Search

Start Over Subject photometry
5871. SEAMBHs IX. 10 new H{beta} light curves
ID:
ivo://CDS.VizieR/J/ApJ/856/6
Title:
SEAMBHs IX. 10 new H{beta} light curves
Short Name:
J/ApJ/856/6
Date:
21 Oct 2021
Publisher:
CDS
Description:
As one paper in a series reporting on a large reverberation mapping campaign of super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs), we present the results of 10 SEAMBHs monitored spectroscopically during 2015-2017. Six of them are observed for the first time, and have generally higher 5100{AA} luminosities than the SEAMBHs monitored in our campaign from 2012 to 2015; the remaining four are repeat observations to check if their previous lags change. Similar to the previous SEAMBHs, the H{beta} time lags of the newly observed objects are shorter than the values predicted by the canonical RH{beta}-L5100 relation of sub-Eddington AGNs, by factors of ~2-6, depending on the accretion rate. The four previously observed objects have lags consistent with previous measurements. We provide linear regressions for the RH{beta}-L5100 relation, solely for the SEAMBH sample and for low-accretion AGNs. We find that the relative strength of Fe ii and the profile of the H{beta} emission line can be used as proxies of accretion rate, showing that the shortening of H{beta} lags depends on accretion rates. The recent SDSS-RM discovery of shortened H{beta} lags in AGNs with low accretion rates provides compelling evidence for retrograde accretion onto the black hole. These evidences show that the canonical RH{beta}-L5100 relation holds only in AGNs with moderate accretion rates. At low accretion rates, it should be revised to include the effects of black hole spin, whereas the accretion rate itself becomes a key factor in the regime of high accretion rates.
5872. SEAMBHs. V. The third year
ID:
ivo://CDS.VizieR/J/ApJ/825/126
Title:
SEAMBHs. V. The third year
Short Name:
J/ApJ/825/126
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014 and 2015. Ten new targets were selected from the quasar sample of the Sloan Digital Sky Survey (SDSS), which have generally been more luminous than the SEAMBH candidates in the last two years. H{beta} lags ({tau}_H{beta}_) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known R_H{beta}_-L_5100_ relation. The five quasars have dimensionless accretion rates of dM/dt=10-10^3^. Combining these with measurements of the previous SEAMBHs, we find that the reduction of H{beta} lags depends tightly on accretion rates, {tau}_H{beta}_/{tau}_R-L_{propto}(dM/dt)^-0.42^, where {tau}_R-L_ is the H{beta} lag from the normal R_H{beta}_-L_5100_ relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: R_H{beta}_={alpha}_1_l_44_^{beta}1^min [1,(dM/dt)/(dM/dt)_c_)^-{gamma}1^], where l_44_=L_5100_/10^44^erg/s is the 5100{AA} continuum luminosity, and the coefficients are {alpha}_1_=29.6_-2.8_^+2.7^ lt-day, {beta}1=0.56_-0.03_^+0.03^, {gamma}1=0.52_-0.16_^+0.33^, and (dM/dt)_c_=11.19_-6.22_^+2.29^. This relation is applicable to AGNs over a wide range of accretion rates, from 10^-3^ to 10^3^. Implications of this new relation are briefly discussed.
5873. SEAMBHs XII. Reberberation mapping for 15 PG QSOs
ID:
ivo://CDS.VizieR/J/ApJS/253/20
Title:
SEAMBHs XII. Reberberation mapping for 15 PG QSOs
Short Name:
J/ApJS/253/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we present the first results of the long-term high-cadence spectroscopic monitoring of 15 PG quasars with relatively strong FeII emission, as a part of a broader reverberation mapping campaign performed using the Calar Alto Observatory's 2.2m telescope. The V-band, 5100{AA} continuum, and H{beta} broad emission line light curves are measured for a set of quasars for periods ranging from dozens to more than a hundred epochs between 2017 May and 2020 July. Accurate time lags between the variations of the H{beta} broad-line fluxes and the optical continuum strength are obtained for all 15 quasars, ranging from 17.0_-3.2_^+2.5^ to 95.9_-23.9_^+7.1^ days in the rest frame. The virial masses of the central supermassive black holes are derived for all 15 quasars, ranging between 0.50_-0.19_^+0.18^ and 19.17_-2.73_^+2.98^ in units of 10^7^M_{sun}_. For 11 of the objects in our sample, this is the first reverberation analysis to be published. Of the rest, two objects have been the subject of previous reverberation studies, but we determine time lags for these that are only half as long as those found in the earlier investigations, which had only been able to sample much more sparsely. The remaining two objects have previously been monitored with high sampling rates. Our results here are consistent with the earlier findings, in the sense that the time lag and the line width vary inversely, consistent with virialization.
