PHL 6625: A Minor Merger-associated QSO Behind NGC 247

Tao, L., Feng, H., Shen, Y., Ho, L. C., Ge, J., Kaaret, P., Mao, S. & Liu, X.

Research output: Contribution to journalArticlepeer-review


PHL 6625 is a luminous quasi-stellar object (QSO) at z = 0.3954 located behind the nearby galaxy NGC 247 (z = 0.0005). Hubble Space Telescope observations revealed an arc structure associated with it. We report on spectroscopic observations with the Very Large Telescope and multiwavelength observations from the radio to the X-ray band for the system, suggesting that PHL 6625 and the arc are a close pair of merging galaxies, instead of a strong gravitational lens system. The QSO host galaxy is estimated to be (4-28) × 10 10 M and the mass of the companion galaxy is estimated to be M = (6.8 ± 2.4) × 10 9 M suggesting that this is a minor merger system. The QSO displays typical broad emission lines, from which a black hole mass of about (2-5) × 10 8 M and an Eddington ratio of about 0.01-0.05 can be inferred. The system represents an interesting and rare case where a QSO is associated with an ongoing minor merger, analogous to Arp 142.

Original languageEnglish (US)
Article number118
JournalThe Astrophysical journal
Issue number2
StatePublished - Jun 1 2017


  • galaxies: active
  • galaxies: interactions
  • galaxies: nuclei
  • quasars: supermassive black holes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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