- ID:
- ivo://CDS.VizieR/J/ApJ/724/714
- Title:
- Velocity dispersions of MS1054-03 & Coma galaxies
- Short Name:
- J/ApJ/724/714
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured velocity dispersions ({sigma}) for a sample of 36 galaxies with J<21.2 or M_r_<-20.6mag in MS 1054-03, a massive cluster of galaxies at z=0.83. Our data are of uniformly high quality down to our selection limit, our 16h exposures typically yielding errors of only {delta}({sigma})~10% for L* and fainter galaxies. By combining our measurements with data from the literature, we have 53 cluster galaxies with measured dispersions, and HST/ACS-derived sizes, colors and surface brightness. This sample is complete for the typical L^*^ galaxy at z~1, unlike most previous z~1 cluster samples which are complete only for the massive cluster members (>10^11^M_{sun}_). We find no evidence for a change in the tilt of the fundamental plane (FP).
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- ID:
- ivo://CDS.VizieR/J/MNRAS/465/3784
- Title:
- Very thin discs galaxies properties
- Short Name:
- J/MNRAS/465/3784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the properties of galaxies with very thin discs (VTDs) using a sample of 85 objects whose stellar disc radial-to-vertical scale ratio determined from photometric decomposition, exceeds 9. We present evidences of similarities between the VTD galaxies and low surface brightness (LSB) disc galaxies, and conclude that both small and giant LSB galaxies may reveal themselves as VTD, edge-on galaxies. Our VTD galaxies are mostly bulgeless, and those with large radial scalelength tend to have redder colours. We performed spectral observations of 22 VTD galaxies with the Dual Imaging Spectrograph on the 3.5 m telescope at the Apache Point Observatory. The spectra with good resolution (R~5000) allow us to determine the distance and the ionized gas rotation curve maximum for the galaxies. Our VTD galaxies have low dust content, in contrast to regular disc galaxies. Apparently, VTD galaxies reside in specific cosmological low-density environments and tend to have less connection with filaments. Comparing a toy model that assumes marginally low star formation in galactic discs with obtained gas kinematics data, we conclude that there is a threshold central surface density of about 88M_{sun}_/pc^2^, which we observe in the case of very thin, rotationally supported galactic discs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/502/4815
- Title:
- Very young galaxies in the local Universe
- Short Name:
- J/MNRAS/502/4815
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the local Universe, there are a handful of dwarf compact star-forming galaxies with extremely low oxygen abundances. It has been proposed that they are young, having formed a large fraction of their stellar mass during their last few hundred Myr. However, little is known about the fraction of young stellar populations in more massive galaxies. In a previous article, we analysed 404000 Sloan Digital Sky Survey spectra to identify a surprisingly large sample of more massive very young galaxies (VYGs), defined to have formed at least 50 per cent of their stellar mass within the last 1Gyr. Here, we investigate in detail the properties of a subsample of 207 galaxies that are VYGs according to all three of our spectral models. We compare their properties with those of control sample galaxies (CSGs). We find that VYGs tend to have higher surface brightness and to be more compact, dusty, asymmetric, and clumpy than CSGs. Analysis of a subsample with H I detections reveals that VYGs are more gas rich than CSGs. VYGs tend to reside more in the inner parts of low-mass groups and are twice as likely as CSGs to be interacting with a neighbour galaxy. On the other hand, VYGs and CSGs have similar gas metallicities and large-scale environments (relative to filaments and voids). These results suggest that gas-rich interactions and mergers are the main mechanisms responsible for the recent triggering of star formation in low-redshift VYGs, except for the lowest mass VYGs, where the starbursts would arise from a mixture of mergers and gas infall.
- ID:
- ivo://CDS.VizieR/J/ApJ/453/48
- Title:
- VI photometry of HST faint field galaxies
- Short Name:
- J/ApJ/453/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0=<Imag<22.0mag. We compare the global properties of the ellipticals and early- and late-type spirals and find a non-negligible fraction (13/144) of compact blue [(V-I)<1.0mag] systems with r^1/4^ profiles. We give the differential galaxy number counts for ellipticals and early-type spirals independently and find that the data are consistent with no-evolution predictions based on conventional flat Schechter luminosity functions (LFs) and a standard cosmology. Conversely, late-type/irregulars show a steeply rising differential number count with slope ({delta}logN/{delta}m)=0.64+/-0.1. No-evolution models based on the Loveday et al. (1992ApJ...390..338L) and Marzke et al. (1994AJ....108..437M & 1994ApJ...428...43M) local luminosity functions underpredict the late-type/irregular counts by 1.0 and 0.5dex, respectively, at Imag=21.75mag. Examination of the irregulars alone shows that ~50% appear inert and the remainder have multiple cores. If the inert galaxies represent a non-evolving late-type population, then a Loveday-like LF ({alpha}=~-1.0) is ruled out for these types, and an LF with a steep faint end ({alpha}=~-1.5) is suggested. If multiple core structure indicates recent star formation, then the observed excess of faint blue field galaxies is likely a result of et evolutionary processes acting on a steep field LF for late-type/irregulars. The evolutionary mechanism is unclear, but 60% of the multiple-core irregulars show close companions. To reconcile a Marzke-like LF with the faint redshift surveys, this evolution must be preferentially occurring in the brightest late-type galaxies with z>=0.5 at m_I_=21.75mag.
- ID:
- ivo://CDS.VizieR/J/A+A/343/86
- Title:
- Virgo cluster radio luminosity function. I.
