Comprehensive analysis of the transient X-ray pulsar MAXI J1409-619
Abstract
We probe the properties of the transient X-ray pulsar MAXI J1409-619 through RXTE and Swift follow-up observations of the outburst in 2010. We are able to phase-connect the pulse arrival times for the 25 d episode during the outburst. We suggest that either an orbital model (with Porb ≃ 14.7(4) d) or a noise process due to random torque fluctuations (with Sr ≈ 1.3 × 10-18 Hz2 s-2 Hz-1) is plausible to describe the residuals of the timing solution. The frequency derivatives indicate a positive torque-luminosity correlation, which implies temporary accretion disc formation during the outburst. We also discover several quasi-periodic oscillations in company with their harmonics whose centroid frequencies decrease as the source flux decays. The variation of the pulsed fraction and spectral power-law index of the source with X-ray flux is interpreted as the sign of transition from a critical to a sub-critical accretion regime at the critical luminosity within the range of 6 × 1037-1.2 × 1038 erg s-1. Using pulse-phase-resolved spectroscopy, we show that the phases with higher flux tend to have lower photon indices, indicating that the polar regions produce spectrally harder emission.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2020
- DOI:
- 10.1093/mnras/staa1562
- arXiv:
- arXiv:1911.02871
- Bibcode:
- 2020MNRAS.496.1768D
- Keywords:
-
- stars: neutron - pulsars: individual: MAXI J1409-619 - accretion;
- accretion discs;
- stars: neutron - pulsars: individual: MAXI J1409‑619 - accretion;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 28 pages, 15 figures, revised version accepted for publication in MNRAS Main Journal