High-energy transients Gehrels, Neil; Cannizzo, John K.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
06/2013, Volume:
371, Issue:
1992
Journal Article
Peer reviewed
We present an overview of high-energy transients in astrophysics, highlighting important advances over the past 50 years. We begin with early discoveries of y-ray transients, and then delve into ...physical details associated with a variety of phenomena. We discuss some of the unexpected transients found by Fermi and Swift, many of which are not easily classifiable or in some way challenge conventional wisdom. These objects are important insofar as they underscore the necessity of future, more detailed studies.
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Swift discovered the high-redshift GRB 050319 with the Burst Alert Telescope (BAT) and began observing with its narrow-field instruments only 225 s after the burst onset. The afterglow X-ray emission ...was monitored by the XRT up to 28 days after the burst. The light curve shows a decay with three different phases, each characterized by a distinct slope: an initial steep decay with a power-law index of 65.5, a second phase characterized by a flat decay slope of 60.54, and a third phase with a decay slope of 61.14. During the first phase the spectral energy distribution is softer than in the following two phases, and the photon index is consistent with the GRB prompt spectrum. The extrapolation of the BAT light curve to the XRT band suggests that the initial fast-decaying phase of the XRT afterglow might be the low-energy tail of the prompt emission. The second break in the afterglow light curve occurs about 27,000 s after the burst. The spectral energy distribution before and after the second break does not change, and it can be tentatively interpreted as a jet break or the end of a delayed or continuous energy injection phase.
Low States in Cataclysmic Variables King, Andrew R; Cannizzo, John K
Astrophysical journal/The Astrophysical journal,
05/1998, Volume:
499, Issue:
1
Journal Article
Time-Domain Astronomy with Swift, Fermi and Lobster Gehrels, Neil; Barthelmy, Scott D.; Cannizzo, John K.
Proceedings of the International Astronomical Union,
09/2011, Volume:
7, Issue:
S285
Journal Article
Peer reviewed
The dynamic transient gamma-ray sky is revealing many interesting results, largely due to findings by Fermi and Swift. The list includes new twists on gamma-ray bursts (GRBs), a GeV flare from a ...symbiotic star, GeV flares from the Crab Nebula, high-energy emission from novae and supernovae, and, within the last year, a new type of object discovered by Swift—a jetted tidal disruption event. In this review we present highlights of these exciting discoveries. A new mission concept called Lobster is also described; it would monitor the X-ray sky at order-of-magnitude higher sensitivity than current missions can.
We examine AAVSO (American Association of Variable Star Observers) light curves of 16 Z Camelopardalis systems with measured orbital periods, with particular focus on intervals away from standstill. ...During these times, most of the systems display a sawtooth‐like outburst behavior, with quiescent intervals comparable to the outburst durations. We report the discovery of a linear relation between the characteristic outburst period and orbital period for these systems, which is given by
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackageOT2,OT1{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\langle P_{\mathrm{out}\,}( \mathrm{days}\,) \rangle =62.0( \pm 7.7) P_{\mathrm{orb}\,}( \mathrm{days}\,) +2.41( \pm 1.87) $ \end{document}
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