Search

Start Over Subject radio astronomy Subject galaxies
1. Abundance of X-shaped radio sources. I. VLA survey
ID:
ivo://CDS.VizieR/J/ApJS/220/7
Title:
Abundance of X-shaped radio sources. I. VLA survey
Short Name:
J/ApJS/220/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
Cheung (2007, J/AJ/133/2097) identified a sample of 100 candidate X-shaped radio galaxies using the NRAO FIRST survey; these are small-axial-ratio extended radio sources with off-axis emission. Here, we present radio images of 52 of these sources that have been made from archival Very Large Array data with resolution of about 1". Fifty-one of the 52 were observed at 1.4GHz, 7 were observed at 1.4 and 5GHz, and 1 was observed only at 5GHz. We also present overlays of the Sloan Digital Sky Survey red images for 48 of the sources, and DSS-II overlays for the remainder. Optical counterparts have been identified for most sources, but there remain a few empty fields. Our higher resolution VLA images along with FIRST survey images of the sources in the sample reveal that extended extragalactic radio sources with small axial ratios are largely (60%) cases of double radio sources with twin lobes that have off-axis extensions, usually with inversion-symmetric structure. The available radio images indicate that at most 20% of sources might be genuine X-shaped radio sources that could have formed by a restarting of beams in a new direction following an interruption and axis flip. The remaining 20% are in neither of these categories.
2. A case study of the HI content of HCG 16
ID:
ivo://CDS.VizieR/J/A+A/632/A78
Title:
A case study of the HI content of HCG 16
Short Name:
J/A+A/632/A78
Date:
21 Oct 2021
Publisher:
CDS
Description:
Hickson Compact Group (HCG) 16 is a prototypical compact group of galaxies in an intermediate stage of the evolutionary sequence proposed by Verdes-Montenegro et al. (2001A&A...377..812V), where its galaxies are losing gas to the intra-group medium (IGrM). The group hosts galaxies that are HI-normal, HI-poor, centrally active with both AGN and starbursts, as well as a likely new member and a 160kpc long HI tidal feature. Despite being a well-studied group at all wavelengths, no previous study of HCG 16 has focused on its extraordinary HI component. The characteristics of HCG 16 make it an ideal case study for exploring which processes are likely to dominate the late stages of evolution in compact groups, and ultimately determine their end states. In order to build a coherent picture of the evolution of this group we make use of the multi-wavelength data available, but focus particularly on HI as a tracer of interactions and evolutionary phase. We reprocess archival VLA L-band observations of HCG 16 using the multi-scale CLEAN algorithm to accurately recover diffuse features. Tidal features and galaxies are separated in 3 dimensions using the SlicerAstro package. The HI deficiency of the separated galaxies is assessed against the benchmark of recent scaling relations of isolated galaxies. This work has been performed with particular attention to reproducibility and is accompanied by a complete workflow to reproduce all the final data products, figures, and results. Despite the clear disruption of the HI component of HCG 16 we find that it is not globally HI deficient, even though HCG 16a and b have lost the majority of their HI and almost 50% of the group's HI is in the IGrM. The HI content of HCG 16d shows highly disturbed kinematics, with only a marginal velocity gradient that is almost perpendicular to its optical major axis. The ~160kpc long tail extending towards the South-East appears to be part of an even larger structure which spatially and kinematically connects NGC 848 to the North-West corner of the group. This study indicates that in the recent past (1Gyr) galaxies HCG 16a and b likely underwent major interactions that unbound gas without triggering significant star formation. This gas was then swept away by a high speed, close encounter with NGC 848. The starburst events HCG 16c and d, likely initiated by their mutual interaction, have triggered galactic winds which, in the case of HCG 16d, appears to have disrupted its HI reservoir. The tidal features still connected to all these galaxies indicate that more HI will soon be lost to the IGrM, while that which remains in the discs will likely be consumed by star formation episodes triggered by their on-going interaction. This is expected to result in a collection of gas-poor galaxies embedded in a diffuse HI structure, which will gradually (over several Gyr) be evaporated by the UV background, resembling the final stage of the evolutionary model of compact groups.
