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461. Matched SDSS and FIRST Sample
ID:
ivo://CDS.VizieR/J/AJ/137/42
Title:
Matched SDSS and FIRST Sample
Short Name:
J/AJ/137/42
Date:
21 Oct 2021
Publisher:
CDS
Description:
The question as to whether the distribution of radio loudness in active galactic nuclei (AGNs) is actually bimodal has been discussed extensively in the literature. Furthermore, there have been claims that radio loudness depends on black hole mass (M_BH_) and Eddington ratio (L_bol_/L_Edd_).We investigate these claims using the low- redshift broad line AGN sample of Greene & Ho (2007ApJ...667..131G), which consists of 8434 objects at z<0.35 from the Sloan Digital Sky Survey Fourth Data Release (SDSS DR4). We obtained radio fluxes from the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey for the SDSS AGN. Out of the 8434 SDSS AGNs, 821 have corresponding observed radio fluxes in the FIRST survey.
462. MCG+07-47-10 total intensity image at 322MHz
ID:
ivo://CDS.VizieR/J/A+A/595/L8
Title:
MCG+07-47-10 total intensity image at 322MHz
Short Name:
J/A+A/595/L8
Date:
21 Oct 2021
Publisher:
CDS
Description:
Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only ~5 cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75M_{sun}_/yr, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of L_1.4GHz_=1.12x10^22^W/Hz, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS.
463. Medium-band photometry RM of 5 nearby AGNs
ID:
ivo://CDS.VizieR/J/ApJ/884/103
Title:
Medium-band photometry RM of 5 nearby AGNs
Short Name:
J/ApJ/884/103
Date:
21 Oct 2021
Publisher:
CDS
Description:
Reverberation mapping (RM) is one of the most efficient ways to investigate the broad-line region around the central supermassive black holes of active galactic nuclei (AGNs). A common way of performing the RM is to perform a long term spectroscopic monitoring of AGNs, but the spectroscopic monitoring campaign of a large number of AGNs requires an extensive amount of observing time of medium to large size telescopes. As an alternative way, we present the results of photometric RM with medium-band photometry. As the widths of medium-band filters match well with the widths of AGN broad emission lines, the medium-band observation with small telescopes can be a cost-effective way to perform RM. We monitored five nearby AGNs with available spectroscopic RM results showing days to weeks scale variability. Observations were performed for ~3 months with an average of 3 days cadence using three medium-band filters on a 0.43m telescope. The time lags between the continuum and the H{alpha} emission line light curves are calculated using the JAVELIN software and the discrete correlation function. We find time lags of 1.5-15.9d for these AGNs, which are consistent with the time lags derived from previous spectroscopic RM measurements. This result demonstrates that even a 0.5m class telescope can perform RM with medium-bands. Furthermore, we show that RM for tens of thousands AGNs is possible with a dedicated 1m class telescope.
464. Megamaser Cosmology Project. XI. Z74-64 VLBI obs.
ID:
ivo://CDS.VizieR/J/ApJ/890/118
Title:
Megamaser Cosmology Project. XI. Z74-64 VLBI obs.
Short Name:
J/ApJ/890/118
Date:
21 Oct 2021
Publisher:
CDS
Description:
As part of the survey component of the Megamaser Cosmology Project, we have discovered a disk megamaser system in the galaxy CGCG 074-064. Using the Green Bank Telescope and the Very Large Array, we have obtained spectral monitoring observations of this maser system at a monthly cadence over the course of two years. We find that the systemic maser features display line-of-sight accelerations of ~4.4km/s/yr that are nearly constant with velocity, while the high-velocity maser features show accelerations that are consistent with zero. We have also used the High-Sensitivity Array to make a high-sensitivity very long baseline interferometric map of the maser system in CGCG 074-064, which reveals that the masers reside in a thin, edge-on disk with a diameter of ~1.5mas (0.6pc). Fitting a three-dimensional warped disk model to the data, we measure a black hole mass of 2.42_-0.20_^+0.22^x10^7^M_{sun}_ and a geometric distance to the system of 87.6_-7.2_^+7.9^Mpc. Assuming a cosmic microwave background-frame recession velocity of 7308+/-150km/s, we constrain the Hubble constant to H_0_=81.0_-6.9_^+7.4^(stat.)+/-1.4(sys.)km/s/Mpc.
