Identification of a new ultraluminous X-ray source in NGC 1316

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Allak S., AKYÜZ A. , AKSAKER N. , Ela M. O. , Avdan S., SOYDUGAN F.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, cilt.499, sa.4, ss.5682-5689, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 499 Konu: 4
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1093/mnras/staa3073
  • Sayfa Sayıları: ss.5682-5689


In this study, we report identification of a newultraluminous X-ray source (ULX) named as X-7 inNGC1316, with an unabsorbed luminosity of 2.1 x 10(39) erg s(-1) using the two recent Chandra archival observations. The X-7 was detected in the Chandra 2001 observation and was included in the source list of the NGC 1316 as CXOUJ032240.8-371224 with a luminosity of 5.7 x 10(38) erg s(-1). Present luminosity implies a luminosity increase of a factor of similar to 4. The best-fitting spectral model parameters indicate that X-7 has a relatively hot disc and hard spectra. If explained by a disc blackbody model, the mass of compact object is estimated as similar to 8 M-circle dot which is in the range of a stellar-mass black hole. The X-7 shows a relatively long-term count rate variability while no short-term variability is observed. We also identified a unique optical candidate within 0.22 arcsec error circle at 95 per cent confidence level for X-7 using the archival HST/ACS (Hubble Space Telescope/Advanced Camera for Surveys) and HST/WFC3 (The Wide Field Camera 3) data. Absolute magnitude (M-V) of this candidate is -7.8 mag. Its spectral energy distribution is adequately fitted a blackbody model with a temperature of 3100 K indicating an M type supergiant, assuming the donor star dominates the optical emission. In addition, we identified a transient ULX candidate (XT-1) located 6 arcsec away from X-7 has a (high) luminosity of similar to 10(39) erg s(-1) with no visible optical candidate.