Dr. Shardha Jogee Last update = June 2006 This document is organized as follows: 1) Some potential research projects are outlined in section II 2) The extensive multi-wavelength datasets for these projects are described in section I. 3) For publications and ongoing work on these projects see http://www.as.utexas.edu/~sj " Publications" ************************************************************* I. DATASET FOR THE PROJECTS 1) Existing datasets Extensive multi-wavelength (from X ray to radio) datasets exist for the projects. They include space-based observations (e.g., from the Hubble Space Telescope (HST), Chandra, Spitzer), as well as ground-based optical, NIR, and radio data. In order to build these large datasets, we have set up international collaborations and conducted some of the largest and deepest observational surveys to date. As co-I or co-PI on these large projects, I have access to the dataset and catalogs below for our projects: a) GEMS (Galaxy Evolution from Morphology and SEDs): http://www.mpia.de/GEMS/gems.htm GEMS is the largest contiguous field ever imaged with HST (900 arcmin2) in 2 filters (F606W) and F850LP). GEMS provides HST-based morphologies and accurate redshifts from COMBO-17 for 10,000 galaxies down to R<24 in the range: 0.2<1.2. Panchromatic coverage is provided by Spitzer, Chandra (Extended Chandra Deep Field South), and GALEX. b) STAGES (Space Telescope A901/902 Galaxy Evolution Survey) http://www.nottingham.ac.uk/~ppzmeg/stages/ STAGES is a multiwavelength survey oof the Abell 901/902 supercluster to probe the physical drivers of galaxy evolution in dense environments, using HST (80 orbits; ACS F606W), Spitzer (MIPS +IRAC), GALEX (FUV,NUV), Chandra XMM-Newton, COMBO-17 spectro-photometric redshifts, and gravitational lensing mass maps. c) The HST ACS Treasury Survey of the Coma Cluster http://www.as.utexas.edu/~sj/APTProposal14357.pages.pdf The survey will use 164 HST ACS orbits, along with Spitzer, GALEX, Chandra, and ground-based data of of Coma, the richest galaxy cluster in the local Universe, in order to study the impact of environment on galaxy evolution and provide a long-needed legacy database for comparison with environments at different densities and redshift d) GOODS (Great Observatories Origins Deep Survey) http://www.stsci.edu/science/goods/ GOODS unites extremely deep observations from the Spitzer Space Telescope, Hubble, and Chandra, ESA's XMM-Newton, and from the most powerful ground-based facilities, to survey the distant universe to the faintest flux limits across the broadest range of wavelengths. 2) New observations New optical, NIR and radio observations that can be added from UT facilities (CSO, Mc Donald 2.7-m UBVRI Ha imaging; Mc Donald 2..7 m VIRUS-P integral field spectroscopy. ************************************************************** II. SOME RESEARCH PROJECTS Our research program address observational and theoretical aspects of the evolution, structure, and activities of galaxies - over a wide range of redshifts (z = 0 to 3) covering the last 12 billion years. - across diverse environments,ranging from fields to rich clusters. Some potential research projects for postdoc/students are outlined below (P1 to P5). However interested parties are also encouraged to come up with their own projects. P1. Impact of bars on galaxy evolution as function of (z,environment) P2. Galaxy evolution in cluster environments (Coma and Abell clusters) P3. Interaction/Merger and SF history of galaxies over 8 Gyr P4. Dynamics and SFR of galaxy clusters at low and high z P5. What drives AGN and starburst activity in galactic nuclei? P1. Impact of bars on galaxy evolution as function of (z,environment) -------------------------------------------------------------------- 1. Existing Data: GEMS data for field galaxies z=0.2 to 1 (last 2--8 Gyr) SDSS data for field galaxies at z~0 Coma data for cluster galaxies at z=0.005 STAGES Abell Supercluster data for cluster galaxies at z~0.16 2. Science driver and questions to be addressed While external triggers, in the form of major and minor mergers, play a major role in the mass assembly of galaxies, stellar bars are recognized as the most important internal factor that redistributes the angular momentum of the baryonic and dark matter components of disk galaxies, thereby driving their dynamical and secular evolution. The relative importance of stellar bars, minor mergers, and major mergers depends on the epoch being considered. At redshifts z>~2, corresponding to look-back times T_back > 10.4 Gyr observations and theory suggest that galaxy evolution is dominated by violent major mergers . However, mounting evidence suggests that over the period z~1--0, corresponding to the last 8 Gyr, disks underwent a more quiescent evolution not dominated by major mergers. This more quiescent evolution since z~1 can be driven by spontaneously induced stellar bars in isolated galaxies and by tidally induced stellar bars in galaxies