Abstract
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
β
emission line for a total of 44 quasars, and for the broad H
α
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
β
and 13 H
α
lags with
JAVELIN
, 42 H
β
and 17 H
α
lags with
CREAM
, and 16 H
β
and eight H
α
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
β
-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
α
emission is consistent with or slightly longer than that of H
β
. 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).
In Spring 2011, the Lick AGN Monitoring Project observed a sample of 15 bright, nearby Seyfert 1 galaxies in the V band as part of a reverberation mapping campaign. The observations were taken at six ...ground-based telescopes, including the West Mountain Observatory 0.91 m telescope, the 0.76 m Katzman Automatic Imaging Telescope, 0.6 m Super-LOTIS at Kitt Peak, the Palomar 60 inch telescope, and the 2 m Faulkes telescopes North and South. The V-band light curves measure the continuum variability of our sample of Seyferts on an almost daily cadence for 2-3 months. We use image-subtraction software to isolate the variability of the Seyfert nucleus from the constant V-band flux of the host galaxy for the most promising targets, and we adopt standard aperture photometry techniques for the targets with smaller levels of variability. These V-band light curves will be used, with measurements of the broad emission line flux, to measure supermassive black hole masses and to constrain the geometry and dynamics of the broad-line region through dynamical modeling techniques.
We present the variability and time-lag measurements of PG 0934+013 based on a photometric and spectroscopic monitoring campaign over a two year period. We obtained 46 epochs of data from the ...spectroscopic campaign, which was carried out using the Southern African Large Telescope with ∼1 week cadence over two sets of four month-long observing period, while we obtained 80 epochs of B-band imaging data using a few 1 m class telescopes. Due to the seven month gap between the two observing periods, we separately measured the time lags of broad emission lines, including Hβ, by comparing the emission line light curve with the B-band continuum light curve using the cross-correlation function techniques. We determined the Hβ lag, days in the observed frame based on Year 2 data, while the time lag from Year 1 data was not reliably determined. Using the rms spectrum of Year 2 data, we measured the Hβ line dispersion = 668 44 km s−1 after correcting for the spectral resolution. Adopting a virial factor f = 4.47 from Woo et al. (2015), we determined the black hole mass MBH M , based on the Hβ time lag and velocity.
Abstract
We have modeled the velocity-resolved reverberation response of the H
β
broad emission line in nine Seyfert 1 galaxies from the Lick Active Galactic Nucleus (AGN) Monitoring Project 2016 ...sample, drawing inferences on the geometry and structure of the low-ionization broad-line region (BLR) and the mass of the central supermassive black hole. Overall, we find that the H
β
BLR is generally a thick disk viewed at low to moderate inclination angles. We combine our sample with prior studies and investigate line-profile shape dependence, such as
log
10
(
FWHM
/
σ
)
, on BLR structure and kinematics and search for any BLR luminosity-dependent trends. We find marginal evidence for an anticorrelation between the profile shape of the broad H
β
emission line and the Eddington ratio, when using the rms spectrum. However, we do not find any luminosity-dependent trends, and conclude that AGNs have diverse BLR structure and kinematics, consistent with the hypothesis of transient AGN/BLR conditions rather than systematic trends.
Abstract
We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from 2016 April to 2017 May. ...Targeting active galactic nuclei (AGNs) with luminosities of
λ
L
λ
(5100 Å) ≈ 10
44
erg s
−1
and predicted H
β
lags of ∼20–30 days or black hole masses of 10
7
–10
8.5
M
⊙
, our campaign probes luminosity-dependent trends in broad-line region (BLR) structure and dynamics as well as to improve calibrations for single-epoch estimates of quasar black hole masses. Here we present the first results from the campaign, including H
β
emission-line light curves, integrated H
β
lag times (8–30 days) measured against
V
-band continuum light curves, velocity-resolved reverberation lags, line widths of the broad H
β
components, and virial black hole mass estimates (10
7.1
–10
8.1
M
⊙
). Our results add significantly to the number of existing velocity-resolved lag measurements and reveal a diversity of BLR gas kinematics at moderately high AGN luminosities. AGN continuum luminosity appears not to be correlated with the type of kinematics that its BLR gas may exhibit. Follow-up direct modeling of this data set will elucidate the detailed kinematics and provide robust dynamical black hole masses for several objects in this sample.
On 2012 May 17.2 UT, only 1.5 + or - 0.2 days after explosion, we discovered SN 2012cg, a Type Ia supernova (SN Ia) in NGC 4424 (d approximate 15 Mpc). As a result of the newly modified strategy ...employed by the Lick Observatory Supernova Search, a sequence of filtered images was obtained starting 161 s after discovery. Utilizing recent models describing the interaction of supernova (SN) ejecta with a companion star, we rule out a ~ 1 M sub(middot in circle) companion for half of all viewing angles and a red-giant companion for nearly all orientations. SN 2012cg reached a B-band maximum of 12.09 + or - 0.02 mag on 2012 June 2.0 and took ~17.3 days from explosion to reach this, typical for SNe Ia. Our pre-maximum-brightness photometry shows a narrower-than-average B-band light curve for SN 2012cg, though slightly overluminous at maximum brightness and with normal color evolution (including some of the earliest SN Ia filtered photometry ever obtained). Spectral fits to SN 2012cg reveal ions typically found in SNe Ia at early times, with expansion velocities > ~14,000 km s super(-1) at 2.5 days past explosion. Absorption from C II is detected early, as well as high-velocity components of both Si II lambda6355 and Ca II. Our last spectrum (13.5 days past explosion) resembles that of the somewhat peculiar SN Ia 1999aa. This suggests that SN 2012cg will have a slower-than-average declining light curve, which may be surprising given the faster-than-average rising light curve.
KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign ...designed to measure the broad-line region size and estimate the mass of the black hole in this galaxy. We obtained 74 epochs of spectroscopic data using the Kast Spectrograph at the Lick 3 m telescope from 2012 February to November, and obtained complementary V-band images from five other ground-based telescopes. We measured the Hβ light curve lag with respect to the V-band continuum light curve using both cross-correlation techniques (CCF) and continuum light curve variability modeling with the JAVELIN method and found rest-frame lags of τ{sub CCF}=13.53{sub −2.32}{sup +2.03} days and τ {sub JAVELIN} =13.15{sub −1.00}{sup +1.08} days. The Hβ rms line profile has a width of σ{sub line} = 770 ± 49 km s{sup –1}. Combining these two results and assuming a virial scale factor of f = 5.13, we obtained a virial estimate of M{sub BH}=8.06{sub −1.72}{sup +1.59}×10{sup 6}M{sub ⊙} for the mass of the central black hole and an Eddington ratio of L/L {sub Edd} ≈ 0.2. We also obtained consistent but slightly shorter emission-line lags with respect to the Kepler light curve. Thanks to the Kepler mission, the light curve of KA1858+4850 has among the highest cadences and signal-to-noise ratios ever measured for an active galactic nucleus; thus, our black hole mass measurement will serve as a reference point for relations between black hole mass and continuum variability characteristics in active galactic nuclei.
The Type Ia supernova (SN Ia) 2016coj in NGC 4125 (redshift z = 0.00452 0.00006) was discovered by the Lick Observatory Supernova Search 4.9 days after the fitted first-light time (FFLT; 11.1 days ...before B-band maximum). Our first detection (prediscovery) is merely 0.6 0.5 days after the FFLT, making SN 2016coj one of the earliest known detections of an SN Ia. A spectrum was taken only 3.7 hr after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We performed high-quality photometry, low- and high-resolution spectroscopy, and spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN Ia, but the velocity of Si ii λ6355 around peak brightness (∼12,600 ) is a bit higher than that of typical normal SNe. The Si ii λ6355 velocity evolution can be well fit by a broken-power-law function for up to a month after the FFLT. SN 2016coj has a normal peak luminosity ( mag), and it reaches a B-band maximum ∼16.0 days after the FFLT. We estimate there to be low host-galaxy extinction based on the absence of Na i D absorption lines in our low- and high-resolution spectra. The spectropolarimetric data exhibit weak polarization in the continuum, but the Si ii line polarization is quite strong (∼0.9% 0.1%) at peak brightness.
Reverberation mapping is a time-domain technique used to resolve the supermassive black hole’s sphere of influence in active galactic nuclei. We carried out a nine-month reverberation mapping ...campaign to measure the broad-line region size and estimate the mass of the black hole in KA1858+4850, a narrow-line Seyfert 1 galaxy at redshift 0.078 and among the brightest active galaxies monitored by the Kepler mission. We obtained spectroscopic data using the Kast Spectrograph at the Lick 3-m telescope and complementary V-band images from five other ground-based telescopes. We measured the H light curve lag with respect to the V-band continuum light curve, and combined this lag with the Hβ root-mean-square line profile width to obtain a virial estimate of MBH = 8.06 (+1.59, –1.72) × 106 M? for the mass of the central black hole and an Eddington ratio of L/LEdd ≈ 0.2. I also used reverberation mapping to study in detail the broad line region in NGC 5548, a Seyfert 1 galaxy at redshift 0.017. Optical spectroscopic data targeting NGC 5548 were taken in 2014 as part of a larger multi-wavelength reverberation mapping campaign. The ground-based spectra spanned six months and achieved almost daily cadence with observations from five telescopes. We computed the H and He II λ4686 lags relative to both the optical continuum and the UV continuum measured by the Hubble Space Telescope, and found the Hβ–UV lag to be ∼50% longer than the Hβ–optical lag. This suggests that the true broad-line region size is 50% larger than the size that would be inferred from optical data alone. We also measured velocity-resolved lags for H and found a complex velocity-lag structure with shorter lags in the line wings. The responsivity of both the Hβ and He II lines decreased halfway through the campaign, an anomalous phenomenon also observed for the UV emission lines during the same monitoring period. Finally, we showed that, given the optical luminosity of NGC 5548 during our campaign, the measured Hβ lag is a factor of five shorter than the expected value based on the past behavior of NGC 5548. To efficiently process large amounts of reverberation mapping photometry data, I developed an IDL pipeline that is able to automatically extract the aperture photometry magnitude of the AGN, calibrate the individual exposures for nightly variations using reference stars, and construct the relative optical continuum light curve combining data from multiple telescopes. This pipeline has been used in several collaborations, both to monitor AGN variability in real time and to construct photometry light curves from archival data, and its applications can be extended to time-domain studies of any variable object.
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