Abstracts

Supermassive Black Holes (BHs) seem to be ubiquitous in the center of spheroids - elliptical galaxies and bulges of spirals. The tight empirical correlations of the mass of the central BH with the global properties of the host galaxy spheroid (stellar velocity dispersion sigma, mass, and luminosity) indicate a close connection between galaxy formation and nuclear activity in Active Galactic Nuclei (AGNs), a phase in the evolution of galaxies during which the supermassive BH is actively growing through accretion. Several unified formation scenarios have been proposed in which AGN feedback plays an important role by suppressing star formation in massive galaxies. Studying the evolution with redshift of the BH mass scaling relations provides important insights into their origin. Combining HST imaging and Keck spectroscopy of a sample of 40 Seyfert-1 galaxies at z~0.4 and z~0.6, we simultaneously study the evolution of the BH mass - sigma and BH mass - bulge luminosity relations. I will focus on the latter, for which we include a sample of 44 quasars out to z=4.5 taken from literature, with spheroid luminosity and BH mass corrected to a self-consistent calibration, and thereby extend the BH mass range to over two orders of magnitude. Correcting spheroid luminosity for passive evolution and taking into account selection effects, we determine that at fixed present-day V-band luminosity, MBH/L_sph ~ (1+z)^(1.4+/-0.2). This evolutionary trend suggests that BH growth precedes spheroid assembly. Interestingly, the BH mass - total host galaxy luminosity relation is apparently non-evolving. It hints at either a more fundamental relation or that the spheroid grows by a redistribution of stars. I will also present first results of an ongoing project that uses Keck longslit spectra of a sample of 100 Seyfert-1 galaxies in the local Universe to (i) create a robust local baseline for the BH mass - sigma relation and (ii) measure the likely degree of rotational support when obtaining the "global" dispersion from unresolved data of our distant galaxies or from SDSS 3'' fiber spectra.

We present results from a detailed study of cluster red sequence at z~1 from the ACS Intermediate Redshift Cluster Survey (Mei et al. 2009). Our analysis shows that the red sequence is well defined at these redshifts and elliptical and lenticular galaxies lie on similar color-magnitude relations. We analyze the parameters of the early-type color-magnitude relations - scatter, slope and zero-point - as a function of redshift, galaxy properties and cluster mass.

Roughly half of the red elliptical galaxies observed today have formed since z=1. I will present galaxy clustering results from the DEEP2 Redshift Survey that strongly constrain the mechanism responsible for the quenching or cessation of star formation in these galaxies. I will show where this quenching is occurring on large scales and how it can not be due primarily to cluster-specific physics. I will also present results on the clustering of opticallybright quasars and X-ray selected AGN at z=1. I will show new results on the prevalence of outflowing galactic winds at z=1 and discuss their role in quenching star formation. Finally, I will present a new wide-area prism survey that will allow further studies of galaxy evolution to z=1 with the largest faint galaxy survey to date.

The Cold Dark Matter (CDM) paradigm is very successful at explaining the growth of structure on large scales. However, it predicts an excess of structure on sub-galactic scales. Motivated by this discrepancy, we ask the question if dark galaxies (or dim dwarf galaxies) can be found by their tidal gravitational effect on the gas disks of galaxies. I will focus most of this talk on my recent work (Chakrabarti & Blitz 2009) on an analysis of the observed perturbations on the outskirts of the gas disk of the Milky Way to infer and characterize a dark sub-halo that tidally interacted with our galaxy. By comparing the Fourier modes from a large set of high resolution Smoothed Particle Hydrodynamics simulations of a Milky Way like galaxy tidally interacting with dark sub-halos, I showed that the best fit to the observations is produced by a 1:100 satellite with a pericentric approach distance of ~ 5kpc. I will also demonstrate a fundamental property of parabolic orbits that allows us to break the degeneracy between the mass and distance cubed in the tidal force. Next, I will show preliminary results that allow us to extend this tidal analysis method to characterize perturbers in generality. Finally, I will end by discussing results from radiative transfer calculations performed with my code RADISHE, that allow us to study the effects of tidal interactions on the emergent infrared SED and images of simulated galaxies.

Gravitational lensing by galaxy clusters was predicted in the 1930s, and finally discovered in 1980s. Since these initial discoveries, several dozen significant cluster lenses have been found. Lensing clusters probe the distribution of massive haloes in the universe; the expected arc production frequency can be predicted from simulations and compared to existing data. Massive lensing clusters act as 'natural telescopes', providing highly magnified images of background sources which cannot otherwise be studied using the current generation of telescopes. The details of the observed lensing in clusters also probes the internal properties of these massive haloes. Most cluster strong lens studies to date have been limited by the small number and heterogeneous nature of the sample of known lenses (most of which are one-off discoveries). I will report on efforts to take the study of strong lensing clusters to a new statistical regime, by identifying and studying two new samples of strong lenses within large catalogs of optically selected galaxy clusters from the RCS-2 and SDSS surveys; in total we have found hundreds of new giant arcs. These efforts are now approximately three-quarters-complete; in this progress report I will describe some of the successes of these studies, and the remaining challenges.

