Faint radio sources in GOODS-N and -S. I. VLA 5GHz
Short Name:
J/ApJ/875/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results from the deep and wide 5GHz radio observations of the Great Observatories Origins Deep Survey (GOODS)-North ({sigma}=3.5{mu}Jy/beam, synthesized beam size {theta}=1.47"x1.42", and 52 sources over 109arcmin^2^) and GOODS-South ({sigma}=3.0{mu}Jy/beam, {theta}=0.98"x0.45", and 88 sources over 190arcmin^2^) fields using the Karl G. Jansky Very Large Array. We derive radio spectral indices {alpha} between 1.4 and 5GHz using the beam-matched images and show that the overall spectral index distribution is broad even when the measured noise and flux bias are considered. We also find a clustering of faint radio sources around {alpha}=0.8, but only within S_5GHz_<150{mu}Jy. We demonstrate that the correct radio spectral index is important for deriving accurate rest-frame radio power and analyzing the radio-FIR correlation, and adopting a single value of {alpha}=0.8 leads to a significant scatter and a strong bias in the analysis of the radio-FIR correlation, resulting from the broad and asymmetric spectral index distribution. When characterized by specific star formation rates, the starburst population (58%) dominates the 5GHz radio source population, and the quiescent galaxy population (30%) follows a distinct trend in spectral index distribution and the radio-FIR correlation. Lastly, we offer suggestions on sensitivity and angular resolution for future ultra-deep surveys designed to trace the cosmic history of star formation and AGN activity using radio continuum as a probe.
A list of probable ring galaxies with a limiting magnitude of 17.5 has been prepared based on visual inspection of the film copies of the J SRC/ESO survey. About 88% of the sample of 125 selected objects seem to be new, hitherto unrecognized as ring galaxies. The candidate objects have been classified following the ring structure and the nucleus appearance.
Spitzer data at 24, 70, and 160um and ground-based H{alpha} images are analyzed for a sample of 189 nearby star-forming and starburst galaxies to investigate whether reliable star formation rate (SFR) indicators can be defined using the monochromatic infrared dust emission centered at 70 and 160um. We compare recently published recipes for SFR measures using combinations of the 24um and observed H{alpha} luminosities with those using 24um luminosity alone. From these comparisons, we derive a reference SFR indicator for use in our analysis. Linear correlations between SFR and the 70um and 160um luminosity are found for L(70)>~1.4x10^42^erg/s and L(160)>~2x10^42^erg/s, corresponding to SFR>~0.1-0.3M_{sun}_/yr, and calibrations of SFRs based on L(70) and L(160) are proposed. Below those two luminosity limits, the relation between SFR and 70um (160um) luminosity is nonlinear and SFR calibrations become problematic. A more important limitation is the dispersion of the data around the mean trend, which increases for increasing wavelength.
We present the catalogs and source counts for the C_90_ (reference wavelength of 90um) and C_160_ (170um) bands, which were extracted from our analysis of an ISO deep far-infrared survey conducted as part of the Japan/UH ISO cosmology project. The total survey area is ~0.9deg^2^ in two fields within the Lockman Hole. The analysis consists of source extraction using the IRAF DAOPHOT package and simulations carried out by adding artificial sources to the maps to estimate the detection rate, the flux bias, the positional accuracy, and the noise.
The second part of the First Byurakan Survey is aimed at detecting all bright (B<16.5) UV-excess starlike objects in a large area of the sky. By comparison with other major surveys such as the ROSAT All Sky Survey (Cat. <IX/10>, the ROSAT WGACAT (Cat. <IX/12>) catalogue of point sources, the IRAS (Cat. <II/125>) survey, the 6cm Green Bank (Cat. <VIII/52>, the 1.4GHz NRAO VLA (Cat. <J/AJ/115/1693>, and the 92cm Westerbork Northern sky surveys (Cat. <VIII/62>) and with the catalogue of mean UBV data on stars, we estimate the number of AGNs present in the FBS survey and its completeness. We have made spectroscopic observations of nine of the most promising FBS candidates. We have found six new QSOs, bringing the total number of known QSOs in this survey to 42. By comparison with the Bright Quasar Survey, we found that the completeness of this last survey is of the order of 70% rather than 30-50% as suggested by several authors.
The thirteenth list of faint late M and carbon type stars detected on the plates of the First Byurakan Spectral Sky Survey in zone +1{deg}<={delta}<=+13{deg} covering about 3118 sq. degrees is presented. From 285 stars, 161 are newly detected objects: they are 17 carbon stars, 25 carbon star candidates, and 117 M-type stars. The spectral type of two objects is assumed to be between M8 - M9 or late N-subtypes. Among 161 objects, 85 (66 PSC + 19 FSC) are unclassified IRAS sources. Accurate positions, spectral classes, red magnitudes, and color indices are given using several astronomical databases. Finding charts from DSS are given for the most interesting objects.
We present the fourteenth list of faint late M and carbon type stars detected on the plates of the First Byurakan Spectral Sky Survey in the zone +13{deg}<=DE<=+33{deg} covering about 4736deg^2^. From 260 stars, 118 are newly detected objects: they are 19 carbon stars, 5 carbon star candidates, and 94 M-type stars. Among 118 detected objects 73 (57 PSC + 16 FSC) are unclassified IRAS sources. Accurate positions, spectral classes, red magnitudes, color indices, and near-infrared J, H and K photometry are given, using several astronomical databases. Finding charts from DSS are given for the most interesting objects.
We present the fifteenth list of faint late M and Carbon type stars detected on the Digitized First Byurakan Survey (DFBS) spectral plates in the zone with +45{deg}<={delta}<=+49{deg} covering 678.4{deg}^2^. Accurate DSS2 positions, USNO-B1.0 B, R, and I magnitudes, 2MASS near-infrared J, H, and Ks photometry, IRAS PSC/FSC fluxes (when available), approximate spectral types and luminosity class estimations are given for 72 objects from which 9 are new confirmed carbon stars and 63 are M-type stars. For seven Mirids with known pulsation periods the absolute luminosities are derived, using Period-Luminosity relations. Absolute visual magnitudes and distances for five M dwarfs are estimated, using V-I color index. The object FBS 0845+466 is a candidate carbon dwarf with distance r~72pc.
We construct full broad-band models in an analysis of Suzaku observations of nearby Seyfert 1 active galactic nuclei (AGN) (z<=0.2) with exposures >50ks and with greater than 30000 counts in order to study their iron line profiles. This results in a sample of 46 objects and 84 observations. After a full modelling of the broad-band Suzaku and Swift-Burst Alert Telescope data (0.6-100keV), we find complex warm absorption is present in 59 per cent of the objects in this sample which has a significant bearing upon the derived FeK region parameters. Meanwhile 35 per cent of the 46 objects require some degree of high column density partial coverer in order to fully model the hard X-ray spectrum. We also find that a large number of the objects in the sample (22 per cent) require high velocity, high ionization outflows in the FeK region resulting from FeXXV and FeXXVI. A further four AGN feature highly ionized FeK absorbers consistent with zero outflow velocity, making a total of 14/46 (30%) AGN in this sample showing evidence for statistically significant absorption in the FeK region.