5874. SEAMBHs. XI. Mrk 142 X-ray to optical light curves
ID:
ivo://CDS.VizieR/J/ApJ/896/1
Title:
SEAMBHs. XI. Mrk 142 X-ray to optical light curves
Short Name:
J/ApJ/896/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed an intensive accretion disk reverberation mapping campaign on the high accretion rate active galactic nucleus Mrk142 in early 2019. Mrk 142 was monitored with the Neil Gehrels Swift Observatory for four months in X-rays and six different UV/optical filters. Ground-based photometric monitoring was obtained from the Las Cumbres Observatory, the Liverpool Telescope, and the Dan Zowada Memorial Observatory in ugriz filters, as well as from the Yunnan Astronomical Observatory in V. Mrk 142 was highly variable throughout, displaying correlated variability across all wavelengths. We measure significant time lags between the different wavelength lightcurves. In the UV and optical, we find that the wavelength-dependent lags, {tau}({lambda}), generally follow the relation {tau}({lambda}){propto}{lambda}^4/3^, as expected for the T{propto}R^-3/4^ profile of a steady-state, optically thick, geometrically thin accretion disk, though they can also be fit by {tau}({lambda}){propto}{lambda}^2^, as expected for a slim disk. The exceptions are the u and U bands, where an excess lag is observed, as has been observed in other active galactic nuclei and attributed to continuum emission arising in the broad-line region. Furthermore, we perform a flux-flux analysis to separate the constant and variable components of the spectral energy distribution, finding that the flux dependence of the variable component is consistent with the f{nu}{propto}{nu}^1/3^ spectrum expected for a geometrically thin accretion disk. Moreover, the X-ray to UV lag is significantly offset from an extrapolation of the UV/optical trend, with the X-rays showing a poorer correlation with the UV than the UV does with the optical. The magnitude of the UV/optical lags is consistent with a highly super-Eddington accretion rate.
5875. Search for Associations Containing Young stars
ID:
ivo://CDS.VizieR/J/A+A/460/695
Title:
Search for Associations Containing Young stars
Short Name:
J/A+A/460/695
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report results from a high-resolution optical spectroscopic survey aimed to search for nearby young associations and young stars among optical counterparts of ROSAT All-Sky Survey (<IX/10> and <IX/29>, X-ray sources in the Southern Hemisphere. We selected 1953 late-type (B-V>=0.6), potentially young, optical counterparts out of a total of 9574 1RXS sources for follow-up observations. At least one high-resolution spectrum was obtained for each of 1511 targets. This paper is the first in a series presenting the results of the SACY survey. Here we describe our sample and our observations. We describe a convergence method in the (UVW) velocity space to find associations. As an example, we discuss the validity of this method in the framework of the Beta Pic Association.
5876. Search for companions around nearby massive stars
ID:
ivo://CDS.VizieR/J/ApJ/736/89
Title:
Search for companions around nearby massive stars
Short Name:
J/ApJ/736/89
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this study, we present high-contrast imaging of 18 nearby massive stars of which 15 are in the B2-A0 spectral-type range and provide excellent sensitivity to wide companions. By comparing our sensitivities to model predictions of disk instability based on physical criteria for fragmentation and cooling, and using Monte Carlo simulations for orbital distributions, we find that ~85% of such companions should have been detected in our images on average. Given this high degree of completeness, stringent statistical limits can be set from the null-detection result, even with the limited sample size. We find that <30% of massive stars form and retain disk instability planets, brown dwarfs, and very low mass stars of <100M_jup_ within 300AU, at 99% confidence. These results, combined with previous findings in the literature, lead to the conclusion that core accretion is likely the dominant mode of planet formation.
