1. RRI Digital Repository
  2. 04. Astronomy and Astrophysics
  3. Research Papers (A&A)
Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/7487
Full metadata record
DC FieldValueLanguage
dc.contributor.authorPradhan, Pragati-
dc.contributor.authorMaitra, Chandreyee-
dc.contributor.authorPaul, Biswajit-
dc.date.accessioned2020-07-06T04:30:57Z-
dc.date.available2020-07-06T04:30:57Z-
dc.date.issued2020-05-
dc.identifier.citationThe Astrophysical Journal, 2020, Vol.895, Article No.11, p12en_US
dc.identifier.issn0004-637X-
dc.identifier.issn1538-4357(Online)-
dc.identifier.urihttp://hdl.handle.net/2289/7487-
dc.descriptionOpen Accessen_US
dc.description.abstractWe present a broadband spectral-timing analysis of SMC X-1 at different intensity states of its superorbital variation using 10 Suzaku and 6 Nuclear Spectroscopic Telescope Array (NuSTAR) observations. The spectrum in all the states can be described by an absorbed power law with a high-energy cutoff and a blackbody component along with an iron emission line. Compared to other supergiant high-mass X-ray binaries, the Fe Kα line equivalent width is low in SMC X-1—from less than 10 eV in the high state to up to ∼270 eV in the low states. The spectral shape is dependent on flux, with the hard X-ray spectrum steepening with increasing flux. We also report a highly variable normalization of the power-law component across these 16 superorbital states. Pulsations in the hard X-rays for both the instruments were detected in all but two observations. The pulse profiles are near sinusoidal, with two peaks and the relative intensity of the second peak decreasing with decreasing luminosity. These findings suggest that the superorbital modulation in SMC X-1 is not caused by absorption in precessing warped accretion disk alone and there are intrinsic changes in X-rays emanating from the neutron star at different superorbital states. We also note a putative cyclotron line at ∼50 keV in the NuSTAR spectra of three bright states, indicating a possible magnetic field of ∼4.2 × 1012 G. Finally, with the new pulse period measurements reported here, the time base for the secular spin-up of SMC X-1 is increased by thirteen years and the complete pulse period history shows a sudden change in the spin-up trend around 1995en_US
dc.language.isoenen_US
dc.publisherIOP Sciences for The American Astronomical Societyen_US
dc.relation.urihttps://arxiv.org/abs/2004.00664en_US
dc.relation.urihttps://ui.adsabs.harvard.edu/abs/2020ApJ...895...10P/abstracten_US
dc.relation.urihttps://doi.org/10.3847/1538-4357/ab8224en_US
dc.rights2020, The American Astronomical Societyen_US
dc.subjectHigh mass X-ray binary starsen_US
dc.subjectCompact objectsen_US
dc.subjectAstrophysics - High Energy Astrophysical Phenomenaen_US
dc.titleIs Superorbital Modulation in SMC X-1 Caused by Absorption in a Warped Precessing Accretion Disk?en_US
dc.typeArticleen_US
Appears in Collections:Research Papers (A&A)

Files in This Item:
File Description SizeFormat 
2020_ApJ_Vol.895_Article No.10.pdf
  Restricted Access		Open Access1.84 MBAdobe PDFView/Open Request a copy
Show simple item record


Items in RRI Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated.