Discovery of a 0.42-s pulsar in the ultraluminous X-ray source NGC 7793 P13
Abstract
NGC 7793 P13 is a variable (luminosity range ∼100) ultraluminous X-ray source proposed to host a stellar-mass black hole of less than 15 M⊙ in a binary system with orbital period of 64 d and a 18-23 M⊙ B9Ia companion. Within the EXTraS (Exploring the X-ray Transient and variable Sky) project, we discovered pulsations at a period of ∼0.42 s in two XMM-Newton observations of NGC 7793 P13, during which the source was detected at LX ∼ 2.1 × 1039 and 5 × 1039 erg s-1 (0.3-10 keV band). These findings unambiguously demonstrate that the compact object in NGC 7793 P13 is a neutron star accreting at super-Eddington rates. While standard accretion models face difficulties accounting for the pulsar X-ray luminosity, the presence of a multipolar magnetic field with B ∼ few × 1013 G close to the base of the accretion column appears to be in agreement with the properties of the system.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2017
- DOI:
- 10.1093/mnrasl/slw218
- arXiv:
- arXiv:1609.06538
- Bibcode:
- 2017MNRAS.466L..48I
- Keywords:
-
- galaxies: individual: NGC 7793;
- X-rays: binaries;
- X-rays: individual: CXOU J235750.9;
- 323726 (XMMU J235751.1-323725;
- NGC 7793 P13);
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, 5 figures, 2 tables