3. ACT high significance 148 and 218GHz sources
ID:
ivo://CDS.VizieR/J/MNRAS/439/1556
Title:
ACT high significance 148 and 218GHz sources
Short Name:
J/MNRAS/439/1556
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of 191 extragalactic sources detected by the Atacama Cosmology Telescope (ACT) at 148 and/or 218GHz in the 2008 Southern survey. Flux densities span 14 -1700mJy, and we use source spectral indices derived using ACT-only data to divide our sources into two subpopulations: 167 radio galaxies powered by central active galactic nuclei (AGN) and 24 dusty star-forming galaxies (DSFGs). We cross-identify 97 percent of our sources (166 of the AGN and 19 of the DSFGs) with those in currently available catalogues. When combined with flux densities from the Australia Telescope 20GHz survey and follow-up observations with the Australia Telescope Compact Array, the synchrotron-dominated population is seen to exhibit a steepening of the slope of the spectral energy distribution from 20 to 148GHz, with the trend continuing to 218GHz. The ACT dust-dominated source population has a median spectral index, {alpha}_148-218_, of 3.7^+0.62^_-0.86_, and includes both local galaxies and sources with redshift around 6. Dusty sources with no counterpart in existing catalogues likely belong to a recently discovered subpopulation of DSFGs lensed by foreground galaxies or galaxy groups.
4. Active radio galaxies in cluster A569
ID:
ivo://CDS.VizieR/J/AZh/79/963
Title:
Active radio galaxies in cluster A569
Short Name:
J/AZh/79/963
Date:
21 Oct 2021
Publisher:
CDS
Description:
The nature of bright radio sources with known radio spectra in the direction of the nearby cluster of galaxies A569 (z=0.0193) is investigated. The optical identifications of the sources were provided. 45% of these radio sources are associated with compact galaxies. A substantial fraction of these galaxies have active nuclei. Some of them have radio halos.
5. A deep Chandra ACIS survey of M83
ID:
ivo://CDS.VizieR/J/ApJS/212/21
Title:
A deep Chandra ACIS survey of M83
Short Name:
J/ApJS/212/21
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained a series of deep X-ray images of the nearby galaxy M83 using Chandra, with a total exposure of 729ks. Combining the new data with earlier archival observations totaling 61ks, we find 378 point sources within the D_25_ contour of the galaxy. We find 80 more sources, mostly background active galactic nuclei (AGNs), outside of the D_25_contour. Of the X-ray sources, 47 have been detected in a new radio survey of M83 obtained using the Australia Telescope Compact Array. Of the X-ray sources, at least 87 seem likely to be supernova remnants (SNRs), based on a combination of their properties in X-rays and at other wavelengths. We attempt to classify the point source population of M83 through a combination of spectral and temporal analysis. As part of this effort, we carry out an initial spectral analysis of the 29 brightest X-ray sources. The soft X-ray sources in the disk, many of which are SNRs, are associated with the spiral arms, while the harder X-ray sources, mostly X-ray binaries (XRBs), do not appear to be. After eliminating AGNs, foreground stars, and identified SNRs from the sample, we construct the cumulative luminosity function (CLF) of XRBs brighter than 8x10^35^erg/s. Despite M83's relatively high star formation rate, the CLF indicates that most of the XRBs in the disk are low mass XRBs.
6. ALMA Frontier Fields Survey. I.
ID:
ivo://CDS.VizieR/J/A+A/597/A41
Title:
ALMA Frontier Fields Survey. I.
