- ID:
- ivo://CDS.VizieR/J/ApJ/851/21
- Title:
- SDSS RM project first year of observations
- Short Name:
- J/ApJ/851/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present reverberation mapping results from the first year of combined spectroscopic and photometric observations of the Sloan Digital Sky Survey Reverberation Mapping Project. We successfully recover reverberation time delays between the g+i band emission and the broad H{beta} emission line for a total of 44 quasars, and for the broad H{alpha} emission line in 18 quasars. Time delays are computed using the JAVELIN and CREAM software and the traditional interpolated cross-correlation function (ICCF): using well-defined criteria, we report measurements of 32 H{beta} and 13 H{alpha} lags with JAVELIN, 42 H{beta} and 17 H{alpha} lags with CREAM, and 16 H{beta} and eight H{alpha} lags with the ICCF. Lag values are generally consistent among the three methods, though we typically measure smaller uncertainties with JAVELIN and CREAM than with the ICCF, given the more physically motivated light curve interpolation and more robust statistical modeling of the former two methods. The median redshift of our H{beta}-detected sample of quasars is 0.53, significantly higher than that of the previous reverberation mapping sample. We find that in most objects, the time delay of the H{alpha} emission is consistent with or slightly longer than that of H{beta}. We measure black hole masses using our measured time delays and line widths for these quasars. These black hole mass measurements are mostly consistent with expectations based on the local M_BH_-{sigma}* relationship, and are also consistent with single-epoch black hole mass measurements. This work increases the current sample size of reverberation-mapped active galaxies by about two- thirds and represents the first large sample of reverberation mapping observations beyond the local universe (z<0.3).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/882/4
- Title:
- SDSS-RM project: H{alpha}, H{beta} & MgII lines
- Short Name:
- J/ApJ/882/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The width of the broad emission lines in quasars is commonly characterized by either the FWHM or the square root of the second moment of the line profile ({sigma}line) and used as an indicator of the virial velocity of the broad-line region (BLR) in the estimation of black hole (BH) mass. We measure FWHM and {sigma}line for H{alpha}, H{beta}, and MgII broad lines in both the mean and rms spectra of a large sample of quasars from the Sloan Digital Sky Survey Reverberation Mapping project. We introduce a new quantitative recipe to measure {sigma}line that is reproducible, is less susceptible to noise and blending in the wings, and scales with the intrinsic width of the line. We compare the four definitions of line width (FWHM and {sigma}line in mean and rms spectra, respectively) for each of the three broad lines and among different lines. There are strong correlations among different width definitions for each line, providing justification for using the line width measured in single-epoch spectroscopy as a virial velocity indicator. There are also strong correlations among different lines, suggesting that alternative lines to H{beta} can be used to estimate virial BH masses. We further investigate the correlations between virial BH masses using different line width definitions and the stellar velocity dispersion of the host galaxies and the dependence of line shape (characterized by the ratio FWHM/{sigma}line) on physical properties of the quasar. Our results provide further evidence that FWHM is more sensitive to the orientation of a flattened BLR geometry than {sigma}line, but the overall comparison between the virial BH mass and host stellar velocity dispersion does not provide conclusive evidence that one particular width definition is significantly better than the others.
- ID:
- ivo://CDS.VizieR/J/ApJ/901/55
- Title:
- SDSS-RM project: MgII lags from 4yrs monitoring
- Short Name:
- J/ApJ/901/55
- Date:
- 17 Feb 2022 11:27:58
- Publisher:
- CDS
- Description:
- We present reverberation mapping results for the MgII{lambda}2800{AA} broad emission line in a sample of 193 quasars at 0.35<z<1.7 with photometric and spectroscopic monitoring observations from the Sloan Digital Sky Survey Reverberation Mapping project during 2014-2017. We find significant time lags between the MgII and continuum lightcurves for 57 quasars, and define a "gold sample" of 24 quasars with the most reliable lag measurements. We estimate false-positive rates for each lag that range from 1% to 24%, with an average false-positive rate of 11% for the full sample and 8% for the gold sample. There are an additional ~40 quasars with marginal MgII lag detections, which may yield reliable lags after additional years of monitoring. The MgII lags follow a radius-luminosity relation with a best-fit slope that is consistent with {alpha}=0.5, but with an intrinsic scatter of 0.36dex that is significantly larger than found for the H{beta} radius-luminosity relation. For targets with SDSS-RM lag measurements of other emission lines, we find that our MgII lags are similar to the H{beta} lags and ~2-3 times larger than the CIV lags. This work significantly increases the number of MgII broad-line lags and provides additional reverberation-mapped black hole masses, filling the redshift gap at the peak of supermassive black hole growth between the H{beta} and CIV emission lines in optical spectroscopy.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/7
