Physical Sciences and Mathematics Commons^™

Distribution Ofwater Vapor In Molecular Clouds, G Melrick, V Tolls, Ronald L. Snell, E Bergin, D Hollenbach, M Kaufman, D Li, D Neufeld

Astronomy Department Faculty Publication Series

We report the results of a large-area study of water vapor along the Orion Molecular Cloud ridge, the purpose of which was to determine the depth-dependent distribution of gas-phase water in dense molecular clouds. We find that the water vapor measured toward 77 spatial positions along the face-on Orion ridge, excluding positions surrounding the outflow associated with BN/KL and IRc2, display integrated intensities that correlate strongly with known cloud surface tracers such as CN, C₂H, ¹³CO J = 5-4, and HCN, and less well with the volume tracer N₂H⁺. Moreover, at total column …

New Insights Into Galaxy Structure From Galphat– I. Motivation, Methodology And Benchmarks For Sérsic Models, I Yoon, M Weinberg, N Katz

Astronomy Department Faculty Publication Series

We introduce a new galaxy image decomposition tool, galphat (GALaxy PHotometric ATtributes), which is a front-end application of the Bayesian Inference Engine (bie), a parallel Markov chain Monte Carlo package, to provide full posterior probability distributions and reliable confidence intervals for all model parameters. The bie relies on galphat to compute the likelihood function. galphat generates scale-free cumulative image tables for the desired model family with precise error control. Interpolation of this table yields accurate pixellated images with any centre, scale and inclination angle. galphat then rotates the image by position angle using a Fourier shift theorem, yielding high-speed, accurate …

The Murmur Of The Hidden Monster: Chandra's Decadal View Of The Supermassive Black Hole In M31, Z Li, Mr Garcia, Wr Forman, C Jones, Rp Kraft, Dv Lal, Ss Murray, Qd Wang

Astronomy Department Faculty Publication Series

The Andromeda galaxy (M31) hosts a central supermassive black hole (SMBH), known as M31*, which is remarkable for its mass (~10⁸ M ) and extreme radiative quiescence. Over the past decade, the Chandra X-Ray Observatory has pointed to the center of M31 ~100 times and accumulated a total exposure of ~900 ks. Based on these observations, we present an X-ray study of a highly variable source that we associate with M31* based on positional coincidence. We find that M31* remained in a quiescent state from late 1999 to 2005, exhibiting an average 0.5-8 keV luminosity 10³⁶ erg s …

Title: Properties Of The Compact Hii Region Complex G-0.02-0.07, E Mills, Mr Morris, C Lang, H Dong, Qd Wang, A Cotera, S Stolovy

Astronomy Department Faculty Publication Series

Abstract: We present new extinction maps and high-resolution Paschen alpha images of G-0.02-0.07, a complex of compact HII regions located adjacent to the M-0.02-0.07 giant molecular cloud, 6 parsecs in projection from the center of the Galaxy. These HII regions, which lie in projection just outside the boundary of the Sgr A East supernova remnant, represent one of the most recent episodes of star formation in the central parsecs of the Galaxy. The 1.87 micron extinctions of regions A, B and C are almost identical, approximately 1.5 magnitudes. Region D, in contrast, has a peak 1.87 micron extinction of 2.3 …

A Green Bank Telescope Survey For H I 21 Cm Absorption In The Disks And Halos Of Low-Redshift Galaxies*, S Borthakur, Tm Tripp, Min Yun, Dv Bowen, Jd Meiring, Dg York, E Momjian

Astronomy Department Faculty Publication Series

We present an H I 21 cm absorption survey with the Green Bank Telescope (GBT) of galaxy-quasar pairs selected by combining galaxy data from the Sloan Digital Sky Survey (SDSS) and radio sources from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey. Our sample consists of 23 sight lines through 15 low-redshift foreground galaxy-background quasar pairs with impact parameters ranging from 1.7 kpc up to 86.7 kpc. We detected one absorber in the GBT survey from the foreground dwarf galaxy, GQ1042+0747, at an impact parameter of 1.7 kpc and another possible absorber in our follow-up Very Large …

Evidence For 1000 Km S–1 Molecular Outflows In The Local Ulirg Population, A Chung, Min Yun, Gopal Narayanan, M Heyer, Nr Erickson

Astronomy Department Faculty Publication Series

The feedback from galactic outflows is thought to play an important role in shaping the gas content, star formation history, and ultimately the stellar mass function of galaxies. Here we present evidence for massive molecular outflows associated with ultra-luminous infrared galaxies (ULIRGs) in the co-added Redshift Search Receiver ¹²CO (1-0) spectrum. Our stacked spectrum of 27 ULIRGs at z = 0.043-0.11 (ν_rest = 110-120 GHz) shows broad wings around the CO line with ΔV(FWZI) 2000 km s^–1. Its integrated line flux accounts for up to 25% ± 5% of the total CO line luminosity. …

On The Clustering Of Sub-Millimeter Galaxies, Cc Williams, M Giavalisco, C Porciani, Min Yun, A Pope, Ks Scott, Je Austermann, I Aretxaga, B Hatsukade, K-S Lee, Gw Wilson, Jr Cybulski, Dh Hughes, R Kawabe, K Kohno, T Perera, Fp Schloerb

Astronomy Department Faculty Publication Series

We measure the angular two-point correlation function of sub-millimeter galaxies (SMGs) from 1.1-millimeter imaging of the COSMOS field with the AzTEC camera and ASTE 10-meter telescope. These data yields one of the largest contiguous samples of SMGs to date, covering an area of 0.72 degrees^2 down to a 1.26 mJy/beam (1-sigma) limit, including 189 (328) sources with S/N greater than 3.5 (3). We can only set upper limits to the correlation length r_0, modeling the correlation function as a power-law with pre-assigned slope. Assuming existing redshift distributions, we derive 68.3% confidence level upper limits of r_0 < 6-8 h^-1 Mpc at 3.7 mJy, and r_0 < 11-12 h^-1 Mpc at 4.2 mJy. Although consistent with most previous estimates, these upper limits imply that the real r_0 is likely smaller. This casts doubts on the robustness of claims that SMGs are characterized by significantly stronger spatial clustering, (and thus larger mass), than differently selected galaxies at high-redshift. Using Monte Carlo simulations we show that even strongly clustered distributions of galaxies can appear unclustered when sampled with limited sensitivity and coarse angular resolution common to current sub-millimeter surveys. The simulations, however, also show that unclustered distributions can appear strongly clustered under these circumstances. From the simulations, we predict that at our survey depth, a mapped area of two degrees^2 is needed to reconstruct the correlation function, assuming smaller beam sizes of future surveys (e.g. the Large Millimeter Telescope's 6" beam size). At present, robust measures of the clustering strength of bright SMGs appear to be below the reach of most observations.

The Jcmt Nearby Galaxies Legacy Survey – V. The Co(J= 3–2) Distribution And Molecular Outflow In Ngc 4631, Ja Irwin, Cd Wilson, T Wiegert, Gj Bendo, Be Warren, Qd Wang, Fp Israel, S Serjeant, Jh Knapen, E Brinks, Rpj Tilanus, P Van Der Werf, S Muhle

Astronomy Department Faculty Publication Series

We have made the first map of CO(J= 3–2) emission covering the disc of the edge-on galaxy, NGC 4631, which is known for its spectacular gaseous halo. The strongest emission, which we model with a Gaussian ring, occurs within a radius of 5 kpc. Weaker disc emission is detected out to radii of 12 kpc, the most extensive molecular component yet seen in this galaxy. From comparisons with infrared data, we find that CO(J= 3–2) emission more closely follows the hot dust component, rather than the cold dust, consistent with it being a good tracer of …

A Massive Protocluster Of Galaxies At A Redshift Of Z ≈ 5.3, Pl Capak, D Riechers, Nz Scoville, C Carilli, P Cox, R Neri, B Robertson, M Savato, E Schinnerer, L Yan, Gw Wilson, Min Yun, F Civano, M Elvis, A Karim, B Mobasher, Jg Staguhn

