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1361. Globulars with X-ray sources in NGC 5128
ID:
ivo://CDS.VizieR/J/ApJ/682/199
Title:
Globulars with X-ray sources in NGC 5128
Short Name:
J/ApJ/682/199
Date:
21 Oct 2021
Publisher:
CDS
Description:
We detect 353 X-ray point sources, mostly low-mass X-ray binaries (LMXBs), in four Chandra observations of Centaurus A (NGC 5128), the nearest giant early-type galaxy, and correlate this point-source population with the largest available ensemble of confirmed and likely globular clusters (GCs) associated with this galaxy. Of the X-ray sources, 31 are coincident with 30 GCs that are confirmed members of the galaxy by radial velocity measurement (two X-ray sources match one GC within our search radius), while one X-ray source coincides with a GC resolved by Hubble Space Telescope (HST) images. Another 36 X-ray point sources match probable, but spectroscopically unconfirmed, GC candidates.
1362. GMASS photometry
ID:
ivo://CDS.VizieR/J/A+A/549/A63
Title:
GMASS photometry
Short Name:
J/A+A/549/A63
Date:
21 Oct 2021
Publisher:
CDS
Description:
We designed a spectroscopic observing campaign of a sample of both massive, quiescent and star-forming galaxies at z>1.4, called Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS). To determine redshifts and physical properties, such as metallicity, dust content, dynamical masses, and star formation history, we performed ultra-deep spectroscopy with the red-sensitive optical spectrograph FORS2 at the VLT. Our sample consists of objects, within the CDFS/GOODS area, detected at 4.5 micron, to be sensitive to stellar mass rather than star formation intensity. The spectroscopic targets were selected with a photometric redshift constraint (z>1.4) and magnitude constraints (B(AB)<26, I(AB)<26.5), which should ensure that these are faint, distant, and fairly massive galaxies. Up to 30 hours of spectroscopy of 174 spectroscopic targets and 70 additional objects enabled us to determine 210 redshifts, of which 145 are at z>1.4. We publicly release the redshifts and reduced spectra.
1363. GMBCG galaxy cluster catalog from SDSS DR7
ID:
ivo://CDS.VizieR/J/ApJS/191/254
Title:
GMBCG galaxy cluster catalog from SDSS DR7
Short Name:
J/ApJS/191/254
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a large catalog of optically selected galaxy clusters from the application of a new Gaussian Mixture Brightest Cluster Galaxy (GMBCG) algorithm to SDSS Data Release 7 data. The algorithm detects clusters by identifying the red-sequence plus brightest cluster galaxy (BCG) feature, which is unique for galaxy clusters and does not exist among field galaxies. Red-sequence clustering in color space is detected using an Error Corrected Gaussian Mixture Model. We run GMBCG on 8240 deg^2^ of photometric data from SDSS DR7 to assemble the largest ever optical galaxy cluster catalog, consisting of over 55,000 rich clusters across the redshift range from 0.1<z<0.55. We present Monte Carlo tests of completeness and purity and perform cross-matching with X-ray clusters and with the maxBCG sample at low redshift. These tests indicate high completeness and purity across the full redshift range for clusters with 15 or more members.
1364. GMOS-IFU spectroscopy of dwarf galaxy HS 2236+1344
ID:
ivo://CDS.VizieR/J/A+A/569/A110
Title:
GMOS-IFU spectroscopy of dwarf galaxy HS 2236+1344
Short Name:
J/A+A/569/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
The main goal of this study is to carry out a spatially resolved investigation of the warm interstellar medium (ISM) in the extremely metal-poor blue compact dwarf galaxy HS 2236+1344. Special emphasis is laid on the analysis of the spatial distribution of chemical abundances, emission-line ratios and kinematics of the ISM, and to the recent star-forming activity in this galaxy.
1365. GMOS spectroscopic obs. of SNR candidates in M83
ID:
ivo://CDS.VizieR/J/ApJ/839/83
Title:
GMOS spectroscopic obs. of SNR candidates in M83
Short Name:
J/ApJ/839/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results from a spectrophotometric study sampling the 300 candidate supernova remnants (SNRs) in M83 identified through optical imaging with Magellan/IMACS and Hubble Space Telescope/WFC3. Of the 118 candidates identified based on a high [SII]{lambda}{lambda}6716,6731 to H{alpha} emission ratio, 117 show spectroscopic signatures of shock-heated gas, confirming them as SNRs-the largest uniform set of SNR spectra for any galaxy. Spectra of 22 objects with a high [OIII]{lambda}5007 to H{alpha} emission ratio, selected in an attempt to identify young ejecta-dominated SNRs like Cas A, reveal only one (previously reported) object with the broad (1000km/s) emission lines characteristic of ejecta-dominated SNRs, beyond the known SN1957D remnant. The other 20 [OIII]-selected candidates include planetary nebulae, compact HII regions, and one background QSO. Although our spectroscopic sample includes 22 SNRs smaller than 11pc, none of the other objects show broad emission lines; instead their spectra stem from relatively slow (~200km/s) radiative shocks propagating into the metal-rich interstellar medium of M83. With six SNe in the past century, one might expect more of M83's small-diameter SNRs to show evidence of ejecta; this appears not to be the case. We attribute their absence to several factors, including that SNRs expanding into a dense medium evolve quickly to the ISM-dominated phase, and that SNRs expanding into regions already evacuated by earlier SNe are probably very faint.
1366. GMOS/WIYN spectroscopic catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/405/2243
Title:
GMOS/WIYN spectroscopic catalogue
Short Name:
J/MNRAS/405/2243
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the largest spectroscopic follow-up performed in SWIRE ELAIS-N1. We were able to determine redshifts for 289 extragalactic sources. The values of spectroscopic redshifts of the latter have been compared with the estimated values from our photometric redshift code with very good agreement between the two for both galaxies and quasars.
1367. GMRT 153MHz (2m) Radio Mini Survey I.
ID:
ivo://CDS.VizieR/J/A+A/549/A55
Title:
GMRT 153MHz (2m) Radio Mini Survey I.
Short Name:
J/A+A/549/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present wide area, deep, high-resolution 153MHz GMRT observations of the NOAO Bootes field, adding to the extensive, multi-wavelength data of this region. The observations, data reduction, and catalogue construction and description are described here. The seven pointings produced a final mosaic covering 30 square degrees with a resolution of 25". The rms noise is 2mJy/beam in the centre of the image, rising to 4-5mJy/beam on the edges, with an average of 3mJy/beam. Seventy-five per cent of the area has an rms <4mJy/beam. The extracted source catalogue contains 1289 sources detected at 5{sigma}, of which 453 are resolved. We estimate the catalogue to be 92 per cent reliable and 95 per cent complete at an integrated flux density limit of 14mJy. The flux densities and astrometry have been corrected for systematic errors. We calculate the differential source counts which are in good agreement with those in the literature and provide an important step forward in quantifying the source counts at these low frequencies and low flux densities. The GMRT 153MHz sources have been matched to the 1.4GHz NVSS and 327MHz WENSS catalogues and spectral indices were derived.
1368. GMRT observations of head-tail radio galaxies
ID:
ivo://CDS.VizieR/J/AJ/154/169
Title:
GMRT observations of head-tail radio galaxies
Short Name:
J/AJ/154/169
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a study of seven large known head-tail radio galaxies based on observations using the Giant Metrewave Radio Telescope at 240 and 610 MHz. These observations are used to study the radio morphologies and distribution of the spectral indices across the sources. The overall morphology of the radio tails of these sources is suggestive of random motions of the optical host around the cluster potential. The presence of multiple bends and wiggles in several head-tail sources is possibly due to the precessing radio jets. We find steepening of the spectral index along the radio tails. The prevailing equipartition magnetic field also decreases along the radio tails of these sources. These steepening trends are attributed to the synchrotron aging of plasma toward the ends of the tails. The dynamical ages of these sample sources have been estimated to be ~10^8^ yr, which is a factor of six more than the age estimates from the radiative losses due to synchrotron cooling.
1369. GMRT radios sources around J0916+6348 field
ID:
ivo://CDS.VizieR/J/MNRAS/392/1403
Title:
GMRT radios sources around J0916+6348 field
Short Name:
J/MNRAS/392/1403
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep multifrequency observations using the Giant Metrewave Radio Telescope (GMRT) at 153, 244, 610 and 1260MHz of a field centred on J0916+6348, to search for evidence of fossil radio lobes which could be due to an earlier cycle of episodic activity of the parent galaxy, as well as haloes and relics in clusters of galaxies. We do not find any unambiguous evidence of episodic activity in a list of 374 sources, suggesting that such activity is rare even in relatively deep low-frequency observations. We examine the spectra of all the sources by combining our observations with those from the Westerbork Northern Sky Survey (WENSS), NRAO (National Radio Astronomy Observatories) VLA (Very Large Array) Sky Survey (NVSS) and the Faint Images of the Radio Sky at Twenty-Centimeters Survey (FIRST).
1370. GMVA 86GHz Stokes IQU images of 3C84 jet
ID:
ivo://CDS.VizieR/J/A+A/622/A196
Title:
GMVA 86GHz Stokes IQU images of 3C84 jet
Short Name:
J/A+A/622/A196
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report results from a deep polarization imaging of the nearby radio galaxy 3C 84 (NGC 1275). The source was observed with the Global Millimeter VLBI Array (GMVA) at 86GHz at an ultrahigh angular resolution of 50{mu}as (corresponding to 200Rs). We also add complementary multiwavelength data from the Very Long Baseline Array (VLBA; 15 & 43GHz) and from the Atacama Large Millimeter/submillimeter Array (ALMA; 97.5, 233.0, and 343.5GHz). At 86GHz, we measured a fractional linear polarization of ~2% in the VLBI core region. The polarization morphology suggests that the emission is associated with an underlying limb-brightened jet. The fractional linear polarization is lower at 43 and 15GHz (~0.3-0.7% and <0.1%, respectively). This suggests an increasing linear polarization degree toward shorter wavelengths on VLBI scales. We also obtain a large rotation measure (RM) of ~10^5-6^rad/m^2^ in the core at >~43GHz. Moreover, the VLBA 43GHz observations show a variable RM in the VLBI core region during a small flare in 2015. Faraday depolarization and Faraday conversion in an inhomogeneous and mildly relativistic plasma could explain the observed linear polarization characteristics and the previously measured frequency dependence of the circular polarization. Our Faraday depolarization modeling suggests that the RM most likely originates from an external screen with a highly uniform RM distribution. To explain the large RM value, the uniform RM distribution, and the RM variability, we suggest that the Faraday rotation is caused by a boundary layer in a transversely stratified jet. Based on the RM and the synchrotron spectrum of the core, we provide an estimate for the magnetic field strength and the electron density of the jet plasma.

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