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dc.contributor.authorMori, Kaya
dc.contributor.authorHailey, Charles J.
dc.contributor.authorMandel, Shifra
dc.contributor.authorSchutt, Yve E.
dc.contributor.authorBachetti, Matteo
dc.contributor.authorCoerver, Anna
dc.contributor.authorBaganoff, Frederick K.
dc.contributor.authorDykaar, Hannah
dc.contributor.authorGrindlay, Jonathan
dc.contributor.authorHaggard, Daryl
dc.contributor.authorHeuer, Keri
dc.contributor.authorHong, Jaesub
dc.contributor.authorHord, Benjamin J.
dc.contributor.authorJin, Chichuan
dc.contributor.authorNynka, Melania
dc.contributor.authorPonti, Gabriele
dc.contributor.authorTomsick, John A.
dc.date.accessioned2020-02-05T12:28:43Z
dc.date.issued2019-11-11
dc.identifier.citationMori, Kaya, Charles Hailey, Shifra Mandel, Yve Schutt, Matteo Bachetti, Anna Coerver, Frederick Baganoff, Hannah Dykaar, Jonathan Grindlay, Daryl Haggard, Keri Heuer, Jaesub Hong, Benjamin Hord, Chichuan Jin, Melania Nynka, Gabriele Ponti, and John Tomsick. 2019. NuSTAR and Chandra Observations of New X-ray Transients in the Central Parsec of the Galaxy. The Astrophysical Journal 885, no. 2: 15.en_US
dc.identifier.issn1538-4357en_US
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:42389096*
dc.description.abstractWe report NuSTAR and Chandra observations of two X-ray transients, SWIFT J174540.7−290015 (T15) and SWIFT J174540.2−290037 (T37), which were discovered by the Neil Gehrels Swift Observatory in 2016 within r ∼ 1 pc of Sgr A*. NuSTAR detected bright X-ray outbursts from T15 and T37, likely in the soft and hard states, with 3─79 keV luminosities of 8 × 1036 and 3 × 1037 erg s−1, respectively. No X-ray outbursts have previously been detected from the two transients and our Chandra ACIS analysis puts an upper limit of L X ≲ 2 × 1031 erg s−1 on their quiescent 2─8 keV luminosities. No pulsations, significant quasi-periodic oscillations, or type I X-ray bursts were detected in the NuSTAR data. While T15 exhibited no significant red noise, the T37 power density spectra are well characterized by three Lorentzian components. The declining variability of T37 above ν ∼ 10 Hz is typical of black hole (BH) transients in the hard state. NuSTAR spectra of both transients exhibit a thermal disk blackbody, X-ray reflection with broadened Fe atomic features, and a continuum component well described by Comptonization models. Their X-ray reflection spectra are most consistent with high BH spin (a * ≳ 0.9) and large disk density (n e ∼ 1021 cm−3). Based on the best-fit ionization parameters and disk densities, we found that X-ray reflection occurred near the inner-disk radius, which was derived from the relativistic broadening and thermal disk component. These X-ray characteristics suggest the outbursting BH-low-mass X-ray binary scenario for both transients and yield the first BH spin measurements from X-ray transients in the central 100 pc region.en_US
dc.description.sponsorshipAstronomyen_US
dc.language.isoen_USen_US
dc.publisherAmerican Astronomical Societyen_US
dc.relation.hasversionhttp://arxiv.org/abs/1910.03459en_US
dc.relation.hasversionhttp://ui.adsabs.harvard.edu/abs/2019ApJ...885..142M/abstracten_US
dash.licenseLAA
dc.subjectSpace and Planetary Scienceen_US
dc.subjectAstronomy and Astrophysicsen_US
dc.titleNuSTAR and Chandra Observations of New X-Ray Transients in the Central Parsec of the Galaxyen_US
dc.typeJournal Articleen_US
dc.description.versionVersion of Recorden_US
dc.relation.journalThe Astrophysical Journalen_US
dc.date.available2020-02-05T12:28:43Z
dc.identifier.doi10.3847/1538-4357/ab4b47
dc.source.journalApJ
dash.source.volume885;2
dash.source.page142
dash.contributor.affiliatedGrindlay, Jonathan


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