Astronomy Department Faculty Publication Series

Massive clusters of galaxies have been found that date from as early as 3.9 billion years¹ (3.9 Gyr; z = 1.62) after the Big Bang, containing stars that formed at even earlier epochs^{2, 3}. Cosmological simulations using the current cold dark matter model predict that these systems should descend from ‘protoclusters’—early overdensities of massive galaxies that merge hierarchically to form a cluster^{4, 5}. These protocluster regions themselves are built up hierarchically and so are expected to contain extremely massive galaxies that can be observed as luminous quasars and starbursts^{4, 5, …}

The Redshift And Nature Of Aztec/Cosmos 1: A Starburst Galaxy At Z = 4.6*, V Smolcic, Min Yun, Et. Al.

Astronomy Department Faculty Publication Series

Based on broadband/narrowband photometry and Keck DEIMOS spectroscopy, we report a redshift of z = 4.64^+0.06 _–0.08 for AzTEC/COSMOS 1, the brightest submillimeter galaxy (SMG) in the AzTEC/COSMOS field. In addition to the COSMOS-survey X-ray to radio data, we report observations of the source with Herschel/PACS (100, 160 μm), CSO/SHARC II (350 μm), and CARMA and PdBI (3 mm). We do not detect CO(5 → 4) line emission in the covered redshift ranges, 4.56-4.76 (PdBI/CARMA) and 4.94-5.02 (CARMA). If the line is within this bandwidth, this sets 3σ upper limits on the gas mass to 8 × 10 …

Identification Of A Complete 160 Μm Flux-Limited Sample Of Infrared Galaxies In The Iso Lockman Hole 1 Deg2 Deep Fields: Source Properties And Evidence For Strong Evolution In The Fir Luminosity Function For Ulirgs, Ba Jacobs, Db Sanders, Dsn Rupke, H Aussel, Dt Frayer, O Ilbert, Ks Kartaltepe, K Kawara, D-C Kim, E Le Floc'h, T Murayama, V Smolcic, Ja Surace, Y Taniguchi, S Veilleux, Min Yun

Astronomy Department Faculty Publication Series

We have identified a complete, flux-limited (S ₁₆₀>120 mJy) sample of 160 μm selected sources from Spitzer observations of the 1 deg² Infrared Space Observatory (ISO) Deep Field region in the Lockman Hole (LH). Ground-based UV, optical, and near-infrared (NIR) photometry and optical spectroscopy have been used to determine colors, redshifts, and masses for the complete sample of 40 galaxies. Spitzer-IRAC+MIPS photometry, supplemented by ISOPHOT data at 90 μm and 170 μm, has been used to calculate accurate total infrared luminosities, L _IR(8-1000 μm), and to determine the IR luminosity function (LF) of …

Detection Of Strong Millimeter Emission From The Circumstellar Dust Disk Around V1094 Sco: Cold And Massive Disk Around A T Tauri Star In A Quiescent Accretion Phase?, T Tsukagoshi, M Saito, Y Kitamura, M Momose, Y Shimajiri, M Hiramatsu, N Ikeda, K Kamegai, G Wilson, Min Yun, Ks Scott, J Austermann, T Perera, D Hughes, I Aretxaga, P Mauskopf, H Ezawa, K Kohno, R Kawabe

Astronomy Department Faculty Publication Series

We present the discovery of a cold massive dust disk around the T Tauri star V1094 Sco in the Lupus molecular cloud from the 1.1 mm continuum observations with AzTEC on ASTE. A compact (r 320 AU) continuum emission coincides with the stellar position having a flux density of 272 mJy, which is the largest among T Tauri stars in Lupus. We also present the detection of molecular gas associated with the star in the five-point observations in ¹²CO J = 3-2 and ¹³CO J = 3-2. Since our ¹²CO and ¹³CO observations did not …

Iras 15099-5856: Remarkable Mid-Infrared Source With Prominent Crystalline Silicate Emission Embedded In The Supernova Remnant Msh15-52, B_C Koo, Cf Mckee, K-W Suh, D-S Moon, T Onaka, Mg Burton, M Hiramatsu, Ms Bessell, Bm Gaensler, H-J Kim, J-J Lee, W-S Jeong, H-G Lee, M Im, K Tatematsu, K Kohno, R Kawabe, H Ezawa, Gw Wilson, Min Yun, Dh Hughes

