- ID:
- ivo://nasa.heasarc/gmrtspxfls
- Title:
- Giant Metrewave Radio Telescope Spitzer xFLS Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTSPXFLS
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog based on observations of the Spitzer extragalactic First Look Survey (xFLS) field taken at 610 MHz with the Giant Metrewave Radio Telescope (GMRT). Seven individual pointings were observed, covering a total area of ~ 4 square degrees with a resolution of 5.8 x 4.7 arcsec<sup>2</sup>, position angle 60 degrees. The rms noise at the center of the pointings is between 27 and 30 microJansky (µJy) before correction for the GMRT primary beam. The techniques used for data reduction and production of a mosaicked image of the region are described in the reference paper, where the final mosaic, along with a catalog of 3944 sources detected above a ~ 5-sigma threshold, are presented. The survey complements existing radio and infrared data available for this region. For further details of the surveys and data analysis procedures, please refer to the published paper. This table contains the xFLS catalog of 3944 610-MHz radio sources detected by the GMRT, the 05-May-2008 (Release 1.1) version provided to the CDS by the co-author Sally Hales (MRAO, Cambridge). In this version, a rounding error in the right ascension and declination positions listed for some sources in the original 10-May-2007 (Release 1.0) version has been corrected. The source IAU designations remain unchanged, having been based on the correctly computed positions throughout. The main purpose in correcting the positions was to eliminate sporadic mismatches between IAU designation and listed position in the first data release. In other respects the effect on the positions is negligible. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/376/1251">CDS catalog J/MNRAS/376/1251</a> file gmrtfls.dat, the release 1.1 (05-May-2008) version. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/gmrtvvdsvl
- Title:
- Giant Metrewave Radio Telescope VVDS-VLA Deep Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTVVDSVL
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the 5-sigma catalog at 610 MHz of the VIMOS VLT Deep Survey-Very Large Array (VVDS-VLA) deep field obtained from Giant Metrewave Radio Telescope (GMRT) observations. The field is located at RA, Dec = 02:26:00, -04:30:00 (J2000) and covers a 1-square degree area. The GMRT observations imaged the whole 1 square degree field with an angular resolution of 6 arcseconds and an average sensitivity of about 50 µJy/beam. The catalog lists 514 radio sources, 17 of which are fitted with multiple components (between 2 and 5). For these multiple sources, each component (A, B, etc.) is listed separately, and the entire source (indicated by the suffix T in the name) is also listed. Thus, there are 557 entries in this table, 43 of which correspond to multiple components. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/463/519">CDS Catalog J/A+A/463/519</a> file table.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtxl240m
- Title:
- Giant Metrewave Radio Telescope XMM Large Scale Structure 240-MHz Source Catalog
- Short Name:
- GMRTXL240M
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The low-frequency radio survey of the XMM-Large Scale Structure (XMM-LSS) field centered at RA (J2000) = 2<sup>h</sup>24<sup>m</sup>00<sup>s</sup>, Dec (J2000) = -4<sup>0</sup>09'47" aims to study the connection between the extragalactic radio source populations and their environment as traced by X-ray and optical emission. In their paper, the authors present new radio observations of the XMM-LSS field carried out using the Giant Meterwave Radio Telescope (GMRT) at 240 and 610 MHz. These observations complement the observations presented by Cohen at al. (2003, ApJ, 591, 640; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/591/640">CDS Cat. <J/ApJ/591/640></a>) and Tasse et al. (2006, A&A, 456, 791; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/456/791">CDS Cat. <J/A+A/456/791></a>) at 74 and 325 MHz with the Very Large Array (VLA). At 240 and 610 MHz, the authors reach noise levels of ~2.5 and ~0.3 mJy/beam, leading to the detection of 466 and 769 sources over 18.0 and 12.7 degree<sup>2</sup> with resolutions of 14.7 arcseconds and 6.5 arcseconds, respectively. Combining these data with the available source lists at 74 MHz, 325 MHz (Tasse et al., 2006) and 1400MHz (NVSS), the authors built a multifrequency catalog containing 1611 radio sources. They checked for consistency of the astrometry and flux density estimates. They fit a simple synchrotron radiation model to the flux density measurements of the 318 radio sources that were detected in at least 4 bands. While ~26% of them showed signature of spectral ageing, ~6% showed self absorption. This table contains the GMRT 240-MHz source list, comprising 388 single sources and 183 components of multiple sources, for a total of 571 entries. For the multiple sources, each component (A, B, etc.) is listed separately, in order of decreasing brightness. This table was created by the HEASARC in February 2012 based on CS Catalog J/A+A/471/1105 file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtxl610m
