Multiwavelength Observations Of A0620-00 In Quiescence

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dc.contributor.utaustinauthorRobinson, Edward L.en_US
dc.creatorFroning, Cynthia S.en_US
dc.creatorCantrell, Andrew G.en_US
dc.creatorMaccarone, Thomas J.en_US
dc.creatorFrance, Kevinen_US
dc.creatorKhargharia, Juthikaen_US
dc.creatorWinter, Lisa M.en_US
dc.creatorRobinson, Edward L.en_US
dc.creatorHynes, Robert I.en_US
dc.creatorBroderick, Jess W.en_US
dc.creatorMarkoff, Seraen_US
dc.creatorTorres, Manuel A. P.en_US
dc.creatorGarcia, Michaelen_US
dc.creatorBailyn, Charles D.en_US
dc.creatorProchaska, J. Xavieren_US
dc.creatorWerk, Jessicaen_US
dc.creatorThom, Chrisen_US
dc.creatorBeland, Stephaneen_US
dc.creatorDanforth, Charles W.en_US
dc.creatorKeeney, Brianen_US
dc.creatorGreen, James C.en_US
dc.date.accessioned2016-04-28T19:35:01Z
dc.date.available2016-04-28T19:35:01Z
dc.date.issued2011-12en
dc.description.abstractWe present contemporaneous X-ray, ultraviolet, optical, near-infrared, and radio observations of the black hole binary system, A0620-00, acquired in 2010 March. Using the Cosmic Origins Spectrograph on the Hubble Space Telescope, we have obtained the first FUV spectrum of A0620-00 as well as NUV observations with the Space Telescope Imaging Spectrograph. The observed spectrum is flat in the FUV and very faint (with continuum fluxes similar or equal to 1e -17 erg cm(-2) s(-1) angstrom(-1)). The UV spectra also show strong, broad (FWHM similar to 2000 km s(-1)) emission lines of Si IV, CIV, HeII, FeII, and MgII. The Civ doublet is anomalously weak compared to the other lines, which is consistent with the low carbon abundance seen in NIR spectra of the source. Comparison of these observations with previous NUV spectra of A0620-00 shows that the UV flux has varied by factors of 2-8 over several years. We compiled the dereddened, broadband spectral energy distribution (SED) of A0620-00 and compared it to previous SEDs as well as theoretical models. The SEDs show that the source varies at all wavelengths for which we have multiple samples. Contrary to previous observations, the optical-UV spectrum does not continue to drop to shorter wavelengths, but instead shows a recovery and an increasingly blue spectrum in the FUV. We created an optical-UV spectrum of A0620-00 with the donor star contribution removed. The non-stellar spectrum peaks at similar or equal to 3000 angstrom. The peak can be fit with a T = 10,000 K blackbody with a small emitting area, probably originating in the hot spot where the accretion stream impacts the outer disk. However, one or more components in addition to the blackbody are needed to fit the FUV upturn and the red optical fluxes in the optical-UV spectrum. By comparing the mass accretion rate determined from the hot spot luminosity to the mean accretion rate inferred from the outburst history, we find that the latter is an order of magnitude smaller than the former, indicating that similar to 90% of the accreted mass must be lost from the system if the predictions of the disk instability model and the estimated interoutburst interval are correct. The mass accretion rate at the hot spot is 10(5) the accretion rate at the black hole inferred from the X-ray luminosity. To reconcile these requires that outflows carry away virtually all of the accreted mass, a very low rate of mass transfer from the outer cold disk into the inner hot region, and/or radiatively inefficient accretion. We compared our broadband SED to two models of A0620-00 in quiescence: the advection-dominated accretion flow model and the maximally jet-dominated model. The comparison suggests that strong outflows may be present in the system, indicated by the discrepancies in accretion rates and the FUV upturn in flux in the SED.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipNASA/ESA Hubble Space Telescopeen_US
dc.description.sponsorshipNASA NAS 5-26555, NNX08AC146en_US
dc.description.sponsorshipNASA Office of Space Science NNX09AF08Gen_US
dc.description.sponsorshipCommonwealth of Australiaen_US
dc.identifierdoi:10.15781/T2MF85
dc.identifier.Filename2011_12_multiwavelength.pdfen_US
dc.identifier.citationFroning, Cynthia S., Andrew G. Cantrell, Thomas J. Maccarone, Kevin France, Juthika Khargharia, Lisa M. Winter, Edward L. Robinson et al. "Multiwavelength observations of A0620-00 in quiescence." The Astrophysical Journal, Vol. 743, No. 1 (Dec., 2011): 26.en_US
dc.identifier.doi10.1088/0004-637x/743/1/26en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/34814
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectbinaries: closeen_US
dc.subjectinfrared: starsen_US
dc.subjectstars: individual (a0620-00)en_US
dc.subjectstars:en_US
dc.subjectvariables: generalen_US
dc.subjectx-ray binariesen_US
dc.subjectadvection-dominated accretionen_US
dc.subjectblack-hole binariesen_US
dc.subjecttransient a0620-00en_US
dc.subjectxte j1118+480en_US
dc.subjectsecondary staren_US
dc.subjectcentaurus x-4en_US
dc.subjectneutron-starsen_US
dc.subjectjet modelen_US
dc.subjectmassen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleMultiwavelength Observations Of A0620-00 In Quiescenceen_US
dc.typeArticleen_US

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