58 research outputs found
The Sloan Digital Sky Survey Reverberation Mapping Project: No Evidence for Evolution in the M-sigma Relation to z~1
We present host stellar velocity dispersion measurements for a sample of 88
broad-line quasars at 0.10.6) from the Sloan Digital Sky Survey
Reverberation Mapping (SDSS-RM) project. High signal-to-noise ratio coadded
spectra (average S/N~30 per 69 km/s pixel) from SDSS-RM allowed decomposition
of the host and quasar spectra, and measurement 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
(L5100=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-sigma
relation free of caveats by comparing different samples/analyses at disjoint
redshifts. We do not observe evolution of the M-sigma relation in our sample,
up to z~1, but there is an indication that the relation flattens towards higher
redshifts. Coupled with the increasing threshold luminosity with redshift in
our sample, this again suggests certain selection biases are at work, and
simple simulations demonstrate that a constant M-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.Comment: replaced with the accepted version (minor changes and updated
references); ApJ in press; changed title to highlight the main resul
The Lick AGN Monitoring Project: Reverberation Mapping of Optical Hydrogen and Helium Recombination Lines
We have recently completed a 64-night spectroscopic monitoring campaign at
the Lick Observatory 3-m Shane telescope with the aim of measuring the masses
of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected
masses in the range ~10^6-10^7M_sun and also the well-studied nearby active
galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including
NGC 5548) showed optical variability of sufficient strength during the
monitoring campaign to allow for a time lag to be measured between the
continuum fluctuations and the response to these fluctuations in the broad
Hbeta emission, which we have previously reported. We present here the light
curves for the Halpha, Hgamma, HeII 4686, and HeI 5876 emission lines and the
time lags for the emission-line responses relative to changes in the continuum
flux. Combining each emission-line time lag with the measured width of the line
in the variable part of the spectrum, we determine a virial mass of the central
supermassive black hole from several independent emission lines. We find that
the masses are generally consistent within the uncertainties. The time-lag
response as a function of velocity across the Balmer line profiles is examined
for six of the AGNs. Finally we compare several trends seen in the dataset
against the predictions from photoionization calculations as presented by
Korista & Goad. We confirm several of their predictions, including an increase
in responsivity and a decrease in the mean time lag as the excitation and
ionization level for the species increases. Further confirmation of
photoionization predictions for broad-line gas behavior will require additional
monitoring programs for these AGNs while they are in different luminosity
states. [abridged]Comment: 37 pages, 18 figures and 15 tables, accepted for publication in the
Astrophysical Journa
The DRESS trial: a feasibility randomized controlled trial of a neuropsychological approach to dressing therapy for stroke inpatients
Objective: To investigate two approaches to treating patients with persistent dressing problems and cognitive difficulties following stroke.
Design: Pilot randomized controlled trial.
Setting: Inpatient stroke rehabilitation service.
Subjects: Seventy consecutive stroke patients with persistent dressing problems and accompanying cognitive difficulties at two weeks after their stroke.
Interventions: Patients were randomly allocated to six weeks of either a systematic neuropsychological approach, based on analysis of dressing problems and further cognitive testing, or to the control group who received conventional (functional) dressing practice. Both groups received treatment three times a week in accordance with two separately prepared manuals.
Main measures: Nottingham Stroke Dressing Assessment (NSDA), Line Cancellation, 10-hole peg transfer test, Object Decision, Gesture Imitation. Patients were assessed at six weeks after randomization by an independent assessor masked to group allocation.
Results: Both neuropsychological and functional groups improved performance on the NSDA over the treatment period (31% and 22%, respectively) but there was no significant difference between groups at six weeks. However, the neuropsychological group showed a significantly greater improvement on a line cancellation test of visual neglect (t(62) = 2.1, P < 0.05) and a planned subanalysis for those with right hemisphere damage showed a trend towards better dressing outcome (P = 0.07, one-tailed).
Conclusions: Results demonstrate the potential benefits of a systematic neuropsychological approach to dressing therapy, particularly for patients with right hemisphere damage. This study suggests the need for a phase III study evaluating the efficacy of a systematic neuropsychological approach in treating dressing difficulties, targeting patients with right hemisphere stroke and visuospatial impairments
The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview
The Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM) is a
dedicated multi-object RM experiment that has spectroscopically monitored a
sample of 849 broad-line quasars in a single 7 deg field with the SDSS-III
BOSS spectrograph. The RM quasar sample is flux-limited to i_psf=21.7 mag, and
covers a redshift range of 0.1<z<4.5. Optical spectroscopy was performed during
2014 Jan-Jul dark/grey 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 CFHT and the Steward Observatory
Bok telescopes in 2014, with a cadence of ~2 days and covering all lunar
phases. The RM field (RA, DEC=14:14:49.00, +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 6-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.
