On the nature of AX J2049.6+2939/AX J2050.0+2914

Emi Miyata, Kouji Ohta, Ken'ichi Torii, Toshiaki Takeshima, Hiroshi Tsunemi, Takashi Hasegawa, Yasuhiro Hashimoto

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Abstract

AX J2049.6+2939 is a compact X-ray source in the vicinity of the southern blow-up region of the Cygnus Loop supernova remnant. This source was the brightest X-ray source inside the Cygnus Loop observed during the ASCA survey project. The X-ray spectrum was well fitted by a power-law function with a photon index of -2.1±0.1. Short-term timing analysis was performed, and no coherent pulsation was found. Follow-up observations with ASCA have revealed a large variation in X-ray intensity by a factor of ≃50, whereas the spectral shape did not change within the statistical uncertainties. In the second ASCA observation, we found another X-ray source, AX J2050.0+2941, to the northeast of AX J2049.6+2939. During the three ASCA observations, the X-ray intensity of AX J2050.0+2941 varied by a factor of ≃4. No coherent pulsations could be found for AX J2050.0+2941. We have performed optical photometric and spectroscopic observations in the vicinity of AX J2049.6+2939 at KPNO. As a result, all objects brighter than a B-band magnitude of 22 in the error box can be identified with normal stars. Combined with the X-ray results and the fact that there are no radio counterparts, AX J2049.6+2939 is not likely to be either an ordinary rotation-powered pulsar or an active galactic nucleus (AGN). The nature of AX J2049.6+2939 is still unclear, and further observations over a wide energy band are strongly required. As to AX J2050.0+2941, the long-term X-ray variability and the radio counterpart suggests that it is an AGN.

Original languageEnglish
Pages (from-to)1023-1029
Number of pages7
JournalAstrophysical Journal
Volume550
Issue number2 PART 1
Publication statusPublished - 2001 Apr 1

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Keywords

  • ISM: individual (Cygnus Loop)
  • Stars: neutron
  • X-rays: general
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Miyata, E., Ohta, K., Torii, K., Takeshima, T., Tsunemi, H., Hasegawa, T., & Hashimoto, Y. (2001). On the nature of AX J2049.6+2939/AX J2050.0+2914. Astrophysical Journal, 550(2 PART 1), 1023-1029.