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1281. Giant molecular clouds in M31
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.
1282. Giant molecular clouds in M33
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.
1283. Giant molecular clouds in nearby galaxies
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.
1284. Giant molecular clouds in NGC4526 based on ^12^CO
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^.
1285. Giant molecular clouds of M33
ID:
ivo://CDS.VizieR/J/ApJ/661/830
Title:
Giant molecular clouds of M33
Short Name:
J/ApJ/661/830
Date:
21 Oct 2021
Publisher:
CDS
Description:
New observations of CO (J=1->0) line emission from M33, using the 25 element BEARS focal plane array at the Nobeyama Radio Observatory 45m telescope, in conjunction with existing maps from the BIMA interferometer and the FCRAO 14m telescope, give the highest resolution (13") and most sensitive ({sigma}_rms_~60mK) maps to date of the distribution of molecular gas in the central 5.5kpc of the galaxy. A new catalog of giant molecular clouds (GMCs) has a completeness limit of 1.3x10^5^M_{sun}_.
1286. Giant Radio Galaxies in RACS
ID:
ivo://CDS.VizieR/J/other/Galax/9.99
Title:
Giant Radio Galaxies in RACS
Short Name:
J/other/Galax/9.
Date:
22 Feb 2022
Publisher:
CDS
Description:
We report the results of a visual inspection of images of the Rapid ASKAP Continuum Survey (RACS) in search of extended radio galaxies (ERG) that reach or exceed linear sizes on the order of one Megaparsec. We searched a contiguous area of 1059deg^2^ from RA=20h20m to 06h20m, and -50{deg}<Dec<-40{deg} which is covered by deep multi-band optical images of the Dark Energy Survey (DES), and in which previously only three ERGs larger than 1Mpc had been reported. For over 1800 radio galaxy candidates inspected, our search in optical and infrared images resulted in hosts for 1440 ERG, for which spectroscopic and photometric redshifts from various references were used to convert their largest angular size (LAS) to projected linear size (LLS). This resulted in 178 newly discovered giant radio sources (GRS) with LLS>1Mpc, of which 18 exceed 2Mpc and the largest one is 3.4Mpc. Their redshifts range from 0.02 to about 2.0, but only 10 of the 178 new GRS have spectroscopic redshifts. For the 146 host galaxies the median r-band magnitude and redshift are 20.9 and 0.64, while for the 32 quasars or candidates these are 19.7 and 0.75. Merging the six most recent large compilations of GRS results in 458 GRS larger than 1Mpc, so we were able to increase this number by about 39 per cent to now 636.
1287. g'i' photometry in 5 isolated elliptical galaxies
ID:
ivo://CDS.VizieR/J/A+A/577/A59
Title:
g'i' photometry in 5 isolated elliptical galaxies
Short Name:
J/A+A/577/A59
Date:
21 Oct 2021
Publisher:
CDS
Description:
As tracers of star formation, galaxy assembly and mass distribution, globular clusters have provided important clues to our understanding of early-type galaxies. But their study has been mostly constrained to galaxy groups and clusters where early-type galaxies dominate, leaving the properties of the globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted territory. We present Gemini-South/GMOS g'i' observations of five isolated elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271 and NGC 4240. Photometry of their GCSs reveals clear color bimodality in three of them, remaining inconclusive for the other two. All the studied GCSs are rather poor with a mean specific frequency S_N_~1.5, independently of the parent galaxy luminosity. Considering also previous work, it is clear that bimodality and especially the presence of a significant, even dominant, population of blue clusters occurs at even the most isolated systems, casting doubts on a possible accreted origin of metal-poor clusters as suggested by some models. Additionally, we discuss the possible existence of ultra-compact dwarfs around the isolated elliptical NGC 3962.
1288. gi photometry of Bootes I
ID:
ivo://CDS.VizieR/J/MNRAS/461/3702
Title:
gi photometry of Bootes I
Short Name:
J/MNRAS/461/3702
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep stellar photometry of the Bootes I dwarf spheroidal galaxy in g- and i-band filters, taken with the Dark Energy Camera at Cerro Tololo in Chile. Our analysis reveals a large, extended region of stellar substructure surrounding the dwarf, as well as a distinct overdensity encroaching on its tidal radius. A radial profile of the Bootes I stellar distribution shows a break radius indicating the presence of extra-tidal stars. These observations strongly suggest that Bootes I is experiencing tidal disruption, although not as extreme as that exhibited by the Hercules dwarf spheroidal. Combined with revised velocity dispersion measurements from the literature, we see evidence suggesting the need to review previous theoretical models of the Bootes I dwarf spheroidal galaxy.
1289. gi photometry of Sextans dSph galaxy stars
ID:
ivo://CDS.VizieR/J/MNRAS/460/30
Title:
gi photometry of Sextans dSph galaxy stars
Short Name:
J/MNRAS/460/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present wide-field g- and i-band stellar photometry of the Sextans dwarf spheroidal galaxy and its surrounding area out to four times its half-light radius (r_h_=695pc), based on images obtained with the Dark Energy Camera at the 4-m Blanco telescope at CTIO. We find clear evidence of stellar substructure associated with the galaxy, extending to a distance of 82-arcmin (2kpc) from its centre. We perform a statistical analysis of the overdensities and find three distinct features, as well as an extended halo-like structure, to be significant at the 99.7 per cent confidence level or higher. Unlike the extremely elongated and extended substructures surrounding the Hercules dwarf spheroidal galaxy, the overdensities seen around Sextans are distributed evenly about its centre, and do not appear to form noticeable tidal tails. Fitting a King model to the radial distribution of Sextans stars yields a tidal radius r_t_=83.2-arcmin+/-7.1 arcmin (2.08+/-0.18kpc), which implies the majority of detected substructure is gravitationally bound to the galaxy. This finding suggests that Sextans is not undergoing significant tidal disruption from the Milky Way, supporting the scenario in which the orbit of Sextans has a low eccentricity.
1290. GIS catalog project : source catalog
ID:
ivo://CDS.VizieR/J/ApJS/133/1
Title:
GIS catalog project : source catalog
Short Name:
J/ApJS/133/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first X-ray source catalog of the ASCA Medium Sensitivity Survey (AMSS, or the GIS catalog project), constructed from data at Galactic latitudes |b|>10{deg} observed between 1993 May and 1996 December. The catalog utilizes 368 combined fields and contains 1343 sources with the detection significance above 5{sigma} either in the survey bands of 0.7-7keV, 2-10keV, or 0.7-2keV, including target sources. For each source, the ASCA source name, position, a 90% error radius, count rates in the three bands, detection significances, fluxes, and a hardness ratio are provided. With extensive simulations, we carefully evaluate the data quality of the catalog. Results from cross-correlation with other existing catalogs are briefly summarized.