Short Name:
J/A+A/597/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dusty star-forming galaxies are among the most prodigious systems at high redshift (z>1), characterized by high star-formation rates and huge dust reservoirs. The bright end of this population has been well characterized in recent years, but considerable uncertainties remain for fainter dusty star-forming galaxies, which are responsible for the bulk of star formation at high redshift and thus play a key role in galaxy growth and evolution. In this first paper of our series, we describe our methods for finding high redshift faint dusty galaxies using millimeter observations with ALMA. We obtained ALMA 1.1mm mosaic images for three strong-lensing galaxy clusters from the Frontier Fields Survey, which constitute some of the best studied gravitational lenses to date. The ~2'x2' mosaics overlap with the deep HST WFC3/IR footprints and encompass the high magnification regions of each cluster for maximum intrinsic source sensitivity. The combination of extremely high ALMA sensitivity and the magnification power of these clusters allows us to systematically probe the sub-mJy population of dusty star-forming galaxies over a large surveyed area. We present a description of the reduction and analysis of the ALMA continuum observations for the galaxy clusters Abell 2744 (z=0.308), MACS J0416.1-2403 (z=0.396) and MACS J1149.5+2223 (z=0.543), for which we reach observed rms sensitivities of 55, 59 and 71uJy/beam respectively. We detect 12 dusty star-forming galaxies at S/N>=5.0 across the three clusters, all of them presenting coincidence with near-infrared detected counterparts in the HST images. None of the sources fall close to the lensing caustics, thus they are not strongly lensed. The observed 1.1mm flux densities for the total sample of galaxies range from 0.41 to 2.82mJy, with observed effective radii spanning <~0.05" to 0.37"+/-0.21". The lensing-corrected sizes of the detected sources appear to be in the same range as those measured in brighter samples, albeit with possibly larger dispersion.
7. ALMA Frontier Fields Survey. V.
ID:
ivo://CDS.VizieR/J/A+A/633/A160
Title:
ALMA Frontier Fields Survey. V.
Short Name:
J/A+A/633/A160
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Hubble Frontier Fields offer an exceptionally deep window into the high-redshift universe, covering a substantially larger area than the Hubble Ultra-Deep field at low magnification and probing 1-2mags deeper in exceptional high-magnification regions. This unique parameter space, coupled with the exceptional multi-wavelength ancillary data, can facilitate for useful insights into distant galaxy populations. We aim to leverage Atacama Large Millimetre Array (ALMA) band 6 (~263GHz) mosaics in the central portions of five Frontier Fields to characterize the infrared (IR) properties of 1582 ultraviolet (UV)-selected Lyman-Break Galaxies (LBGs) at redshifts of z~2-8. We investigated individual and stacked fluxes and IR excess (IRX) values of the LBG sample as functions of stellar mass (M_star), redshift, UV luminosity and slope {beta}, and lensing magnification. LBG samples were derived from color-selection and photometric redshift estimation with Hubble Space Telescope photometry. Spectral energy distributions (SED)-templates were fit to obtain luminosities, stellar masses, and star formation rates for the LBG candidates. We obtained individual IR flux and IRX estimates, as well as stacked averages, using both ALMA images and u-v visibilities. Two (2) LBG candidates were individually detected above a significance of 4.1-sigma, while stacked samples of the remaining LBG candidates yielded no significant detections. We investigated our detections and upper limits in the context of the IRX-M_star and IRX-{beta} relations, probing at least one dex lower in stellar mass than past studies have done. Our upper limits exclude substantial portions of parameter space and they are sufficiently deep in a handful of cases to create mild tension with the typically assumed attenuation and consensus relations. We observe a clear and smooth trend between M* and {beta}, which extends to low masses and blue (low) {beta} values, consistent with expectations from previous works.
