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771. SHINING I. Survey observational trends
ID:
ivo://CDS.VizieR/J/ApJ/861/94
Title:
SHINING I. Survey observational trends
Short Name:
J/ApJ/861/94
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the Herschel/PACS spectrometer to study the global and spatially resolved far-infrared (FIR) fine-structure line emission in a sample of 52 galaxies that constitute the SHINING survey. These galaxies include star-forming, active-galactic nuclei (AGNs), and luminous infrared galaxies (LIRGs). We find an increasing number of galaxies (and kiloparsec-size regions within galaxies) with low line-to-FIR continuum ratios as a function of increasing FIR luminosity (LFIR), dust infrared color, LFIR to molecular gas mass ratio (LFIR/Mmol), and FIR surface brightness ({Sigma}FIR). The correlations between the [CII]/FIR or [OI]/FIR ratios with {Sigma}FIR are remarkably tight (~0.3dex scatter over almost four orders of magnitude in {Sigma}FIR). We observe that galaxies with L_FIR_/M_mol_>~80L_{sun}_/M_{sun}_ and {Sigma}FIR>~10^11^L_{sun}_/kpc^2^ tend to have weak fine-structure line-to-FIR continuum ratios, and that LIRGs with infrared sizes >~1kpc have line-to-FIR ratios comparable to those observed in typical star-forming galaxies. We analyze the physical mechanisms driving these trends in Paper II. The combined analysis of the [CII], [NII]122{mu}m, and [OIII]88{mu}m lines reveals that the fraction of the [CII] line emission that arises from neutral gas increases from 60% to 90% in the most active star-forming regions and that the emission originating in the ionized gas is associated with low-ionization, diffuse gas rather than with dense gas in HII regions. Finally, we report the global and spatially resolved line fluxes of the SHINING galaxies to enable the comparison and planning of future local and high-z studies.
772. 3{sigma} hard sample of XMDS survey
ID:
ivo://CDS.VizieR/J/A+A/467/73
Title:
3{sigma} hard sample of XMDS survey
Short Name:
J/A+A/467/73
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our goal is to probe the populations of obscured and unobscured AGN investigating their optical-IR and X-ray properties as a function of X-ray flux, luminosity and redshift within a hard X-ray selected sample with wide multiwavelength coverage. We selected a sample of 136 X-ray sources detected at a significance of >=3{sigma} in the 2-10keV band (F_2-10_>~10^-14^erg/cm^2^/s) in a ~1deg^2^ area in the XMM Medium Deep Survey (XMDS, Cat. <J/A+A/439/413>). The XMDS area is covered with optical photometry from the VVDS and CFHTLS surveys and infrared Spitzer data from the SWIRE survey. Based on the X-ray luminosity and X-ray to optical ratio, 132 sources are likely AGN, of which 122 have unambiguous optical - IR identification. The observed optical and IR spectral energy distributions of all identified sources are fitted with AGN/galaxy templates in order to classify them and compute photometric redshifts. X-ray spectral analysis is performed individually for sources with a sufficient number of counts and using a stacking technique for subsamples of sources at different flux levels. Hardness ratios are used to estimate X-ray absorption in individual weak sources.
773. Significance of VLBI/Gaia position offsets
ID:
ivo://CDS.VizieR/J/MNRAS/467/L71
Title:
Significance of VLBI/Gaia position offsets
Short Name:
J/MNRAS/467/L71
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have cross matched the Gaia Data Release 1 secondary data set that contains positions of 1.14 billion objects against the most complete to date catalogue of very long baseline interferometry (VLBI) positions of 11.4 thousand sources, almost exclusively active galactic nuclei. We found 6064 matches, i.e. 53 per cent radio objects. The median uncertainty of VLBI positions is a factor of 4 smaller than the median uncertainties of their optical counterparts. Our analysis shows that the distribution of normalized arc lengths significantly deviates from Rayleigh shape with an excess of objects with small normalized arc lengths and with a number of outliers. We found that 6 per cent matches have radio-optical offsets significant at 99 per cent confidence level. Therefore, we conclude there exists a population of objects with genuine offsets between centroids of radio and optical emission.
