We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the Spitzer satellite in a solar orbit. At high ...magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of from the light-curve modeling. The ground-only and Spitzer-"only" data each provide very strong one-dimensional (1D) constraints on the 2D microlens parallax vector . When combined, these yield a precise measurement of and of the masses of the host and planet Mplanet = 0.41 0.05 MJup. The system lies at a distance DL = 5.2 0.5 kpc from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is (i.e., just over twice the snow line). The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the Gaia proper-motion measurement of the source suffers from a catastrophic 10 error.
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies ...selected to have black holes with masses roughly in the range 106-107 M, as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope, and the 0.80 m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.
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 13 nearby Seyfert 1 ...galaxies with expected masses in the range image10 super(6)-10 super(7) Mimage. We present here the first results from this project-the mass of the central black hole in Arp 151. Strong variability throughout the campaign led to an exceptionally clean H beta lag measurement in this object of image days in the observed frame. Coupled with the width of the H beta emission line in the variable spectrum, we determine a black hole mass of image Mimage, assuming the Onken et al. normalization for reverberation-based virial masses. We also find velocity-resolved lag information within the H beta emission line which clearly shows infalling gas in the H beta -emitting region. Further detailed analysis may lead to a full model of the geometry and kinematics of broad line region gas around the central black hole in Arp 151.
We report the mass and distance measurements of two single-lens events from the 2017 Spitzer microlensing campaign. The ground-based observations yield the detection of finite-source effects, and the ...microlens parallaxes are derived from the joint analysis of ground-based observations and Spitzer observations. We find that the lens of OGLE-2017-BLG-1254 is a 0.60 0.03 M star with DLS = 0.53 0.11 kpc, where DLS is the distance between the lens and the source. The second event, OGLE-2017-BLG-1161, is subject to the known satellite parallax degeneracy, and thus is either a star with DLS = 0.40 0.12 kpc or a star with DLS = 0.53 0.19 kpc. Both of the lenses are therefore isolated stars in the Galactic bulge. By comparing the mass and distance distributions of the eight published Spitzer finite-source events with the expectations from a Galactic model, we find that the Spitzer sample is in agreement with the probability of finite-source effects occurring in single-lens events.
Roman with Rubin Gough-Kelly, Steven; Street, Rachel
Astronomy & geophysics : the journal of the Royal Astronomical Society,
10/2023, Letnik:
64, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Abstract
Steven Gough-Kelly and Rachel Street argue in favour of maximising the science return of major facilities
Abstract
We have modeled the full velocity-resolved reverberation response of the H
β
and He
ii
optical broad emission lines in NGC 3783 to constrain the geometry and kinematics of the low-ionization ...and high-ionization broad-line region (BLR). The geometry is found to be a thick disk that is nearly face-on, inclined at ∼18° to our line of sight, and exhibiting clear ionization stratification, with an extended H
β
-emitting region (
r
median
=
10.07
−
1.12
+
1.10
lt-day) and a more compact and centrally located He
ii
-emitting region (
r
median
=
1.33
−
0.42
=
+
0.34
lt-day). In the H
β
-emitting region, the kinematics are dominated by near-circular Keplerian orbits, but with ∼40% of the orbits inflowing. The more compact He
ii
-emitting region, on the other hand, appears to be dominated by outflowing orbits. The black hole mass is constrained to be
M
BH
=
2.82
−
0.63
+
1.55
×
10
7
M
⊙
, which is consistent with the simple reverberation constraint on the mass based on a mean time delay, line width, and scale factor of 〈
f
〉 = 4.82. The difference in kinematics between the H
β
- and He
ii
-emitting regions of the BLR is intriguing given the recent history of large changes in the ionizing luminosity of NGC 3783 and evidence for possible changes in the BLR structure as a result.
Brown dwarfs and low-mass stellar companions are interesting objects to study since they occupy the mass region between deuterium and hydrogen burning. We report here the serendipitous discovery of a ...low-mass companion in an eccentric orbit around a solar-type main-sequence star. The stellar primary, TYC 2534-698-1, is a G2V star that was monitored both spectroscopically and photometrically over the course of several months. Radial velocity observations indicate a minimum mass of 0.037 M and an orbital period of ~103 days for the companion. Photometry outside of the transit window shows the star to be stable to within ~6 millimags. The semimajor axis of the orbit places the companion in the 'brown dwarf desert' and we discuss potential follow-up observations that could constrain the mass of the companion.
Abstract
Vera C. Rubin Observatory is a ground-based astronomical facility under construction, a joint project of the National Science Foundation and the U.S. Department of Energy, designed to ...conduct a multipurpose 10 yr optical survey of the Southern Hemisphere sky: the Legacy Survey of Space and Time. Significant flexibility in survey strategy remains within the constraints imposed by the core science goals of probing dark energy and dark matter, cataloging the solar system, exploring the transient optical sky, and mapping the Milky Way. The survey’s massive data throughput will be transformational for many other astrophysics domains and Rubin’s data access policy sets the stage for a huge community of potential users. To ensure that the survey science potential is maximized while serving as broad a community as possible, Rubin Observatory has involved the scientific community at large in the process of setting and refining the details of the observing strategy. The motivation, history, and decision-making process of this strategy optimization are detailed in this paper, giving context to the science-driven proposals and recommendations for the survey strategy included in this Focus Issue.
ABSTRACT
We present a GPU-accelerated numerical approach for fast kernel and differential background solutions. The model image proposed in the Bramich Difference Image Analysis (DIA) algorithm is ...analogous to a very simple convolutional neural network (CNN), with a single convolutional filter (i.e. the kernel) and an added scalar bias (i.e. the differential background). Here, we do not solve for the discrete pixel array in the classical, analytical linear least-squares sense. Instead, by making use of PyTorch tensors (GPU compatible multidimensional matrices) and associated deep learning tools, we solve for the kernel via an inherently massively parallel optimization. By casting the DIA problem as a GPU-accelerated optimization that utilizes automatic differentiation tools, our algorithm is both flexible to the choice of scalar objective function, and can perform DIA on astronomical data sets at least an order of magnitude faster than its classical analogue. More generally, we demonstrate that tools developed for machine learning can be used to address generic data analysis and modelling problems.
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