Victoria Grinberg

research

contact:

Victoria Grinberg
grinberg[at]space.mit.de

Kavli Institute for Astrophysics & Space Research
Massachusetts Institute of Technology

Cambridge, MA
USA

Cygnus X-1:
broadband variability of black hole binaries

Cygnus X-1 is the perfect laboratory to study black hole X-ray binaries: it's close-by, bright, persistent and undergoes often X-ray states transitions, which are accompanied by changes in the radio properties of the source (in short: things happen!). It also has a jet, which blows a bubble into the interstellar material, as people has nicely explained in this APOD from 2009 June 8.

The main focus of my work is the analysis of long- and shortterm behavious using data from a campaign with ESA's INTEGRAL satellite (about 10 Ms of data between 2003 and 2012) and a coordinated campaign with NASA's RXTE satellite (bi-weekly coverage from 1996 to 2011) and the Ryle/AMI radio telescope.

Results on Cyg X-1 include:

  • State definition with all sky monitors (Grinberg et. al, 2013, A&A 554, A88, see also A&A highlights). We used the 16 years of mostly bi-weekly RXTE monitoring of Cyg X-1 to map source state based on both spectral and timing behaviour on all sky monitors RXTE-ASM, MAXI, Swift-BAT and Fermi-GBM. The extremly dense all sky monitor coverage enables us to follow the evolution of states and state transitions over almost 18 years with a resolution of a few hours.
  • Detection of polarized gamma-ray emission above 400 keV (P. Laurent, ..., VG, 2011, Science 332, 438, see also the ESA press release). We used 5 megaseconds of data from the INTEGRAL satellite and now have a strong cue towards an origin of this emission in the jet.
  • Detection of very short state transition during the RXTE monitoring of the source (Böck, VG, et al, 2011, AA 533, A8). We've shown that state transitions can happen as quickly as within a few hours and that the strong correlations between timing and spectral parameters hold not only for the long-term, but also for the short-term behaviour.
  • First mid-IR spectroscopic detection of compact jets and the jet break (Rahoui, ... VG, 2011, ApJ 736, A63). We used RXTE and AMI data for the characterisation of the source state and warm-Spitzer data for the IR analysis of the one intermediate and two hard state observations.
    • INTEGRAL monitoring of transient black hole binaries

      [under construction]

      accreting neutron stars

      [under construction]

      instruments and calibrations

      [under construction]