- ID:
- ivo://CDS.VizieR/J/A+A/590/A68
- Title:
- AGN data and absorption-line measurements
- Short Name:
- J/A+A/590/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Doubly ionized silicon (SiIII) is a powerful tracer of diffuse ionized gas inside and outside of galaxies.It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening SiIII-selected absorbers and study the properties of the warm circumgalactic medium (CGM) around low-redshift (z<0.1) galaxies. We analyzed the UV absorption spectra of 303 extragalactic background sources, as obtained with the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). We developed a geometrical model for the absorption-cross section of the CGM around the local galaxy population and compared the observed SiIII absorption statistics with predictions provided by the model. We also compared redshifts and positions of the absorbers with those of ~64,000 galaxies using archival galaxy-survey data to investigate the relation between intervening SiIII absorbers and the CGM. Along a total redshift path of {Delta}z~24, we identify 69 intervening SiIII systems that all show associated absorption from other low and high ions (e.g., HI, SiII, SiIV, CII, CIV). We derive a bias-corrected number density of dN/dz(SiIII)=2.5+/-0.4 for absorbers with column densities log N(SiIII)>12.2, which is ~3 times the number density of strong MgII systems at z=0. This number density matches the expected cross section of a SiIII absorbing CGM around the local galaxy population with a mean covering fraction of <f_c_>=0.69. For the majority (~60 percent) of the absorbers, we identify possible host galaxies within 300km/s of the absorbers and derive impact parameters {rho}<200kpc, demonstrating that the spatial distributions of SiIII absorbers and galaxies are highly correlated. Our study indicates that the majority of SiIII-selected absorbers in our sample trace the CGM of nearby galaxies within their virial radii at a typical covering fraction of ~70 percent. We estimate that diffuse gas in the CGM around galaxies, as traced by SiIII contains substantially more (more than twice as much) baryonic mass than their neutral interstellar medium.
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Search Results
22. AGN feedback
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/28
- Title:
- AGN feedback
- Short Name:
- J/MNRAS/471/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several studies support the existence of a link between the active galactic nucleus (AGN) and star formation activity. Radio jets have been argued to be an ideal mechanism for direct interaction between the AGN and the host galaxy. A drawback of previous surveys of AGN is that they are fundamentally limited by the degeneracy between redshift and luminosity in flux-density limited samples. To overcome this limitation, we present far-infrared Herschel observations of 74 radio-loud quasars (RLQs), 72 radio-quiet quasars (RQQs) and 27 radio galaxies (RGs), selected at 0.9<z<1.1, which span over two decades in optical luminosity. By decoupling luminosity from evolutionary effects, we investigate how the star formation rate (SFR) depends on AGN luminosity, radio-loudness and orientation. We find that (1) the SFR shows a weak correlation with the bolometric luminosity for all AGN sub-samples, (2) the RLQs show an SFR excess of about a factor of 1.4 compared to the RQQs, matched in terms of black hole mass and bolometric luminosity, suggesting that either positive radio-jet feedback or radio AGN triggering is linked to star formation triggering, and (3) RGs have lower SFRs by a factor of 2.5 than the RLQ sub-sample with the same BH mass and bolometric luminosity. We suggest that there is some jet power threshold at which radio-jet feedback switches from enhancing star formation (by compressing gas) to suppressing it (by ejecting gas). This threshold depends on both galaxy mass and jet power.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A21
- Title:
- AGN feedback from CO observations
- Short Name:
- J/A+A/562/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the properties of massive, galactic-scale outflows of molecular gas and investigate their impact on galaxy evolution. We present new IRAM PdBI CO(1-0) observations of local ULIRGs and QSO hosts: clear signature of massive and energetic molecular outflows, extending on kpc scales, is found in the CO(1-0) kinematics of four out of seven sources, with measured outflow rates of several 100M_{sun}_/yr. We combine these new observations with data from the literature, and explore the nature and origin of massive molecular outflows within an extended sample of 19 local galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/535/A69
- Title:
- AGN Fermi/LAT {gamma}-ray and 37GHz fluxes
- Short Name:
- J/A+A/535/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although the Fermi mission has increased our knowledge of {gamma}-ray AGN, many questions remain, such as the site of {gamma}-ray production, the emission mechanism, and the factors that govern the strength of the emission. Using data from a high radio band, 37GHz, uncontaminated by other radiation components besides the jet emission, we study these questions with averaged flux densities over the the first year of Fermi operations. We look for possible correlations between the 100MeV-100GeV band used by the Fermi satellite and 37GHz radio band observed at the Aalto University Metsahovi Radio Telescope, as well as for differences between the {gamma}-ray emission of different AGN subsamples. We use data averaged over the 1FGL period. Our sample includes 249 northern AGN, including a complete sample of 68 northern AGN with a measured average flux density exceeding 1Jy.
