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Multiwavelength spectral timing of black holes and neutron stars: a new step in our understanding of accretion processes

Final Report Summary - ACCRETION STATES (Multiwavelength spectral timing of black holes and neutron stars: a new step in our understanding of accretion processes)

PROJECT OBJECTIVES

The goal of the project is to carry out a comprehensive and homogeneous study on the different accretion regimes observed in accreting neutron stars and black hole binary systems. To do that, the fellow should use the largest available sample of observations of these objects, providing a reference point for further studies in the field. The results obtained could be considered unique, since e.g. time scales in accreting super massive black holes are not that suitable for human studies.

DESCRIPTION OF THE WORK
The project was divided in two parts, one focussed on the analysis of black holes systems, which was done during the first year of the project, and another focussed on the analysis of neutron star systems. The analysis was focussed on the X-ray spectral/timing properties of a large sample of systems (10+ black holes; 50 Neutron stars) and how they are connected to their multi-wavelength properties (e.g. radio jets), the later being the main expertise of the host. Besides these two key studies, yielding one publication each [see 1 and 2 below], the fellow actively participated as co-author in other works very related to the project (for a total of 19 publications). He also led a multi-wavelength study on a newly discovered black hole system (3).
DESCRIPTION OF THE MAIN RESULTS
-The three main results of the project were published in the following papers:
1. Munoz-Darias, T., Coriat M., Plant D. S., Ponti G., Fender R. P., Dunn R. J. H., Inclination and relativistic effects in the outburst evolution of black hole transients, MNRAS, 432, 1330, 1337, 6/2013
2. Munoz-Darias, T., Fender, R. P., Motta, S. E., Belloni, T., Black hole-like hysteresis and accretion states in neutron star low mass X-ray binaries, accepted in MNRAS, 07/2014 (arXiv:1407.1318)
3. Munoz-Darias, T., de Ugarte Postigo A., Russell D. M. et al., The optical counterpart of the bright X-ray transient Swift J1745-26, MNRAS, 432, 1133, 1137, 6/2013

-Complementary Publications:
4. Armas Padilla, M., Wijnands, R., Degenaar, N., Munoz-Darias, T., Casares, J., Fender, R. P., Swift J1357.2-0933: the faintest black hole?, submitted to MNRAS Lett. (arXiv:1404.2134) 06/2014
5. Ponti, G., Munoz-Darias, T., Fender, R. P., submitted to MNRAS, 04/2014
6. Coti Zelati, M. et al. (13 authors; includes Munoz-Darias, T.), Engulfing a radio pulsar: the case of PSR J1023+0038, submitted to MNRAS, 04/2014
7. Motta, S. E., Casella, P., Munoz-Darias, T., Henze, M., Sanna, A., Fender, R. P., Belloni, T., Geometrical constraints on the origin of timing signals from black holes, submitted to MNRAS, 03/2014
8. Plant D. S., Fender R. P., Ponti G., Munoz-Darias, T., Coriat M., Revealing accretion onto black holes: X-ray reflection throughout three outbursts of GX 3394, submitted to MNRAS, 02/2014 (revised version submitted 04/2014)
9. Plant D. S., Fender R. P., Ponti G., Munoz-Darias, T., Coriat M., The truncated and evolving inner accretion disc of the black hole GX 339-4, submitted to A&A (arXiv:1309.4781) 04/2014
10. D’Elia, V. et al. (22 authors; includes Munoz-Darias, T.), VLT/X-shooter spectroscopy of the GRB 120327A afterglow, A&A, 564A, 38D, 04/2014
11. Motta S. E., Munoz-Darias, T., Fender R., Stella L. Belloni T. M., Black hole spin measurements through the relativistic precession model: XTE J1550-564, MNRAS, 439, L65, 03/2014
12. Motta S. E., Belloni T. M., Stella L., Munoz-Darias, T., Fender R., Precise mass and spin measurements for a stellar-mass black hole through X-ray timing: the case of GRO J1655-40, MNRAS, 437, 2554, 01/2014
13. Baglio M. C., D’Avanzo P., Munoz-Darias, T., Breton R. P., Campana S., The long-term evolution of the X-ray pulsar XTE J1814-338: a receding jet contribution to the quiescent optical emission?, A&A, 559, A42, 11/2013
14. De Marco B. et al. (7 authors; includes Munoz-Darias, T.), Time lags in the ultraluminous X-ray source NGC 5408 X-1: implications for the black hole mass, MNRAS, 2522, 10/2013
15. Shaw A. W. et al. (9 authors; includes Munoz-Darias, T.), A 420-day X-ray/optical modulation and extended X-ray dips in the short-period transient Swift J1753.5-0127 MNRAS, 433, 740, 745, 7/2013
16. Kuulkers E. et al. (15 authors; includes Munoz-Darias, T.), MAXI J1659-152: the shortest orbital period black-hole transient in outburst, A&A, 552, A32, 4/2013
17. Corral-Santana J. M., Casares J., Munoz-Darias, T. et al., A Black Hole Nova Obscured by an Inner Disk Torus, Science, 339, 1048, 1051, 3/2013
18. Soleri P., Munoz-Darias, T., Motta S. et al., A complex state transition from the black hole candidate Swift J1753.5-0127 MNRAS, 429, 1244, 1257, 2/2013
19. Motta S., Homan J., Munoz-Darias, T. et al., Discovery of two simultaneous non-harmonically related quasi-periodic oscillations in the 2005 outburst of the black hole binary GRO J1655-40, MNRAS, 427, 595, 606, 11/2012

FINAL RESULTS
The project has two main and clear results:
*We have shown how the observing properties of black hole systems depend on its viewing angle with respect to the Earth. We can explain many of the observed differences through relativistic effects expected to be present in accretion discs
*We find that hysteresis patterns between Compton dominated and thermal dominated accretion states are common in neutron star systems. We show that hysteresis does not require large changes in luminosity and it is the natural form that state transitions take below ~ 30 % of the Eddington Luminosity. At higher accretion rates neutron stars do not show hysteresis, and they remain in a thermal dominated, low variability state. We have compared this behaviour with that observed in systems harbouring black holes, showing that the spectral, timing and multi-wavelength properties of a given source can be determined by its location in the fast variability-luminosity diagram, which, therefore, provides a common framework for neutron star and black hole accretion states