A. J. Tetarenko, G. R. Sivakoff, J. C.A. Miller-Jones, P. A. Curran, T. D. Russell, I. M. Coulson, S. Heinz, D. Maitra, S. B. Markoff, S. Migliari, G. R. Petitpas, M. P. Rupen, A. P. Rushton, D. M. Russell, C. L. Sarazin

Research output: Contribution to journalArticlepeer-review


We present the results of our observations of the early stages of the 2012-2013 outburst of the transient black hole X-ray binary (BHXRB), Swift J1745-26, with the Very Large Array, Submillimeter Array, and James Clerk Maxwell telescope (SCUBA-2). Our data mark the first multiple-band mm and sub-mm observations of a BHXRB. During our observations the system was in the hard accretion state producing a steady, compact jet. The unique combination of radio and mm/sub-mm data allows us to directly measure the spectral indices in and between the radio and mm/sub-mm regimes, including the first mm/sub-mm spectral index measured for a BHXRB. Spectral fitting revealed that both the mm (230 GHz) and sub-mm (350 GHz) measurements are consistent with extrapolations of an inverted power law from contemporaneous radio data (1-30 GHz). This indicates that, as standard jet models predict, a power law extending up to mm/sub-mm frequencies can adequately describe the spectrum, and suggests that the mechanism driving spectral inversion could be responsible for the high mm/sub-mm fluxes (compared to radio fluxes) observed in outbursting BHXRBs. While this power law is also consistent with contemporaneous optical data, the optical data could arise from either jet emission with a jet spectral break frequency of υbreak ≳ 1 × 1014 Hz or the combination of jet emission with a lower jet spectral break frequency of υbreak ≳ 2 × 1011 Hz and accretion disk emission. Our analysis solidifies the importance of the mm/sub-mm regime in bridging the crucial gap between radio and IR frequencies in the jet spectrum, and justifies the need to explore this regime further.

Original languageEnglish (US)
Article number30
JournalAstrophysical Journal
Issue number1
StatePublished - May 20 2015


  • Black hole physics
  • ISM: jets and outflows
  • Radio continuum: stars
  • Stars: individual (Swift J1745-26)
  • Submillimeter: stars
  • X-rays: binaries

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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