5877. Search for companions with VLT/NACO
ID:
ivo://CDS.VizieR/J/A+A/509/A52
Title:
Search for companions with VLT/NACO
Short Name:
J/A+A/509/A52
Date:
21 Oct 2021
Publisher:
CDS
Description:
Since November 2002, we have conducted the largest deep imaging survey of the young, nearby associations of the southern hemisphere. Our goal is detection and characterization of substellar companions at intermediate (10-500AU) physical separations. We have observed a sample of 88 stars, mostly G to M dwarfs, that we essentially identify as younger than 100Myr and closer to Earth than 100pc. The VLT/NACO adaptive optics instrument of the ESO Paranal Observatory was used to explore the faint circumstellar environment between typically 0.1 and 10". We report the discovery of 17 new close (0.1-5.0") multiple systems. HIP 108195AB and C (F1III-M6), HIP 84642AB (a~14AU, K0-M5) and TWA 22AB (a~1.8AU; M6-M6) confirmed comoving systems. TWA 22AB is likely to be a astrometric calibrator that can be used to test evolutionary predictions. Among our complete sample, a total of 65 targets observed with deep coronagraphic imaging. About 240 faint candidates were detected around 36 stars. Follow-up observations VLT or HST for 83% of these stars enabled us to identify a fraction of contaminants. The latest results about the substellar companions to GSC 08047-00232, AB Pic and 2M1207, confirmed during this survey and published earlier, are reviewed. Finally, the statistical analysis of our complete set of coronagraphic limits enables us to place constraints on the physical and properties of giant planets between typically 20 and 150AU.
5878. Search for duplicity in periodic Be stars
ID:
ivo://CDS.VizieR/J/A+A/385/488
Title:
Search for duplicity in periodic Be stars
Short Name:
J/A+A/385/488
Date:
21 Oct 2021
Publisher:
CDS
Description:
Four Be stars, HR 1960, HR 2968, HR 3237 and HR 3642, selected according to their periodic variations in Hipparcos and Geneva photometries, have been monitored from 1998 until 2001 with the Coralie spectrograph. HR 1960 and HR 3237 are two new spectroscopic binaries, HR 3642 is a new lambda Eri star, and HR 2968 is stable.
5879. Search for planetary companions with Spitzer/IRAC
ID:
ivo://CDS.VizieR/J/ApJ/700/1647
Title:
Search for planetary companions with Spitzer/IRAC
Short Name:
J/ApJ/700/1647
Date:
21 Oct 2021
Publisher:
CDS
Description:
Fomalhaut and {epsilon} Eridani are two young, nearby stars that possess extended debris disks whose structures suggest the presence of perturbing planetary objects. With its high sensitivity and stable point-spread function, Spitzer/Infrared Array Camera (IRAC) is uniquely capable of detecting cool, Jupiter-like planetary companions whose peak emission is predicted to occur near 4.5um. We report on deep IRAC imaging of these two stars, taken at 3.6 and 4.5um using subarray mode and in all four channels in wider-field full array mode. Observations acquired at two different telescope roll angles allowed faint surrounding objects to be separated from the stellar diffraction pattern. No companion candidates were detected at the reported position of Fomalhaut b with 3{sigma} model-dependent mass upper limits of 3M_J_ (for an age of 200Myr). Around {epsilon} Eridani, we instead set a limit of 4 and <~1M_J_ (1Gyr model age) at the inner and outer edge of the submillimeter debris ring, respectively. These results are consistent with non-detections in recent near-infrared imaging searches, and set the strongest limits to date on the presence of planets outside {epsilon} Eridani submillimeter ring.
5880. Search for Planets in Hot Jupiter Systems
ID:
ivo://CDS.VizieR/J/AcA/70/181
Title:
Search for Planets in Hot Jupiter Systems
Short Name:
J/AcA/70/181
Date:
21 Oct 2021
Publisher:
CDS
Description:
Origins of giant planets on tight orbits, so called hot Jupiters, are a long-lasting question in the planetary formation and evolution theory. The answer seems to be hidden in architectures of those systems that remain only partially understood. Using multi-sector time-series photometry from the Transiting Exoplanet Survey Satellite, we searched for additional planets in the KELT-18, KELT-23, KELT-24, Qatar-8, WASP-62, WASP-100, WASP-119, and WASP-126 planetary systems using both the transit technique and transit timing method. Our homogeneous analysis has eliminated the presence of transiting companions down to the terrestrial-size regime in the KELT-23 and WASP-62 systems, and down to mini-Neptunes or Neptunes in the remaining ones. Transit timing analysis has revealed no sign of either long-term trends or periodic perturbations for all the studied hot Jupiters, including the WASP-126 b for which deviations from a Keplerian model were claimed in the literature. The loneliness of the planets of the sample speaks in favor of the high-eccentricity migration mechanism that probably brought them to their tight orbits observed nowadays. As a by-product of our study, the transit light curve parameters were redetermined with a substantial improvement of the precision for six systems. For KELT-24 b, a joint analysis allowed us to place a tighter constraint on its orbital eccentricity.