I will present results from a study of proto-globular cluster candidates in the interacting galaxy system Arp 284 (NGC 7714/5). Studies of the Antennae and M51 have suggested that the majority of young massive star clusters dissipate in ~20 Myr due to mass loss. The time scale and mass dependence of this effect are still controversial, due in part to the complex star formation histories of these systems. Arp 284 is at a much earlier stage in its interaction, making the star formation history somewhat simpler. We search for the dissolution effect using cluster colors obtained from archival HST data and estimate ages for over 150 clusters using evolutionary synthesis models. We find that clusters in NGC 7714 are generally less than 20 Myr old, while the bridge between the two galaxies may host an older population. However, the significance of these results is uncertain due to observational limitations.

Galaxy clusters are the most massive virialised structures in the Universe. Their number density depends on both the geometry of the Universe and the rate at which structure grows. Galaxy clusters are also rich in relatively dust-free, early-type galaxies, which are known to host only Type Ia supernovae. Evidence from several surveys now suggest that Type Ia supernovae hosted by early-type galaxies are better standard candles than Type Ia supernovae hosted by galaxies of other types. In this talk I will describe how clusters can be used as a dark energy probe, both through the number density of clusters and the through the Type Ia supernovae that can be found in them.

The aim of this talk is to discuss the physical, structural and evolutionary properties of early-type galaxies (ETG). Strong size evolution of ETG between z?1.5 and the present has been reported by several authors. On the other hand, stellar populations of these massive ETG appear to evolve only passively since then. The role of the environment in both processes remains poorly understood. Here we present a new study in which we derive stellar masses, ages, star formation histories (SFH) and sizes of massive ETG in high-density environments at z~1.3 (RDCS1252, Lynx-E, Lynx-W) and compare them with those measured in similarly mass-selected samples of contemporaries in low-density environment (GOODS). Robust estimates of these parameters are obtained by sampling the entire relevant domain of emission of the different stellar populations, from rest-frame UV to NIR. Sizes are measured from deep ACS data available in all environments. We find that a fraction of ETG in the field employs longer timescales to assemble their mass than their cluster contemporaries. Hence we conclude that, while the formation epoch of early-types only depends on their masses (downsizing), the environment does regulate the timescales of their SFH. We also find that the evolution in size at fixed mass both in the cluster and in the field between z = 1.3 and the present is a factor of 2. A combination of structural evolution of individual galaxies through the accretion of companions and the continuous formation of ETG through increasingly gas-poor mergers is one plausible explanation of our observations.

The star formation rates (SFRs) of Lyman Break Galaxies (LBGs) are typically estimated based on their UV properties or mid-IR photometry using local relations that are assumed to be true at high redshift (eg. reddening laws, IR SEDs). Recently, several lensed LBGs have been discovered with large magnifications allowing detailed infrared studies of this otherwise unobservable population. I'll present the Spitzer mid-IR spectra and mid- to far-IR photometry of two lensed LBGs, cB58 and the "Cosmic Eye." With these data we can test whether or not these locally determined relations are valid for high redshift starbursts.

The Curious Case of the MESS Starburst Galaxies Eddie Laag (UCR)

This talk introduces the Multi-wavelength Extreme Starburst Sample (MESS), a new catalog of 138 star-forming galaxies (0.1 < z < 0.3) optically selected from SDSS using emission line strength diagnostics to have SFR > 50 solar masses per year. The MESS is designed to complement other existing samples of starburst galaxies, such as the luminous infrared galaxies (LIRGs), commonly selected from wide area infrared and submillimeter surveys. Observations using the multiband imaging photometer (MIPS; 24, 70 and 160 micron channels) on the Spitzer Space Telescope have been completed. These data combined with visible, near-IR, and radio observations are providing new insight into the LIRG and ULIRG phenomenon. In terms of optical properties, the MESS span the range between the ``blue cloud'' and the red sequence. It is thought that dust obscuration plays an important role in a possible evolutionary process connecting LIRGS, ULIRGs, E+A galaxies, and for those objects containing AGN, QSOs. The selection criterion for the MESS suggests they may be less obscured than typical ULIRGs or LIRGs, making them possible candidates for a link between the latter and E+A galaxies. We discuss this relationship between the MESS and samples selected through alternative criteria in terms of their spectroscopic, and visible through far-infrared mophological properties; and attempt to place them in this sequence. Early imaging results in K-band also indicate an intriguing number of disturbed morphologies.

