- ID:
- ivo://CDS.VizieR/J/A+A/601/A81
- Title:
- FIRST catalog of FR II radio galaxies
- Short Name:
- J/A+A/601/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We built a catalog of 122 FR II radio galaxies, called FRIICAT, selected from a published sample obtained by combining observations from the NVSS, FIRST, and SDSS surveys. The catalog includes sources with redshift <=0.15, an edge-brightened radio morphology, and those with at least one of the emission peaks located at radius r larger than 30 kpc from the center of the host. The radio luminosity at 1.4GHz of the FRIICAT sources covers the range L1.4~10^39.5^-10^42.5^erg/s. The FRIICAT catalog has 90% of low and 10% of high excitation galaxies (LEGs and HEGs), respectively. The properties of these two classes are significantly different. The FRIICAT LEGs are mostly luminous (-20>~Mr>~-24), red early-type galaxies with black hole masses in the range 10^8^<~M_BH_<~10^9^M_{sun}_; they are essentially indistinguishable from the FR Is belonging to the FRICAT. The HEG FR IIs are associated with optically bluer and mid-IR redder hosts than the LEG FR IIs and to galaxies and black holes that are smaller, on average, by a factor ~2. FR IIs have a factor ~3higher average radio luminosity than FR Is. Nonetheless, most (~90%) of the selected FR IIs have a radio power that is lower, by as much as a factor of ~100, than the transition value between FR Is and FR IIs found in the 3C sample. The correspondence between the morphological classification of FR I and FR II and the separation in radio power disappears when including sources selected at low radio flux thresholds, which is in line with previous results. In conclusion, a radio source produced by a low power jet can be edge brightened or edge darkened, and the outcome is not related to differences in the optical properties of the host galaxy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/607/60
- Title:
- FIRST-2MASS faint sources
- Short Name:
- J/ApJ/607/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a sample of bright near-infrared sources that are detected at radio wavelengths but undetected on the first-generation Palomar Observatory Sky Survey (POSSI) plates in order to search for a population of dust-obscured quasars. Optical and infrared spectroscopic follow-up of the sample has led to the discovery of 17 heavily reddened quasars (B-K>6.5), 14 of which are reported here for the first time. This has allowed us to define a region in the R-K, J-K color plane in which 50% of the radio-selected objects are highly reddened quasars. We compare the surface density of this previously overlooked population to that of ultraviolet-excess radio-selected quasars, finding that they make up ~20% of the total quasar population for K<~15.5.
- ID:
- ivo://CDS.VizieR/J/AJ/121/1872
- Title:
- FIRST radio-selected QSOs
- Short Name:
- J/AJ/121/1872
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained single-epoch optical photometry for 202 quasars, taken from the FIRST Bright Quasar Survey (FBQS), which span a wide range in radio loudness. Comparison with the magnitudes of these objects on the POSS-I plates provides by far the largest sample of long-term variability amplitudes for radio-selected quasars yet produced. We find the quasars to be more variable in the blue than in the red band, consistent with work on optically selected samples. The previously noted trend of decreasing variability with increasing optical luminosity applies only to radio-quiet objects. Furthermore, we do not confirm a rise in variability amplitude with redshift, nor do we see any dependence on radio flux or luminosity. The variability over a radio-optical flux ratio range spanning a factor of 60000 from radio-quiet to extreme radio-loud objects is largely constant, although there is a suggestion of greater variability in the extreme radio-loud objects. We demonstrate the importance of Malmquist bias in variability studies and develop a procedure to correct for the bias in order to reveal the underlying variability properties of the sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/185/32
- Title:
- First-year SDSS-II SN results
- Short Name:
- J/ApJS/185/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04<z<0.42, discovered during the first season (Fall 2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in the redshift "desert" between low- and high-redshift SN Ia surveys. Within the framework of the MLCS2K2 light-curve fitting method, we use the SDSS-II SN sample to infer the mean reddening parameter for host galaxies, R_V_=2.18+/-0.14_stat_+/-0.48_syst_, and find that the intrinsic distribution of host-galaxy extinction is well fitted by an exponential function, P(A_V_)=exp(-A_V_/{tau}_V_), with {tau}_V_=0.334+/-0.088mag. We combine the SDSS-II measurements with new distance estimates for published SN data from the ESSENCE survey, the Supernova Legacy Survey (SNLS), the Hubble Space Telescope (HST), and a compilation of Nearby SN Ia measurements. A new feature in our analysis is the use of detailed Monte Carlo simulations of all surveys to account for selection biases, including those from spectroscopic targeting.