774. Size and Structure of AGN in NGC 5548
ID:
ivo://CDS.VizieR/J/ApJ/510/659
Title:
Size and Structure of AGN in NGC 5548
Short Name:
J/ApJ/510/659
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of 3 yr of ground-based observations of the Seyfert 1 galaxy NGC 5548, which, combined with previously reported data, yield optical continuum and broad-line H{beta} light curves for a total of 8 yr. The light curves consist of over 800 points, with a typical spacing of a few days between observations. During this 8 yr period, the nuclear continuum has varied by more than a factor of 7, and the H{beta} emission line has varied by a factor of nearly 6. The H{beta} emission line responds to continuum variations with a time delay or lag of {=~}10--20 days, the precise value varying somewhat from year to year. We find some indications that the lag varies with continuum flux in the sense that the lag is larger when the source is brighter.
775. Sizes of MRC radio galaxies and QSOs
ID:
ivo://CDS.VizieR/J/ApJ/766/37
Title:
Sizes of MRC radio galaxies and QSOs
Short Name:
J/ApJ/766/37
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the currently popular orientation-based unified scheme, a radio galaxy appears as a quasar when its principal radio-axis happens to be oriented within a certain cone opening angle around the observer's line of sight. Due to geometrical projection, the observed sizes of quasars should therefore appear smaller than those of radio galaxies. We show that this simple, unambiguous prediction of the unified scheme is not borne out by the actually observed angular sizes of radio galaxies and quasars. Except in the original 3CR sample, based on which the unified scheme was proposed, in other much larger samples no statistically significant difference is apparent in the size distributions of radio galaxies and quasars. The population of low-excitation radio galaxies with apparently no hidden quasars inside, which might explain the observed excess number of radio galaxies at low redshifts, cannot account for the absence of any foreshortening of the sizes of quasars at large redshifts. On the other hand, from infrared and X-ray studies, there is evidence of a hidden quasar within a dusty torus in many radio galaxies, at z>0.5. It is difficult to reconcile this with the absence of foreshortening of quasar sizes at even these redshifts, and perhaps one has to allow that the major radio axis may not have anything to do with the optical axis of the torus. Otherwise, to resolve the dichotomy of radio galaxies and quasars, a scheme quite different from the present might be required.
776. S7 observations with WiFeS of active galaxies
ID:
ivo://CDS.VizieR/J/ApJS/217/12
Title:
S7 observations with WiFeS of active galaxies
Short Name:
J/ApJS/217/12
Date:
21 Oct 2021
Publisher:
CDS
Description:
Here we describe the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) and present results on 64 galaxies drawn from the first data release. The S7 uses the Wide Field Spectrograph (WiFeS) mounted on the ANU 2.3m telescope located at the Siding Spring Observatory to deliver an integral field of 38x25 arcsec at a spectral resolution of R=7000 in the red (530-710nm), and R=3000 in the blue (340-560nm). From these data cubes we have extracted the narrow-line region spectra from a 4 arcsec aperture centered on the nucleus. We also determine the H{beta} and [OIII]{lambda}5007 fluxes in the narrow lines, the nuclear reddening, the reddening-corrected relative intensities of the observed emission lines, and the H{beta} and [OIII]{lambda}5007 luminosities determined from spectra for which the stellar continuum has been removed. We present a set of images of the galaxies in [OIII]{lambda}5007, [NII]{lambda}6584, and H{alpha}, which serve to delineate the spatial extent of the extended narrow-line region and also to reveal the structure and morphology of the surrounding HII regions. Finally, we provide a preliminary discussion of those Seyfert 1 and Seyfert 2 galaxies that display coronal emission lines in order to explore the origin of these lines.
777. Soft X-Ray-Selected AGNs complete sample
ID:
ivo://CDS.VizieR/J/AJ/127/156
Title:
Soft X-Ray-Selected AGNs complete sample
Short Name:
J/AJ/127/156
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the optical spectra and simple statistical analysis for a complete sample of 110 soft X-ray-selected AGNs. About half of the sources are narrow-line Seyfert 1 galaxies (NLS1's), which have the steepest X-ray spectra, the strongest Fe II emission, and slightly weaker [O III] {lambda}5007 emission than broad-line Seyfert 1's (BLS1's). Kolmogorov-Smirnov tests show that NLS1's and BLS1's have clearly different distributions of the X-ray spectral slope {alpha}_X_, X-ray short-term variability, and Fe II equivalent widths and luminosity and Fe II/H{beta} ratios.