Triton is one of the few bodies in the solar system with observed cryo-volcanic activity, in the form of plumes (Soderblom et al. 1990). Prompted by evidence from previous observations at ground and space-based telescopes of possible seasonal surface changes on Triton (Young & Stern 1999), we proposed to confirm and characterize these changes using the HST ACS instrument to image Triton at UV, B, V, I and Methane-band wavelengths over as much of its surface as visible from near Earth in 2005. Preliminary analysis indicates a rotation light curve amplitude in excess of that predicted by static models (Hillier et al. 1994 & Hillier 1999) for visual wavelengths, and significant departures from observations taken 12 years earlier in the UV. We will describe in detail these differences which set constraints on activity and surface temperature as well as composition. Such constraints have profound implications for our understanding of Triton's evolution as well as the history of other outer solar system bodies that may undergo similar geophysical processes or have similar composition, such as Pluto (Buratti et al. 2003, Young et al. 2001).

References
Buratti, B.J., Hillier, J.K., Heinze, A.,Hicks, M.D., Tryka, K.A., Mosher, J.A., Ward, J., Garske, M., Young, J., & Atienza-Rosel, J. Icarus, 162, 171.
Hillier, J., Veverka, J., Helfenstein, P., & Lee, P. 1994, Icarus, 109, 296.
Hillier, J.K. 1999, Icarus, 139, 202.
Soderblom, L.A., Becker, T.L., Kieffer, S.W., Brown, R.H., Hansen, C.J., & Johnson, T.V. 1990, Science, 250, 410.
Young, L.A., & Stern, A.S. 1999, AJ, 122, 449.
Young, E. F.; Binzel, R. P.; Crane, K. 2001, AJ, 121, 552.

As impressively as Lambda-CDM simulations appear to reproduce the large scale structure of the universe, comparisons on smaller scales have so far proven less convincing. Detailed comparisons on galaxy cluster scales are now within reach, but our analysis methods have been lacking in two ways. Strong lens modeling techniques have been unable to fully process the large numbers of multiple images revealed in recent deep multiband ACS observations. We discuss how this problem has been overcome, resulting in more accurate and detailed mass maps than those attainable previously. In particular, we present our Abell 1689 massmap, the only to perfectly reproduce all the observed strong lensing features. At this point our second shortcoming becomes apparent. It is unclear how best to extract the information contained in such a detailed, minimal-assumption mass map! Many previous analyses have focused on measuring the radial profiles and central concentrations of their mass models. A few others have placed modest constraints on galaxy halo truncation radii. We discuss the feasibility of obtaining new physical measurements such as the substructure mass function and the degree to which light traces mass.

I will present radio, Mid-IR, optical and X-ray data of young dust-reddened quasars. These quasars were selected using the FIRST-2MASS survey and have large optical reddenings (E(B-V) ~ 1.0). I will mostly relate Spitzer data to the Hubble ACS images of these objects. They were revealed to be young quasars in which the host galaxies show clear signs of merger. The red quasars are most likely an evolutionary step in the lifetime of a quasar in which the dust of the merging galaxies is still settling in and might be further evidence linking ULIRGs/Starburst to Quasars. The Spitzer spectra for these red quasars resemble more ULIRG-type spectra for the objects with the most disturbed and interacting hosts. They show clear PAH features and moderate Silicate absorption and a steepening in the MIPS Mid-IR emission, dominated by warm dust. However, there are also examples of clear AGN-type simple power-law spectra. I will try to tie the optical and Mid-IR together and relate this to other possible evolutionary QSO phenomena, like BAL quasars.

Exploring the Decline of Star Formation Since z=1

Optical and IR surveys have shown a factor of ten decline in the cosmic star formation rate density since z=1. Explanations have ranged from a decline in triggered bursts such as mergers, to more secular processes such as gas depletion or quenching. At z=1, the bulk of the cosmic star formation appears to be occurring in luminous infrared galaxies (LIRGs), with star formation rates in excess of 20 solar masses per year. Locally, LIRGs are very rare and are generally starbursts produced in mergers of gas rich spirals. At z=1, we have found that the majority of LIRGs are isolated spiral galaxies. While this rules out major mergers as triggers for the majority of z=1 LIRGs, other processes may contribute such as minor mergers, bar instabilities, or interactions. Our work, however, suggests that while these processes may be occurring in the distant LIRGs they are also occurring in the general field population. In fact, we find the bulk of galaxies at z=1 show elevated star formation compared with today and the decline in star formation since then may simply be a matter of gas depletion.

Stars, gas and dust in ellipticals: the mass-metallicity relation in different galactic components

I will present recent theoretical results on the formation and the high redshift assembly of spheroids. These findings have been obtained by utilising different and complementary techniques: chemodynamical models offer great insight in the radial abundance gradients in the stars; while state semi-analytic codes implementing a detailed treatment of the chemical evolution allow an exploration of the role of the galactic mass in shaping many observed relations. The results will be shown by following the path represented by the evolution of the mass-metallicity relation in stars, gas and dust. I will show how, under a few sensible assumptions, it is possible to reproduce a large number of observables ranging from the Xrays to the Infrared. I will also present predictions on the evolution of both the metallicity gradients and the mass-metallicity relation that can be verified by means of the forthcoming observational facilities.