- Title:
- SDSS-RM project: peak velocities of QSOs
- Short Name:
- J/ApJ/831/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasar emission lines are often shifted from the systemic velocity due to various dynamical and radiative processes in the line-emitting region. The level of these velocity shifts depends both on the line species and on quasar properties. We study velocity shifts for the line peaks (not the centroids) of various narrow and broad quasar emission lines relative to systemic using a sample of 849 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. The coadded (from 32 epochs) spectra of individual quasars have sufficient signal-to-noise ratio (S/N) to measure stellar absorption lines to provide reliable systemic velocity estimates, as well as weak narrow emission lines. The large dynamic range in quasar luminosity (~2dex) of the sample allowed us to explore potential luminosity dependence of the velocity shifts. We derive average line peak velocity shifts as a function of quasar luminosity for different lines, and quantify their intrinsic scatter. We further quantify how well the peak velocity can be measured as a function of continuum S/N, and demonstrate that there is no systematic bias in the velocity measurements when S/N is degraded to as low as ~3 per SDSS pixel (~69kms/s). Based on the observed line shifts, we provide empirical guidelines on redshift estimation from [OII]{lambda}3727, [OIII]{lambda}5007, [NeV]{lambda}3426, MgII, CIII], HeII{lambda}1640, broad H{beta}, CIV, and SiIV, which are calibrated to provide unbiased systemic redshifts in the mean, but with increasing intrinsic uncertainties of 46, 56, 119, 205, 233, 242, 400, 415, and 477kms/s, in addition to the measurement uncertainties. These results demonstrate the infeasibility of measuring quasar redshifts to better than ~200kms/s with only broad lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/216/4
- Title:
- SDSS-RM project: technical overview
- Short Name:
- J/ApJS/216/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project is a dedicated multi-object RM experiment that has spectroscopically monitored a sample of 849 broad-line quasars in a single 7deg^2^ field with the SDSS-III Baryon Oscillation Spectroscopic Survey spectrograph. The RM quasar sample is flux-limited to i_psf_=21.7mag, and covers a redshift range of 0.1<z<4.5 without any other cuts on quasar properties. Optical spectroscopy was performed during 2014 January-July dark/gray time, with an average cadence of ~4 days, totaling more than 30 epochs. Supporting photometric monitoring in the g and i bands was conducted at multiple facilities including the Canada-France-Hawaii Telescope (CFHT) and the Steward Observatory Bok telescope in 2014, with a cadence of ~2 days and covering all lunar phases. The RM field (RAJ2000=14:14:49.00, DEJ2000=+53:05:00.0) lies within the CFHT-LS W3 field, and coincides with the Pan-STARRS 1 (PS1) Medium Deep Field MD07, with three prior years of multi-band PS1 light curves. The SDSS-RM six month baseline program aims to detect time lags between the quasar continuum and broad line region (BLR) variability on timescales of up to several months (in the observed frame) for ~10% of the sample, and to anchor the time baseline for continued monitoring in the future to detect lags on longer timescales and at higher redshift. SDSS-RM is the first major program to systematically explore the potential of RM for broad-line quasars at z>0.3, and will investigate the prospects of RM with all major broad lines covered in optical spectroscopy.
- ID:
- ivo://CDS.VizieR/J/ApJ/805/96
- Title:
- SDSS-RM project: velocity dispersions of QSOs
- Short Name:
- J/ApJ/805/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present host stellar velocity dispersion measurements for a sample of 88 broad-line quasars at 0.1<z<1 (46 at z>0.6) from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. High signal-to-noise ratio coadded spectra (average S/N~30 per 69km/s pixel) from SDSS-RM allowed for the decomposition of the host and quasar spectra and for measurements of the host stellar velocity dispersions and black hole (BH) masses using the single-epoch (SE) virial method. The large sample size and dynamic range in luminosity (L_5100_=10^43.2-44.7^erg/s) lead to the first clear detection of a correlation between SE virial BH mass and host stellar velocity dispersion far beyond the local universe. However, the observed correlation is significantly flatter than the local relation, suggesting that there are selection biases in high-z luminosity-threshold quasar samples for such studies. Our uniform sample and analysis enable an investigation of the redshift evolution of the M_{dot}_-{sigma}_*_ relation relatively free of caveats by comparing different samples/analyses at disjoint redshifts. We do not observe evolution of the M_{dot}_-{sigma}_*_ relation in our sample up to z~1, but there is an indication that the relation flattens toward higher redshifts. Coupled with the increasing threshold luminosity with redshift in our sample, this again suggests that certain selection biases are at work, and simple simulations demonstrate that a constant M_{dot}_-{sigma}_*_ relation is favored to z~1. Our results highlight the scientific potential of deep coadded spectroscopy from quasar monitoring programs, and offer a new path to probe the co-evolution of BHs and galaxies at earlier times.
