Testing the Kerr Black Hole Hypothesis with GX 339-4 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 339-4 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 α13: ${\alpha }_{13}=-{0.012}_{-0.039}^{+0.011}$ (lamppost coronal geometry) and ${\alpha }_{13}=-{0.010}_{-0.018}^{+0.024}$ (broken power-law emissivity profile) at a 90% confidence level, where the Kerr metric corresponds to α13 = 0. We investigate the systematic uncertainties by fitting the data with different models.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2021
- DOI:
- 10.3847/1538-4357/abccbd
- arXiv:
- arXiv:2010.13474
- Bibcode:
- 2021ApJ...907...31T
- Keywords:
-
- Kerr metric;
- Astrophysical black holes;
- Stellar mass black holes;
- X-ray astronomy;
- 887;
- 98;
- 1611;
- 1810;
- Astrophysics - High Energy Astrophysical Phenomena;
- General Relativity and Quantum Cosmology
- E-Print:
- 10 pages, 5 figures. v2: refereed version