SDSS-RM will provide guidance on future multi-object RM campaigns on larger
scales, and is aiming to deliver more than tens of BLR lag detections for a
homogeneous sample of quasars. We describe the motivation, design and
implementation of this program, and outline the science impact expected from
the resulting data for RM and general quasar science.Comment: 25 pages, submitted to ApJS; project website at http://www.sdssrm.or
The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta
We have recently completed a 64-night spectroscopic monitoring campaign at
the Lick Observatory 3-m Shane telescope with the aim of measuring the masses
of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected
masses in the range ~10^6-10^7 M_sun and also the well-studied nearby active
galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including
NGC 5548) showed optical variability of sufficient strength during the
monitoring campaign to allow for a time lag to be measured between the
continuum fluctuations and the response to these fluctuations in the broad
Hbeta emission. We present here the light curves for the objects in this sample
and the subsequent Hbeta time lags for the nine objects where these
measurements were possible. The Hbeta lag time is directly related to the size
of the broad-line region, and by combining the lag time with the measured width
of the Hbeta emission line in the variable part of the spectrum, we determine
the virial mass of the central supermassive black hole in these nine AGNs. The
absolute calibration of the black hole masses is based on the normalization
derived by Onken et al. We also examine the time lag response as a function of
velocity across the Hbeta line profile for six of the AGNs. The analysis of
four leads to ambiguous results with relatively flat time lags as a function of
velocity. However, SBS 1116+583A exhibits a symmetric time lag response around
the line center reminiscent of simple models for circularly orbiting broad-line
region (BLR) clouds, and Arp 151 shows an asymmetric profile that is most
easily explained by a simple gravitational infall model. Further investigation
will be necessary to fully understand the constraints placed on physical models
of the BLR by the velocity-resolved response in these objects.Comment: 24 pages, 16 figures and 13 tables, submitted to Ap
The Sloan Digital Sky Survey Reverberation Mapping Project: First broad-line Hβ and Mg II lags at z ≳ 0.3 from six-month spectroscopy
Support for the work of Y.S. was provided by NASA through Hubble Fellowship grant number HST-HF-51314, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. K.H. acknowledges support from UK Science and Technology Facilities Council (STFC) grant ST/M001296/1. C.J.G. and W.N.B. acknowledge support from NSF grant AST-1517113 and the V.M. Willaman Endowment. B.M.P. is grateful for support from the National Science Foundation through grant AST-1008882. K.D.D. is supported by an NSF AAPF fellowship awarded under NSF grant AST-1302093. J.R.T. acknowledges support from NASA through Hubble Fellowship grant HST-HF-51330 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS 5-26555. M.S. acknowledges support from the China Scholarship Council (No. [2013]3009). L.C.H. is supported by the Chinese Academy of Science through grant No. XDB09030102 (Emergence of Cosmological Structures) from the strategic Priority Research Program, and from the National Natural Science Foundation of China through grant No. 11473002. L.J. acknowledges the support from a 985 project at Peking University. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science.Reverberation mapping (RM) measurements of broad-line region (BLR) lags in z > 0.3 quasars are important for directly measuring black hole masses in these distant objects, but so far there have been limited attempts and success given the practical difficulties of RM in this regime. Here we report preliminary results of 15 BLR lag measurements from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project, a dedicated RM program with multi-object spectroscopy designed for RM over a wide redshift range. The lags are based on the 2014 spectroscopic light curves alone (32 epochs over six months) and focus on the Hβ and Mg II broad lines in the 100 lowest-redshift (z 0.3 is not yet possible owing to the limitations in our current sample. Our results demonstrate the general feasibility and potential of multi-object RM for z > 0.3 quasars.Publisher PDFPeer reviewe
The Sloan Digital Sky Survey Reverberation Mapping Project: Hα and Hβ reverberation measurements from first-year spectroscopy and photometry
Funding: UK Sciences and Technology Facilities Council STFC grant ST/M001296/1 (KH).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 Hβ emission line for a total of 44 quasars, and for the broad Hα 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 Hβ and 13 Hα lags with JAVELIN, 42 Hβ and 17 Hα lags with CREAM, and 16 Hβ and eight Hα 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 Hβ-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 Hα emission is consistent with or slightly longer than that of Hβ. 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 – 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).PostprintPeer reviewe
