A5085692434- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- History and Developments in Astronomy
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Adaptive optics and wavefront sensing
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- X-ray Spectroscopy and Fluorescence Analysis
- Calibration and Measurement Techniques
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Atomic and Molecular Physics
- Geophysics and Gravity Measurements
- Medical Imaging Techniques and Applications
- Advanced X-ray Imaging Techniques
Carnegie Observatories
2013-2022
Carnegie Institution for Science
2013-2022
Michigan State University
2007-2010
University of California, Berkeley
1989-2007
Optica
2007
Harvard University Press
2007
University of Hawaiʻi at Mānoa
2007
University of Hawaii System
2007
University of Florida
2007
Tel Aviv University
2007
We use multifiber spectroscopy of 12 poor groups galaxies to address (1) whether the are bound systems or chance projections along line sight; (2) why members each group have not already merged form a single galaxy, despite groups' high galaxy densities, short crossing times, and likely environments for galaxy-galaxy mergers; (3) how might evolve in these groups, where collisional effects intragroup gas tidal influences global potential weaker than rich clusters. Each has fewer about five...
Fast radio bursts (FRBs) are one of the most tantalizing mysteries sky; their progenitors and origins remain unknown until now no rapid multiwavelength follow-up an FRB has been possible. New instrumentation decreased time between observation discovery from years to seconds, enables polarimetry be performed on FRBs for first time. We have discovered (FRB 140514) in real-time 14 May, 2014 at 17:14:11.06 UTC Parkes telescope triggered other wavelengths within hours event. 140514 was found with...
We use a cosmological chemodynamical simulation to study how the group environment impacts star formation (SF) properties of disk galaxies. The simulated has total mass M ~ 8 × 1012 M☉ and X-ray luminosity LX 1041 erg s−1. Our suggests that ram pressure is not sufficient in this remove cold gas from Vrot 150 km s−1 galaxy. However, majority hot galaxy stripped over timescale approximately 1 Gyr. Since cooling hot-gas component provides source for new gas, stripping effectively cuts off...
▪ Abstract ROSAT observations indicate that approximately half of all nearby groups galaxies contain spatially extended X-ray emission. The radial extent the emission is typically 50–500 h −1 100 kpc or 10–50% virial radius group. Diffuse generally restricted to at least one early-type galaxy. spectroscopy suggests mechanism most likely a combination thermal bremsstrahlung and line This interpretation requires entire volume be filled with hot, low-density gas known as intragroup medium. ASCA...
We use ROSAT PSPC data to study the X-ray properties of a sample 12 poor groups that have extensive membership information. Diffuse emission is detected in nine these groups. In all but one X-ray-detected groups, centered on luminous elliptical galaxy. Fits surface brightness profiles suggest presence two components The first component central galaxy and extended scales 20-40 h-1 kpc. location extent this component, combined with its temperature (~0.7- 0.9 keV) luminosity (~1041-42 h-2 ergs...
Results obtained from an X-ray spectral survey of nearby Seyfert galaxies using XMM–Newton are reported. The sample was optically selected, well defined, complete in B magnitude, and distance limited: it consists the nearest ( Mpc) 27 (9 type 1, 18 2) taken Ho et al. (1997a, ApJS, 112, 315) sample. This is one largest atlases hard spectra low-luminosity active ever assembled. All nuclear sources except two 2s detected between 2 10 keV, half for first time ever, average all them. Nuclear...
view Abstract Citations (229) References (67) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multiwavelength Tests of the Dusty Torus Model for Seyfert Galaxies Mulchaey, John S. ; Koratkar, Anuradha Ward, Martin J. Wilson, Andrew Whittle, Mark Antonucci, Robert R. Kinney, Anne L. Hurt, Todd We present a compilation emission properties sample 116 galaxies based on both previously unpublished data and measurements available in literature. These include fluxes...
We use a recent near-infrared imaging survey of samples Seyfert and normal galaxies to study the role bars in fueling nuclear activity. The active galaxy sample includes Revised Shapely-Ames (RSA) catalog Sandage & Tammann's extension this catalog. were selected match Hubble type, redshift, inclination, blue luminosity. All both classified as barred RSA are also near-infrared. In addition, ~55% nonbarred show evidence for at 2.1 μm. Overall, ~70% observed bar structures. incidence is...
Results of an analysis archival Exosat and HEAO 1-A2 observations Cyg X-1 are presented. It is found, in agreement with Ebisawa (1991), that the X-ray spectrum exhibits a 'high-energy excess' above 8 keV, similar to seen Ginga spectra AGN. shown, on basis likelihood ratio test, data significantly better fit by Compton reflection model than partial covering model. Even energy resolution GSPC, it found derived iron line shape very dependent continuum used. The best-fit temperature for...
We present a study of extended galaxy halo gas through HI and OVI absorption over two decades in projected distance at $z\approx0.2$. The is based on sample $95$ galaxies from highly complete ($ > 80\%$) survey faint ($L 0.1L_*$) with archival quasar spectra $53$ the literature. A clear anti-correlation found between (OVI) column density virial radius normalized distance, $d/R_{\rm h}$. Strong systems densities greater than $10^{14.0}$ ($10^{13.5}$) cm$^{-2}$ are for $48$ $54$ ($36$ $42$) $d...
We examine the star formation properties of group and field galaxies in two surveys, Sloan Digital Sky Survey (at z∼ 0.08) Group Environment Evolution Collaboration (GEEC; at 0.4). Using ultraviolet imaging from Galaxy Explorer space telescope, along with optical and, for GEEC, near-infrared photometry, we compare observed spectral energy distributions to large suites stellar population synthesis models. This allows us accurately determine rates masses. find that star-forming all...
