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721. SAMI Galaxy Survey. Gas surface densities
ID:
ivo://CDS.VizieR/J/MNRAS/468/3965
Title:
SAMI Galaxy Survey. Gas surface densities
Short Name:
J/MNRAS/468/3965
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stars form in cold molecular clouds. However, molecular gas is difficult to observe because the most abundant molecule (H_2_) lacks a permanent dipole moment. Rotational transitions of CO are often used as a tracer of H_2_, but CO is much less abundant and the conversion from CO intensity to H_2_ mass is often highly uncertain. Here we present a new method for estimating the column density of cold molecular gas ({Sigma}_gas_) using optical spectroscopy. We utilize the spatially resolved H{alpha} maps of flux and velocity dispersion from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. We derive maps of {Sigma}_gas_ by inverting the multi-freefall star formation relation, which connects the star formation rate surface density ({Sigma}_SFR_) with {Sigma}_gas_ and the turbulent Mach number (M). Based on the measured range of {Sigma}_SFR_=0.005-1.5M_{sun}_/yr/kpc^2^ and M=18-130, we predict {Sigma}_gas_=7-200M_{sun}_/pc^2^ in the star-forming regions of our sample of 260 SAMI galaxies. These values are close to previously measured {Sigma}_gas_ obtained directly with unresolved CO observations of similar galaxies at low redshift. We classify each galaxy in our sample as 'star-forming' (219) or 'composite/AGN/shock' (41), and find that in 'composite/AGN/shock' galaxies the average {Sigma}_SFR_, M and {Sigma}_gas_ are enhanced by factors of 2.0, 1.6 and 1.3, respectively, compared to star-forming galaxies. We compare our predictions of {Sigma}_gas_ with those obtained by inverting the Kennicutt-Schmidt relation and find that our new method is a factor of 2 more accurate in predicting {Sigma}_gas_, with an average deviation of 32 per cent from the actual {Sigma}_gas_.
722. SAMP. III. Opt. LCs and spectra of two AGNs
ID:
ivo://CDS.VizieR/J/ApJ/886/93
Title:
SAMP. III. Opt. LCs and spectra of two AGNs
Short Name:
J/ApJ/886/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
Active galactic nuclei (AGNs) show a correlation between the size of the broad line region and the monochromatic continuum luminosity at 5100{AA}, allowing black hole mass estimation based on single-epoch spectra. However, the validity of the correlation is yet to be clearly tested for high-luminosity AGNs. We present the first reverberation mapping results of the Seoul National University AGN Monitoring Project (SAMP), which is designed to focus on luminous AGNs for probing the high end of the size-luminosity relation. We report time lag measurements of two AGNs, namely, 2MASSJ10261389+5237510 and SDSSJ161911.24+501109.2, using the light curves obtained over an ~1000d period with an average cadence of 10 and 20d, respectively, for photometry and spectroscopy monitoring. Based on a cross-correlation analysis and H{beta} line width measurements, we determine the H{beta} lag as 41.8_-6.0_^+4.9^ and 52.6_-14.7_^+17.6^ days in the observed frame, and black hole mass as 3.65_-0.57_^+0.49^x10^7^M_{sun}_ and 23.02_-6.56_^+7.81^x10^7^M_{sun}_, respectively, for 2MASS J1026 and SDSS J1619.
723. Sample of 966 AGNs
ID:
ivo://CDS.VizieR/J/other/RAA/20.25
Title:
Sample of 966 AGNs
Short Name:
J/other/RAA/20.2
Date:
03 Dec 2021 00:39:07
Publisher:
CDS
Description:
Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type I and type II (FRI&II) radio galaxies. Following our previous work, we present a latest sample of 966 sources with measured radio flux densities of the core and extended components. The sample includes 83 BL Lacs, 473 flat spectrum radio quasars, 101 Seyferts, 245 galaxies, 52 FRIs&IIs and 12 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and radio spectral index extends over all the sources in a large sample presented.
724. Sample of 2400 AGNs
ID:
ivo://CDS.VizieR/J/other/RAA/19.70
Title:
Sample of 2400 AGNs
Short Name:
J/other/RAA/19.7
Date:
21 Oct 2021
Publisher:
CDS
Description:
Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type I/II (FRI/II) radio galaxies. Following our previous work (Fan et al., 2011RAA....11.1413F), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRII galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.
