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Physical Sciences and Mathematics Commons™

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Series

Astrophysics and Astronomy

2006

University of Massachusetts Amherst

Articles 1 - 30 of 34

Full-Text Articles in Physical Sciences and Mathematics

Nature And Completeness Of Galaxies Detected In The Two Micron All Sky Survey, Dh Mcintosh, Ef Bell, Md Weinberg, N Katz Jan 2006

Nature And Completeness Of Galaxies Detected In The Two Micron All Sky Survey, Dh Mcintosh, Ef Bell, Md Weinberg, N Katz

Astronomy Department Faculty Publication Series

The Two Micron All Sky Survey (2MASS) provides the most comprehensive data set of near-infrared galaxy properties. We cross correlate the well-defined and highly complete spectroscopic selection of over 155 000 bright (r≤ 17.5 mag) galaxies in the Sloan Digital Sky Survey (SDSS) main galaxy sample (MGS) with 2MASS sources to explore the nature and completeness of the 2MASS (K-band) selection of nearby galaxies. Using estimates of total galaxy brightness direct from the 2MASS and SDSS public catalogues, corrected only for Galactic extinction, we find that 2MASS detects 90 per cent of the MGS brighter than r= 17 mag. We …

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The Morphological Diversities Among Star-Forming Galaxies At High Redshifts In The Great Observatories Origins Deep Survey, S Ravindranath, M Giavalisco, Hc Ferguson, C Conselice, N Katz, M Weinberg, J Lotz, M Dickinson, Sm Fall, B Mobasher, C Papovich Jan 2006

The Morphological Diversities Among Star-Forming Galaxies At High Redshifts In The Great Observatories Origins Deep Survey, S Ravindranath, M Giavalisco, Hc Ferguson, C Conselice, N Katz, M Weinberg, J Lotz, M Dickinson, Sm Fall, B Mobasher, C Papovich

Astronomy Department Faculty Publication Series

We used the deep, multiwavelength images obtained by the Great Observatories Origins Deep Survey (GOODS) to identify ~4700 Lyman break galaxies (LBGs) at z > 2.5, and 292 starburst galaxies at z ~ 1.2. We present the results from morphological analysis based on light profile shape and ellipticity for ~1333 of the most luminous LBGs. About 40% of LBGs at z ~ 3 have exponential profiles, ~30% of the galaxies have steep (r1/4-like) profiles, and ~30% of LBGs have multiple cores of disturbed morphologies suggestive of close pairs or mergers. The fraction of spheriod-like LBGs decrease by about 15% from z …

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The Cosmological Significance Of High-Velocity Cloud Complex H, Jd Simon, L Blitz, Aa Cole, Md Weinberg, M Cohen Jan 2006

The Cosmological Significance Of High-Velocity Cloud Complex H, Jd Simon, L Blitz, Aa Cole, Md Weinberg, M Cohen

Astronomy Department Faculty Publication Series

We have used new and archival infrared and radio observations to search for a dwarf galaxy associated with the high-velocity cloud (HVC) known as `complex H.' Complex H is a large (Ω gtrsim 400 deg2) and probably nearby (d = 27 kpc) HVC whose location in the Galactic plane has hampered previous investigations of its stellar content. The H I mass of the cloud is 2.0 × 107(d/27 kpc)2 Msun, making complex H one of the most massive HVCs if its distance is more than ~20 kpc. Virtually all similar H I clouds in other galaxy groups are associated with …

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Dark Matter Halo Response To The Disc Growth, Jh Choi, Y Lu, Hj Mo, Md Weinberg Jan 2006

