Infrared Observations of GRO J1655–40: Constraints on the Black Hole Mass

October 17, 2022 · View on GitHub

MSc dissertation, Francis T. O'Donovan, October 2003.

Source: https://library.ucc.ie/record=b1373041

Mirrors:

https://github.com/proinsias/infrared-observations/blob/master/pdf/mastersThesis.pdf

Contact: Check out my webpage for contact details.

Please cite using the following BibTex entry:

@mastersthesis{odonovan2003infraredobs,
  title={Infrared Observations of GRO J1655–40: Constraints on the Black Hole Mass},
  author={{O'Donovan}, F.~T.},
  school={National University of Ireland, Cork},
  year=2003,
  month=10,
}

We present k_s – and J–band photometry of GRO J1655–40 during two epochs of observation, and determine the dereddened and absolute magnitudes of this star system. We derive a range of spectral types (F0–G2 III–IV) for the secondary star in GRO J1655–40, using our j_0-k_0 colour estimate for this soft X–ray transient. We find the absolute magnitude of GRO J1655–40 to be similar to that of another long period soft X–ray transient.

The first high signal–to–noise K–band spectrum of a black hole X–ray transient system (GRO J1655–40) is presented. This is used to show that the quiescent contribution of the accretion disk in GRO J1655–40 to the total flux of the system in the K–band is negligible. We are therefore able to measure with certainty the binary inclination from the light curve of this stellar system, and place real bounds on the mass of the primary star in GRO J1655–40. GRO J1655–40 is also shown to have a similar spectrum to that of an F5–F7 III–IV star.

The ellipsoidal modulation observed in the k_s –band is modelled using ELC, to obtain an inclination of 64_deg-70_deg and a mass ratio of 2.5–6 for the system. These values concur with past results. The derived primary mass, m_x , suggests that the compact object in GRO J1655–40 is a black hole.

An attempt is made to model the system in outburst, taking the ellipsoidal variability of the secondary star and the eclipse of a bright accretion disk into account. The resultant fit is poor, a consequence of the asymmetries of the disk and flickering in the k_s –band. The outburst light curve of GRO J1655–40 is shown to display an eclipse of the accretion disk, consistent with the high inclination of the system.

Many thanks to @glouppe for inspiration and README template from his thesis.