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2 results on '"K V Sokolovsky"'

1. Early Spectral Evolution of Classical Novae: Consistent Evidence for Multiple Distinct Outflows

Author

E. Aydi, L. Chomink, L. Izzo, E. J. Harvey, J. Leahy-McGregor, J. Strader, D. A. H. Buckley, K. V. Sokolovsky, A. Kawash, C. S. Kochanek, J. D. Linford, B. D. Metzger, K. Mukai, M. Orio, B. J. Shappee, L. Shishkovsky, E. Steinberg, S J. Swihart, J. L. Sokoloski, F. M. Walter, and P. A. Woudt

Subjects
Astronomy
Abstract

The physical mechanism driving mass ejection during a nova eruption is still poorly understood. Possibilities include ejection in a single ballistic event, a common-envelope interaction, a continuous wind, or some combination of these processes. Here, we present a study of 12 Galactic novae, for which we have premaximum high-resolution spectroscopy. All 12 novae show the same spectral evolution. Before optical peak, they show a slow P Cygni component. After peak, a fast component quickly arises, while the slow absorption remains superimposed on top of it, implying the presence of at least two physically distinct flows. For novae with high-cadence monitoring, a third, intermediate-velocity component is also observed. These observations are consistent with a scenario where the slow component is associated with the initial ejection of the accreted material and the fast component with a radiation-driven wind from the white dwarf. When these flows interact, the slow flow is swept up by the fast flow, producing the intermediate component. These colliding flows may produce theγ-ray emission observed in some novae. Our spectra also show that the transient heavy-element absorption lines seen in some novae have the same velocity structure and evolution as the other lines in the spectrum, implying an association with the nova ejecta rather than a preexisting circumbinary reservoir of gas or material ablated from the secondary. While this basic scenario appears to qualitatively reproduce multiwavelength observations of classical novae, substantial theoretical and observational work is still needed to untangle the rich diversity of nova properties.

Published
2020
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2. Exploring the Connection between Parsec-scale Jet Activity and Broadband Outbursts in 3C 279.

Author

B. Rani, S. G. Jorstad, A. P. Marscher, I. Agudo, K. V. Sokolovsky, V. M. Larionov, P. Smith, D. A. Mosunova, G. A. Borman, T. S. Grishina, E. N. Kopatskaya, A. A. Mokrushina, D. A. Morozova, S. S. Savchenko, Yu. V. Troitskaya, I. S. Troitsky, C. Thum, S. N. Molina, and C. Casadio

Subjects
VERY long baseline interferometry, MULTIWALLED carbon nanotubes, POLARIZATION (Nuclear physics), NUCLEAR magnetic resonance, GALACTIC nuclei
Abstract

We use a combination of high-resolution very long baseline interferometry (VLBI) radio and multiwavelength flux density and polarization observations to constrain the physics of the dissipation mechanism powering the broadband flares in 3C 279 during an episode of extreme flaring activity in 2013–2014. Six bright flares superimposed on a long-term outburst are detected at γ-ray energies. Four of the flares have optical and radio counterparts. The two modes of flaring activity (faster flares sitting on top of a long-term outburst) present at radio, optical, and γ-ray frequencies are missing in X-rays. X-ray counterparts are only observed for two flares. The first three flares are accompanied by ejection of a new VLBI component (NC2), suggesting the 43 GHz VLBI core as the site of energy dissipation. Another new component, NC3, is ejected after the last three flares, which suggests that the emission is produced upstream from the core (closer to the black hole). The study therefore indicates multiple sites of energy dissipation in the source. An anticorrelation is detected between the optical percentage polarization (PP) and optical/γ-ray flux variations, while the PP has a positive correlation with optical/γ-ray spectral indices. Given that the mean polarization is inversely proportional to the number of cells in the emission region, the PP versus optical/γ-ray anticorrelation could be due to more active cells during the outburst than at other times. In addition to the turbulent component, our analysis suggests the presence of a combined turbulent and ordered magnetic field, with the ordered component transverse to the jet axis. [ABSTRACT FROM AUTHOR]

Published
2018
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