465. Mergers and galaxy-galaxy interactions
ID:
ivo://CDS.VizieR/J/MNRAS/464/3882
Title:
Mergers and galaxy-galaxy interactions
Short Name:
J/MNRAS/464/3882
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS) to confirm a connection between dust-obscured active galactic nuclei (AGNs) and galaxy merging. Using a new, volume-limited (z<=0.08) catalogue of visually selected major mergers and galaxy-galaxy interactions from the SDSS, with stellar masses above 2x10^10^M_{sun}_, we find that major mergers (interactions) are 5-17 (3-5) times more likely to have red [3.4]-[4.6] colours associated with dust-obscured or 'dusty' AGNs, compared to non-merging galaxies with similar masses. Using published fibre spectral diagnostics, we map the [3.4]-[4.6] versus [4.6]-[12] colours of different emission-line galaxies and find that one-quarter of Seyferts have colours indicative of a dusty AGN. We find that AGNs are five times more likely to be obscured when hosted by a merging galaxy, half of AGNs hosted by a merger are dusty, and we find no enhanced frequency of optical AGNs in merging over non-merging galaxies. We conclude that undetected AGNs missed at shorter wavelengths are at the heart of the ongoing AGN-merger connection debate. The vast majority of mergers hosting dusty AGNs are star forming and located at the centres of M_halo_<10^13^Mc1l_{sun}_ groups. Assuming plausibly short-duration dusty-AGN phases, we speculate that a large fraction of gas-rich mergers experience a brief obscured AGN phase, in agreement with the strong connection between central star formation and black hole growth seen in merger simulations.
466. Merging galaxies in COSMOS to z~1
ID:
ivo://CDS.VizieR/J/AJ/148/137
Title:
Merging galaxies in COSMOS to z~1
Short Name:
J/AJ/148/137
Date:
21 Oct 2021
Publisher:
CDS
Description:
The role of major mergers in galaxy and black hole formation is not well-constrained. To help address this, we develop an automated method to identify late-stage galaxy mergers before coalescence of the galactic cores. The resulting sample of mergers is distinct from those obtained using pair-finding and morphological indicators. Our method relies on median-filtering of high-resolution images to distinguish two concentrated galaxy nuclei at small separations. This method does not rely on low surface brightness features to identify mergers, and is therefore reliable to high redshift. Using mock images, we derive statistical contamination and incompleteness corrections for the fraction of late-stage mergers. The mock images show that our method returns an uncontaminated (<10%) sample of mergers with projected separations between 2.2 and 8kpc out to z~1. We apply our new method to a magnitude-limited (m_FW814_<23) sample of 44164 galaxies from the COSMOS HST/ACS catalog. Using a mass-complete sample with log M_{star}_/M_{sun}_>10.6 and 0.25<z<=1.00, we find ~5% of systems are late-stage mergers. Correcting for incompleteness and contamination, the fractional merger rate increases strongly with redshift as {\bf R}_merge_\propto(1+z)^3.8+/-0.9^, in agreement both with earlier studies and with dark matter halo merger rates. Separating the sample into star-forming and quiescent galaxies shows that the merger rate for star-forming galaxies increases strongly with redshift, (1+z)^4.5+/-1.3^, while the merger rate for quiescent galaxies is consistent with no evolution, (1+z)^1.1+/-1.2^. The merger rate also becomes steeper with decreasing stellar mass. Limiting our sample to galaxies with spectroscopic redshifts from zCOSMOS, we find that the star formation rates and X-ray selected active galactic nucleus (AGN) activity in likely late-stage mergers are higher by factors of ~2 relative to those of a control sample. Combining our sample with more widely separated pairs, we find that 8+/-5% of star formation and 20+/-8% of AGN activity are triggered by close encounters (<143kpc) or mergers, providing additional evidence that major mergers are not the only channels for star formation and black hole growth.
467. Meudon TITAN code
ID:
ivo://vopdc.obspm/luth/titan/cea
Title:
Meudon TITAN code
Short Name:
TITAN
Date:
10 Jan 2017
Publisher:
Paris Astronomical Data Centre - LUTH
Description:
TITAN is a computer program for calculating the interactions of a dilute plane-parallel medium with electromagnetic radiation. It includes all atomic processes: absorption, recombination, diffusion, excitation, deexcitation of atoms and ions, heating and cooling of the gas, and it solves the radiation transfer, in order to obtain the spectra reemitted by the medium. It handles plan parallel slabs in non LTE steady state, for various physical conditions and various illuminations, valid in many astrophysical situations. It is specifically designed for warm-hot (8000 to 10**8 K) and thick media (till an electron scattering optical depth of several tens) emitting and absorbing in the X-ray range (density from 10**5 to 10**14 cm-3). It computes the physical parameters, ionisation degrees, temperature, density, and the spectrum of the radiated light in each point of the slab, by solving simultaneously the ionisation equations, the equations of statistical equilibrium, the thermal equations and the radiation transfer, using iteration processes.