Dark Matter Halo Response To The Disc Growth, Jh Choi, Y Lu, Hj Mo, Md Weinberg

Astronomy Department Faculty Publication Series

We consider the sensitivity of the circular-orbit adiabatic contraction approximation to the baryon condensation rate and the orbital structure of dark matter haloes in the Λ cold dark matter (ΛCDM) paradigm. Using one-dimensional hydrodynamic simulations including the dark matter halo mass accretion history and gas cooling, we demonstrate that the adiabatic approximation is approximately valid even though haloes and discs may assemble simultaneously. We further demonstrate the validity of the simple approximation for ΛCDM haloes with isotropic velocity distributions using three-dimensional N-body simulations. This result is easily understood: an isotropic velocity distribution in a cuspy halo requires more circular orbits …

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From Galaxy-Galaxy Lensing To Cosmological Parameters, J Yoo, Jl Tinker, Dh Weinberg, Z Zheng, N Katz, R Dave Jan 2006

From Galaxy-Galaxy Lensing To Cosmological Parameters, J Yoo, Jl Tinker, Dh Weinberg, Z Zheng, N Katz, R Dave

Astronomy Department Faculty Publication Series

Galaxy-galaxy lensing uses the weak distortion of background sources to measure the mean excess surface density profile, ΔΣ(r), around a sample of foreground lensing galaxies. We develop a method for combining ΔΣ(r) with the galaxy-galaxy correlation function ξgg(r) to constrain the matter density parameter Ωm and the matter fluctuation amplitude σ8, going beyond the linear biasing model to reach the level of accuracy demanded by current and future measurements. We adopt the halo occupation distribution (HOD) framework and test its applicability to this problem by examining the effects of …

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Galaxy Merger Statistics And Inferred Bulge-To-Disk Ratios In Cosmological Sph Simulations, Ah Maller, N Katz, D Keres, R Dave, Dh Weinberg Jan 2006

Galaxy Merger Statistics And Inferred Bulge-To-Disk Ratios In Cosmological Sph Simulations, Ah Maller, N Katz, D Keres, R Dave, Dh Weinberg

Astronomy Department Faculty Publication Series

We construct merger trees for galaxies identified in a cosmological hydrodynamic simulation and use them to characterize predicted merger rates as a function of redshift, galaxy mass, and merger mass ratio. At z = 0.3, we find a mean rate of 0.054 mergers per galaxy per Gyr above a 1 : 2 mass ratio threshold for massive galaxies (baryonic mass above 6.4 × 1010 M), but only 0.018 Gyr-1 for lower mass galaxies. The mass ratio distribution is R for the massive galaxy sample, so high-mass mergers dominate the total merger growth rate. The predicted rates increase …

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Probing Galaxy Formation With He Ii Cooling Lines, Yj Yang, Ai Zabludoff, R Dave, Dj Eisenstein, Pa Pinto, N Katz, Dh Weinberg, Ej Barton Jan 2006

Probing Galaxy Formation With He Ii Cooling Lines, Yj Yang, Ai Zabludoff, R Dave, Dj Eisenstein, Pa Pinto, N Katz, Dh Weinberg, Ej Barton

Astronomy Department Faculty Publication Series

Using high-resolution cosmological simulations, we study hydrogen and helium gravitational cooling radiation from gas accretion by young galaxies. We focus on the He II cooling lines, which arise from gas with a different temperature history (Tmax ~ 105 K) than H I line-emitting gas. We examine whether three major atomic cooling lines, H I λ1216, He II λ1640, and He II λ304, are observable, finding that Lyα and He II λ1640 cooling emission at z = 2-3 are potentially detectable with deep narrowband (R > 100) imaging and/or spectroscopy from the ground. While the expected strength of …

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Predicting The Starquakes In Psr J0537–6910, J Middleditch, Fe Marshall, Qd Wang, Ev Gotthelf, W Zhang Jan 2006

Predicting The Starquakes In Psr J0537–6910, J Middleditch, Fe Marshall, Qd Wang, Ev Gotthelf, W Zhang

Astronomy Department Faculty Publication Series

We report on more than 7 yr of monitoring of PSR J0537-6910, the 16 ms pulsar in the LMC, using data acquired with RXTE. During this campaign the pulsar experienced 23 sudden increases in frequency ("glitches") amounting to a total gain of over 6 ppm of rotation frequency superposed on its gradual spin-down of = -2 × 10-10 Hz s-1. The time interval from one glitch to the next obeys a strong linear correlation to the amplitude of the first glitch, with a mean slope of about 400 days ppm-1 (6.5 days μHz-1), …

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Non-Equilibrium Ionization Model For Stellar Cluster Winds And Its Application, L Ji, Qd Wang, J Kwan Jan 2006

Non-Equilibrium Ionization Model For Stellar Cluster Winds And Its Application, L Ji, Qd Wang, J Kwan

Astronomy Department Faculty Publication Series

We have developed a self-consistent physical model for superstellar cluster winds based on combining a 1D steady-state adiabatic wind solution and a non-equilibrium ionization calculation. Comparing with the case of collisional ionization equilibrium, we find that the non-equilibrium ionization effect is significant in the regime of a high ratio of energy to mass input rate and manifests in a stronger soft X-ray flux in the inner region of the star cluster. Implementing the model in X-ray data analysis softwares (e.g. xspec) directly facilitates comparisons with X-ray observations. Physical quantities such as the mass and energy input rates of stellar winds …

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G359.95-0.04: An Energetic Pulsar Candidate Near Sgr A*, Qd Wang, Fj Lu, Ev Gotthelf Jan 2006

G359.95-0.04: An Energetic Pulsar Candidate Near Sgr A*, Qd Wang, Fj Lu, Ev Gotthelf

Astronomy Department Faculty Publication Series

We report the discovery of a prominent non-thermal X-ray feature located near the Galactic centre that we identify as an energetic pulsar wind nebula. This feature, G359.95-0.04, lies 1-lyr north of Sgr A* (in projection), is comet like in shape, and has a power-law spectrum that steepens with increasing distance from the putative pulsar. The distinct spectral and spatial X-ray characteristics of the feature are similar to those belonging to the rare class of ram-pressure confined pulsar wind nebulae. The luminosity of the nebula at the distance of Sgr A*, consistent with the inferred X-ray absorptions, is Lx∼ …

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Chandra Observations Of The Galactic Center: High Energy Processes At Arcsecond Resolution, Qd Wang Jan 2006

Chandra Observations Of The Galactic Center: High Energy Processes At Arcsecond Resolution, Qd Wang

Astronomy Department Faculty Publication Series

About 2 million seconds of Chandra observing time have been devoted to the Galactic Center (GC), including large-scale surveys and deep pointings. These observations have led to the detection of about 4000 discrete X-ray sources and the mapping of diffuse X-ray emission in various energy bands. In this review, I frst summarize general results from recent studies and then present close-up views of the three massive star clusters (Arches, Quintuplet, and GC) and their interplay with the Galactic nuclear environment.

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Chandra Detection Of Fe Xvii In Absorption: Iron Abundance In The Hot Gaseous Interstellar Medium, Y Yao, N Schulz, Qd Wang, M Nowak Jan 2006

Chandra Detection Of Fe Xvii In Absorption: Iron Abundance In The Hot Gaseous Interstellar Medium, Y Yao, N Schulz, Qd Wang, M Nowak

Astronomy Department Faculty Publication Series

The iron depletion level and the gas-phase iron abundance in the hot (~106 K) interstellar medium (ISM) are critical to our understanding of its energy balance as well as the thermal sputtering, cooling, and heating processes of dust grains. Here, we report on the first detection of the Fe XVII absorption line at 15.02 Å from the hot ISM in the spectrum of the low-mass X-ray binary 4U 1820-303 observed with the Chandra X-Ray Observatory. By jointly analyzing this absorption line with those from O VII, O VIII, and Ne IX ions in the same spectrum, we obtain …

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An Optical Study Of Stellar And Interstellar Environments Of Seven Luminous And Ultraluminous X-Ray Sources, Cj Ramsey, Rm Williams, Ra Gruendl, C-Hr Chen, Y-H Chu, Qd Wang Jan 2006

An Optical Study Of Stellar And Interstellar Environments Of Seven Luminous And Ultraluminous X-Ray Sources, Cj Ramsey, Rm Williams, Ra Gruendl, C-Hr Chen, Y-H Chu, Qd Wang

Astronomy Department Faculty Publication Series

We have studied the stellar and interstellar environments of two luminous X-ray sources and five ultraluminous X-ray sources (ULXs) in order to gain insight into their nature. Archival Hubble Space Telescope images were used to identify the optical counterparts of the ULXs Ho IX X-1 and NGC 1313 X-2, and to make photometric measurements of the local stellar populations of these and the luminous source IC 10 X-1. We obtained high-dispersion spectroscopic observations of the nebulae around these seven sources to search for He II λ4686 emission and to estimate the expansion velocities and kinetic energies of these nebulae. Our …

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The Xmm-Newton/Chandra Monitoring Campaign Of The Galactic Center Region, R Wijnands, Jjm In't Zand, M Rupen, T Maccarone, J Homan, R Cornelisse, R Fender, J Grindlay, M Van Der Klis, E Kuulkers, Cb Markwardt, Jca Miller-Jones, Qd Wang Jan 2006

The Xmm-Newton/Chandra Monitoring Campaign Of The Galactic Center Region, R Wijnands, Jjm In't Zand, M Rupen, T Maccarone, J Homan, R Cornelisse, R Fender, J Grindlay, M Van Der Klis, E Kuulkers, Cb Markwardt, Jca Miller-Jones, Qd Wang

Astronomy Department Faculty Publication Series

We present the first results of our X-ray monitoring campaign on a 1.7 square degree region centered on Sgr A* using the satellites XMM-Newton and Chandra. The purpose of this campaign is to monitor the behavior (below 10 keV) of X-ray sources (both persistent and transient) which are too faint to be detected by monitoring instruments aboard other satellites currently in orbit (e.g., Rossi X-ray Timing Explorer; INTEGRAL). Our first monitoring observations (using the HRC-I aboard Chandra) were obtained on June 5, 2005. Most of the sources detected could be identified with foreground sources, such as …

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The Interplay Between Star Formation And The Nuclear Environment Of Our Galaxy: Deep X-Ray Observations Of The Galactic Centre Arches And Quintuplet Clusters, Qd Wang, H Dong, C Lang Jan 2006

The Interplay Between Star Formation And The Nuclear Environment Of Our Galaxy: Deep X-Ray Observations Of The Galactic Centre Arches And Quintuplet Clusters, Qd Wang, H Dong, C Lang

Astronomy Department Faculty Publication Series

The Galactic centre (GC) provides a unique laboratory for a detailed examination of the interplay between massive star formation and the nuclear environment of our Galaxy. Here, we present a 100-ks Chandra Advanced CCD Imaging Spectrometer (ACIS) observation of the Arches and Quintuplet star clusters. We also report on a complementary mapping of the dense molecular gas near the Arches cluster made with the Owens Valley Millimeter Array. We present a catalogue of 244 point-like X-ray sources detected in the observation. Their number–flux relation indicates an overpopulation of relatively bright X-ray sources, which are apparently associated with the clusters. The …

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Antenna-Coupled Tes Bolometers For The Spider Experiment, Cl Kuo, P Ade, Jj Bock, P Day, A Goldin, S Golwala, M Halpern, G Hilton, W Holmes, V Hristov, K Irwin, Wc Jones, M Kenyon, Ae Lange, Hg Leduc, C Mactavish, T Montroy, Cb Netterfield, P Rossinot, J Ruhl, A Vayonakis, G Wang, Min Yun Jan 2006

Antenna-Coupled Tes Bolometers For The Spider Experiment, Cl Kuo, P Ade, Jj Bock, P Day, A Goldin, S Golwala, M Halpern, G Hilton, W Holmes, V Hristov, K Irwin, Wc Jones, M Kenyon, Ae Lange, Hg Leduc, C Mactavish, T Montroy, Cb Netterfield, P Rossinot, J Ruhl, A Vayonakis, G Wang, Min Yun

Astronomy Department Faculty Publication Series

SPIDER is a proposed balloon-borne experiment designed to search for the imprints of gravity waves on the polarization of the cosmic microwave background radiation. The required wide frequency coverage, large number of sensitive detectors, and the stringent power constraints on a balloon are made possible by antenna-coupled TES bolometers. Several prototype devices have been fabricated and optically characterized. Their spectral and angular responses agree well with the theoretical expectations.

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Supercam: A 64-Pixel Heterodyne Imaging Array For The 870-Micron Atmospheric Window (Proceedings Paper), C Groppi, C Walker, C Kulesa, P Putz, D Golish, P Gensheimer, A Hedden, S Bussmann, S Weinreb, T Kuiper, J Kooi, G Jones, J Bardin, H Mani, A Lichtenberger, Gopal Narayanan Jan 2006

Supercam: A 64-Pixel Heterodyne Imaging Array For The 870-Micron Atmospheric Window (Proceedings Paper), C Groppi, C Walker, C Kulesa, P Putz, D Golish, P Gensheimer, A Hedden, S Bussmann, S Weinreb, T Kuiper, J Kooi, G Jones, J Bardin, H Mani, A Lichtenberger, Gopal Narayanan

Astronomy Department Faculty Publication Series

We report on the development of SuperCam, a 64 pixel, superheterodyne camera designed for operation in the astrophysically important 870 μm atmospheric window. SuperCam will be used to answer fundamental questions about the physics and chemistry of molecular clouds in the Galaxy and their direct relation to star and planet formation. The advent of such a system will provide an order of magnitude increase in mapping speed over what is now available and revolutionize how observational astronomy is performed in this important wavelength regime. Unlike the situation with bolometric detectors, heterodyne receiver systems are coherent, retaining information about both …

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Kinematics Of Protostellar Objects In The Ρ Ophiuchus A Region, Gopal Narayanan, Dw Logan Jan 2006

Kinematics Of Protostellar Objects In The Ρ Ophiuchus A Region, Gopal Narayanan, Dw Logan

Astronomy Department Faculty Publication Series

We present the detection of infall, rotation, and outflow kinematic signatures toward both a protostellar source, VLA 1623, and what was initially thought to be a pre-protostellar core, SM 1N, in the ρ Ophiuchus A region. The kinematic signatures of early star formation were detected in the dense molecular gas surrounding the embedded sources using high signal-to-noise ratio millimeter and submillimeter data. Centroid velocity maps made with HCO+ J = 4 → 3 and J = 1 → 0 line emission exhibit the blue bulge signature of infall, which is predicted to be seen when infall motion dominates over …

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On The Origin Of Cold Dark Matter Halo Density Profiles, Y Lu, Hj Mo, N Katz, Md Weinberg Jan 2006

On The Origin Of Cold Dark Matter Halo Density Profiles, Y Lu, Hj Mo, N Katz, Md Weinberg

Astronomy Department Faculty Publication Series

N-body simulations predict that cold dark matter (CDM) halo-assembly occurs in two phases: (i) a fast-accretion phase with a rapidly deepening potential well; and (ii) a slow-accretion phase characterized by a gentle addition of mass to the outer halo with little change in the inner potential well. We demonstrate, using one-dimensional simulations, that this two-phase accretion leads to CDM haloes of the Navarro, Frenk & White (NFW) form and provides physical insight into the properties of the mass-accretion history that influence the final profile. Assuming that the velocities of CDM particles are effectively isotropized by fluctuations in the gravitational potential …

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Submillimeter Wave Astronomy Satellite Observations Of Comet 9p/Tempel 1 And Deep Impact, F Bensch, Gj Melnick, Da Neufeld, M Harwit, Ronald L. Snell, Bm Patten, V Tolls Jan 2006

Submillimeter Wave Astronomy Satellite Observations Of Comet 9p/Tempel 1 And Deep Impact, F Bensch, Gj Melnick, Da Neufeld, M Harwit, Ronald L. Snell, Bm Patten, V Tolls

Astronomy Department Faculty Publication Series

On 4 July 2005 at 5:52 UT the Deep Impact mission successfully completed its goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on the nucleus and ejecting material into the coma of the comet. NASA's Submillimeter Wave Astronomy Satellite (SWAS) observed the 110–101 ortho-water ground-state rotational transition in Comet 9P/Tempel 1 before, during, and after the impact. No excess emission from the impact was detected by SWAS and we derive an upper limit of 1.8×107 kg on the water ice evaporated by the impact. However, the water production rate of …

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Spitzer Observations Of Hydrogen Deuteride, Da Neufeld, Jd Green, Dj Hollenbach, P Sonnentrucker, Gj Melnick, Ea Bergin, Ronald L. Snell, Wj Forrest, Dm Watson, Mj Kaufman Jan 2006

Spitzer Observations Of Hydrogen Deuteride, Da Neufeld, Jd Green, Dj Hollenbach, P Sonnentrucker, Gj Melnick, Ea Bergin, Ronald L. Snell, Wj Forrest, Dm Watson, Mj Kaufman

Astronomy Department Faculty Publication Series

No abstract provided.

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Star Formation And Feedback In Smoothed Particle Hydrodynamic Simulations - I. Isolated Galaxies, G Stinson, A Seth, N Katz, J Wadsley, F Governato, T Quinn Jan 2006

Star Formation And Feedback In Smoothed Particle Hydrodynamic Simulations - I. Isolated Galaxies, G Stinson, A Seth, N Katz, J Wadsley, F Governato, T Quinn

Astronomy Department Faculty Publication Series

We present an analysis of star formation and feedback recipes appropriate for galactic smoothed particle hydrodynamics simulations. Using an isolated Milky Way-like galaxy, we constrain these recipes based on well-established observational results. Our star formation recipe is based on that of Katz with the additional inclusion of physically motivated supernova feedback recipes. We propose a new feedback recipe in which Type II supernovae are modelled using an analytical treatment of blastwaves. With this feedback mechanism and a tuning of other star formation parameters, the star formation in our isolated Milky Way-like galaxy follows the slope and normalization of the observed …

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Entrainment Mechanisms For Outflows In The L1551 Star-Forming Region, Irena Stojimirovív, Gopal Narayanan, Ronald L. Snell, John Bally Jan 2006

Entrainment Mechanisms For Outflows In The L1551 Star-Forming Region, Irena Stojimirovív, Gopal Narayanan, Ronald L. Snell, John Bally

Astronomy Department Faculty Publication Series

We present high sensitivity 12/13CO(1-0) molecular line maps covering the full extent of the parsec scale L1551 molecular outflow, including the redshifted east-west (EW) flow. We also present 12CO(3-2) data that extends over a good fraction of the area mapped in the 1-0 transition. We compare the molecular data to widefield, narrow-band optical emission in Hα. While there are multiple outflows in the L1551 cloud, the main outflow is oriented at 50\arcdeg position angle and appears to be driven by embedded source(s) in the central IRS 5 region. The 3-2 data indicate that there may be molecular emission associated with …

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Co(1-0) In Z Gtrsim 4 Quasar Host Galaxies: No Evidence For Extended Molecular Gas Reservoirs, Da Riechers, F Walter, Cl Carilli, Kk Knudsen, Ky Lo, Dj Benford, Jg Staguhn, Tr Hunter, F Bertoldi, C Henkel, Km Menten, Axel Weiss, Min Yun, Nz Scoville Jan 2006

Co(1-0) In Z Gtrsim 4 Quasar Host Galaxies: No Evidence For Extended Molecular Gas Reservoirs, Da Riechers, F Walter, Cl Carilli, Kk Knudsen, Ky Lo, Dj Benford, Jg Staguhn, Tr Hunter, F Bertoldi, C Henkel, Km Menten, Axel Weiss, Min Yun, Nz Scoville

Astronomy Department Faculty Publication Series

We present 12CO(J = 1 → 0) observations of the high-redshift quasi-stellar objects (QSOs) BR 1202-0725 (z = 4.69), PSS J2322+1944 (z = 4.12), and APM 08279+5255 (z = 3.91) using the NRAO Green Bank Telescope (GBT) and the MPIfR Effelsberg 100 m telescope. We detect, for the first time, the CO ground-level transition in BR 1202-0725. For PSS J2322+1944 and APM 08279+5255, our observations result in line fluxes that are consistent with previous NRAO Very Large Array (VLA) observations, but they reveal the full line profiles. We report a typical lensing-corrected velocity-integrated intrinsic 12 …

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The Bolocam 1.1 Mm Lockman Hole Galaxy Survey: Sharc Ii 350 Μm Photometry And Implications For Spectral Models, Dust Temperatures, And Redshift Estimation, Gt Laurent, J Glenn, E Egami, Gh Rieke, Rj Ivison, Min Yun, Je Aguirre, Pr Maloney, D Haig Jan 2006

The Bolocam 1.1 Mm Lockman Hole Galaxy Survey: Sharc Ii 350 Μm Photometry And Implications For Spectral Models, Dust Temperatures, And Redshift Estimation, Gt Laurent, J Glenn, E Egami, Gh Rieke, Rj Ivison, Min Yun, Je Aguirre, Pr Maloney, D Haig

Astronomy Department Faculty Publication Series

We present 350 μm photometry of all 17 galaxy candidates in the Lockman Hole detected in a 1.1 mm Bolocam survey. Several of the galaxies were previously detected at 850 μm, at 1.2 mm, in the infrared by Spitzer, and in the radio. Nine of the Bolocam galaxy candidates were detected at 350 μm, and two new candidates were serendipitously detected at 350 μm (bringing the total in the literature detected in this way to three). Five of the galaxies have published spectroscopic redshifts, enabling investigation of the implied temperature ranges and a comparison of photometric redshift techniques. For …

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Powerful High-Velocity Dispersion Molecular Hydrogen Associated With An Intergalactic Shock Wave In Stephan's Quintet, Pn Appleton, Kc Xu, W Reach, Ma Dopita, Y Gao, N Lu, Cc Popescu, Jw Sulentic, Rj Tuffs, Min Yun Jan 2006

Powerful High-Velocity Dispersion Molecular Hydrogen Associated With An Intergalactic Shock Wave In Stephan's Quintet, Pn Appleton, Kc Xu, W Reach, Ma Dopita, Y Gao, N Lu, Cc Popescu, Jw Sulentic, Rj Tuffs, Min Yun

Astronomy Department Faculty Publication Series

We present the discovery of strong mid-infrared emission lines of molecular hydrogen of apparently high-velocity dispersion (~870 km s-1) originating from a group-wide shock wave in Stephan's Quintet. These Spitzer Space Telescope observations reveal emission lines of molecular hydrogen and little else. This is the first time an almost pure H2 line spectrum has been seen in an extragalactic object. Along with the absence of PAH-dust features and very low excitation ionized gas tracers, the spectra resemble shocked gas seen in Galactic supernova remnants, but on a vast scale. The molecular emission extends over 24 kpc along …