- ID:
- ivo://CDS.VizieR/J/AJ/133/313
- Title:
- AGN from RASS and SDSS DR5
- Short Name:
- J/AJ/133/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe further results of a program aimed at yielding ~104 fully characterized optical identifications of ROSAT X-ray sources. Our program employs X-ray data from the ROSAT All Sky Survey (RASS) and both optical imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS). RASS/SDSS data from 5740deg^2^ of sky spectroscopically covered in SDSS Data Release 5 provide an expanded catalog of 7000 confirmed quasars and other active galactic nuclei (AGNs) that are probable RASS identifications. Again, in our expanded catalog the identifications as X-ray sources are statistically secure, with only a few percent of the SDSS AGNs likely to be randomly superposed on unrelated RASS X-ray sources.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1418
- Title:
- AGN jet kinematics
- Short Name:
- J/AJ/130/1418
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present total and polarized intensity images of 15 active galactic nuclei obtained with the Very Long Baseline Array at 7mm (43GHz) wavelength at 17 epochs from 1998 March to 2001 April. At some epochs the images are accompanied by nearly simultaneous polarization measurements at 3mm (86GHz) with the Berkeley-Illinois-Maryland Association (BIMA) array (Hat Creek, California), 1.35/0.85mm (230/350GHz) with the James Clerk Maxwell Telescope (JCMT; using SCUBA and its polarimeter, and at the Steward Observatory 1.5m telescope (Mount Lemmon, Arizona) with the Two-Holer Polarimeter/Photometer over an effective wavelength range of ~6000-7000{AA}. Here we analyze the 7mm images to define the properties of the jets of two radio galaxies, five BL Lac objects, and eight quasars on angular scales >~0.1mas. We determine the apparent velocities of 106 features in the jets.
- ID:
- ivo://CDS.VizieR/J/ApJ/737/101
- Title:
- AGN pairs from SDSS-DR7. I.
- Short Name:
- J/ApJ/737/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy-galaxy mergers and close interactions have long been regarded as a viable mechanism for channeling gas toward the central supermassive black holes (SMBHs) of galaxies which are triggered as active galactic nuclei (AGNs). AGN pairs, in which the central SMBHs of a galaxy merger are both active, are expected to be common from such events. We conduct a systematic study of 1286 AGN pairs at \bar{z}~0.1 with line-of-sight velocity offsets {Delta}v<600km/s and projected separations r_p_<100h^-1^_70_kpc, selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS, Cat. II/294). This AGN pair sample was drawn from 138070 AGNs optically identified based on diagnostic emission line ratios and/or line widths. The fraction of AGN pairs with 5h^-1^_70_kpc<~r_p_<100h^-1^_70_kpc among all spectroscopically selected AGNs at 0.02<z<0.16 is 3.6% after correcting for SDSS spectroscopic incompleteness; ~30% of these pairs show morphological tidal features in their SDSS images, and the fraction becomes >~80% for pairs with the brightest nuclei.
- ID:
- ivo://CDS.VizieR/J/AJ/131/84
- Title:
- AGNs and host galaxies information
- Short Name:
- J/AJ/131/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad-line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification.
- ID:
- ivo://CDS.VizieR/J/AJ/114/2353
- Title:
- AGNs and QSOs behind nearby galaxies
- Short Name:
- J/AJ/114/2353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data are given for 16 extragalactic objects (predominantly AGN) behind the Magellanic Clouds and for 146 quasar candidates behind the nearby galaxies NGC 45, 185, 253, 2366, 2403 and 6822, IC 1613, M31, and M33. The Magellanic Cloud objects were identified by their X-ray emission, and precise optical and X-ray positions and optical photometry and spectra are presented for all of these. The quasar candidates surrounding the other nearby galaxies were identified through a CFHT slitless spectral survey. Although redshifts for only eight of these candidates have been obtained, previous observations indicate that the majority are likely to be quasars. A subsample of 49 of the brighter objects could confidently be used, in addition to the Magellanic Cloud sources, as probes of the gas in nearby galaxies for rotation curve studies, for studies of their halos, for comparison with higher redshift QSO absorption lines, or as references for proper motion studies.
- ID:
- ivo://CDS.VizieR/J/ApJS/150/165
- Title:
- AGNs emission-line from Post-COSTAR
- Short Name:
- J/ApJS/150/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present consistent emission-line measurements for active galactic nuclei (AGNs), useful for reliable statistical studies of emission line properties. This paper joins a series including similar measurements of 993 spectra from the Large Bright Quasar Survey and 174 spectra of AGNs obtained from the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) prior to the installation of COSTAR. This time we concentrate on 220 spectra obtained with the FOS after the installation of COSTAR, completing the emission line analysis of all FOS archival spectra. We use the same automated technique as in previous papers, which accounts for Galactic extinction, models blended optical and UV iron emission, includes Galactic and intrinsic absorption lines, and models emission lines using multiple Gaussians. We present UV and optical emission line parameters (equivalent widths, fluxes, FWHM, and line positions) for a large number (28) of emission lines including upper limits for undetected lines. Further scientific analyses will be presented in subsequent papers.