Astronomy Department Faculty Publication Series

We report new mid-infrared observations of the remarkable object IRAS 15099-5856 using the space telescopes AKARI and Spitzer, which demonstrate the presence of prominent crystalline silicate emission in this bright source. IRAS 15099-5856 has a complex morphology with a bright central compact source (IRS1) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only at >= 10 um. The Spitzer MIR spectrum of IRS1 shows prominent emission features from Mg-rich crystalline silicates, strong [Ne II] 12.81 um and several other faint ionic lines. We model the MIR spectrum as thermal emission from dust and compare …

The Redshift Search Receiver 3 Mm Wavelength Spectra Of 10 Galaxies, Ronald L. Snell, Gopal Narayanan, Min Yun, M Heyer, A Chung, William M. Irvine, Nr Erickson, G Liu

Astronomy Department Faculty Publication Series

The 3 mm wavelength spectra of 10 galaxies have been obtained at the Five College Radio Astronomy Observatory using a new, very broadband receiver and spectrometer, called the Redshift Search Receiver (RSR). The RSR has an instantaneous bandwidth of 37 GHz covering frequencies from 74 to 111 GHz and has a spectral resolution of 31 MHz (~100 km s^–1). During tests of the RSR on the FCRAO 14 m telescope the complete 3 mm spectra of the central regions of NGC 253, Maffei 2, NGC1068, IC 342, M82, NGC 3079, NGC 3690, NGC 4258, Arp 220, and NGC …

Galactic Coronae In The Intracluster Environment: Semiconfined Stellar-Feedback-Driven Outflows, Z Lu, Qd Wang

Astronomy Department Faculty Publication Series

Recently X-ray observations have shown the regular presence of compact galactic coronae around intermediate-mass spheroid galaxies embedded in the intracluster/intragroup medium (ICM). We conduct 2D hydrodynamic simulations to study the quasi-steady-state properties of such coronae as the natural products of the ongoing distributed stellar feedback semiconfined by the thermal and ram pressures of the ICM. We find that the temperature of a simulated corona depends primarily on the specific energy of the feedback, consistent with the lack of correlation between the observed hot gas temperature and K-band luminosity of galaxies. The simulated coronae typically represent subsonic outflows, chiefly because …

X-Ray Emission From The Sombrero Galaxy: A Galactic-Scale Outflow, Z Li, C Jones, Wr Forman, Rp Krafts, Dv Lal, Rd Stefano, Lr Spitler, S Tang, Qd Wang, M Gilfanov, M Revnivtsev

Astronomy Department Faculty Publication Series

Based on new and archival Chandra observations of the Sombrero galaxy (M 104 = NGC 4594), we study the X-ray emission from its nucleus and the extended X-ray emission in and around its massive stellar bulge. We find that the 0.3-8 keV luminosity of the nucleus appears constant at ~2.4 × 10⁴⁰ erg s^-1, or ~10^–7 of its Eddington luminosity, on three epochs between 1999 December and 2008 April, but drops by a factor of two in the 2008 November observation. The 2-6 keV unresolved emission from the bulge region closely follows the K-band starlight …

The Single-Degenerate Binary Origin Of Tycho's Supernova As Traced By The Stripped Envelope Of The Companion, Fj Lu, Qd Wang, My Ge, Jl Qu, Xj Yang, Sj Zheng, Y Chen

Astronomy Department Faculty Publication Series

We propose that a nonthermal X-ray arc inside the remnant of Tycho's supernova (SN) represents the interaction between the SN ejecta and the companion star's envelope lost in the impact of the explosion. The X-ray emission of the remnant further shows an apparent shadow casted by the arc in the opposite direction of the explosion site, consistent with the blocking of the SN ejecta by the envelope. This scenario supports the single degenerate binary origin of Tycho's SN. The properties of the X-ray arc, together with the previous detection of the companion candidate and its space velocity by Ruiz-Lapuente et …