- ID:
- ivo://CDS.VizieR/J/ApJ/570/100
- Title:
- BeppoSAX HELLAS survey. V.
- Short Name:
- J/ApJ/570/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopic identifications of hard X-ray (5-10keV) selected sources belonging to the High-Energy Large-Area Survey sample obtained with BeppoSAX down to a 5-10keV flux limit of F(5-10kev)~3x10^-14^erg/cm^2^/s. The sample consists of 118 sources. There are 25 sources that have been identified through correlations with catalogs of known sources. A spectroscopic identification for 49 more has been searched for with the telescope. The results of 13 fields were empty down to R=21. There were 37 sources identified as type 1 active galactic nuclei (AGNs) and nine as type 2 AGNs. The remaining sources are five narrow emission-line galaxies, six clusters, two BL Lac objects, one radio galaxy, and one star.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/859/116
- Title:
- BH masses and Eddington ratios of Type 2 QSOs
- Short Name:
- J/ApJ/859/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Type 2 quasars are an important constituent of active galaxies, possibly representing the evolutionary precursors of traditionally studied type 1 quasars. We characterize the black hole (BH) mass (MBH) and Eddington ratio (Lbol/LEdd) for 669 type 2 quasars selected from the Sloan Digital Sky Survey, using BH masses estimated from the MBH-{sigma}* relation and bolometric corrections scaled from the extinction-corrected [OIII]{lambda}5007 luminosity. When stellar velocity dispersions cannot be measured directly from the spectra, we estimate them from the core velocity dispersions of the narrow emission lines [OII]{lambda}{lambda}3726,3729, [SII]{lambda}{lambda}6716,6731, and [OIII]{lambda}5007, which are shown to trace the gravitational potential of the stars. Energy input from the active nucleus still imparts significant perturbations to the gas kinematics, especially to high-velocity, blueshifted wings. Nonvirial motions in the gas become most noticeable in systems with high Eddington ratios. The BH masses of our sample of type 2 quasars range from MBH~10^6.5^ to 10^10.4^M_{sun}_ (median 10^8.2^M_{sun}_). Type 2 quasars have characteristically large Eddington ratios (Lbol/LEdd~10^-2.9^-10^1.8^; median 10^-0.7^), slightly higher than in type 1 quasars of similar redshift; the luminosities of ~20% of the sample formally exceed the Eddington limit. The high Eddington ratios may be consistent with the notion that obscured quasars evolve into unobscured quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A54
- Title:
- B0355+508 reduced spectra
- Short Name:
- J/A+A/633/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Phosphorus-bearing species are essential to the formation of life on Earth, however they have barely been detected in the interstellar medium. In particular, towards star-forming regions only PN and PO have been identified so far. Since only a small number of detections of P-bearing molecules are available, their chemical formation pathways are not easy to constrain and are thus highly debatable. An important factor still missing in the chemical models is the initial elemental abundance of phosphorus, that is, the depletion level of P at the start of chemical models of dense clouds. In order to overcome this problem, we study P-bearing species in diffuse and translucent clouds. In these objects phosphorus is expected to be mainly in the gas phase and therefore the elemental initial abundance needed in our chemical simulations corresponds to the cosmic one and is well constrained. For the study of P-bearing chemistry we used an advanced chemical model. We updated and significantly extended the P-chemistry network based on chemical databases and previous literature. We performed single-pointing observations with the IRAM 30m telescope in the 3mm range towards the line of sight to the strong continuum source B0355+508 aiming for the (2-1) transitions of PN, PO, HCP, and CP. This line of sight incorporates five diffuse and/or translucent clouds. The (2-1) transitions of the PN, PO, HCP, and CP were not detected. We report high signal-to-noise-ratio detections of the (1-0) lines of ^13^CO, HNC, and CN along with a first detection of C^34^S towards this line of sight. We have attempted to reproduce the observations of HNC, CN, CS, and CO in every cloud with our model by applying typical physical conditions for diffuse or translucent clouds. We find that towards the densest clouds with v_LSR_= -10, -17 km/s the best-fit model is given by the parameters (n_H_, A_V_, T_gas_) = (300cm^-3^, 3mag, 40K). According to our best-fit model, the most abundant P-bearing species are HCP and CP (1e-10). The molecules PN, PO, and PH_3_ also show relatively high predicted abundances of 1e-11. We show that the abundances of these species are sensitive to visual extinction, cosmic-ray ionization rate, and the diffusion-to-desorption energy ratio on dust grains. The production of P-bearing species is favored towards translucent rather than diffuse clouds, where the environment provides a stronger shielding from the interstellar radiation. Based on our improved model, we show that the (1-0) transitions of HCP, CP, PN, and PO are expected to be detectable with estimated intensities of up to ~200mK.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/268
- Title:
- Bright QSOs in Southern Hemisphere (QUBRICS)
- Short Name:
- J/ApJ/887/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of absorptions along the lines of sight to bright high-z QSOs is an invaluable cosmological tool that provides a wealth of information on the inter-/circum-galactic medium, dark matter, primordial elements, reionization, fundamental constants, and general relativity. Unfortunately, the number of bright (i<~18) QSOs at z>~2 in the southern hemisphere is much lower than that in the north, due to the lack of wide multiwavelength surveys at decl. {delta}<0{deg}, hampering the effectiveness of observations from southern observatories. In this work we present a new method based on Canonical Correlation Analysis to identify such objects, taking advantage of a number of available databases: Skymapper, Gaia DR2, WISE, and 2MASS. Our QSO candidate sample lists 1476 sources with i<18 over 12400deg^2^ in the southern hemisphere. With a preliminary campaign we observed spectroscopically 69 of them, confirming 54 new bright QSOs at z>2.5, corresponding to a success rate of our method of ~80%. Furthermore, we estimate a completeness of ~90% of our sample at completion of our observation campaign. The new QSOs confirmed by this first and the forthcoming campaigns (QUBRICS survey) will be the targets of subsequent studies using higher resolution spectrographs, like ESPRESSO, UVES, and (in the long term) ELT/HIRES.
- ID:
- ivo://CDS.VizieR/J/ApJ/710/613
- Title:
- Broad HI absorbers
- Short Name:
- J/ApJ/710/613
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compile a catalog of reliable BLA (thermally broadened Ly{alpha} absorber) candidates along seven active galactic nucleus sight lines from a larger set of Ly{alpha} absorbers observed by the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST). We compare our measurements based on independent reduction and analysis of the data to those published by other research groups. We examine the detailed structure of each absorber and determine a reliable line width and column density. Purported BLAs are grouped into probable (15), possible (48), and non-BLA (56) categories. Based on 164 measured curve of growth (COG) HI line measurements, we statistically correct the observed line widths via a Monte Carlo simulation. Finally, we present new, high signal-to-noise ratio observations of several of the BLA candidate lines from Early Release Observations made by the Cosmic Origins Spectrograph on HST.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/581
- Title:
- Broad-line Balmer decrements in blue AGN
- Short Name:
- J/MNRAS/383/581
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated the broad-line Balmer decrements (H{alpha/H{beta}) for a large, homogeneous sample of Seyfert 1 galaxies and quasi-stellar objects (QSOs) using spectroscopic data obtained in the Sloan Digital Sky Survey. The sample, drawn from the Fourth Data Release, comprises 446 low-redshift (z<=0.35) active galactic nuclei (AGN) that have blue optical continua as indicated by the spectral slopes in order to minimize the effect of dust extinction. We find that (i) the distribution of the intrinsic broad-line H{alpha}/H{beta} ratio can be well described by log-Gaussian, with a peak at H{alpha}/H{beta}=3.06 and a standard deviation of about 0.03dex only; (ii) the Balmer decrement does not correlate with AGN properties such as luminosity, accretion rate and continuum slope, etc.; (iii) on average, the Balmer decrements are found to be only slightly larger in radio-loud sources (3.37) and sources having double-peaked emission-line profiles (3.27) compared to the rest of the sample. We therefore suggest that the broad-line H{alpha}/H{beta} ratio can be used as a good indicator for dust extinction in the AGN broad-line region; this is especially true for radio-quiet AGN with regular emission-line profiles, which constitute the vast majority of the AGN population.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A29
- Title:
- BR 1202-0725 system in [CII] line
- Short Name:
- J/A+A/559/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a kinematical analysis of the [CII] line emission of the BR 1202-0725 system at z~4.7 using ALMA science verification observations. The most prominent sources of this system are a quasar (QSO) and a submillimeter galaxy (SMG), separated by a projected distance of about ~24kpc and characterized by very high star formation rates, higher than 1000M_{sun}_/yr. However, the ALMA observations reveal that these galaxies apparently have undisturbed rotating disks, which is at variance with the commonly accepted scenario in which strong star formation activity is induced by a major merger.We also detected faint components which, after spectral deblending, were spatially resolved from the main QSO and SMG emissions. The relative velocities and positions of these components are compatible with orbital motions within the gravitational potentials generated by the QSO host galaxy and the SMG, suggesting that they are smaller galaxies in interaction or gas clouds in accretion flows of tidal streams. Moreover, we did not find any clear spectral evidence for outflows caused by active galactic nuclei or stellar feedback. This suggests that the high star formation rates might be induced by interactions or minor mergers with these companions, which do not affect the large-scale kinematics of the disks, however. Alternatively, the strong star formation may be fueled by the accretion of pristine gas from the host halo. Our kinematical analysis also indicates that the QSO and the SMG have similar dynamical masses, mostly in the form of molecular gas, and that the QSO host galaxy and the SMG are seen close to face-on with slightly different disk inclinations: the QSO host galaxy is seen almost face-on (i~15{deg}), while the SMG is seen at higher inclinations (i~25{deg}). Finally, the ratio between the black hole mass of the QSO, obtained from new X-shooter spectroscopy, and the dynamical mass of the host galaxy is similar to value found in very massive local galaxies, suggesting that the evolution of black hole galaxy relations is probably better studied with dynamical than with stellar host galaxy masses.
- ID:
- ivo://CDS.VizieR/J/AJ/153/157
- Title:
- Candidate ICRF flat-spectrum radio sources. III.
- Short Name:
- J/AJ/153/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ~160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58m European Southern Observatory New Technology Telescope, and the two 8.2m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/495
- Title:
- Catalogue of 1806 MgII absorbers from SDSS DR3
- Short Name:
- J/MNRAS/371/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the mean halo mass of z=~0.5 MgII absorbers using the cross-correlation (over comoving scales 0.05-13h^-1^Mpc) between 1806 MgII quasar absorption systems and ~250000 luminous red galaxies (LRGs), both selected from the Sloan Digital Sky Survey Data Release 3.
- ID:
- ivo://CDS.VizieR/J/MNRAS/247/182
- Title:
- Catalogue of quasar candidates
- Short Name:
- J/MNRAS/247/182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper gives a list of all quasar candidates obtained from an automated computer search performed on 11 grens plates. The description of the main characteristics of the survey is given along with the latest improvements in the selection techniques. Particular attention has been paid to understanding and quantifying selection effects. This allows the construction of homogeneous samples having well-understood characteristics. The noteworthy aspect of our homogenization process is the correction that we apply to our probability classes in order to take into account the signal-to-noise differences; at a given magnitude, among plates of different limiting magnitudes. Since such homogeneous material is rare, this catalogue is of general interest. Each grens plate covers about 1 square degree with typical limiting magnitude of B~21. Data are given with all relevant quantities needed to understand the characteristics of the survey. We expect that over 100 of the 125 higher probability class candidates are quasars. A third of the ~400 lower probability objects should also be quasars. This material is well-suited to follow-up spectroscopy with fibre spectrographs.