725. Sample of 877 blazars
ID:
ivo://CDS.VizieR/J/other/AstBu/70.264
Title:
Sample of 877 blazars
Short Name:
J/other/AstBu/70
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the synchrotron component of the spectral energy distribution on the sample of 877 blazars using ASDC SED Builder Tool with available broadband data from the literature. Our sample includes 423 flat-spectrum radio sources (FSRQs), 361 BL Lac objects and candidates, and 93 blazars of uncertain type. We have made an estimation of the synchrotron peak frequency for the 875 objects and further classified them as high, intermediate and low synchrotron peaked sources (HSPs/ISPs/LSPs). For each source NVSS name (RA (HHMMSS) and DEC (DDMMSS) for the J2000.0 epoch), alias, redshift, R band magnitude, synchrotron peak frequency, correlation coefficient, flux density at 4.8GHz, SED class, blazar type and selection method are presented.
726. Sample of 467 GPS candidates
ID:
ivo://CDS.VizieR/J/other/AstBu/68.262
Title:
Sample of 467 GPS candidates
Short Name:
J/other/AstBu/68
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a comprehensive analysis of continuous radio spectra of a sample of Gigahertz-Peaked Spectrum (GPS) sources are reported. The sources are selected from a flux-density-complete sample (S more or equal 200mJy at 4.8 or 5GHz) using multifrequency measurements of the RATAN-600 radio telescope and data from the CATS astrophysical catalogs support system. The analysis revealed a very small number (1-2%) of "classical" GPS objects, which is significantly less than the expected fraction of 10%. GPS galaxies are found to have narrower and steeper radio spectra than quasars. The low-frequency part of the spectrum is seen to become steeper with increasing redshift. Galaxies and quasars at the same z have comparable angular sizes, whereas their luminosities may differ by one order of magnitude. At large redshifts there is a deficit of objects with low (several GHz) peak frequencies. The number of GPS galaxies decreases sharply with redshift, and most of them are found at z between 0.01 and 1.81. GPS quasars are found at large redshifts, from 0.11 to 3.99. A quarter of the sample consists of blazars whose spectra may temporarily have a convex shape when the object is in active state.
727. Sample of starburst nucleus galaxies
ID:
ivo://CDS.VizieR/J/A+AS/130/285
Title:
Sample of starburst nucleus galaxies
Short Name:
J/A+AS/130/285
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents optical long-slit spectroscopic observations of 105 barred Markarian IRAS galaxies. These observations are used to determine the spectral type (starburst or Seyfert) of emission-line regions in the nucleus and along the bar of the galaxies, in order to define a homogeneous sample of Starburst Nucleus Galaxies (SBNGs). Our selection criteria (ultraviolet excess, far infrared emission and barred morphology) have been very efficient for selecting star-forming galaxies, since our sample of 221 emission-line regions includes 82% nuclear or extranuclear starbursts. The contamination by Seyferts is low (9%). The remaining galaxies (9%) are objects with ambiguous classification (HII or LINER). The dust content and H{alpha} luminosity increase towards the nuclei of the galaxies. No significant variation of the electron density is found between nuclear and bar HII regions. However, the mean H{alpha} luminosity and electron density in the bar are higher than in typical disk HII regions. We investigate different mechanisms for explaining the excess of nitrogen emission observed in our starburst nuclei. There is no evidence for the presence of a weak hidden active galactic nucleus in our starburst galaxies. The cause of this excess is probably a selective enrichment of nitrogen in the nuclei of the galaxies, following a succession of short and intense bursts of star formation. Our sample of SBNGs, located at a mean redshift of 0.015, has moderate H{alpha} (10^41^erg/s) and far infrared (10^10^L{sun}) luminosities. The types are distributed equally among early- and late-type giant spirals with a slight preference for Sbc/Sc types because of their barred morphology. The majority (62%) of SBNGs are isolated with no sign of gravitational interaction. In terms of distance, luminosity and level of interaction, SBNGs are intermediate between HII galaxies and luminous infrared galaxies.
