- ID:
- ivo://CDS.VizieR/J/MNRAS/427/1135
- Title:
- Properties of radio-loud BAL quasars
- Short Name:
- J/MNRAS/427/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We recently presented radio observations of a large sample of radio-loud broad absorption line (BAL) quasars from the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at Twenty-cm surveys, as well as a well matched sample of unabsorbed quasars, primarily to measure their radio spectral indices and estimate ensemble orientations. Here, we analyse the SDSS spectra of these samples and compare the rest-frame ultraviolet properties of radio-loud BAL and non-BAL quasars. Ultraviolet properties include the continuum shape, emission-line measurements of CIV, AlIII, CIII], FeII and MgII, and BAL properties including the balnicity index, absorption index and minimum and maximum outflow velocities. We find that radio-loud BAL quasars have similar ultraviolet properties compared to radio-loud non-BAL sources, though they do appear to have redder continua and stronger FeII emission, which is consistent with what is found for radio-quiet BAL sources. No correlations exist between outflow properties and orientation (radio spectral index), suggesting that BAL winds along any line of sight are driven by the same mechanisms. There are also few correlations between spectral index and other properties. We conclude that BAL outflows occur along all lines of sight with similar strengths and velocities.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/400/1493
- Title:
- QSOs Lyman alpha emission line spectra
- Short Name:
- J/MNRAS/400/1493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arguably the best hope of understanding the tail end of the re-ionization of the intergalactic medium (IGM) at redshift z>6 is through the detection and characterization of the Gunn-Peterson damping wing absorption of the IGM in bright quasar spectra. However, the use of quasar spectra to measure the IGM damping wing requires a model of the quasar's intrinsic Lyman{alpha} emission line. Here we quantify the uncertainties in the intrinsic line shapes, and how those uncertainties affect the determination of the IGM neutral fraction. We have assembled a catalogue of high-resolution Hubble Space Telescope spectra of the emission lines of unobscured low-redshift quasars, and have characterized the variance in the shapes of their lines. We then add simulated absorption from the high-redshift IGM to these quasar spectra in order to determine the corresponding uncertainties in re-ionization constraints using current and future samples of z>6 quasar spectra. We find that, if the redshift of the Lyman{alpha} emission line is presumed to coincide with the systemic redshift determined from metal lines, the inferred IGM neutral fraction is systematically biased to low values due to a systematic blueshift of the Lyman{alpha} line relative to the metal lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/669/791
- Title:
- Quasar black hole masses
- Short Name:
- J/ApJ/669/791
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the time-dependent variations of ultraviolet (UV) black hole mass estimates of quasars in the Sloan Digital Sky Survey (SDSS). From SDSS spectra of 615 high-redshift (1.69<z<4.75) quasars with spectra from two epochs, we estimate black hole masses using a single-epoch technique, which employs an additional, automated night-sky line removal and relies on UV continuum luminosity and CIV {lambda}1549 emission-line dispersion. Mass estimates show variations between epochs at about the 30% level for the sample as a whole. We determine that for our full sample, measurement error in the line dispersion likely plays a larger role than the inherent variability in terms of contributing to variations in mass estimates between epochs. However, we use the variations in quasars with r-band spectral signal-to-noise ratio greater than 15 to estimate that the contribution to these variations from inherent variability is roughly 20%. We conclude that these differences in black hole mass estimates between epochs indicate that variability does not make a large contribution to the current factor of 2 scatter between mass estimates derived from low- and high-ionization emission lines.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A87
- Title:
- Quasar composite made from bright QSOs
- Short Name:
- J/A+A/585/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasi-stellar object (QSO) spectral templates are important both to QSO physics and for investigations that use QSOs as probes of intervening gas and dust. However, combinations of various QSO samples obtained at different times and with different instruments so as to expand a composite and to cover a wider rest frame wavelength region may create systematic effects, and the contribution from QSO hosts may contaminate the composite. We have constructed a composite spectrum from luminous blue QSOs at 1<z<2.1 selected from the Sloan Digital Sky Survey (SDSS). The observations with X-shooter simultaneously cover ultraviolet (UV) to near-infrared (NIR) light, which ensures that the composite spectrum covers the full rest-frame range from Ly{beta} to 11350{AA} without any significant host contamination. Assuming a power-law continuum for the composite we find a spectral slope of {alpha}{lambda}=1.70+/-0.01, which is steeper than previously found in the literature. We attribute the differences to our broader spectral wavelength coverage, which allows us to effectively avoid fitting any regions that are affected either by strong QSO emissions lines (e.g., Balmer lines and complex [FeII] blends) or by intrinsic host galaxy emission. Finally, we demonstrate the application of the QSO composite spectrum for evaluating the reddening in other QSOs.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A150
- Title:
- Quasars as standard candles. III.
- Short Name:
- J/A+A/642/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of ~2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM-Newton. The sample can be used to investigate the non-linear relation between the UV and X-ray luminosity of quasars, and to build a Hubble diagram up to redshift z~7.5. We selected sources that are neither reddened by dust in the optical/UV nor obscured by gas in the X-rays, and whose X-ray fluxes are free from flux-limit related biases. After checking for any possible systematics, we confirm, in agreement with our previous works, that (i) the X-ray to UV relation provides distance estimates matching those from supernovae up to z~1.5, and (ii) its slope shows no redshift evolution up to z~5. We provide a full description of the methodology for testing cosmological models, further supporting a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat LambdaCDM model up to z~1.5-2, but strong deviations emerge at higher redshifts. Since we have minimized all non-negligible systematic effects, and proven the stability of the Lx-Lo relation at high redshifts, we conclude that an evolution of the expansion rate of the Universe should be considered as a possible explanation for the observed deviation, rather than some systematic (redshift-dependent) effect associated with high-redshift quasars.