- Short Name:
- J/A+A/343/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We cross-correlate the galaxies brighter than m_B_=18 in the Virgo cluster with the radio sources in the NVSS survey (1.4GHz), resulting in 180 radio-optical identifications. We determine the radio luminosity function of the Virgo galaxies, separately for the early- and late-types. Late-type galaxies develop radio sources with a probability proportional to their optical luminosity. In fact their radio/optical (R_B_) distribution is gaussian, centered at log R_B_~-0.5, i.e. the radio luminosity is ~0.3 of the optical one. The probability of late-type galaxies to develop radio sources is almost independent of their detailed Hubble type, except for Sa (and S0+S0a) which are a factor of ~5 less frequent than later types at any R_B_. Giant elliptical galaxies feed "monster" radio sources with a probability strongly increasing with mass. However the frequency of fainter radio sources is progressively less sensitive on the system mass. The faintest giant E galaxies (M_B_=-17) have a probability of feeding low power radio sources similar to that of dwarf E galaxies as faint as M_B_=-13.
- ID:
- ivo://CDS.VizieR/II/286
- Title:
- VIRMOS deep imaging survey. VVDS-F02 catalog
- Short Name:
- II/286
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Franco-Italian VIRMOS project has delivered the VIMOS spectrograph for the European Southern Observatory Very Large Telescope (ESO-VLT). VIMOS is a VIsible imaging Multi-Object Spectrograph with outstanding multiplex capabilities: with 10 arcsec slits, spectra can be taken of 600 objects simultaneously. In integral field mode, a 6400-fibre Integral Field Unit (IFU) provides spectroscopy for all objects covering a 54x54arcsec^2^ area.
- ID:
- ivo://CDS.VizieR/J/ApJS/205/13
- Title:
- VLA 1.4GHz survey of ECDF-S (DR2)
- Short Name:
- J/ApJS/205/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep radio observations at 1.4GHz for the Extended Chandra Deep Field South were performed in 2007 June through September and presented in a first data release. The survey was made using six separate pointings of the Very Large Array with over 40hr of observation per pointing. In the current paper, we improve on the data reduction to produce a second data release (DR2) mosaic image. This DR2 image covers an area of about a third of a square degree, reaches a best rms sensitivity of 6uJy, and has a typical sensitivity of 7.4uJy per 2.8" by 1.6" beam. We also present a more comprehensive catalog, including sources down to peak flux densities of five or more times the local rms noise along with information on source sizes and relevant pointing data. We discuss in some detail the consideration of whether sources are resolved under the complication of a radio image created as a mosaic of separate pointings each suffering some degree of bandwidth smearing, and the accurate evaluation of the flux densities of such sources. Finally, the radio morphologies and optical/near-IR counterpart identifications are used to identify 17 likely multiple-component sources and arrive at a catalog of 883 radio sources, which is roughly double the number of sources contained in the first data release.
- ID:
- ivo://CDS.VizieR/J/MNRAS/498/1278
- Title:
- VLA NLS1s southern sample
- Short Name:
- J/MNRAS/498/1278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of new radio observations carried out with the Karl G. Jansky Very Large Array C-configuration at 5.5GHz for a sample of southern narrow-line Seyfert 1 galaxies (NLS1s). This work increases the number of known radio-detected NLS1s in the southern hemisphere, and confirms that the radio emission of NLS1s is mainly concentrated in a central region at kpc-scale and only a few sources show diffuse emission. In radio-quiet NLS1s, the radio luminosity tends to be higher in steep-spectrum sources and be lower in flat-spectrum sources, which is opposite to radio-loud NLS1s. This may be because the radio emission of steep NLS1s is dominated by misaligned jets, AGN-driven outflows, or star formation superposing on a compact core. Instead the radio emission of flat NLS1s may be produced by a central core which has not yet developed radio jets and outflows. We discover new NLS1s harboring kpc-scale radio jets and confirm that a powerful jet does not require a large-mass black hole to be generated. We also find sources dominated by star formation. These NLS1s could be new candidates in investigating the radio emission of different mechanisms.
- ID:
- ivo://CDS.VizieR/J/AJ/151/74
- Title:
- VLA/VLBA obscured radio-loud active galactic nuclei
- Short Name:
- J/AJ/151/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Yan et al. 2012AJ....144..124Y. In this paper, we present both high-resolution radio continuum images for all of these sources and H I 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.5" and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ~three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H I 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral "window" (i.e., the percentage of H I 21 cm absorption-line detections could be as high as ~90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H I detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H I absorption may well be present but is masked by the RFI. Future searches for highly redshifted H I and molecular absorption can easily find more distant CSOs among bright, "blank field" radio sources, but will be severely hampered by an inability to determine accurate spectroscopic redshifts due to their lack of rest-frame UV continuum.
- ID:
- ivo://CDS.VizieR/J/AJ/127/3609
- Title:
- VLBI observations of southern ICRF sources
- Short Name:
- J/AJ/127/3609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 8.4GHz very long baseline interferometry (VLBI) observations of 69 southern hemisphere extragalactic sources in the International Celestial Reference Frame. These are the first in a series of observations intended to image all such sources at milliarcsecond resolution in order to determine their continued suitability for reference-frame use based on intrinsic structure. We use the resultant images to calculate a core fraction, that is, the ratio of core flux density to total flux density, for all observed sources. The resulting distribution, with a mean value of 0.83, suggests that most sources are relatively compact. However, just over half the observed sources show significant extended emission in the form of multiple compact components. These sources are probably poorly suited for high-accuracy reference-frame use unless intrinsic structure and potential variability can be taken into account. Our observations represent the first large, comprehensive VLBI imaging survey in the southern hemisphere, significantly extending the existing limited VLBI surveys and, along with some well-known objects, containing many sources that have never been imaged at milliarcsecond resolution. The overlap with Very Long Baseline Array images of sources between 0{deg} and -35{deg} declination helps determine the limits to imaging with the southern hemisphere-accessible telescopes.