- ID:
- ivo://CDS.VizieR/J/AJ/151/142
- Title:
- Five years of blazar observations with VERITAS
- Short Name:
- J/AJ/151/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E>100 GeV) {gamma}-ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ~570 hr. The sample includes several unidentified Fermi-Large Area Telescope (LAT) sources (located at high Galactic latitude) as well as all the sources from the second Fermi-LAT catalog (Nolan et al. 2012, J/ApJS/199/31) that are contained within the field of view of the VERITAS observations. We have also performed optical spectroscopy measurements in order to estimate the redshift of some of these blazars that do not have spectroscopic distance estimates. We present new optical spectra from the Kast instrument on the Shane telescope at the Lick observatory for 18 blazars included in this work, which allowed for the successful measurement or constraint on the redshift of four of them. For each of the blazars included in our sample, we provide the flux upper limit in the VERITAS energy band. We also study the properties of the significance distributions and we present the result of a stacked analysis of the data set, which shows a 4{sigma} excess.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/12
- Title:
- FMOS-COSMOS survey III. 0.7<z<2.5 galaxies
- Short Name:
- J/ApJS/220/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the H{alpha} emission line that falls within the H-band (1.6-1.8{mu}m) spectroscopic window from star-forming galaxies with 1.4<z<1.7 and M_stellar_>~10^10^M_{sun}_. With the high multiplex capability of FMOS, it is now feasible to construct samples of over 1000 galaxies having spectroscopic redshifts at epochs that were previously challenging. The high-resolution mode (R~2600) effectively separates H{alpha} and [NII]{lambda}6585, thus enabling studies of the gas-phase metallicity and photoionization state of the interstellar medium. The primary aim of our program is to establish how star formation depends on stellar mass and environment, both recognized as drivers of galaxy evolution at lower redshifts. In addition to the main galaxy sample, our target selection places priority on those detected in the far-infrared by Herschel/PACS to assess the level of obscured star formation and investigate, in detail, outliers from the star formation rate (SFR)--stellar mass relation. Galaxies with H{alpha} detections are followed up with FMOS observations at shorter wavelengths using the J-long (1.11-1.35{mu}m) grating to detect H{beta} and [OIII]{lambda}5008 which provides an assessment of the extinction required to measure SFRs not hampered by dust, and an indication of embedded active galactic nuclei. With 460 redshifts measured from 1153 spectra, we assess the performance of the instrument with respect to achieving our goals, discuss inherent biases in the sample, and detail the emission-line properties. Our higher-level data products, including catalogs and spectra, are available to the community.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/131
- Title:
- Follow-up of candidate counterparts of S190814bv
- Short Name:
- J/ApJ/890/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulted from a neutron star-black hole (NSBH) merger, or potentially a low-mass binary BH merger. Due to the low false-alarm rate and the precise localization (23deg^2^ at 90%), S190814bv presented the community with the best opportunity yet to directly observe an optical/near-infrared counterpart to an NSBH merger. To search for potential counterparts, the GROWTH Collaboration performed real-time image subtraction on six nights of public Dark Energy Camera images acquired in the 3 weeks following the merger, covering >98% of the localization probability. Using a worldwide network of follow-up facilities, we systematically undertook spectroscopy and imaging of optical counterpart candidates. Combining these data with a photometric redshift catalog, we ruled out each candidate as the counterpart to S190814bv and placed deep, uniform limits on the optical emission associated with S190814bv. For the nearest consistent GW distance, radiative transfer simulations of NSBH mergers constrain the ejecta mass of S190814bv to be M_ej_<0.04M_{sun}_ at polar viewing angles, or M_ej_<0.03M_{sun}_ if the opacity is {kappa}<2cm^2^g^-1^. Assuming a tidal deformability for the NS at the high end of the range compatible with GW170817 results, our limits would constrain the BH spin component aligned with the orbital momentum to be {chi}<0.7 for mass ratios Q<6, with weaker constraints for more compact NSs.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/170
- Title:
- Follow-up resources for high-redshift GRBs
- Short Name:
