High Energy Astrophysics Group

02/05/2020

Matthias Bissinger ne Kuehnel and co-authors' paper, "The giant outburst of 4U 0115+634 in 2011 with Suzaklu and RXTE: Minimizing cyclotron line biases" has been accepted for publication in Astronomy and Astrophysics (http://arxiv.org/abs/1912.06725).

We present an analysis of X-ray spectra of the high mass X-ray binary 4U 0115+634 as observed with Suzaku and RXTE in 2011 July, during the fading phase of a giant X-ray outburst. We used a continuum model consisting of an absorbed cutoff power-law and an ad-hoc Gaussian emission feature centered ar...

12/12/2019

Richard Lingenfelter's paper, "The Origin of Cosmic Rays: How Their Composition Defines Their Sources and Sites and the Processes of Their Mixing, Injection, and Acceleration" has been published in The Astrophysical Journal Supplement Series, 245:30 (https://doi.org/10.3847/1538-4365/ab4b58). Galactic cosmic ray source compositions from H to Pb and 10^8 - 10^14 eV differ from solar-local interstellar compositions by ~20-200 times. The paper shows that a 4:1 mixing ratio of the swept-up interstellar medium to the core collapse metallicity in OB cluster super bubbles, and the highly biased grain sputtering injection through diffusive shock acceleration at the reverse shock radius, produces compositions that match major cosmic ray abundances to within 35%.

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02/02/2019

Ruediger Staubert and co-authors' paper, "Cyclotron Lines in highly magnetized neutron stars" has been published in Astronomy and Astrophysics volume 662, starting page A61 of 2019. This paper presents an excellent review of cyclotron line studies and the physics involved.

02/02/2019

Paul Hemphill and co-authors' paper, "The First NuSTAR Observation of 4U1538-522: Updated Orbital Ephemeris and a Strengthening Case for an Evolving Cyclotron Line Energy" has been accepted for publication. The paper can be found in the preprint archive as arXiv:1901.11071. They find a secular increase in the cyclotron line centroid, and thus the increase in the magnetic field in the cyclotron resonance scattering region.

01/23/2019

Massimo Tinto and others within the Center for Astrophysics and Space Sciences are developing a white paper for the 2020 Decadal Review in support of a mid-frequency space-based gravity wave mission that could fly before LISA and would provide early warning of black hole mergers for LIGO.

11/19/2018

Sibasish Laha and co-authors have had their paper, "A Study of X-ray Emission of Galaxies Hosting Molecular Outflows (MOX Sample)", accepted for publication by The Astrophysical Journal. This is one paper in a series trying to understand outflows and their effect on galactic evolution.

11/19/2018

Ruediger Staubert and members of the MAGNET collaboration have had their paper, "Cyclotron Lines in highly magnetized Neutron Stars", accepted for publication in Astronomy and Astrophysics. It is a review of the subject with uptodate information on the known accreting X-ray pulsars with detected cyclotron lines that yield a direct measure of the neutron star's magnetic field.

05/02/2018

NASA's Rossi X-ray Timing Explorer (RXTE) reentered Earth's atmosphere on April 30, 2018 at about 14:45 UTC (10:45am EDT). Its final moments may have given it a nice view of the Caribbean sea near Aruba or Curacao.

XTE was launched on December 30, 1995, and was then renamed in honor of Bruno Rossi (and got the "R" added to its acronym), a famous Italian-American physicist instrumental in pioneering the detectors that enabled the first cosmic X-ray observations. After an extraordinarily productive 16 years of scientific discovery the observatory was decommissioned in January 2012.

RXTE used three separate but complementary instruments to observe the X-ray sky. The All Sky Monitor (ASM), built at the Massachusetts Institute of Technology (MIT), provided views of the whole sky. Searching for new X-ray sources or changes in known ones, the ASM watched for new observing opportunities for RXTE's larger area detectors. The Proportional Counter Array (PCA), a set of five nearly-identical proportional counter detectors built here at GSFC,
was RXTE's "workhorse" telescope, providing large area, low background and high time resolution for detailed studies of X-ray sources in the 2 - 60 keV energy band. The High Energy X-ray Timing Experiment (HEXTE), built at the University of California San Diego (UCSD), extended RXTE's fast timing capabilities from 20 - 200 keV.

It's no exaggeration to say that RXTE re-wrote the text books on high energy astrophysics, especially for studies of compact stars. After a 16 year science mission, 3,100+ refereed publications (with > 95,000 citations), 90+ PhD theses, many first discoveries, its legacy lives on in the operation of current missions like NICER and Swift, as well
as many proposed future missions such as LOFT, eXTP, and STROBE-X, that seek to exploit these discoveries to further our understanding of the extreme universe. Not to mention that the RXTE data archive is still revealing new discoveries and continues to be in high demand.

04/28/2018

After over 22 years in orbit and 16 years of superb observations of cosmic X-ray sources, the Rossi X-ray Timing Explorer will re-enter the atmosphere and and be destroyed on Monday April 30 or Tuesday May 1. Our thanks to the hundreds of people who made RXTE possible and generated the amazing RXTE science. This was a great experience.

08/15/2017

Matthias Kuehnel and co-authors' paper, "Evidence for different accretion regimes in GRO J1008-57" has been accepted for publication in Astronomy & Astrophysics. Also, our paper, "A precessing Be disk as a possible model for occultation events in GX 304-1" has a Monthly Notices of the Royal Astronomical Society designation of Kuehnel et al. 2017, MNRAS, 471, 1553. Bravo to Matthias for his excellent work on both papers.

07/20/2017

Felix Fuerst and collaborators have had their paper, "Studying the accretion geometry of EXO 2030+375 at luminosities close to the propeller regime" accepted for publication in Astronomy & Astrophysics.

06/14/2017

Dr. Sibasish Laha has joined the High Energy Astrophysics group, and will work with Drs Rothschild and Markowitz on column density variability in active galaxies. He will also pursue investigations of active galaxy winds. Welcome, Sibasish.