778. Space telescope RM project. II. Swift data
ID:
ivo://CDS.VizieR/J/ApJ/806/129
Title:
Space telescope RM project. II. Swift data
Short Name:
J/ApJ/806/129
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent intensive Swift monitoring of the Seyfert 1 galaxy NGC 5548 yielded 282 usable epochs over 125 days across six UV/optical bands and the X-rays. This is the densest extended active galactic nucleus (AGN) UV/optical continuum sampling ever obtained, with a mean sampling rate <0.5 day. Approximately daily Hubble Space Telescope UV sampling was also obtained. The UV/optical light curves show strong correlations (r_max_=0.57-0.90) and the clearest measurement to date of interband lags. These lags are well-fit by a {tau}{propto}{lambda}^4/3^ wavelength dependence, with a normalization that indicates an unexpectedly large disk radius of ~0.35+/-0.05lt-day at 1367{AA}, assuming a simple face-on model. The U band shows a marginally larger lag than expected from the fit and surrounding bands, which could be due to Balmer continuum emission from the broad-line region as suggested by Korista and Goad. The UV/X-ray correlation is weaker (r_max_<0.45) and less consistent over time. This indicates that while Swift is beginning to measure UV/optical lags in general agreement with accretion disk theory (although the derived size is larger than predicted), the relationship with X-ray variability is less well understood. Combining this accretion disk size estimate with those from quasar microlensing studies suggests that AGN disk sizes scale approximately linearly with central black hole mass over a wide range of masses.
779. Space telescope RM project. I. NGC5548
ID:
ivo://CDS.VizieR/J/ApJ/806/128
Title:
Space telescope RM project. I. NGC5548
Short Name:
J/ApJ/806/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe the first results from a six-month long reverberation-mapping experiment in the ultraviolet based on 171 observations of the Seyfert 1 galaxy NGC 5548 with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Significant correlated variability is found in the continuum and broad emission lines, with amplitudes ranging from ~30% to a factor of two in the emission lines and a factor of three in the continuum. The variations of all the strong emission lines lag behind those of the continuum, with HeII{lambda}1640 lagging behind the continuum by ~2.5 days and Ly{alpha}{lambda}1215, CIV{lambda}1550, and SiIV{lambda}1400 lagging by ~5-6 days. The relationship between the continuum and emission lines is complex. In particular, during the second half of the campaign, all emission-line lags increased by a factor of 1.3-2 and differences appear in the detailed structure of the continuum and emission-line light curves. Velocity-resolved cross-correlation analysis shows coherent structure in lag versus line of sight velocity for the emission lines; the high-velocity wings of CIV respond to continuum variations more rapidly than the line core, probably indicating higher velocity broad-line region clouds at smaller distances from the central engine. The velocity-dependent response of Ly{alpha}, however, is more complex and will require further analysis.
780. Space telescope RM project. V. NGC5548 sp. monitoring
ID:
ivo://CDS.VizieR/J/ApJ/837/131
Title:
Space telescope RM project. V. NGC5548 sp. monitoring
Short Name:
J/ApJ/837/131
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multiwavelength reverberation mapping campaign. The campaign spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes. The H{beta} and HeII{lambda}4686 broad emission-line light curves lag that of the 5100{AA} optical continuum by 4.17_-0.36_^+0.36^days and 0.79_-0.34_^+0.35^days, respectively. The H{beta} lag relative to the 1158{AA} ultraviolet continuum light curve measured by the Hubble Space Telescope is ~50% longer than that measured against the optical continuum, and the lag difference is consistent with the observed lag between the optical and ultraviolet continua. This suggests that the characteristic radius of the broad-line region is ~50% larger than the value inferred from optical data alone. We also measured velocity-resolved emission-line lags for H{beta} and found a complex velocity-lag structure with shorter lags in the line wings, indicative of a broad-line region dominated by Keplerian motion. The responses of both the H{beta} and He II emission lines to the driving continuum changed significantly halfway through the campaign, a phenomenon also observed for CIV, Ly{alpha}, HeII(+OIII]), and SiIV(+OIV]) during the same monitoring period. Finally, given the optical luminosity of NGC5548 during our campaign, the measured H{beta} lag is a factor of five shorter than the expected value implied by the R_BLR_-L_AGN_ relation based on the past behavior of NGC 5548.