- ID:
- ivo://CDS.VizieR/J/MNRAS/448/2879
- Title:
- Spectropolarimetry of active galaxy 3C 390.3
- Short Name:
- J/MNRAS/448/2879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here we present the spectropolarimetric observations of the radio-loud active galaxy 3C 390.3 in the period 2009-2014 (24 epochs). The galaxy has been observed with the 6-m telescope of Special Astrophysical Observatory of the Russian Academy of Science (SAO RAS) using the Spectral Camera with Optical Reducer for Photometric and Interferometric Observations (SCORPIO) spectropolarimeter. We explore the variability and lags in the polarized light of the continuum and broad H{alpha} line. We give the Stokes parameters Q, U, degree of linear polarization P and the position angle of the polarization plane, {phi}, for 24 epochs. We find a small lag (10-40 d) between the unpolarized and polarized continuum that is significantly smaller than the estimated lags for the unpolarized broad emission lines (lag(H{alpha}) ~138-186 and lag(H{beta}) ~60-79 d). This shows that the region of the variable polarized continuum is significantly smaller than the broad line region, indicating that a part of the polarized continuum is coming from the jet. The lag of the polarized light in the H{alpha} line (89-156 d) indicates an additional component to the disc one that has an outflowing velocity of ~-1200 km/s. This region seems to depolarize the polarized broad H{alpha} line emitted from the disc and scattered in the inner part of the torus.
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- ID:
- ivo://CDS.VizieR/J/ApJS/250/26
- Title:
- Spectroscopic follow-up of the QUBRICS quasars
- Short Name:
- J/ApJS/250/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the spectroscopic follow-up of the QUasars as BRIght beacons for Cosmology in the Southern Hemisphere (QUBRICS; Calderone+ 2019, J/ApJ/887/268) survey. The selection method is based on a machine-learning approach applied to photometric catalogs, covering an area of ~12400deg^2^ in the Southern Hemisphere. The spectroscopic observations started in 2018 and identified 55 new, high-redshift (z>=2.5), bright (i<=18) quasi-stellar objects (QSOs), with the catalog published in late 2019. Here we report the current status of the survey, bringing the total number of bright QSOs at z>=2.5 identified by QUBRICS to 224. The success rate of the QUBRICS selection method, in its most recent training, is estimated to be 68%. The predominant contaminant turns out to be lower-z QSOs at z<2.5. This survey provides a unique sample of bright QSOs at high z available for a number of cosmological investigations. In particular, carrying out the redshift drift measurements (Sandage Test) in the Southern Hemisphere, using the High Resolution Spectrograph at the 39m Extremely Large Telescope appears to be possible with less than 2500hr of observations spread over 30 targets in 25yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/42
- Title:
- Spectroscopic monitoring of blazar S5 0716+714
- Short Name:
- J/ApJ/902/42
- Date:
- 10 Mar 2022 15:02:00
- Publisher:
- CDS
- Description:
- In this paper, we report new results of spectroscopic observations of {gamma}-ray blazar S5 0716+714 from 2019 September to 2020 March with the 2.4m optical telescope at Lijiang Observatory of Yunnan Observatories. The median cadence of observations is ~1 day. During the second observation period (Epoch2), the observational data reveal an extremely bright state and a bluer-when-brighter (BWB) chromatism. The BWB trend of Epoch2 differs significantly from that of the first observation period (Epoch1). A significantly brightness-dependent BWB chromatism emerges in the total data of Epoch1 and Epoch2. The BWB trend becomes weaker toward the brighter states, and likely becomes saturated at the highest state. Based on a log-parabolic function, a power law of synchrotron peak flux and frequency {nu}p, and a power law of the curvature of synchrotron spectrum and its {nu}p, simulation well reproduces the brightness-dependent BWB trend of S5 0716+714. The BWB trend is seemingly controlled by the shift of {nu}p with respect to the observational window, and effectively may be dominated by the variations of electron average energy and magnetic field in the emitting region.
