2013/01/21 by I. Caballero, K. Pottschmidt, D. M. Marcu +24 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Binary number #Cyclotron #Flux (metallurgy) #Light curve #Physics #Plasma #Pulsars and Gravitational Waves Research #astro-ph.HE
paper · pdf · doi:10.1088/2041-8205/764/2/l23
5 pages, 4 figures, accepted for publication in ApJ Letters
arxiv created 2013/01/21 · openalex publication_date 2013/02/04 · arxiv updated 2015/06/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The Be/X-ray binary A 0535+26 showed a normal (type I) outburst in 2009 August. It is the fourth in a series of normal outbursts associated with the periastron, but is unusual because it presented a double-peaked light curve. The two peaks reached a flux of ∼450 mCrab in the 15–50 keV range. We present results of the timing and spectral analysis of INTEGRAL , RXTE , and Suzaku observations of the outburst. The energy-dependent pulse profiles and their evolution during the outburst are studied. No significant differences with respect to other normal outbursts are observed. The centroid energy of the fundamental cyclotron line shows no significant variation during the outburst. A spectral hardening with increasing luminosity is observed. We conclude that the source is accreting in the sub-critical regime. We discuss possible explanations for the double-peaked outburst.