undergoing minor mergers or tidal interactions with mass ratios below 1:4. We are addressing the following questions on bars over z=0 to 1 (last 8 Gyr): - a) How frequent are bars at intermediate redshifts ? See Jogee et al 2004; Elmegreen et al 04 vs Abraham et al 99. - b) Bars, bulges, and disks Is there evidence that bars are building bulges (disky high v/sigma bulges and peanut shaped bulges) in disk galaxies, as postulated in secular evolutionary scenarios. Do disks and bar scale lengths grow concurrently? - c) Bar--starburst connection Are actively star-forming galaxies at z~0 to 1 (over the last 8 Gyr) preferentially barred compared to quiescent galaxies? What fraction of the cosmic SFR over comes from bar-induced SF? - d) Bar--AGN connection What is the relationship between bars and AGN at z~0 to 1? - e) Bar lifetime Are bars long-lived over nearly a Hubble time or do they recurrently dissolve and reform on a much shorter timescale What does the bar lifetime imply about the gas accretion history of disk galaxies from $z \sim$~1 to 0? - f) What do bars imply on the properties of DM halo? 3. We are also looking at bars as a function of environment. a) What is the frequency of bars in cluster vs field galaxies? b) Bars, bulges, and disks in clusters c) Bar--starburst connection in clusters d) Bar--AGN connection in clusters P2. Galaxy evolution in cluster environments (Coma and Abell clusters) --------------------------------------------------------------------- 1. Existing Data Coma data for cluster galaxies at z=0.005 STAGES Abell Supercluster data for cluster galaxies at z~0.16 SDSS data for field galaxies at z~0 2. Science driver and questions to be addressed In cluster of galaxies, a range of environmental processes including galaxy-galaxy interactions (tidal interactions, harassment), and galaxy-ICM interactions (e.g., ram pressure stripping) can dramatically influence the evolution of galaxies. Such processes can remove or redistribute the gas in galaxies, shape the SF/AGN activity and morphological transformation of galaxies. They may even partly account for the morphology-density relation in clusters. We will investigate the following: a) What fraction of galaxies in clusters show morphological distortions? (based on visual classes, CAS A-S parameters, and Gini-M20 ? b) What fraction of galaxies in clusters show evidence of tidal interactions, harassment, and ram pressure stripping,? In order to constrain these questions: we will compare the properties such as (color/stellar populations, SF activity, disk scale length, distance from center of Coma cluster, gas content) of galaxies with and and without morphological distortion in order to assess the impact of external triggers. We will also try to disentangle between tidal interactions or harassment versus ram pressure stripping by checking for truncation which is a feature of the latter process only. c) What fraction of SF in clusters seem tidally induced? d) What is the effect of the cluster environment on morphological features, disks, bulges and bars? What is the frequency of bars in cluster vs field galaxies? Is there evidence for a bar--starburst connection or bar--AGN connection in clusters? e) What is the NIR, optical and Halpha luminosity function at the faint end? How does this compare to the logarithmic slope (-1.8) of the low-mass end of the Cold Dark Matter (CDM) mass function? f) How are stellar populations (from colors and color gradients) and internal chemical evolution of galaxies affected by the cluster environment? P3. Interaction/Merger and SF history of galaxies over 8 Gyr -------------------------------------------------------------y 1. Existing Data GEMS data for field galaxies z=0.2 to 1 (last 2--8 Gyr) SDSS data for field galaxies at z~0 2. Science driver and questions to be addressed External triggers, in the form of major and minor mergers, play a major role in the mass assembly of galaxies. The relative importance of stellar bars, minor mergers, and major mergers depends on the epoch being considered. At redshifts z>~2, corresponding to look-back times T_back > 10.4 Gyr observations and theory suggest that galaxy evolution is dominated by violent major mergers . However, mounting evidence suggests that over the period z~1--0, corresponding to the last 8 Gyr, disks underwent a more quiescent evolution, NOT dominated by major mergers. Instead, it appears that this more quiescent evolution since z~1 may be driven by moderate tidal interactions, minor mergers with mass ratios below 1:4, and spontaneously or tidally-induced stellar bars. However, very few empirical constraints exist on the following questions a) How does the frequency of tidal interactions/minor mergers varies with time over the last 8 Gyr (i.e over z=0 to 1)? b) How much of the cosmic SFR from z=0 to 1 is produced by galaxies undergoing tidal interactions/minor mergers? This is an important question as over the period z=0-1, the cosmic SFR density declines by an order of magnitude in the Madau plot.Is this decline related to a decline in the rate of minor mergers/tidal interactions? Is it related to a decline in the cold gas supply of galaxies due to internal SF and lower external gas accretion rate from cosmological filaments or cannibalized companions? c) How do tidal interactions/minor mergers impact the bulges bars and disks defining the Hubble sequence? d) How much of the AGN activity over z=0 to 1 comes from galaxies undergoing tidal interactions/minor mergers? P4. Dynamics and SFR of galaxy clusters at low and high z -------------------------------------------------------- This project is under development. 