728. Sample of weak blazars at mas resolution
ID:
ivo://CDS.VizieR/J/A+A/577/A36
Title:
Sample of weak blazars at mas resolution
Short Name:
J/A+A/577/A36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We started a follow-up investigation of the "Deep X-ray Radio Blazar Survey" objects with declination >-10{deg} to better understand the blazar phenomenon. We undertook a survey with the European Very Long Baseline Interferometry Network at 5GHz to make the first images of a complete sample of weak blazars, aiming at a follow-up comparison between high- and low-power samples of blazars. We observed 87 sources with the EVN at 5GHz during the period October 2009 to May 2013. The observations were correlated at the Max-Planck-Institut fuer Radioastronomie and at the Joint Institute for VLBI in Europe. The correlator output was analysed using both the AIPS and DIFMAP software packages. All of the sources observed were detected. Point-like sources are found in 39 cases on a milli-arcsecond scale, and 48 show core-jet structure. The total flux density distribution at 5GHz has a median value <S>=44^+23^_-10_mJy. A total flux density <=150mJy is observed in 68 out of 87 sources. Their brightness temperature T_b_ ranges between 10^7^K and 10^12^K. According to the spectral indices previously obtained with multi-frequency observations, 58 sources show a flat spectral index, and 29 sources show a steep spectrum or a spectrum peaking at a frequency around 1-2GHz. Adding to the DXRBS objects we observed those already observed with ATCA in the Southern sky, we found that 14 blazars and a Steep Spectrum Radio Quasars, are associated to {gamma}-ray emitters. We found that 56 sources can be considered blazars. We also detected 2 flat spectrum narrow line radio galaxies. About 50% of the blazars associated to a {gamma}-ray object are BLLacs, confirming that they are more likely detected among blazars {gamma}-emitters. We confirm the correlation found between the source core flux density and the {gamma}-ray photon fluxes down to fainter flux densities. We also found that weak blazars are also weaker {gamma}-ray emitters compared to bright blazars. Twenty-two sources are SSRQs or Compact Steep-spectrum Sources, and 7 are GigaHz Peaked Sources. The available X-ray ROSAT observations allow us to suggest that CSS and GPS quasars are not obscured by large column of cold gas surrounding the nuclei. We did not find any significant difference in X-ray luminosity between CSS and GPS quasars.
729. Scintillation of AGNs observed with the VLA
ID:
ivo://CDS.VizieR/J/ApJ/756/29
Title:
Scintillation of AGNs observed with the VLA
Short Name:
J/ApJ/756/29
Date:
21 Oct 2021
Publisher:
CDS
Description:
The fraction of compact active galactic nuclei (AGNs) that exhibit interstellar scintillation (ISS) at radio wavelengths, as well as their scintillation amplitudes, have been found to decrease significantly for sources at redshifts z>~2. This can be attributed to an increase in the angular sizes of the {mu}as-scale cores or a decrease in the flux densities of the compact {mu}as cores relative to that of the mas-scale components with increasing redshift, possibly arising from (1) the space-time curvature of an expanding universe, (2) AGN evolution, (3) source selection biases, (4) scatter broadening in the ionized intergalactic medium (IGM) and intervening galaxies, or (5) gravitational lensing. We examine the frequency scaling of this redshift dependence of ISS to determine its origin, using data from a dual-frequency survey of ISS of 128 sources at 0<~z<~4. We present a novel method of analysis which accounts for selection effects in the source sample.
730. SDSS AGN from ROSAT PSPC
ID:
ivo://CDS.VizieR/J/AJ/132/1475
Title:
SDSS AGN from ROSAT PSPC
Short Name:
J/AJ/132/1475
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of 1744 type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) spectroscopic catalog with X-ray counterparts in the White-Giommi-Angelini Catalog (WGACAT) of ROSAT PSPC pointed observations. Of 1744 X-ray sources, 1410 (80.9%) are new AGN identifications. Of 4574 SDSS DR4 AGNs for which we found radio matches in the catalog of radio sources from the Faint Images of the Radio Sky at Twenty cm survey, 224 turned up in our sample of SDSS X-ray AGNs. The sample objects are given in a catalog that contains optical and X-ray parameters and supporting data, including redshifts; it also contains radio emission parameters where available. We illustrate the content of our catalog and its potential for AGN science by providing statistical relationships for the catalog data.