Testing the Kerr Black Hole Hypothesis with GX 3394 by a Combined Analysis of Its Thermal Spectrum and Reflection Features
Abstract
We analyze simultaneous observations with NuSTAR and Swift of the black hole binary GX 3394 in which we clearly detect both a strong thermal component and prominent relativistic reflection features. We employ nkbb and relxill_nk, which are the state of the art of, respectively, the thermal and reflection models to test the Kerr black hole hypothesis. We obtain unprecedented precise measurements of the Johannsen deformation parameter α_{13}: ${\alpha }_{13}={0.012}_{0.039}^{+0.011}$ (lamppost coronal geometry) and ${\alpha }_{13}={0.010}_{0.018}^{+0.024}$ (broken powerlaw emissivity profile) at a 90% confidence level, where the Kerr metric corresponds to α_{13} = 0. We investigate the systematic uncertainties by fitting the data with different models.
 Publication:

The Astrophysical Journal
 Pub Date:
 January 2021
 DOI:
 10.3847/15384357/abccbd
 arXiv:
 arXiv:2010.13474
 Bibcode:
 2021ApJ...907...31T
 Keywords:

 Kerr metric;
 Astrophysical black holes;
 Stellar mass black holes;
 Xray astronomy;
 887;
 98;
 1611;
 1810;
 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 10 pages, 5 figures. v2: refereed version