1. Science driver and questions to be addressed We will take advantage of the unique capabilities of the IFU unit, VIRUS-P on the 2.7 m at Mc Donald in order to study the star formation rates, dynamics, stellar-plus-gas kinematics of a reference sample of galaxy clusters over the redshift range 0.005 to 3. This study will put important constraints on the evolution of both the cosmic SFR density and the mass assembly history of galaxies as a function of redshift over z=0.005 to 2 (corresponding to the last 10.4 Gyr). The project will serve as the reference baseline for studies of galaxies at higher redshift. and in different environments (fields and clusters). 2. New observations We will perform 2-D integral field spectroscopy using VIRUS-P, The fov of VIRUS-P is very large (110" x 109" or 3.3 sq arcmin) compared to the typical IFU fov of a few ". The Line of interest include [O II], Hbeta, [O III] for SFR, and Mg b line for stellar dynamics. The parameters for Virus-P on the 2.7 m:. - active fiber diameter = 4.19 arcsec. - Size of IFU = 110" x 109" or 3.3 sq arcmin with 1/3 fill factor. (Three dithered exposures will fill 3.5 sq. arcminutes) - 3 sigma per resolution element at AB(B)=21.5 in 40 minutes So a 2 hour observation is required for full filled-in area of the IFU - The spectrograph parameters are:5 pixels per resolution element unbinned (2048^2 format CCD. There are 2 modes a) for DEX mode grating, coverage= 3400-5700 A, R~850 at central wavelength, so this is about 5.4A/resolution element or ~1.1A/pxl b) The "galaxy dynamics" mode grating has coverage = 4540 to 5260 A 4900 A central wavelength and R~2800 (1.8A/resolution element). 3. Existing observations For clusters like Coma and STAGES, have the multi-wavelength imaging data from X ray to radio, including HST ACS, Spitzer, Chandra, GALEX, and VLA data. See section III. These can be combined with the spectroscopy. P5. What drives AGN and starburst activity in galactic nuclei? -------------------------------------------------------------- 1. Existing observations : the MAIN survey See http://www.as.utexas.edu/~sj/link-sn-agn.html The molecular gas in active and inactive nuclei survey or MAIN survey (Jogee, Baker, Sakamoto, Scoville) is the largest interferometric radio survey done to date of molecular gas in active and inactive galactic nuclei.The survey is a combination of high resolution (1"-2" or 100-200 pc) CO(1-0) and C0(2-1) observations, along with HCN(1-0) observations take over 2000--2003 at Caltech's OVRO mm array, combined with three published high resolution surveys : the Sakamoto et al. (1999) CO(1-0) survey of CO-luminous spirals,the Jogee et al (1999; 2005) CO (1-0) survey of starbursts and non-starbursts, and the Baker (2000) CO (1-0) and CO (2-1) survey of AGN with broad Halpha emission. The sample consists of 44 nearby moderately inclined galaxies, which host active (AGN) and inactive (IGN) galactic nuclei and show an order of magnitude variation in star formation efficiency. 2. Science driver and questions to be addressed The goal of the survey is to explore physical conditions and dynamical properties of the molecular gas, and constrain the drivers of the activity levels. In particular a) If all galaxies harbor central black holes, then why do only some galaxies show active nuclei? Are the distribution, kinematics, and properties of the molecular gas different in active (AGN) and inactive (IGN) galactic nuclei? b) Do active (AGN) and inactive (IGN) galactic nuclei differ in the stellar potential in terms of non-axisymmetric features, such as nuclear bars, nuclear spirals, etc, which may help to fuel AGN? c) Do active (AGN) and inactive (IGN) galactic nuclei differ in terms of circumnuclear star formation rate and gas mass fraction? One hypothesis is that a high circumnuclear gas mass fraction can trigger efficient circumnuclear star formation which starves a black hole or washes out its accretion spectrum. The low Toomre Q values in circumnuclear regions of high star formation efficiency (Jogee 2001; Jogee et al 2006), the high Q values in several Seyfert, and the low molecular gas mass fraction (Sakamoto et al. 1999) in several AGN lend some support to this hypothesis. d) Why do galactic nuclei show an order of magnitude variation in star formation efficiency?