2021A&A...656A.105T


Query : 2021A&A...656A.105T

2021A&A...656A.105T - Astronomy and Astrophysics, volume 656A, 105-105 (2021/12-1)

Fitting strategies of accretion column models and application to the broadband spectrum of Cen X-3.

THALHAMMER P., BISSINGER M., BALLHAUSEN R., POTTSCHMIDT K., WOLFF M.T., STIERHOF J., SOKOLOVA-LAPA E., FURST F., MALACARIA C., GOTTLIEB A., MARCU-CHEATHAM D.M., BECKER P.A. and WILMS J.

Abstract (from CDS):

Due to the complexity of modeling the radiative transfer inside the accretion columns of neutron star binaries, their X-ray spectra are still commonly described with phenomenological models, for example, a cutoff power law. While the behavior of these models is well understood and they allow for a comparison of different sources and studying source behavior, the extent to which the underlying physics can be derived from the model parameters is very limited. During recent years, several physically motivated spectral models have been developed to overcome these limitations. Their application, however, is generally computationally much more expensive and they require a high number of parameters which are difficult to constrain. Previous works have presented an analytical solution to the radiative transfer equation inside the accretion column assuming a velocity profile that is linear in the optical depth. An implementation of this solution that is both fast and accurate enough to be fitted to observed spectra is available as a model in XSPEC. The main difficulty of this implementation is that some solutions violate energy conservation and therefore have to be rejected by the user. We propose a novel fitting strategy that ensures energy conservation during the χ2-minimization which simplifies the application of the model considerably. We demonstrate this approach as well as a study of possible parameter degeneracies with a comprehensive Markov-chain Monte Carlo analysis of the complete parameter space for a combined NuSTAR and Swift/XRT dataset of Cen X-3. The derived accretion-flow structure features a small column radius of ∼63 m and a spectrum dominated by bulk-Comptonization of bremsstrahlung seed photons, in agreement with previous studies.

Abstract Copyright: © ESO 2021

Journal keyword(s): X-rays: binaries - stars: neutron - stars: individual: Cen X-3 - methods: data analysis

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* BQ Cam HXB 03 34 59.9116110096 +53 10 23.296879776   17.16 15.42 14.26 13.04 O8.5Ve 449 1
2 V* X Per HXB 03 55 23.0777456088 +31 02 45.039836148 6.090 6.840 6.720     O9.5III 953 0
3 V* V779 Cen HXB 11 21 15.0920532528 -60 37 25.630264596   14.4 12.27     O9III/Veq 1048 0
4 V* HZ Her LXB 16 57 49.8110126616 +35 20 32.486555472 11.90 14.89 13.63 13.88   B3/6ep 2019 0

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2023.01.30-22:45:58

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