- Title:
- Giant Metrewave Radio Telescope XMM Large Scale Structure 610-MHz Source Catalog
- Short Name:
- GMRTXL610M
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The low-frequency radio survey of the XMM-Large Scale Structure (XMM-LSS) field centered at RA (J2000) = 2<sup>h</sup>24<sup>m</sup>00<sup>s</sup>, Dec (J2000) = -4<sup>0</sup>09'47" aims to study the connection between the extragalactic radio source populations and their environment as traced by X-ray and optical emission. In their paper, the authors present new radio observations of the XMM-LSS field carried out using the Giant Meterwave Radio Telescope (GMRT) at 240 and 610 MHz. These observations complement the observations presented by Cohen at al. (2003, ApJ, 591, 640; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/591/640">CDS Cat. <J/ApJ/591/640></a>) and Tasse et al. (2006, A&A, 456, 791; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/456/791">CDS Cat. <J/A+A/456/791></a>) at 74 and 325 MHz with the Very Large Array (VLA). At 240 and 610 MHz, the authors reach noise levels of ~2.5 and ~0.3 mJy/beam, leading to the detection of 466 and 769 sources over 18.0 and 12.7 degree<sup>2</sup> with resolutions of 14.7 arcseconds and 6.5 arcseconds, respectively. Combining these data with the available source lists at 74 MHz, 325 MHz (Tasse et al., 2006) and 1400MHz (NVSS), the authors built a multifrequency catalog containing 1611 radio sources. They checked for consistency of the astrometry and flux density estimates. They fit a simple synchrotron radiation model to the flux density measurements of the 318 radio sources that were detected in at least 4 bands. While ~26% of them showed signature of spectral ageing, ~6% showed self absorption. This table contains the GMRT 610-MHz source list, comprising 592 single sources and 445 components of multiple sources, for a total of 1037 entries. For the multiple sources, each component (A, B, etc.) is listed separately, in order of decreasing brightness. This table was created by the HEASARC in February 2012 based on CS Catalog J/A+A/471/1105 file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJS/149/343
- Title:
- Giant molecular clouds in M33
- Short Name:
- J/ApJS/149/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first interferometric ^12^CO (J=1->0) map of the entire H{alpha} disk of M33. The 13" diameter synthesized beam corresponds to a linear resolution of 50pc, sufficient to distinguish individual giant molecular clouds (GMCs). From these data we generated a catalog of 148 GMCs with an expectation that no more than 15 of the sources are spurious. The catalog is complete down to GMC masses of 1.5x10^5^M_{sun}_ and contains a total mass of 2.3x10^7^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJ/654/240
- Title:
- Giant molecular clouds in M31
- Short Name:
- J/ApJ/654/240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Berkeley-Illinois-Maryland Association (BIMA) millimeter interferometer observations of giant molecular clouds (GMCs) along a spiral arm in M31. The observations consist of a survey using the compact configuration of the interferometer and follow-up, higher resolution observations on a subset of the detections in the survey. The data are processed using an analysis algorithm designed to extract GMCs and correct their derived properties for observational biases, thereby facilitating comparison with Milky Way data. The algorithm identifies 67 GMCs, of which 19 have a sufficient signal-to-noise ratio to accurately measure their properties. The GMCs in this portion of M31 are indistinguishable from those found in the Milky Way, having a similar size-line width relationship and distribution of virial parameters, confirming the results of previous, smaller studies. The velocity gradients and angular momenta of the GMCs are comparable to the values measured in M33 and the Milky Way, and in all cases are below expected values based on the local galactic shear. The studied region of M31 has an interstellar radiation field, metallicity, Toomre Q parameter, and midplane volume density similar to those of the inner Milky Way, so the similarity of GMC populations between the two systems is not surprising.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A108
- Title:
- Giant molecular clouds in M33
- Short Name:
- J/A+A/542/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of a systematic CO(2-1) survey at 12" resolution covering most of the Local Group spiral M33, which, at a distance of 840kpc, is close enough for individual giant molecular clouds (GMCs) to be identified. The goal of this work is to study the properties of the GMCs in this subsolar metallicity galaxy. The CPROPS (Cloud PROPertieS) algorithm was used to identify 337 GMCs in M33, the largest sample to date for an external galaxy. The sample is used to study the GMC luminosity function, or mass spectrum under the assumption of a constant N(H_2_)/I_CO_ ratio.
