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1941. 24yr of radio observations of V404 Cygni
ID:
ivo://CDS.VizieR/J/ApJ/874/13
Title:
24yr of radio observations of V404 Cygni
Short Name:
J/ApJ/874/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Relativistic outflows are believed to be a common feature of black hole X-ray binaries (BHXBs) at the lowest accretion rates, when they are in their "quiescent" spectral state. However, we still lack a detailed understanding of how quiescent jet emission varies with time. Here we present 24yr of archival radio observations (from the Very Large Array and the Very Long Baseline Array) of the BHXB V404 Cygni in quiescence (totaling 150 observations from 1.4 to 22GHz). The observed flux densities follow lognormal distributions with means and standard deviations of (<logf{nu}>,{sigma}_logf{nu}_)=(-0.53,0.19) and (-0.53,0.30) at 4.9 and 8.4GHz, respectively (where f{nu} is the flux density in units of mJy). As expected, the average radio spectrum is flat with a mean and standard deviation of (<{alpha}_r_,{sigma}_{alpha}r_)=(0.02,0.65), where f{nu}{propto}{nu}^{alpha}_r_^. We find that radio flares that increase the flux density by factors of 2-4 over timescales as short as <10 minutes are commonplace, and that long-term variations (over 10-4000 day timescales) are consistent with shot-noise impulses that decay to stochastic variations on timescales <~10 days (and perhaps as short as tens of minutes to several hr). We briefly compare the variability characteristics of V404 Cygni to jetted active galactic nuclei, and we conclude with recommendations on how to account for variability when placing quiescent BHXB candidates with radio luminosities comparable to V404 Cygni (L_R_~10^28^erg/s) onto the radio/X-ray luminosity plane.
1942. 10yr of radio-to-gamma-ray obs. of 1ES 1215+30.3
ID:
ivo://CDS.VizieR/J/ApJ/891/170
Title:
10yr of radio-to-gamma-ray obs. of 1ES 1215+30.3
Short Name:
J/ApJ/891/170
Date:
19 Jan 2022 09:02:08
Publisher:
CDS
Description:
Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and VERITAS, we present an extensive study of the long-term multiwavelength radio-to-gamma-ray flux-density variability, with the addition of a couple of short-time radio-structure and optical polarization observations of the blazar 1ES 1215+303 (z=0.130), with a focus on its gamma-ray emission from 100MeV to 30TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the gamma-ray and optical flux baseline, and a linear correlation between these two bands are observed over the ten-year period. Typical HBL behaviors are identified in the radio morphology and broadband spectrum of the source. Three stationary features in the innermost jet are resolved by Very Long Baseline Array at 43.1, 22.2, and 15.3GHz. We employ a two-component synchrotron self-Compton model to describe different flux states of the source, including the epoch during which an extreme shift in energy of the synchrotron peak frequency from infrared to soft X-rays is observed.
1943. Zelenchuk survey 9h<=RA<=12h, 0<=DE<=8{deg}
ID:
ivo://CDS.VizieR/J/other/BSAO/45.136
Title:
Zelenchuk survey 9h<=RA<=12h, 0<=DE<=8{deg}
Short Name:
J/other/BSAO/45.
Date:
21 Oct 2021
Publisher:
CDS
Description:
Optical identification of Zelenchuk Survey radio sources at 3.9GHz from 9h to 12h in right ascension and between 0{deg} and 8{deg} in declination is reported in this paper. Some optical characteristics of identified radio sources are presented in the table.
1944. ZFOURGE catalogue of AGN candidates
ID:
ivo://CDS.VizieR/J/MNRAS/457/629
Title:
ZFOURGE catalogue of AGN candidates
Short Name:
J/MNRAS/457/629
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate active galactic nuclei (AGN) candidates within the FourStar Galaxy Evolution Survey (ZFOURGE) to determine the impact they have on star formation in their host galaxies. We first identify a population of radio, X-ray, and infrared-selected AGN by cross-matching the deep Ks-band imaging of ZFOURGE with overlapping multiwavelength data. From this, we construct a mass-complete (log(M*/M_{sun}_)>=9.75), AGN luminosity limited sample of 235 AGN hosts over z=0.2-3.2. We compare the rest-frame U-V versus V-J (UVJ) colours and specific star formation rates (sSFRs) of the AGN hosts to a mass-matched control sample of inactive (non-AGN) galaxies. UVJ diagnostics reveal AGN tend to be hosted in a lower fraction of quiescent galaxies and a higher fraction of dusty galaxies than the control sample. Using 160{mu}m Herschel PACS data, we find the mean specific star formation rate of AGN hosts to be elevated by 0.34-/-0.07dex with respect to the control sample across all redshifts. This offset is primarily driven by infrared-selected AGN, where the mean sSFR is found to be elevated by as much as a factor of ~5. The remaining population, comprised predominantly of X-ray AGN hosts, is found mostly consistent with inactive galaxies, exhibiting only a marginal elevation. We discuss scenarios that may explain these findings and postulate that AGN are less likely to be a dominant mechanism for moderating galaxy growth via quenching than has previously been suggested.
1945. z<0.5 PG quasars IR energy distributions
ID:
ivo://CDS.VizieR/J/ApJ/854/158
Title:
z<0.5 PG quasars IR energy distributions
Short Name:
J/ApJ/854/158
Date:
21 Oct 2021
Publisher:
CDS
Description:
The interstellar medium is crucial to understanding the physics of active galaxies and the coevolution between supermassive black holes and their host galaxies. However, direct gas measurements are limited by sensitivity and other uncertainties. Dust provides an efficient indirect probe of the total gas. We apply this technique to a large sample of quasars, whose total gas content would be prohibitively expensive to measure. We present a comprehensive study of the full (1 to 500{mu}m) infrared spectral energy distributions of 87 redshift <0.5 quasars selected from the Palomar-Green sample, using photometric measurements from 2MASS, WISE, and Herschel, combined with Spitzer mid-infrared (5-40{mu}m) spectra. With a newly developed Bayesian Markov Chain Monte Carlo fitting method, we decompose various overlapping contributions to the integrated spectral energy distribution, including starlight, warm dust from the torus, and cooler dust on galaxy scales. This procedure yields a robust dust mass, which we use to infer the gas mass, using a gas-to-dust ratio constrained by the host galaxy stellar mass. Most (90%) quasar hosts have gas fractions similar to those of massive, star-forming galaxies, although a minority (10%) seem genuinely gas-deficient, resembling present-day massive early-type galaxies. This result indicates that "quasar mode" feedback does not occur or is ineffective in the host galaxies of low-redshift quasars. We also find that quasars can boost the interstellar radiation field and heat dust on galactic scales. This cautions against the common practice of using the far-infrared luminosity to estimate the host galaxy star formation rate.
1946. ZTF observations of FRB 180916.J0158+65
ID:
ivo://CDS.VizieR/J/ApJ/896/L2
Title:
ZTF observations of FRB 180916.J0158+65
Short Name:
J/ApJ/896/L2
Date:
07 Dec 2021
Publisher:
CDS
Description:
The discovery rate of fast radio bursts (FRBs) is increasing dramatically thanks to new radio facilities. Meanwhile, wide-field instruments such as the 47deg^2^ Zwicky Transient Facility (ZTF) survey the optical sky to study transient and variable sources. We present serendipitous ZTF observations of the Canadian Hydrogen Intensity Mapping Experiment (CHIME) repeating source FRB180916.J0158+65 that was localized to a spiral galaxy 149Mpc away and is the first FRB suggesting periodic modulation in its activity. While 147 ZTF exposures corresponded to expected high-activity periods of this FRB, no single ZTF exposure was at the same time as a CHIME detection. No >3{sigma} optical source was found at the FRB location in 683 ZTF exposures, totaling 5.69hr of integration time. We combined ZTF upper limits and expected repetitions from FRB 180916.J0158+65 in a statistical framework using a Weibull distribution, agnostic of periodic modulation priors. The analysis yielded a constraint on the ratio between the optical and radio fluences of {eta}<~200, corresponding to an optical energy E_opt_<~3x10^46^erg for a fiducial 10Jy.ms FRB (90% confidence). A deeper (but less statistically robust) constraint of {eta}<~3 can be placed assuming a rate of r(>5Jy.ms)=1hr^-1^ and 1.2+/-1.1 FRB occurring during exposures taken in high-activity windows. The constraint can be improved with shorter per-image exposures and longer integration time, or observing FRBs at higher Galactic latitudes. This work demonstrated how current surveys can statistically constrain multiwavelength counterparts to FRBs even without deliberately scheduled simultaneous radio observation.