We present an analysis of galaxies in groups and clusters at 0.8 < z 1.2, from the GCLASS GEEC2 spectroscopic surveys. compute a 'conversion fraction' fconvert that represents fraction were prematurely quenched by their environment. For massive galaxies, Mstar > 1010.3 M⊙, we find ∼ 0.4 ∼0.6 clusters, similar to comparable measurements = 0. This means time between first accretion into more halo final star formation quenching is tp 2 Gyr. substantially longer than estimated required for...
ABSTRACT We present a compilation of UBVRIz light curves 51 type II supernovae discovered during the course four different surveys 1986–2003: Cerro Tololo Supernova Survey, Calán/Tololo Program (C&T), Optical and Infrared Survey (SOIRS), Carnegie Type (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy contamination, calibrated from foreground stars. This work presents these photometric data, studies color evolution using bands, explores...
The form of the galaxy luminosity function (GLF) in poor groups—regions intermediate density that are common environments for galaxies—is not well understood. Multiobject spectroscopy and wide-field CCD imaging now allow us to measure GLF bound group members directly (i.e., without statistical background subtraction) compare with GLFs field rich clusters. We use R-band images 1.5 × degree2 mosaics obtain photometry galaxies fields six nearby (2800 < cz 7700 km s-1) groups which we have...
view Abstract Citations (209) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Intragroup Medium in Poor Groups of Galaxies Mulchaey, John S. ; Davis, David Mushotzky, Richard F. Burstein, We have used the ROSAT PSPC to search for diffuse, extended X-ray emission a sample 14 galaxy groups. A diffuse component was found four cases. Combining our new analysis with published observations, we that total 48 groups varying size and velocity...
A search was conducted for a hot intragroup medium in 109 low-redshift galaxy groups observed with the ROSAT PSPC. Evidence diffuse, extended X-ray emission is found at least 61 groups. Approximately one-third of these detections have not been previously reported literature. Most are detected out to less than half virial radius ROSAT. Although some spiral-rich do contain an medium, diffuse restricted that one early-type galaxy.
The VLA has been used at 3.6 and 20 cm to image a sample of about 50 early-type Seyfert galaxies with recessional velocities less than 7,000 km/s total visual magnitude 14.5. nuclear radio structures 2.0's in the tend be aligned [OIII] Halpha+[NII] even though extents are smaller by factor ~2->5. This alignment, previously known for individual Seyferts `linear' sources, is here shown characteristic as class. also show significant alignment between emission-line ([OIII] Halpha+[NII]) axes...
If active galactic nuclei (AGN) are powered by the accretion of matter onto massive black holes, how does gas in host galaxy lose required angular momentum to approach hole? Gas easily transfers stars strong bars, making them likely candidates. Although ground-based searches for bars galaxies using both optical and near-infrared surface brightness have not found any excess relative quiescent galaxies, been able rule out small-scale nuclear bars. To look these we use Hubble Space Telescope...
Numerical simulations predict that some poor groups of galaxies have merged by the present epoch into giant ellipticals (cf. Barnes 1989). To identify possible remnants such mergers, we compiled a sample nearby, isolated (Colbert, Mulchaey, & Zabludoff 1998). ASCA observations first galaxy studied, NGC 1132 reveal an X-ray halo extends out to at least 250 kpc. The temperature, metallicity and luminosity 1132's are comparable those group halos. total mass inferred from emission is also...
The low redshift Universe (z<~0.5) is not a dull place. Processes leading to the suppression of star formation and morphological transformation are prevalent: this particularly evident in dramatic upturn fraction S0-type galaxies clusters. However, until now, process environment has remained unidentified. We present HST-based analysis redshift-space selected group field environments at z~0.4. Groups contain much higher S0s fixed luminosity than lower density field, with >99.999% confidence....
(Abridged) We present an imaging and spectroscopic survey of galaxies in fields around QSOs HE0226-4110, PKS0405-123, PG1216+069. The are selected to have ultraviolet echelle spectra available, which uncover 195 Lya absorbers 13 OVI along the three sightlines. obtain robust redshifts for 1104 rest-frame absolute magnitude M_R-5log h <~ -16 at projected physical distances rho 4 h^{-1} Mpc from QSOs. HST/WFPC2 images PKS0405-123 PG1216+069 available studying optical morphologies absorbing...
We have measured the luminous active galactic nucleus (AGN) population in a large sample of clusters galaxies and find evidence for substantial increase cluster AGN from z ∼ 0.05 to 1.3. The present now includes 32 galaxies, including 15 above = 0.4, which corresponds three-fold compared our previous work at high redshift. At < we obtained new observations candidates six additional found no members. Our total 17 low-redshift contains only two AGNs, while redshifts there are 18 such or an...
We introduce our survey of galaxy groups at 0.85 < z 1, as an extension the Group Environment and Evolution Collaboration. Here we present first results, based on Gemini GMOS-S nod-and-shuffle spectroscopy seven selected from spectroscopically confirmed, extended XMM detections in COSMOS. use photometric redshifts to select potential group members for spectroscopy, target galaxies with r 24.75. In total, have over 100 confirmed members, four >15 members. The dynamical mass estimates are good...
With Hubble Space Telescope imaging, we investigate the progenitor population and formation mechanisms of intracluster light (ICL) for 23 galaxy groups clusters ranging from 3$\times10^{13}<$M$_{500,c}$ [M$_\odot$]$<9\times10^{14}$ at 0.29$<$z$<$0.89. The color gradients BCG+ICL become bluer with increasing radius out to 53-100 kpc all but one system, suggesting that violent relaxation after major mergers BCG cannot be dominant source ICL. For luminosity r$<$100 (0.08-0.13 r$_{500,c}$) is...