* Astronomy

Blobrana · L

RE: SGR 0501+4516

Blobrana · L

On Aug. 22, 2008, NASA's Swift satellite reported multiple blasts of radiation from a rare object known as a soft gamma repeater, or SGR, some 15,000 light years away. This ancient stellar remnant is one the most magnetised objects in the universe. Only 15 are known to exist.
Astronomers think the eruptions of SGRs arise from the most highly magnetised objects in the universe -- magnetars, or neutron stars -- the crushed cores of exploded stars -- that, for reasons not yet known, possess ultra-strong magnetic fields. With fields 100 trillion times stronger than Earth's, a magnetar placed half the moon's distance would wipe the magnetic strips of every credit card on the planet.

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Blobrana · L

On Aug. 22, 2008, NASA's Swift satellite reported multiple blasts of radiation from a rare object known as a soft gamma repeater, or SGR. Now, astronomers report an in-depth study of these eruptions using the European Space Agency's XMM-Newton and International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellites.
The object, designated SGR 0501+4516, was the first of its type discovered in a decade and is only the fifth confirmed SGR.

"Some sources are extremely active, but others can be quiet for a decade or more. This suggests many members of this class remain unknown" - Nanda Rea, University of Amsterdam, who led the study.

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Blobrana · L

Title: The first outburst of the new magnetar candidate SGR 0501+4516
Authors: Nanda Rea, GianLuca Israel, Roberto Turolla, Paolo Esposito, Sandro Mereghetti, Diego Gotz, Silvia Zane, Andrea Tiengo, Kevin Hurley, Marco Feroci, Martin Still, Vladimir Yershov, Christoph Winkler, Rosalba Perna, Federico Bernardini, Pietro Ubertini, Luigi Stella, Sergio Campana, Michiel van der Klis, Peter M. Woods

We report here on the outburst onset and evolution of the new Soft Gamma Repeater SGR 0501+4516. We monitored the new SGR with XMM-Newton starting on 2008 August 23, one day after the source became burst-active, and continuing with 4 more observations, with the last one on 2008 September 30. Combining the data with the Swift-XRT and Suzaku data, we modelled the outburst decay over 160 days, and we found that the source flux decreased exponentially with a timescale of t_c=23.8 days. In the first XMM-Newton observation a large number of short X-ray bursts were observed, the rate of which decayed drastically in the following observations. We found large changes in the spectral and timing behaviour of the source during the outburst, with softening emission as the flux decayed, and the non-thermal soft X-ray spectral component fading faster than the thermal one. Almost simultaneously to our XMM-Newton observations (on 2008 August 29 and September 2), we observed the source in the hard X-ray range with INTEGRAL, which clearly detected the source up to ~100keV in the first pointing, while giving only upper limits during the second pointing, discovering a variable hard X-ray component fading in less than 10 days after the bursting activation. We performed a phase-coherent X-ray timing analysis over about 160 days starting with the burst activation and found evidence of a strong second derivative period component (\ddot{P} = -1.6(4)x10^{-19} s/s^{-2}). Thanks to the phase-connection, we were able to study the phase-resolved spectral evolution of SGR 0501+4516 in great detail. We also report on the ROSAT quiescent source data, taken back in 1992 when the source exhibits a flux ~80 times lower than that measured during the outburst, and a rather soft, thermal spectrum.

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Blobrana · L

An enormous eruption has found its way to Earth after travelling for many thousands of years across space. Studying this blast with ESA's XMM-Newton and Integral space observatories, astronomers have discovered a dead star belonging to a rare group: the magnetars.
X-Rays from the giant outburst arrived on Earth on 22 August 2008, and triggered an automatic sensor on the NASA-led, international Swift satellite. Just twelve hours later, XMM-Newton zeroed in and began to collect the radiation, allowing the most detailed spectral study of the decay of a magnetar outburst.
The outburst lasted for more than four months, during which time hundreds of smaller bursts were measured. Nanda Rea from the University of Amsterdam led the team that performed the research.

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