- ID:
- ivo://CDS.VizieR/J/ApJ/772/107
- Title:
- Giant molecular clouds in nearby galaxies
- Short Name:
- J/ApJ/772/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We resolve 182 individual giant molecular clouds (GMCs) larger than 2.5x10^5^M_{sun}_ in the inner disks of 5 large nearby spiral galaxies (NGC 2403, NGC 3031, NGC 4736, NGC 4826, and NGC 6946) to create the largest such sample of extragalactic GMCs within galaxies analogous to the Milky Way. Using a conservatively chosen sample of GMCs most likely to adhere to the virial assumption, we measure cloud sizes, velocity dispersions, and ^12^CO(J=1-0) luminosities and calculate cloud virial masses. The average conversion factor from CO flux to H_2_ mass (or X_CO_) for each galaxy is 1-2x10^20^/cm2 (K.km/s)^-1^, all within a factor of two of the Milky Way disk value (~2x10^20^/cm2(K.km/s)^-1^). We find GMCs to be generally consistent within our errors between the galaxies and with Milky Way disk GMCs; the intrinsic scatter between clouds is of order a factor of two. Consistent with previous studies in the Local Group, we find a linear relationship between cloud virial mass and CO luminosity, supporting the assumption that the clouds in this GMC sample are gravitationally bound. We do not detect a significant population of GMCs with elevated velocity dispersions for their sizes, as has been detected in the Galactic center. Though the range of metallicities probed in this study is narrow, the average conversion factors of these galaxies will serve to anchor the high metallicity end of metallicity-X_CO_ trends measured using conversion factors in resolved clouds; this has been previously possible primarily with Milky Way measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/803/16
- Title:
- Giant molecular clouds in NGC4526 based on ^12^CO
- Short Name:
- J/ApJ/803/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high spatial resolution (~20pc) of ^12^CO(2-1) observations of the lenticular galaxy NGC 4526. We identify 103 resolved giant molecular clouds (GMCs) and measure their properties: size R, velocity dispersion {sigma}_v_, and luminosity L. This is the first GMC catalog of an early-type galaxy. We find that the GMC population in NGC 4526 is gravitationally bound, with a virial parameter {alpha}~1. The mass distribution, dN/dM{propto}M^-2.39+/-0.03^, is steeper than that for GMCs in the inner Milky Way, but comparable to that found in some late-type galaxies. We find no size-line width correlation for the NGC 4526 clouds, in contradiction to the expectation from Larson's relation. In general, the GMCs in NGC 4526 are more luminous, denser, and have a higher velocity dispersion than equal-size GMCs in the Milky Way and other galaxies in the Local Group. These may be due to higher interstellar radiation field than in the Milky Way disk and weaker external pressure than in the Galactic center. In addition, a kinematic measurement of cloud rotation shows that the rotation is driven by the galactic shear. For the vast majority of the clouds, the rotational energy is less than the turbulent and gravitational energy, while the four innermost clouds are unbound and will likely be torn apart by the strong shear at the galactic center. We combine our data with the archival data of other galaxies to show that the surface density {Sigma} of GMCs is not approximately constant, as previously believed, but varies by ~3 orders of magnitude. We also show that the size and velocity dispersion of the GMC population across galaxies are related to the surface density, as expected from the gravitational and pressure equilibrium, i.e., {sigma}_v_R^-1/2^{propto}{Sigma}^1/2^.
- ID:
- ivo://CDS.VizieR/J/ApJS/212/2
- Title:
- Giant molecular clouds in the 4th Galactic quadrant
- Short Name:
- J/ApJS/212/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Columbia University-Universidad de Chile CO Survey of the southern Milky Way is used to separate the CO(1-0) emission of the fourth Galactic quadrant within the solar circle into its dominant components, giant molecular clouds (GMCs). After the subtraction of an axisymmetric model of the CO background emission in the inner southern Galaxy, 92 GMCs are identified, and for 87 of them the twofold distance ambiguity is solved. Their total molecular mass is M(H_2_)=1.14+/-0.05x10^8^M_{sun}_, accounting for around 40% of the molecular mass estimated from an axisymmetric analysis of the H_2_ volume density in the Galactic disk, M(H_2_)_disk_=3.03x10^8^M_{sun}_. The large-scale spiral structure in the southern Galaxy, within the solar circle, is traced by the GMCs in our catalog; three spiral arm segments, the Centaurus, Norma, and 3 kpc expanding arm, are analyzed. After fitting a logarithmic spiral arm model to the arms, tangent directions at 310{deg}, 330{deg}, and 338{deg}, respectively, are found, consistent with previous values from the literature. A complete CS(2-1) survey toward IRAS point-like sources with far-IR colors characteristic of ultracompact H II regions is used to estimate the massive star formation rate per unit H_2_ mass (MSFR) and the massive star formation efficiency ({epsilon}) for GMCs. The average MSFR for GMCs is 0.41+/-0.06L_{sun}_/M_{sun}_, and for the most massive clouds in the Norma arm it is 0.58+/-0.09L_{sun}_/M_{sun}_. Massive star formation efficiencies of GMCs are, on average, 3% of their available molecular mass.