Comprehensive analysis of the transient X-ray pulsar MAXI J1409 619

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Donmez Ç. K., Serim M. M., Inam S. C., Sahiner S., Serim D., Baykal A.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, cilt.496, sa.2, ss.1768-1783, 2020 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 496 Sayı: 2
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1093/mnras/staa1562
  • Dergi Adı: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Applied Science & Technology Source, Communication Abstracts, INSPEC, Metadex, zbMATH, DIALNET, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.1768-1783
  • Anahtar Kelimeler: stars: neutron, pulsars: individual: MAXI J1409-619, accretion, accretion discs, QUASI-PERIODIC OSCILLATIONS, MAGNETIC NEUTRON-STARS, TIMING NOISE, ACCRETION, DISCOVERY, TORQUES, FIELDS
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

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.