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1352. Radio-loud QSOs at z~4
- ID:
- ivo://CDS.VizieR/J/MNRAS/348/857
- Title:
- Radio-loud QSOs at z~4
- Short Name:
- J/MNRAS/348/857
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained spectra of 60 red, star-like objects (m_E_<18.8) identified with FIRST radio sources, S_1.4GHz_>1mJy. Eight are quasi-stellar objects (QSOs) with redshift z>3.6. Combined with our earlier pilot search, our sample of 121 candidates yields a total of 18 z>3.6 QSOs (10 of these with z>4.0). 8 per cent of candidates with S_1.4GHz_<10mJy and 37 per cent of candidates with S_1.4GHz_>10mJy are QSOs with z>3.6. The surface density of m_E_<18.8, S_1.4GHz_>1mJy, z>4 QSOs is 0.003deg^-2^. This is currently the only well-defined sample of radio-loud QSOs at z~4 selected independently of radio spectral index. The QSOs are highly luminous in the optical (eight have M_B_<28, q_0_=0.5, H_0_=50km/s/Mpc). The SEDs are as varied as those seen in optical searches for high-redshift QSOs, but the fraction of objects with weak (strongly self-absorbed) Ly emission is marginally higher (3 out of 18) than for high-redshift QSOs from SDSS (5 out of 96).
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/2818
- Title:
- 87 radio loud quasars (RLS) with 3.6<=z<=4.4
- Short Name:
- J/MNRAS/449/2818
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtain a sample of 87 radio-loud quasi-stellar objects (QSOs) in the redshift range 3.6<=z<=4.4 by cross-correlating sources in the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio survey (S_1.4GHz_>1mJy) with star-like objects having r<20.2 in Sloan Digital Sky Survey (SDSS) Data Release 7. Of these 87 QSOs, 80 are spectroscopically classified in previous work (mainly SDSS), and form the training set for a search for additional such sources. We apply our selection to 2916 FIRST-DR7 pairs and find 15 likely candidates. Seven of these are confirmed as high-redshift quasars, bringing the total to 87. The candidates were selected using a neural-network, which yields 97 percent completeness (fraction of actual high-z QSOs selected as such) and an efficiency (fraction of candidates which are high-z QSOs) in the range of 47-60 percent. We use this sample to estimate the binned optical luminosity function (LF) of radio-loud QSOs at z~4, and also the LF of the total QSO population and its comoving density. Our results suggest that the radio-loud fraction at high z is similar to that at low z and that other authors may be underestimating the fraction at high z. Finally, we determine the slope of the optical LF and obtain results consistent with previous studies of radio-loud QSOs and of the whole population of QSOs. The evolution of the LF with redshift was for many years interpreted as a flattening of the bright-end slope, but has recently been re-interpreted as strong evolution of the break luminosity for high-z QSOs, and our results, for the radio-loud population, are consistent with this.
- ID:
- ivo://CDS.VizieR/J/A+AS/134/221
- Title:
- Radio-loud ROSAT sources near NEP
- Short Name:
- J/A+AS/134/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A deep and large-area survey of the North Ecliptic Pole region was made with the ROSAT All-Sky Survey and the VLA to elucidate the population of radio-loud extragalactic objects. A region of 29.3 square degrees was surveyed with sensitivities around 5x10^-14^erg/s/cm^2^ in the soft X-ray band and 1mJy at 1.5GHz. Optical counterparts were sought on digitized Schmidt plates from POSS-I and II. Seventy-four reliable RASS-VLA sources were found. The sample is a heterogeneous mixture of Seyfert galaxies, quasars, BL Lac objects, galaxy clusters and groups containing a radio galaxy. Optical magnitudes range from B=~14 to B>22. Three results are noteworthy: (1) the bimodality in the ratio of radio to optical emission seen in optically- and X-ray-selected AGN samples is also evident in the ROSAT-VLA objects; (2) X-ray and radio selection is an effective method for locating poor galaxy clusters and groups; and (3) a considerable population of optically faint but X-ray/radio-bright objects is present. This last group may be either distant clusters with radio galaxies or "red quasars".
- ID:
- ivo://CDS.VizieR/J/AZh/79/501
- Title:
- Radio luminosities of normal & millisecond pulsars
- Short Name:
- J/AZh/79/501
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of comparative statistical analysis of the integrated radio luminosities of normal and millisecond pulsars are presented. The analysis is based on our own measurements of the flux densities, spectra and integrated radio luminosities of the millisecond pulsars., as well as data from the literature used to determine the integrated radio luminosities for 545 pulsars.
- ID:
- ivo://CDS.VizieR/J/AZh/71/762
- Title:
- Radio luminosities of 232 pulsars
- Short Name:
- J/AZh/71/762
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Total radio luminosities of 232 pulsars are calculated using new data on mean spectra. For 88% of these pulsars, luminosities lie in the range 10^27^-10^30^erg/s. It is shown that pulsar luminosity remains constant over a period of a few million years. Mean radiation power increases with period P as P^0.5^. An increase in luminosity with the rotational energy loss rate is found.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/87
- Title:
- Radio luminosity function of FSRQs
- Short Name:
- J/ApJ/842/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the radio luminosity function (LF) of flat-spectrum radio quasars (FSRQ), using the largest and most complete sample to date. Cross-matching between the FIRST 20cm and GB6 6cm radio surveys, we find 638 flat-spectrum radio sources above 220mJy at 1.4GHz; of these, 327 are classified and verified using optical spectroscopy data, mainly from Sloan Digital Sky Survey Data Release 12. We also considered flat-spectrum radio sources that lack both literature references and optical spectroscopy, and we identified 12 out of the 43 such sources to potentially be FSRQs, using their WISE colors. From the fully identified sample of 242 FSRQs, we derived the radio LF and cosmic evolution of blazars at 1.4GHz, finding good agreement with previous work at 5GHz. The number density of FSRQs increases dramatically to a redshift of z~2 and then declines for higher redshifts. Furthermore, the redshift at which the quasar density peaks is clearly dependent on luminosity, with more luminous sources peaking at higher redshifts. The approximate best-fit LF for a luminosity-dependent evolutionary model is a broken power-law with slopes ~0.7 and ~1.7 below and above the break luminosity, logL_1.4_~43.8erg/s, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/504/127
- Title:
- Radio maps of Infrared Dark Cloud 18223-3
- Short Name:
- J/A+A/504/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine an Infrared Dark Cloud (IRDC) at high spatial resolution as a means to study rotation, outflow, and infall at the onset of massive star formation. The IRDC 18223-3 was observed at 1.1mm and 1.3mm with the Submillimeter Array (SMA) and follow-up short spacing information was obtained with the IRAM 30m telescope. Additional data were taken at 3mm with the IRAM Plateau de Bure interferometer (PdBI).
- ID:
- ivo://CDS.VizieR/J/AJ/133/1331
- Title:
- Radio observation of HDFS at 2.5, 5.2, and 8.7GHz
- Short Name:
- J/AJ/133/1331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep radio observations of a wide region centered on the Hubble Deep Field-South have been performed, providing one of the most sensitive sets of radio observations acquired on the Australia Telescope Compact Array to date. A central rms of ~10uJy is reached at four frequencies (1.4, 2.5, 5.2, and 8.7GHz). In this paper the full source catalogs from the 2.5, 5.2, and 8.7GHz observations are presented to complement Paper II (Huynh et al., 2005, Cat. J/AJ/130/1373) in this series, along with a detailed analysis of image quality and noise. We produce a consolidated catalog by matching sources across all four frequencies of our survey.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/23
- Title:
- Radio observation of the transient CSS161010
- Short Name:
- J/ApJ/895/23
- Date:
- 16 Mar 2022 00:23:37
- Publisher:
- CDS
- Description:
- We present X-ray and radio observations of the Fast Blue Optical Transient CRTS-CSS161010J045834-081803 (CSS161010 hereafter) at t=69-531days. CSS161010 shows luminous X-ray (Lx~5x1039erg/s) and radio (L{nu}~1029erg/s/Hz) emission. The radio emission peaked at ~100days post-transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blast wave. CSS161010 launched a mildly relativistic outflow with velocity {Gamma}{beta}c>~0.55c at ~100days. This is faster than the non- relativistic AT 2018cow ({Gamma}{beta}c~0.1c) and closer to ZTF18abvkwla ({Gamma}{beta}c>~0.3c at 63days). The inferred initial kinetic energy of CSS161010 (Ek>~1051erg) is comparable to that of long gamma-ray bursts, but the ejecta mass that is coupled to the mildly relativistic outflow is significantly larger (~0.01-0.1M{odot}). This is consistent with the lack of observed {gamma}-rays. The luminous X-rays were produced by a different emission component to the synchrotron radio emission. CSS161010 is located at ~150Mpc in a dwarf galaxy with stellar mass M*~107M{sun} and specific star formation rate sSFR~0.3/Gyr. This mass is among the lowest inferred for host galaxies of explosive transients from massive stars. Our observations of CSS161010 are consistent with an engine-driven aspherical explosion from a rare evolutionary path of a H-rich stellar progenitor, but we cannot rule out a stellar tidal disruption event on a centrally located intermediate-mass black hole. Regardless of the physical mechanism, CSS161010 establishes the existence of a new class of rare (rate<0.4% of the local core-collapse supernova rate) H-rich transients that can launch mildly relativistic outflows.