- ID:
- ivo://CDS.VizieR/J/ApJ/811/91
- Title:
- SDSS-RM project: z<1 QSO host galaxies
- Short Name:
- J/ApJ/811/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasar host galaxies are key for understanding the relation between galaxies and the supermassive black holes (SMBHs) at their centers. We present a study of 191 broad-line quasars and their host galaxies at z<1 using high signal-to-noise ratio (S/N) spectra produced by the Sloan Digital Sky Survey Reverberation Mapping project. Clear detection of stellar absorption lines allows a reliable decomposition of the observed spectra into nuclear and host components, using spectral models of quasar and stellar radiations as well as emission lines from the interstellar medium. We estimate age, mass M*, and velocity dispersion {sigma}* of the host stars, the star formation rate (SFR), quasar luminosity, and SMBH mass M_{dot}_ for each object. The quasars are preferentially hosted by massive galaxies with M*~10^11^M_{sun}_ characterized by stellar ages around 1 billion yr, which coincides with the transition phase of normal galaxies from the blue cloud to the red sequence. The host galaxies have relatively low SFRs and fall below the main sequence of star-forming galaxies at similar redshifts. These facts suggest that the hosts have experienced an episode of major star formation sometime in the past 1 billion yr, which was subsequently quenched or suppressed. The derived M_{dot}_-{sigma}* and M_{dot}_-M* relations agree with our past measurements and are consistent with no evolution from the local universe. The present analysis demonstrates that reliable measurements of stellar properties of quasar host galaxies are possible with high-S/N fiber spectra, which will be acquired in large numbers with future powerful instruments such as the Subaru Prime Focus Spectrograph.
- ID:
- ivo://CDS.VizieR/J/ApJS/166/470
- Title:
- SDSS-Spitzer type I QSOs IR photometry
- Short Name:
- J/ApJS/166/470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the mid-infrared (MIR) and optical properties of type 1 (broad-line) quasars detected by the Spitzer Space Telescope. The MIR color-redshift relation is characterized to z~3, with predictions to z=7. We demonstrate how combining MIR and optical colors can yield even more efficient selection of active galactic nuclei (AGNs) than MIR or optical colors alone. Composite spectral energy distributions (SEDs) are constructed for 259 quasars with both Sloan Digital Sky Survey and Spitzer photometry, supplemented by near-IR, GALEX, VLA, and ROSAT data, where available.
- ID:
- ivo://CDS.VizieR/J/AJ/134/973
- Title:
- SDSS Stripe 82 star catalogs
- Short Name:
- J/AJ/134/973
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a standard star catalog constructed using multiple SDSS photometric observations (at least four per band, with a median of 10) in the ugriz system. The catalog includes 1.01 million nonvariable unresolved objects from the equatorial stripe 82 (|{delta}_J2000.0_|<1.266{deg}) in the right ascension range 20^h^34^m^-4^h^00^m^ and with the corresponding r-band (approximately Johnson V-band) magnitudes in the range 14-22. The distributions of measurements for individual sources demonstrate that the photometric pipeline correctly estimates random photometric errors, which are below 0.01mag for stars brighter than 19.5, 20.5, 20.5, 20, and 18.5 in ugriz, respectively (about twice as good as for individual SDSS runs). Several independent tests of the internal consistency suggest that the spatial variation of photometric zero points is not larger than ~0.01mag (rms). In addition to being the largest available data set with optical photometry internally consistent at the ~1% level, this catalog provides a practical definition of the SDSS photometric system. Using this catalog, we show that photometric zero points for SDSS observing runs can be calibrated within a nominal uncertainty of 2% even for data obtained through 1mag thick clouds, and we demonstrate the existence of He and H white dwarf sequences using photometric data alone. Based on the properties of this catalog, we conclude that upcoming large-scale optical surveys such as the Large Synoptic Survey Telescope will be capable of delivering robust 1% photometry for billions of sources.
- ID:
- ivo://CDS.VizieR/J/AJ/122/503
- Title:
- SDSS u*g*r*i*z* photometry and redshift of QSOs
- Short Name:
- J/AJ/122/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present data for over 100 high-redshift quasars found in ~700deg^2^ by the Sloan Digital Sky Survey (SDSS), using automated selection algorithms applied to SDSS imaging data and with spectroscopic confirmation obtained during routine spectroscopic observations by the Sloan 2.5 m telescope. The SDSS spectra cover the wavelength range 3900-9200{AA}E at a spectral resolution of 1800 and have been obtained for 116 quasars with redshifts greater than 3.94; 92 of these objects were previously uncatalogued, significantly increasing the current list of published z>4 quasars. The paper also reports observations of seven additional new z>4 quasars; all were selected from the SDSS imaging survey and spectroscopically confirmed with observations by the Apache Point Observatory's 3.5 m telescope or the Hobby-Eberly Telescope.
