arXiv subjects

Y. S. Efimov

Publications and source records attributed to Y. S. Efimov.

7 recordsLinked to original sources

arXiv2010

Polarimetric Remote Sensing of Solar System Objects

This book outlines the basic physical principles and practical methods of polarimetric remote sensing of Solar System objects and summarizes numerous advanced applications of polarimetry in geophysics and planetary astrophysics. In the first chapter we present a complete and rigorous theory of electromagnetic scattering by disperse media directly based on the Maxwell equations and describe advanced physically based modeling tools. This is followed, in Chapter 2, by a theoretical analysis of polarimetry as a remote-sensing tool and an outline of basic principles of polarimetric measurements and their practical implementations. In Chapters 3 and 4, we describe the results of extensive ground-based, aircraft, and spacecraft observations of numerous Solar System objects (the Earth and other planets, planetary satellites, Saturn's rings, asteroids, trans-Neptunian objects, and comets). Theoretical analyses of these data are used to retrieve optical and physical characteristics of planetary surfaces and atmospheres as well as to identify a number of new phenomena and effects. This monograph is intended for science professionals, educators, and graduate students specializing in remote sensing, astrophysics, atmospheric physics, optics of disperse and disordered media, and optical particle characterization.

astro-ph.EP↗

arXiv2010

Reverberation Mapping Measurements of Black Hole Masses in Six Local Seyfert Galaxies

We present the final results from a high sampling rate, multi-month, spectrophotometric reverberation mapping campaign undertaken to obtain either new or improved Hbeta reverberation lag measurements for several relatively low-luminosity AGNs. We have reliably measured thetime delay between variations in the continuum and Hbeta emission line in six local Seyfert 1 galaxies. These measurements are used to calculate the mass of the supermassive black hole at the center of each of these AGNs. We place our results in context to the most current calibration of the broad-line region (BLR) R-L relationship, where our results remove outliers and reduce the scatter at the low-luminosity end of this relationship. We also present velocity-resolved Hbeta time delay measurements for our complete sample, though the clearest velocity-resolved kinematic signatures have already been published.

astro-ph.CO↗

arXiv2010

Relativistic plasma as the dominant source of the optical continuum emission in the broad-line radio galaxy 3C 120

We report a relation between radio emission in the inner jet of the Seyfert galaxy 3C 120 and optical continuum emission in this galaxy. Combining the optical variability data with multi-epoch high-resolution very long baseline interferometry observations reveals that an optical flare rises when a superluminal component emerges into the jet and its maxima is related to the passage of such component through the location a stationary feature at a distance of ~1.3 parsecs from the jet origin. This indicates that a significant fraction of the optical continuum produced in 3C 120 is non-thermal and it can ionize material in a sub-relativistic wind or outflow. We discuss implications of this finding for the ionization and structure of the broad emission line region, as well as for the use of broad emission lines for determining black hole masses in radio-loud AGN.

astro-ph.CO↗

arXiv2009

Diverse Broad Line Region Kinematic Signatures From Reverberation Mapping

A detailed analysis of the data from a high sampling rate, multi-month reverberation mapping campaign, undertaken primarily at MDM Observatory with supporting observations from telescopes around the world, reveals that the Hbeta emission region within the broad line regions (BLRs) of several nearby AGNs exhibit a variety of kinematic behaviors. While the primary goal of this campaign was to obtain either new or improved Hbeta reverberation lag measurements for several relatively low luminosity AGNs (presented in a separate work), we were also able to unambiguously reconstruct velocity-resolved reverberation signals from a subset of our targets. Through high cadence spectroscopic monitoring of the optical continuum and broad Hbeta emission line variations observed in the nuclear regions of NGC 3227, NGC 3516, and NGC 5548, we clearly see evidence for outflowing, infalling, and virialized BLR gas motions, respectively.

astro-ph.CO↗

arXiv2009

A Revised Broad-Line Region Radius and Black Hole Mass for the Narrow-Line Seyfert 1 NGC 4051

We present the first results from a high sampling rate, multi-month reverberation mapping campaign undertaken primarily at MDM Observatory with supporting observations from telescopes around the world. The primary goal of this campaign was to obtain either new or improved Hbeta reverberation lag measurements for several relatively low luminosity AGNs. We feature results for NGC 4051 here because, until now, this object has been a significant outlier from AGN scaling relationships, e.g., it was previously a ~2-3sigma outlier on the relationship between the broad-line region (BLR) radius and the optical continuum luminosity - the R_BLR-L relationship. Our new measurements of the lag time between variations in the continuum and Hbeta emission line made from spectroscopic monitoring of NGC 4051 lead to a measured BLR radius of R_BLR = 1.87 (+0.54 -0.50) light days and black hole mass of M_BH = 1.73 (+0.55 -0.52) x 10^6 M_sun. This radius is consistent with that expected from the R_BLR-L relationship, based on the present luminosity of NGC 4051 and the most current calibration of the relation by Bentz et al. (2009a). We also present a preliminary look at velocity-resolved Hbeta light curves and time delay measurements, although we are unable to reconstruct an unambiguous velocity-resolved reverberation signal.

astro-ph.CO↗

arXiv2003

Polarimetric evolution of V838 Mon

We present the results of our polarimetric and spectropolarimetric monitoring of V838 Monocerotis, performed at Asiago and Crimean observatories during and after the multiple outbursts that occurred in January-March 2002. The polarization of the object is mainly due to interstellar polarization (P=2.48%). Intrinsic polarization up to 0.7% at 5000 A is present during the second maximum of the object (February 2002). This intrinsic component increases toward shorter wavelengths but our limited spectral coverage (5000-7500 A) does not allow conclusive inferences about its origin. A strong depolarization across the Halpha profile is observed. The interstellar polarization gives a lower limit to the reddening of E(B-V)>0.28, with E(B-V)=0.5 being the most probable value. A normal ratio of total to selective absorption (R_V=3.22+-0.17) was derived from the wavelength of maximum interstellar polarization. This suggests a low (if any) contribution by circumstellar material with peculiar dust to gas ratio. A polarimetric map of a portion of the light echo shows a complex polarization distribution reaching P_max=45%.

astro-ph↗

arXiv2002

Diffraction-limited speckle interferometry and modeling of the circumstellar envelope of R CrB at maximum and minimum light

We present the first speckle interferometric observations of R CrB, the prototype of a class of peculiar stars which undergo irregular declines in their visible light curves. The observations were carried out with the 6m telescope at the Special Astrophysical Observatory near maximum light (V=7, 1996 Oct. 1) and at minimum light (V=10.61, 1999 Sep. 28). A spatial resolution of 75mas was achieved in the K-band. The dust shell around R CrB is partially resolved, and the visibility is approximately 0.8 at a spatial frequency of 10 cycles/arcsec. The two-dimensional power spectra obtained at both epochs do not show any significant deviation from circular symmetry. The visibility function and spectral energy distribution obtained near maximum light can be simultaneously fitted with a model consisting of the central star and an optically thin dust shell with density proportional to r^-2. The inner boundary of the shell is found to be 82Rstar (19mas) with a temperature of 920K. However, this simple model fails to simultaneously reproduce the visibility and spectral energy distribution obtained at minimum light. We show that this discrepancy can be attributed to thermal emission from a newly formed dust cloud.

astro-ph↗