The Sloan Digital Sky Survey Reverberation Mapping project : key results
Funding: Y.S. acknowledges support from NSF grants AST-1715579 and AST-2009947. C.J.G. acknowledges support from NSF grants AST-2009949 and AST-2108667. J.I.L. is supported by the Eric and Wendy Schmidt AI in Science Postdoctoral Fellowship, a Schmidt Futures program. Y.H. was supported as an Eberly Research Fellow by the Eberly College of Science at the Pennsylvania State University. J.R.T. acknowledges support from NSF grants CAREER-1945546, AST-2009539, and AST-2108668. W.N.B. acknowledges support from NSF grant AST-2106990 and the Eberly Endowment at Penn State. L.C.H. was supported by the National Science Foundation of China (11721303, 11991052, 12011540375, 12233001) and the China Manned Space Project (CMS-CSST-2021-A04, CMS-CSST-2021-A06). C.T. acknowledges Tsinghua University for the support to her work.We present the final data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping (RM) project, a precursor to the SDSS-V Black Hole Mapper RM program. This data set includes 11 yr photometric and 7 yr spectroscopic light curves for 849 broad-line quasars over a redshift range of 0.1 < z < 4.5 and a luminosity range of Lbol = 1044−47.5 erg s−1, along with spectral and variability measurements. We report 23, 81, 125, and 110 RM lags (relative to optical continuum variability) for broad Hα, Hβ, Mg ii, and C iv using the SDSS-RM sample, spanning much of the luminosity and redshift ranges of the sample. Using 30 low-redshift RM active galactic nuclei with dynamical-modeling black hole masses, we derive a new estimate of the average virial factor of ⟨logf⟩ = 0.62±0.07 for the line dispersion measured from the rms spectrum. The intrinsic scatter of individual virial factors is 0.31 ± 0.07 dex, indicating a factor of 2 systematic uncertainty in RM black hole masses. Our lag measurements reveal significant R–L relations for Hβ and Mg ii at high redshift, consistent with the latest measurements based on heterogeneous samples. While we are unable to robustly constrain the slope of the R–L relation for C iv given the limited dynamic range in luminosity, we found substantially larger scatter in C iv lags at fixed L1350. Using the SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for Hβ, Mg ii, and C iv, which are consistent with their respective RM masses as well as between the SE recipes from two different lines, over the luminosity range probed by our sample. The new Hβ and Mg ii recipes are approximately unbiased estimators at given RM masses, but there are systematic biases in the C iv recipe. The intrinsic scatter of SE masses around RM masses is ∼0.45 dex for Hβ and Mg ii, increasing to ∼0.58 dex for C iv.Peer reviewe
The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results
We present the final data from the Sloan Digital Sky Survey Reverberation
Mapping (SDSS-RM) project, a precursor to the SDSS-V Black Hole Mapper
Reverberation Mapping program. This data set includes 11-year photometric and
7-year spectroscopic light curves for 849 broad-line quasars over a redshift
range of 0.1<z<4.5 and a luminosity range of Lbol=1E44-47.5 erg/s, along with
spectral and variability measurements. We report 23, 81, 125, and 110
reverberation mapping lags (relative to optical continuum variability) for
broad Halpha, Hbeta, MgII and CIV using the SDSS-RM sample, spanning much of
the luminosity and redshift ranges of the sample. Using 30 low-redshift RM AGNs
with dynamical-modeling black hole masses, we derive a new estimate of the
average virial factor of =0.62+-0.07 for the line dispersion measured
from the RMS spectrum. The intrinsic scatter of individual virial factors is
0.31+-0.07 dex, indicating a factor of two systematic uncertainty in RM black
hole masses. Our lag measurements reveal significant R-L relations for Hbeta
and MgII at high redshift, consistent with the latest measurements based on
heterogeneous samples. While we are unable to robustly constrain the slope of
the R-L relation for CIV given the limited dynamical range in luminosity, we
found substantially larger scatter in CIV lags at fixed L1350. Using the
SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for
Hbeta, MgII and CIV, which are consistent with their respective RM masses as
well as between the SE recipes from two different lines, over the luminosity
range probed by our sample. The new Hbeta and MgII recipes are approximately
unbiased estimators at given RM masses, but there are systematic biases in the
CIV recipe. The intrinsic scatter of SE masses around RM masses is ~0.45 dex
for Hbeta and MgII, increasing to ~0.58 dex for CIV.Comment: 33 pages. Data products available at
ftp://quasar.astro.illinois.edu/public/sdssrm/final_result
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