468. MEXSAS catalogue
ID:
ivo://CDS.VizieR/J/A+A/593/A55
Title:
MEXSAS catalogue
Short Name:
J/A+A/593/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Most investigations of the X-ray variability of active galactic nuclei (AGN) have been concentrated on the detailed analyses of individual, nearby sources. A relatively small number of studies have treated the ensemble behaviour of the more general AGN population in wider regions of the luminosity-redshift plane. We want to determine the ensemble variability properties of a rich AGN sample, called Multi-Epoch XMM Serendipitous AGN Sample (MEXSAS), extracted from the fifth release of the XMM-Newton Serendipitous Source Catalogue (XMMSSC-DR5), with redshift between 0.1 and 5, and X-ray luminosities in the 0.5-4.5keV band between 10^42^ and 10^47^erg/s. We urge caution on the use of the normalised excess variance (NXS), noting that it may lead to underestimate variability if used improperly. We use the structure function (SF), updating our previous analysis for a smaller sample. We propose a correction to the NXS variability estimator, accounting for the light curve duration in the rest frame on the basis of the knowledge of the variability behaviour gained by SF studies. We find an ensemble increase of the X-ray variability with the rest-frame time lag tau, given by tau^0.12^. We confirm an inverse dependence on the X-ray luminosity, approximately as L_X^-0.19^. We analyse the SF in different X-ray bands, finding a dependence of the variability on the frequency as nu^-0.15^, corresponding to a softer when brighter trend. In turn, this dependence allows us to parametrically correct the variability estimated in observer-frame bands to that in the rest frame, resulting in a moderate shift upwards (V-correction). Ensemble X-ray variability of AGNs is best described by the structure function. An improper use of the normalised excess variance may lead to an underestimate of the intrinsic variability, so that appropriate corrections to the data or the models must be applied to prevent these effects.
469. ~420MHz uGMRT obs. of MIR selected radio-loud AGN
ID:
ivo://CDS.VizieR/J/ApJS/255/28
Title:
~420MHz uGMRT obs. of MIR selected radio-loud AGN
Short Name:
J/ApJS/255/28
Date:
11 Mar 2022
Publisher:
CDS
Description:
We present results from a spectroscopically blind search for associated and intervening HI 21cm and OH 18cm absorption lines toward 88 active galactic nuclei (AGN) at 2<z<5 using the uGMRT. The sample of AGN with 1.4GHz spectral luminosity in the range 10^27-29.3^W/Hz is selected using mid-infrared colors and closely resembles the distribution of the underlying quasar population. The search for associated or proximate absorption, defined to be within 3000km/s of the AGN redshift, led to one HI 21cm absorption detection (M1540-1453; z_abs_=2.1139). This is only the fourth known absorption at z>2. The detection rate (1.6_-1.4_^+3.8^%) suggests a low covering factor of the cold neutral medium (CNM; T~100K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Ly{alpha} systems (DLAs), has comoving absorption path lengths of {Delta}X=130.1 and 167.7 for HI and OH, respectively. The corresponding number of absorbers per unit comoving path length are <=0.014 and <=0.011, respectively. The former is at least 4.5 times lower than that of DLAs and consistent with the CNM cross section estimated using H_2_ and CI absorbers at z>2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path ~9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of HI 21cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z>2.
470. Microlensing maps for a cusp configuration
ID:
ivo://CDS.VizieR/J/A+A/553/A53
Title:
Microlensing maps for a cusp configuration
Short Name:
J/A+A/553/A53
Date:
21 Oct 2021
Publisher:
CDS
Description:
We provide the microlensing maps generated to study microlensing in the mid-infrared range for a cusp-configuration lensed AGN. The maps provided correspond to images which are respectively saddle-point and minimum of the arrival time surface. We also provide simulated images of sources with a disc-like brightness profile or a ring-like brightness profile corresponding to an accretion disc or a torus brightness distribution. These source profiles should be convolved with microlensing maps of the same spatial resolution to simulate microlensing of the corresponding source and generate probability density function (PDF) of microlensing similar to those shown in Figures 3,4,5,8. These maps can also be used to generate synthetic microlensing lightcurves (Figure 9) or derive PDF for the Rcusp relation (Figure 10).