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Full-Text Articles in Physical Sciences and Mathematics

Fermi-Lat Daily Monitoring Observations Of The Microquasar Cygnus X-1, Austin P. Waldron, Stephen R. Hood, Arash Bodaghee Apr 2017

Fermi-Lat Daily Monitoring Observations Of The Microquasar Cygnus X-1, Austin P. Waldron, Stephen R. Hood, Arash Bodaghee

Georgia College Student Research Events

Detection of gamma-ray emission from microquasars is important for understanding particle acceleration in the jet, and for constraining leptonic/hadronic emission models. We present a continuation of a 1-d likelihood analysis on gamma-ray observations by Fermi-LAT (0.1-10 GeV) of the accreting black hole candidate Cygnus X-1. Combining this gamma-ray data with available X-ray monitoring data from Swift and MAXI allowed us to reveal over a dozen days (in 2008-2016) during which Cyg X-1 displayed low-significance (3-4 sigma) excesses, many of which were contemporaneous with apparent transitions in the X-rays.

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Faint X‐Ray Structure In The Crab Pulsar Wind Nebula, F. D. Seward, W. H. Tucker, R. A. Fesen Dec 2006

Faint X‐Ray Structure In The Crab Pulsar Wind Nebula, F. D. Seward, W. H. Tucker, R. A. Fesen

Dartmouth Scholarship

We report on a Chandra observation of the Crab Nebula that gives the first clear view of the faint boundary of the Crab's X-ray-emitting pulsar wind nebula. There is structure in all directions. Fingers, loops, bays, and the south pulsar jet all indicate that either filamentary material or the magnetic field is controlling the relativistic electrons. In general, spectra soften as distance from the pulsar increases but do not change rapidly along linear features. This is particularly true for the pulsar jet. The termination of the jet is abrupt; the east side is close to an [O III] optical filament, …

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Chandra Observations Of The Luminous, Oxygen‐Rich Supernova Remnants In The Irregular Galaxy Ngc 4449, Daniel J. Patnaude, Robert A. Fesen Apr 2003

Chandra Observations Of The Luminous, Oxygen‐Rich Supernova Remnants In The Irregular Galaxy Ngc 4449, Daniel J. Patnaude, Robert A. Fesen

Dartmouth Scholarship

An analysis of a 29 ks Chandra ACIS-S observation of the young, Cassiopeia A–like supernova remnant in the irregular galaxy NGC 4449 is presented. The observed 0.5–2.1 keV spectrum reveals the likely presence of several emission lines. A nonequilibrium ionization fit to the spectrum suggests an overabundance of oxygen around 20 times solar, consistent with the remnant’s UV and optical emission-line properties. We discuss the remnant’s approximate X-ray–derived elemental abundances and compare its X-ray spectrum and luminosity with other oxygen-rich remnants

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