- ID:
- ivo://CDS.VizieR/J/ApJS/255/16
- Title:
- Quiet-Sun MgII h & k line profiles from IRIS
- Short Name:
- J/ApJS/255/16
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We derived high-precision reference profiles of the MgII h and k lines that represent the quiet Sun during a minimum of the solar activity. To do so, we used the broad catalog of full-Sun mosaics obtained by the Interface Region Imaging Spectrograph (IRIS). To minimize the influence of the local variations due to the on-disk solar features and to achieve low levels of uncertainties, we used 12 IRIS full-Sun mosaics without sunspots or other significant signs of solar activity. These mosaics were obtained between 2019 April and 2020 September in the near-ultraviolet spectral range. In this paper, we present the disk-averaged reference profiles of MgII h and MgII k lines, together with a series of reference profiles spanning the distance between the disk center and the solar limb. These series of profiles offer a detailed representation of the center-to-limb variation of both MgII h and MgII k lines. The reference MgII h and k line profiles provided in this paper can be used as the incident radiation boundary condition for radiative-transfer modeling of prominences, spicules, and other coronal and chromospheric structures.
- ID:
- ivo://CDS.VizieR/J/ApJ/701/1965
- Title:
- Radial dust properties of SINGS galaxies
- Short Name:
- J/ApJ/701/1965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed analysis of the radial distribution of dust properties in the SINGS sample, performed on a set of ultraviolet (UV), infrared (IR), and HI surface brightness profiles, combined with published molecular gas profiles and metallicity gradients. By applying physical dust models to our radial spectral energy distributions, we have derived radial profiles of the total dust mass surface density, the fraction of the total dust mass contributed by polycyclic aromatic hydrocarbons (PAHs), and the intensity of the radiation field heating the grains.
- ID:
- ivo://CDS.VizieR/J/ApJ/658/1006
- Title:
- Radial profiles for 161 face-on spirals
- Short Name:
- J/ApJ/658/1006
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present specific star formation rate (sSFR) radial profiles for a sample of 161 relatively face-on spiral galaxies from the GALEX Atlas of Nearby Galaxies. The sSFR profiles are derived from GALEX and 2MASS (FUV-K) color profiles after a proper SFR calibration of the UV luminosity and K-band mass-to-light ratio are adopted. The (FUV-K) profiles were first corrected for foreground Galactic extinction and later for internal extinction using the ratio of the total-infrared (TIR) to FUV emission. For those objects where TIR-to-FUV ratio radial profiles were not available, the (FUV-NUV) color profiles were used as a measure of the UV slope. The sSFR radial gradients derived from these profiles allow us to quantify the inside-out scenario for the growth of spiral disks for the first time in the local universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/828/47
- Title:
- Radial velocities of the Be star HR 2142
- Short Name:
- J/ApJ/828/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets of ultraviolet observations from the International Ultraviolet Explorer (IUE) and ground-based H{alpha} observations. We measured radial velocities for the Be star component from these spectra and computed a revised orbit. In order to search for the spectral signature of the hot subdwarf, we cross-correlated the short wavelength end of each IUE spectrum with a model hot star spectrum, and then we used the predicted Doppler shifts of the subdwarf to shift-and-add all the cross-correlation functions to the frame of the subdwarf. This merged function shows the weak signal from the spectral lines of the hot star, and a best fit is obtained with a mass ratio M_2_/M_1_=0.07+/-0.02, companion temperature T_eff_>=43+/-5kK, projected rotational velocity Vsini<30km/s, and a monochromatic flux ratio near 1170{AA} of f_2_/f_1_>0.009+/-0.001. This hot subdwarf creates a one-armed spiral, tidal wake in the disk of the Be star, and we present a circumbinary disk model that can explain the occurrence of shell absorption lines by gas enhancements that occur where gas crossing the gap created by the subdwarf strikes the disk boundaries. The faint companion of HR 2142 may be representative of a significant fraction of Be stars with undetected former mass donor companion stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/940
- Title:
- Radio and UV spectra of HVC toward the MC
- Short Name:
- J/ApJ/702/940
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the spectra of 139 early-type Large Magellanic Cloud (LMC) stars observed with Far Ultraviolet Spectroscopic Explorer and with deep radio Parkes HI 21cm observations along with those stars, we search for and analyze the absorption and emission from high-velocity gas at +90<={nu}_LSR_<=+175km/s. The HI column density of the high-velocity clouds (HVCs) along these sightlines ranges from <1018.4 to 1019.2cm^-2^. The incidence of the HVC metal absorption is 70%, significantly higher than the HI emission occurrence of 32%. We find that the mean metallicity of the HVC is [OI/HI]=-0.51+/-^0.12^_0.16_. This is the first example of a large (>10^6^M_{sun}_) HVC complex that is linked to stellar feedback occurring in a dwarf spiral galaxy.
