Recurring X-ray outbursts in the supernova impostor SN 2010da in NGC 300

B. Binder, B. F. Williams, A. K.H. Kong, T. J. Gaetz, P. P. Plucinsky, E. D. Skillman, A. Dolphin

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

We present new observations of the 'supernova impostor' SN 2010da using the Chandra X-ray Observatory and the Hubble Space Telescope. During the initial 2010 outburst, the 0.3-10 keV luminosity was observed by Swift to be ~5 × 1038 erg s-1 and faded by a factor of ~25 in a four month period. Our two new Chandra observations show a factor of ~10 increase in the 0.35-8 keV X-ray luminosity, from~4×1036 to 4×1037 erg s-1 in~6months, and the X-ray spectrum is consistent in both observations with a power-law with a photon index of Γ ~0. We find evidence of X-ray spectral state changes: When SN 2010da is in a high-luminosity state, the X-ray spectrum is harder (Γ ~0) compared to the low-luminosity state (Γ ~ 1.2 ± 0.8). Using our Hubble observations, we fit the colour-magnitude diagram of the coeval stellar population to estimate a time since formation of the SN 2010da progenitor system of ≲5 Myr. Our observations are consistent with SN 2010da being a high-mass X-ray binary (HMXB) composed of a neutron star and a luminous blue variable-like companion, although we cannot rule out the possibility that SN 2010da is an unusually X-ray bright massive star. The ≲5 Myr age is consistent with the theoretically predicted delay time between the formation of a massive binary and the onset of the HMXB phase. It is possible that the initial 2010 outburst marked the beginning of X-ray production in the system, making SN 2010da possibly the first massive progenitor binary ever observed to evolve into an HMXB.

Original languageEnglish (US)
Pages (from-to)1636-1643
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume457
Issue number2
DOIs
StatePublished - Apr 1 2016

Bibliographical note

Publisher Copyright:
© 2016 The Authors.

Keywords

  • Stars: early-type
  • Stars: massive
  • X-rays: binaries X-rays: individual: SN 2010da

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