8. ALMA submm galaxies multi-wavelength data
ID:
ivo://CDS.VizieR/J/ApJ/839/58
Title:
ALMA submm galaxies multi-wavelength data
Short Name:
J/ApJ/839/58
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a multi-wavelength analysis of 52 submillimeter galaxies (SMGs), identified using ALMA 870{mu}m continuum imaging in a pilot program to precisely locate bright SCUBA-2-selected submillimeter sources in the UKIDSS Ultra Deep Survey (UDS) field. Using the available deep (especially near-infrared) panoramic imaging of the UDS field at optical-to-radio wavelengths we characterize key properties of the SMG population. The median photometric redshift of the bright ALMA/SCUBA-2 UDS (AS2UDS) SMGs that are detected in a sufficient number of wavebands to derive a robust photometric redshift is z=2.65+/-0.13. However, similar to previous studies, 27% of the SMGs are too faint at optical-to-near-infrared wavelengths to derive a reliable photometric redshift. Assuming that these SMGs lie at z>~3 raises the median redshift of the full sample to z=2.9+/-0.2. A subset of 23 unlensed, bright AS2UDS SMGs have sizes measured from resolved imaging of their rest- frame far-infrared emission. We show that the extent and luminosity of the far-infrared emission are consistent with the dust emission arising from regions that are, on average, optically thick at a wavelength of {lambda}_0_>=75{mu}m (1{sigma} dispersion of 55-90{mu}m). Using the dust masses derived from our optically thick spectral energy distribution models, we determine that these galaxies have a median hydrogen column density of N_H_=9.8_-0.7_^+1.4^x10^23^cm^-2^, or a corresponding median V-band obscuration of Av=540_-40_^+80^mag, averaged along the line of sight to the source of their rest-frame ~200{mu}m emission. We discuss the implications of this extreme attenuation by dust for the multi-wavelength study of dusty starbursts and reddening-sensitive tracers of star formation.
9. AMIGA XIII. HI properties
ID:
ivo://CDS.VizieR/J/A+A/609/A17
Title:
AMIGA XIII. HI properties
Short Name:
J/A+A/609/A17
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the largest catalogue of HI single dish observations of isolated galaxies to date, as part of the multi-wavelength compilation being performed by the AMIGA project (Analysis of the interstellar Medium in Isolated GAlaxies). Despite numerous studies of the HI content of galaxies, no revision has been made for the most isolated L* galaxies since Haynes & Giovanelli (1984AJ.....89..758H). The AMIGA sample has been demonstrated to be almost "nurture free", therefore, by creating scaling relations for the HI content of these galaxies we will define a metric of HI normalcy in the absence of interactions. The catalogue comprises of our own HI observations with Arecibo, Effelsberg, Nancay and GBT, and spectra collected from the literature. In total we have measurements or constraints on the HI masses of 844 galaxies from the Catalogue of Isolated Galaxies (CIG). The multi-wavelength AMIGA dataset includes a revision of the B-band luminosities, optical diameters, morphologies, and isolation. Due to the large size of the catalogue, these revisions permit cuts to be made to ensure isolation and a high level of completeness, which was not previously possible. With this refined dataset we fit HI scaling relations based on luminosity, optical diameter and morphology. Our regression model incorporates all the data, including upper limits, and accounts for uncertainties in both variables, as well as distance uncertainties. The HI scaling relations of the AMIGA sample define an up-to-date metric of the HI content of almost "nurture free" galaxies. These relations allow the expected HI mass, in the absence of interactions, of an individual galaxy to be predicted to within 0.25dex (for typical measurement uncertainties). These relations are thus suitable for use as statistical measures of the impact of interactions on the neutral gas content of galaxies.
10. 6 and 20cm flux densities of radio galaxies
ID:
ivo://CDS.VizieR/J/A+A/342/378
Title:
6 and 20cm flux densities of radio galaxies
Short Name:
J/A+A/342/378
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss the "angular size-redshift" relation for compact radio sources distributed over a wide range of redshifts 0.011<=z<=4.72. Our study is based on a sample of 330 5 GHz VLBI contour maps taken from the literature. Unlike extended source samples, the "angular size - redshift" relation for compact radio sources appears consistent with the predictions of standard Friedmann world models with q_0_=~0.5 without the need to consider evolutionary or selection effects due to a "linear size-luminosity" dependence. By confining our analysis to sources having a spectral index, -0.38<={alpha}<=0.18, and a total radio luminosity, Lh^2^>= 10^26^W/Hz (H_0_=100hkm/s/Mpc, q_0_=0.5 used as a numerical example), we are able to restrict the dispersion in the "angular size-redshift" relation. The best fitting regression analysis in the framework of the Friedmann-Robertson-Walker model gives the value of the deceleration parameter q_0_=0.21+/-0.30 if there are no evolutionary or selection effects due to a "linear size-luminosity", "linear size-redshift" or "linear size-spectral index" dependence.