- ID:
- ivo://CDS.VizieR/J/MNRAS/453/1562
- Title:
- CRTS close supermassive black hole binaries
- Short Name:
- J/MNRAS/453/1562
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz frequency gravitational waves). Following our detection of a 5.2-year periodic signal in the quasar PG 1302-102, we present a novel analysis of the optical variability of 243 500 known spectroscopically confirmed quasars using data from the Catalina Real-time Transient Survey (CRTS) to look for close (<0.1pc) SMBH systems. Looking for a strong Keplerian periodic signal with at least 1.5 cycles over a baseline of nine years, we find a sample of 111 candidate objects. This is in conservative agreement with theoretical predictions from models of binary SMBH populations. Simulated data sets, assuming stochastic variability, also produce no equivalent candidates implying a low likelihood of spurious detections. The periodicity seen is likely attributable to either jet precession, warped accretion discs or periodic accretion associated with a close SMBH binary system. We also consider how other SMBH binary candidates in the literature appear in CRTS data and show that none of these are equivalent to the identified objects. Finally, the distribution of objects found is consistent with that expected from a gravitational-wave-driven population. This implies that circumbinary gas is present at small orbital radii and is being perturbed by the black holes. None of the sources is expected to merge within at least the next century. This study opens a new unique window to study a population of close SMBH binaries that must exist according to our current understanding of galaxy and SMBH evolution.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/3786
- Title:
- CSS and GPS radio sources sample
- Short Name:
- J/MNRAS/458/3786
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dependence of the turnover frequency on the linear size is presented for a sample of Giga-hertz Peaked Spectrum and Compact Steep Spectrum radio sources derived from complete samples. The dependence of the luminosity of the emission at the peak frequency with the linear size and the peak frequency is also presented for the galaxies in the sample. The luminosity of the smaller sources evolve strongly with the linear size. Optical depth effects have been included to the 3D model for the radio source of Kaiser to study the spectral turnover. Using this model, the observed trend can be explained by synchrotron self-absorption. The observed trend in the peak-frequency-linear-size plane is not affected by the luminosity evolution of the sources.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A53
- Title:
- CTS C30.10 SALT long-slit spectra
- Short Name:
- J/A+A/570/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasars can be used as a complementary tool to SN Ia to probe the distribution of dark energy in the Universe by measuring the time delay of the emission line with respect to the continuum. The understanding of the MgII emission line structure is important for cosmological application and for the black hole mass measurements of intermediate redshift quasars. Knowing the shape of MgII line and its variability allows for identification which part of the line should be used to measure the time delay and the black hole mass. We thus aim at determining the structure and the variability of the MgII line, as well as the underlying FeII pseudo-continuum. We performed five spectroscopic observations of a quasar CTS C30.10 (z=0.9000) with the SALT telescope between December 2012 and March 2014, and we studied the variations in the spectral shape in the 2700{AA}-2900{AA} rest frame. We show that the MgII line in this source consists of two kinematic components, which makes the source representative of type B quasars. Both components were modeled well with a Lorentzian shape, and they vary in a similar way. The FeII contribution seems to be related only to the first (blue) MgII component. Broad band spectral fitting instead favor the use of the whole line profile. The contribution of the narrow line region to MgII is very low, below 2%. The MgII variability is lower than the variability of the continuum, which is consistent with the simple reprocessing scenario. The variability level of CTS C30.10 and the measurement accuracy of the line and continuum is high enough to expect that further monitoring will allow the time delay between the MgII line and continuum to be measured.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/610
- Title:
- Damped Ly{alpha} systems at z<1.65
- Short Name:
- J/ApJ/636/610
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of our Hubble Space Telescope Cycle 11 survey for low-redshift (z<1.65) damped Ly{alpha} (DLA) systems in the UV spectra of quasars selected from the Sloan Digital Sky Survey (SDSS) Early Data Release (Cat. <J/AJ/123/567>). These quasars have strong intervening MgII-FeII systems that are known signatures of high column density neutral gas. In total, including our previous surveys, UV observations of Ly{alpha} absorption in 197 MgII systems with z<1.65 and rest equivalent width (REW) W_0_^{lambda}2796^>=0.3{AA} have now been obtained.
- ID:
- ivo://CDS.VizieR/J/A+A/508/133
- Title:
- Damped Lyman{alpha} absorbers in z>4 QSOs
- Short Name:
- J/A+A/508/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a survey of damped (DLA, logN(HI)>20.3) and sub-damped Lyman-{alpha} systems (19.5<logN(HI)<20.3) at z>2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4<z_em_<6.3. Intermediate resolution (R~4300) spectra were obtained with the Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total of 100 systems with logN(HI)>19.5 were detected of which 40 systems are damped Lyman-{alpha} systems for an absorption length of {Delta}X= 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs.
- ID:
- ivo://CDS.VizieR/J/other/PASA/19.455
- Title:
- Damped Lyman alpha absorption of QSOs
- Short Name:
- J/other/PASA/19.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio properties of the background quasars, when known. Around 60 quasars have radio flux densities above 0.1Jy and approximately half of these have optical magnitudes brighter than V=18. This compilation should prove useful in several areas of extragalactic/cosmological research.
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/998
- Title:
- Damped Lyman{alpha} systems
- Short Name:
- J/MNRAS/392/998
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index=[EW({AA})/{Delta}v(km/s)]x1000 from high-resolution spectra of the MgII {lambda}2796 profile. This sample represents an increase in the sub-DLA statistics by a factor of 4 over the original D-index sample. We investigate various techniques to define the velocity spread ({Delta}v) of the MgII line to determine an optimal D-index for the identification of DLAs. The success rate of DLA identification is 50-55 per cent, depending on the velocity limits used, improving by a few per cent when the column density of FeII is included in the D-index calculation. We recommend the set of parameters that are judged to be most robust, have a combination of high DLA identification rate (57 per cent) and low DLA miss rate (6 per cent) and most cleanly separate the DLAs and sub-DLAs (Kolmogorov-Smirnov probability 0.5 per cent). These statistics demonstrate that the D-index is the most efficient technique for selecting low-redshift DLA candidates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/3428
- Title:
- Damped Lyman Alpha systems equivalent width
- Short Name:
- J/MNRAS/471/3428
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive the statistical properties of neutral gas at redshifts 0.11<z<1.65 from ultraviolet (UV) measurements of quasar Ly{alpha} absorption lines corresponding to 369 MgII systems with W{lambda}2796_0_>=0.3{AA}. In addition to the 41 damped Lyman alpha (DLA) systems presented in Rao et al. (2006ApJ...636..610R, Cat. J/ApJ/636/610), the current DLA sample includes 29 newly discovered DLAs. Formally, this DLA sample includes 70 systems with N_HI_>=2*10^20^atoms/cm^2^. We find that the incidence of DLAs, or the product of their gas cross-section and their comoving number density, can be described by n_DLA_(z)=(0.027+/-0.007)(1+z)^(1.682+/-0.200)^ over the redshift range of 0<z<5. The cosmic mass density of neutral gas can be described by {Omega}_DLA_(z)=(4.77+/-1.60)x10^-4^(1+z)^(0.64+/-0.27)^. The low-redshift column density distribution function is well fitted by a power law of the form f(N)~N^{beta}^ with {beta}=-1.46+/-0.20. It is consistent with the high redshift as well as z=0 estimates at the high-column density end but lies between them at the low-column density end. We discuss possible N_HI_ and metallicity bias in Mg II-selected DLA samples and show that such biases do not exist in the current data at z<1.65. Thus, at least at z<1.65, DLAs found through MgII selection statistically represent the true population of DLAs. However, we caution that studies of DLA metallicities should take into account the relative incidence of DLAs with respect to W_0_{lambda}2796^ (or gas velocity spread) in order to
- ID:
- ivo://CDS.VizieR/J/AJ/155/110
- Title:
- Deep CFHT imaging of VVDS-F22 field. II. Quasars
- Short Name:
- J/AJ/155/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a faint quasar survey in a one-square-degree field. The aim is to test the Y-K/g-z and J-K/i-Y color selection criteria for quasars at faint magnitudes to obtain a complete sample of quasars based on deep optical and near-infrared color-color selection and to measure the faint end of the quasar luminosity function (QLF) over a wide redshift range. We carried out a quasar survey based on the Y-K/g-z and J-K/i-Y quasar selection criteria, using the deep Y-band data obtained from our CFHT/WIRCam Y-band images in a two-degree field within the F22 field of the VIMOS VLT deep survey, optical co-added data from Sloan Digital Sky Survey Stripe 82 and deep near-infrared data from the UKIDSS Deep Extragalactic Survey in the same field. We discovered 25 new quasars at 0.5<z<4.5 and i<22.5 mag within one-square-degree field. The survey significantly increases the number of faint quasars in this field, especially at z~2-3. It confirms that our color selections are highly complete in a wide redshift range (z<4.5), especially over the quasar number density peak at z~2-3, even for faint quasars. Combining all previous known quasars and new discoveries, we construct a sample with 109 quasars and measure the binned QLF and parametric QLF. Although the sample is small, our results agree with a pure luminosity evolution at lower redshift and luminosity evolution and density evolution model at redshift z>2.5.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A52
- Title:
- Deep Chandra survey in J1030+0524 field
- Short Name:
- J/A+A/637/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the X-ray source catalog for the 479ks Chandra exposure of the SDSS J1030+0524 field, that is centered on a region that shows the best evidence to date of an overdensity around a z>6 quasar, and also includes a galaxy overdensity around a Comptonthick Fanaro-Riley type II (FRII) radio galaxy at z=1.7. Using wavdetect for initial source detection and ACIS Extract for source photometry and significance assessment, we create preliminary catalogs of sources that are detected in the full (0.5-7.0keV), soft (0.5-2.0keV), and hard (2-7keV) bands, respectively. We produce X-ray simulations that mirror our Chandra observation to filter our preliminary catalogs and get a completeness level of > 91% and a reliability level of 95% in each band. The catalogs in the three bands are then matched into a final main catalog of 256 unique sources. Among them, 244, 193, and 208 are detected in the full, soft, and hard bands, respectively. The Chandra observation covers a total area of 335 arcmin2, and reaches flux limits over the central few square arcmins of ~3x10^-16^, 6x10^-17^, and 2x10^-16^erg/cm2/s in the full, soft, and hard bands, respectively This makes J1030 field the fifth deepest extragalactic X-ray survey to date. The field is part of the Multiwavelength Survey by Yale-Chile (MUSYC), and is also covered by optical imaging data from the Large Binocular Camera (LBC) at the Large Binocular Telescope (LBT), near-IR imaging data from the Canada France Hawaii Telescope WIRCam (CFHT/WIRCam), and Spitzer IRAC. Thanks to its dense multi-wavelength coverage, J1030 represents a legacy field for the study of large-scale structures around distant accreting supermassive black holes. Using a likelihood ratio analysis, we associate multi-band (r, z, J, and 4.5um) counterparts for 252 (98.4%) of the 256 Chandra sources, with an estimated reliability of 95%. Finally, we compute the cumulative number of sources in each X-ray band, finding that they are in general agreement with the results from the Chandra Deep Fields.
