BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550–5418 BURSTS

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dc.citation.firstpage54
dc.citation.journalTitleThe Astrophysical Journal
dc.citation.lastpage66
dc.citation.volumeNumber756
dc.contributor.authorLin, Lin
dc.contributor.authorBaring, Matthew G.
dc.contributor.authorGranot, Jonathan
dc.contributor.authorKouveliotou, Chryssa
dc.contributor.authorKaneko, Yuki
dc.contributor.authorVan Der Horst, Alexander
dc.contributor.authorGruber, David
dc.contributor.authorVon Kienlin, Andreas
dc.contributor.authorYounes, George
dc.contributor.authorWatts, Anna L.
dc.contributor.authorGehrels, Neil
dc.date.accessioned2013-03-13T19:09:52Z
dc.date.available2014-03-19T05:10:04Z
dc.date.issued2012
dc.description.abstractWe present the results of our broadband spectral analysis of 42 SGR J1550−5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5–10 keV). Our earlier analysis of the GBM data found that the SGR J1550−5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5–200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT–GBM analysis clearly shows for the first time that the SGR J1550−5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550−5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550−5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550−5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.
dc.embargo.terms1 year
dc.identifier.citationLin, Lin, Baring, Matthew G., Granot, Jonathan, et al.. "BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550–5418 BURSTS." <i>The Astrophysical Journal,</i> 756, (2012) The American Astronomical Society: 54-66. http://dx.doi.org/10.1088/0004-637X/756/1/54.
dc.identifier.doihttp://dx.doi.org/10.1088/0004-637X/756/1/54
dc.identifier.urihttps://hdl.handle.net/1911/70568
dc.language.isoeng
dc.publisherThe American Astronomical Society
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.subject.keywordpulsars
dc.subject.keywordindividual (SGR J1550−5418, 1E 1547.0−5408, PSR J1550−5418) – stars
dc.subject.keywordneutron – X-rays
dc.subject.keywordbursts
dc.titleBROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550–5418 BURSTS
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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