas - this is the first time you can do both Selecting galaxies by both gas and stars provides the most unbiased view -CDM models predict the baryons in galaxies. The fraction in gas and stars is dependent on astrophysics Note that the molecular component is missing so it is not ALL baryons The relationship between gas, stars, (dark matter) provides information on astrophysics

Early heating of the Universe The luminosity and the HI mass functions help constrain models The HI+stellar mass function would provide a better constraint Mo et al. 2005

“Astrophysics”: What drives the gas-to-stars ratio in galaxies What environment has the largest impact on galaxy properties? Is the impact of environment a large scale effect or a small scale effect? Are neighbors, groups, or clusters the most effective/responsible for the impact on galaxies? What is the most important, tidal interactions, ram pressure stripping, galaxy harassment?

ALFALFA only ALFALFA + SDSS SDSS only Selecting galaxies by their gas AND stars allows for the detection of a diverse set of objects

Galaxy Distributions in ALFALFA/SDSS sub-regions Northern Virgo Region 2 * ALFALFA sources  SDSS sources Sample different environments even in these small regions

Statistics from the Sub-regions Matches SDSS-only ALFALFA-only N. Virgo 12h30m< RA <14h 13d< DEC <16d 170 286 51 Region 2 8h< RA <9h30m 13d< DEC <16d 76 313 30

Log(Mstar) = 13.98 dVirgo = 1.7 vel = -170 km/s

Log(Mstar) = 13.98 dVirgo = 6.0 vel = 7594 km/s

Log(Mstar) = 13.98

Log(Mstar) = 13.98 dVirgo = 16.4 vel = 6857 km/s

Log(Mstar) = 13.98

Summary This survey will teach us a tremendous amount about the baryon content of local galaxies We will be able to examine the relationship between environment and the baryonic properties of galaxies We will have the least biased view of the baryonic components of galaxies to date But… it is only a z=0 constraint on galaxy evolution

Using EVLA to study baryons at higher z Study the change in baryon distribution over time and environment Most detectable galaxies will be identified in other surveys EVLA will provide imaging capability and resolution Can map the continuum as well as the lines Targeted samples favor more strongly star-forming systems Can we get deep enough over enough area to diversify the sample by including a deep, blind, HI study?