- J/ApJ/746/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As the number of observed gamma-ray bursts (GRBs) continues to grow, follow-up resources need to be used more efficiently in order to maximize science output from limited telescope time. As such, it is becoming increasingly important to rapidly identify bursts of interest as soon as possible after the event, before the afterglows fade beyond detectability. Studying the most distant (highest redshift) events, for instance, remains a primary goal for many in the field. Here, we present our Random Forest Automated Triage Estimator for GRB redshifts (RATE GRB-z) for rapid identification of high-redshift candidates using early-time metrics from the three telescopes onboard Swift. While the basic RATE methodology is generalizable to a number of resource allocation problems, here we demonstrate its utility for telescope-constrained follow-up efforts with the primary goal to identify and study high-z GRBs. For each new GRB, RATE GRB-z provides a recommendation--based on the available telescope time--of whether the event warrants additional follow-up resources. We train RATE GRB-z using a set consisting of 135 Swift bursts with known redshifts, only 18 of which are z > 4. Cross-validated performance metrics on these training data suggest that ~56% of high-z bursts can be captured from following up the top 20% of the ranked candidates, and ~84% of high-z bursts are identified after following up the top ~40% of candidates. We further use the method to rank 200 + Swift bursts with unknown redshifts according to their likelihood of being high-z.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/57
- Title:
- Follow-up spectroscopy of Ly{alpha} 3<z<7 emitters
- Short Name:
- J/ApJ/815/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the relationship between the spectral shape of the Ly{alpha} emission and the UV morphology of the host galaxy using a sample of 304 Ly{alpha}-emitting BVi-dropouts at 3<z<7 in the Great Observatories Origins Deep Survey and Cosmic Evolution Survey fields. Using our extensive reservoir of high-quality Keck DEIMOS spectra combined with Hubble Space Telescope WFC3 data, we measure the Ly{alpha} line asymmetries for individual galaxies and compare them to axial ratios measured from observed J- and H-band (restframe UV) images. We find that the Ly{alpha} skewness exhibits a large scatter at small elongation (a/b<2), and this scatter decreases as the axial ratio increases. Comparison of this trend to radiative transfer models and various results from the literature suggests that these high-redshift Ly{alpha} emitters are not likely to be intrinsically round and symmetric disks, but they probably host galactic outflows traced by Ly{alpha} emitting clouds. The ionizing sources are centrally located, and the optical depth is a good indicator of the absorption and scattering events on the escape path of Ly{alpha} photons from the source. Our results find no evidence of evolution in Ly{alpha} asymmetry or axial ratio with look-back time.
- ID:
- ivo://CDS.VizieR/J/ApJ/874/8
- Title:
- Follow-up spectroscopy of SDSS changing-look QSOs
- Short Name:
- J/ApJ/874/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Active galactic nuclei (AGNs) that show strong rest-frame optical/UV variability in their blue continuum and broad line emission are classified as changing-look AGN, or at higher luminosities, changing-look quasars (CLQs). These surprisingly large and sometimes rapid transitions challenge accepted models of quasar physics and duty cycles, offer several new avenues for study of quasar host galaxies, and open a wider interpretation of the cause of differences between broad and narrow-line AGN. To better characterize extreme quasar variability, we present follow-up spectroscopy as part of a comprehensive search for CLQs across the full Sloan Digital Sky Survey (SDSS) footprint using spectroscopically confirmed quasars from the SDSS DR7 catalog. Our primary selection requires large-amplitude (|{Delta}g|>1mag, |{Delta}r|>0.5mag) variability over any of the available time baselines probed by the SDSS and Pan-STARRS 1 surveys. We employ photometry from the Catalina Sky Survey to verify variability behavior in CLQ candidates where available, and confirm CLQs using optical spectroscopy from the William Herschel, MMT, Magellan, and Palomar telescopes. For our adopted signal-to-noise ratio threshold on variability of broad H{beta} emission, we find 17 new CLQs, yielding a confirmation rate of >~20%. These candidates are at lower Eddington ratio relative to the overall quasar population, which supports a disk-wind model for the broad line region. Based on our sample, the CLQ fraction increases from 10% to roughly half as the continuum flux ratio between repeat spectra at 3420{AA} increases from 1.5 to 6. We release a catalog of more than 200 highly variable candidates to facilitate future CLQ searches.