- ID:
- ivo://CDS.VizieR/J/ApJS/112/315
- Title:
- Spectroscopic parameters of Seyfert nuclei
- Short Name:
- J/ApJS/112/315
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have completed an optical spectroscopic survey of the nuclear regions (r<=200pc) of a large sample of nearby galaxies. Although the main objectives of the survey are to search for low-luminosity active galactic nuclei and to quantify their luminosity function, the database can be used for a variety of other purposes. This paper presents measurements of the spectroscopic parameters for the 418 emission-line nuclei, along with a compilation of the global properties of all 486 galaxies in the survey. Stellar absorption generally poses a serious obstacle to obtaining accurate measurement of emission lines in nearby galactic nuclei. We describe a procedure for removing the starlight from the observed spectra in an efficient and objective manner. The main parameters of the emission lines (intensity ratios, fluxes, profile widths, and equivalent widths) are measured and tabulated, as are several stellar absorption-line and continuum indices useful for studying the stellar population. Using standard nebular diagnostics, we determine the probable ionization mechanisms of the emission-line objects. The resulting spectral classifications provide extensive information on the demographics of emission-line nuclei in the nearby regions of the universe. This new catalog contains over 200 objects showing spectroscopic evidence for recent star formation and an equally large number of active galactic nuclei, including 46 that show broad H{alpha} emission. These samples will serve as the basis of future studies of nuclear activity in nearby galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A31
- Title:
- Spectroscopic study of 283 AGNs in Coma
- Short Name:
- J/A+A/534/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma supercluster whose density spans two orders of magnitude from the sparse filaments to the cores of rich clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/1713
- Title:
- Spectroscopy of X-ray sources in ECDF-S
- Short Name:
- J/ApJ/693/1713
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of our optical spectroscopy program aimed to provide redshifts and identifications for the X-ray sources in the Extended Chandra Deep Field South. A total of 339 sources were targeted using the IMACS spectrograph at the Magellan telescopes and the VIMOS spectrograph at the VLT. We measured redshifts for 186 X-ray sources, including archival data and a literature search. We find that the active galactic nucleus (AGN) host galaxies have on average redder rest-frame optical colors than nonactive galaxies, and that they live mostly in the "green valley". The dependence of the fraction of AGNs that are obscured on both luminosity and redshift is confirmed at high significance and the observed AGN spatial density is compared with the expectations from existing luminosity functions. These AGNs show a significant difference in the mid-IR to X-ray flux ratio for obscured and unobscured AGNs, which can be explained by the effects of dust self-absorption on the former. This difference is larger for lower luminosity sources, which is consistent with the dust opening angle depending on AGN luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/23
- Title:
- Spectroscopy of 88 z<0.7 SDSS QSOs
- Short Name:
- J/ApJS/201/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a systematic search for subparsec supermassive black hole (BH) binaries among z<~0.7 Sloan Digital Sky Survey quasars. These are predicted by models of supermassive BH and host galaxy coevolution, therefore their census and population properties constitute an important test of these models. In our working hypothesis, one of the two BHs accretes at a much higher rate than the other and carries with it the only broad emission line region of the system, making the system analogous to a single-lined spectroscopic binary star. Accordingly, we used spectroscopic principal component analysis to search for broad H{beta} emission lines that are displaced from the quasar rest frame by |{Delta}{nu}|>~1000km/s. This method also yields candidates for rapidly recoiling BHs. Of the 88 candidates, several were previously reported in the literature. We found a correlation between the peak offset and skewness of the broad H{beta} profiles, suggesting a common physical explanation for these profiles. We carried out follow-up spectroscopic observations of 68 objects to search for changes in the peak velocities of the H{beta} lines.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/3335
- Title:
- SPIRE observations of Herschel-BAT sample
- Short Name:
- J/MNRAS/456/3335
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present far-infrared (FIR) and submillimetre photometry from the Herschel Space Observatory's Spectral and Photometric Imaging Receiver (SPIRE) for 313 nearby (z<0.05) active galactic nuclei (AGN). We selected AGN from the 58 month Swift Burst Alert Telescope (BAT) catalogue, the result of an all-sky survey in the 14-195keV energy band, allowing for a reduction in AGN selection effects due to obscuration and host galaxy contamination. We find 46 per cent (143/313) of our sample is detected at all three wavebands and combined with our Photoconductor Array Camera and Spectrometer (PACS) observations represents the most complete FIR spectral energy distributions of local, moderate-luminosity AGN. We find no correlation among the 250, 350, and 500{mu}m luminosities with 14-195keV luminosity, indicating the bulk of the FIR emission is not related to the AGN. However, Seyfert 1s do show a very weak correlation with X-ray luminosity compared to Seyfert 2s and we discuss possible explanations. We compare the SPIRE colours (F_250_/F_350_ and F_350_/F_500_) to a sample of normal star-forming galaxies, finding the two samples are statistically similar, especially after matching in stellar mass. But a colour-colour plot reveals a fraction of the Herschel-BAT AGN are displaced from the normal star-forming galaxies due to excess 500{mu}m emission (E_500_). Our analysis shows E_500_ is strongly correlated with the 14-195keV luminosity and 3.4/4.6{mu}m flux ratio, evidence the excess is related to the AGN. We speculate these sources are experiencing millimetre excess emission originating in the corona of the accretion disc.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/167
- Title:
- Spitzer AGN candidates in CDFN
- Short Name:
- J/ApJ/660/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We define a sample of 62 galaxies in the Chandra Deep Field-North whose Spitzer IRAC SEDs exhibit the characteristic power-law emission expected of luminous AGNs. We study the multi-wavelength properties of this sample and compare the AGNs selected in this way to those selected via other Spitzer color-color criteria. Only 55% of the power-law galaxies are detected in the X-ray catalog at exposures of >0.5Ms, although a search for faint emission results in the detection of 85% of the power-law galaxies at the >=2.5sigma detection level. Most of the remaining galaxies are likely to host AGNs that are heavily obscured in the X-ray. Because the power-law selection requires the AGNs to be energetically dominant in the near- and mid-infrared, the power-law galaxies comprise a significant fraction of the Spitzer-detected AGN population at high luminosities and redshifts. The high 24um detection fraction also points to a luminous population. The power-law galaxies comprise a subset of color-selected AGN candidates.
- ID:
- ivo://CDS.VizieR/J/ApJS/184/230
- Title:
- Spitzer high-resolution MIR spectral atlas
- Short Name:
- J/ApJS/184/230
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an atlas of Spitzer/IRS high-resolution (R~600) 10-37um spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation [NeV] line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4um), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2um, and a previously unreported emission feature at 10.75um. An unidentified absorption feature at 13.7um is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the HI 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.