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Chandra Acis Spectroscopy Of N157b: A Young Composite Supernova Remnant In A Superbubble, Y Chen, Qd Wang, Ev Gotthelf, B Jiang, Y-H Chu, R Gruendl Jan 2006

Chandra Acis Spectroscopy Of N157b: A Young Composite Supernova Remnant In A Superbubble, Y Chen, Qd Wang, Ev Gotthelf, B Jiang, Y-H Chu, R Gruendl

Astronomy Department Faculty Publication Series

We present a Chandra ACIS observations of N157B, a young supernova remnant (SNR) located in the 30 Doradus star formation region of the Large Magellanic Cloud. This remnant contains the most energetic pulsar known (PSR J053747.39-691020.2; = 4.8 × 1038 ergs s-1), which is surrounded by a X-ray-bright nonthermal nebula that likely represents a toroidal pulsar wind terminal shock observed edge-on. Two of the eight pointlike X-ray sources detected in the observation are shown to have near-IR and optical counterparts (within 05 offsets), which are identified as massive stellar systems in the Cloud. We confirm the nonthermal …

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An Xmm–Newton Observation Of The Massive Edge-On Sb Galaxy Ngc 2613, Z Li, Qd Wang, Ja Irwin, T Chaves Jan 2006

An Xmm–Newton Observation Of The Massive Edge-On Sb Galaxy Ngc 2613, Z Li, Qd Wang, Ja Irwin, T Chaves

Astronomy Department Faculty Publication Series

We present an XMM–Newton observation of the massive edge-on Sb galaxy NGC 2613. We discover that this galaxy contains a deeply embedded active nucleus with a 0.3–10 keV luminosity of 3.3 × 1040 erg s−1 and a line-of-sight absorption column of 1.2 × 1023 cm−2. Within the 25 mag arcsec−2 optical B-band isophote of the galaxy, we detect an additional four sources with an accumulated luminosity of 4.3 × 1039 erg s−1. The bulk of the unresolved X-ray emission spatially follows the near-infrared (NIR) K-band surface brightness distribution; the …

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A Deep Radio Survey Of Abell 2125. Iii. The Cluster Core: Merging And Stripping, Fn Owen, Wc Keel, Qd Wang, Mj Ledlow, Ge Morrison Jan 2006

A Deep Radio Survey Of Abell 2125. Iii. The Cluster Core: Merging And Stripping, Fn Owen, Wc Keel, Qd Wang, Mj Ledlow, Ge Morrison

Astronomy Department Faculty Publication Series

We use radio, near-IR, optical, and X-ray observations to examine dynamic processes in the central region of the rich galaxy cluster Abell 2125. In addition to the central triple of E and cD galaxies, including members of both major dynamical subsystems identified from a redshift survey, this region features a galaxy showing strong evidence for ongoing gas stripping during a high-velocity passage through the gas in the cluster core. The disk galaxy C153 exhibits a plume stretching toward the cluster center seen in soft X-rays by Chandra, parts of which are also seen in [O II] emission and near-UV …

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A Chandra Catalog Of X-Ray Sources In The Central 150 Pc Of The Galaxy, Mp Muno, Fe Bauer, Rm Bandyopadhyay, Qd Wang Jan 2006

A Chandra Catalog Of X-Ray Sources In The Central 150 Pc Of The Galaxy, Mp Muno, Fe Bauer, Rm Bandyopadhyay, Qd Wang

Astronomy Department Faculty Publication Series

We present the catalog of X-ray sources detected in a shallow Chandra survey of the inner 2° × 08 of the Galaxy and in two deeper observations of the Radio Arches and Sgr B2. The catalog contains 1352 objects that are highly absorbed (NH 4 × 1022 cm-2) and are therefore likely to lie near the Galactic center (D 8 kpc), and 549 less absorbed sources that lie within 6 kpc of Earth. On the basis of the inferred luminosities of the X-ray sources and the expected numbers of various classes of objects, we …

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