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Chandra Observation of a Group of Galaxies HCG 80: Does the Spiral-Only Group Have Hot Intragroup Gas?

Naomi Ota·Umeyo Morita·Tetsu Kitayama·Takaya Ohashi
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Abstract

We present an analysis of Chandra X-ray observations of a compact group of galaxies, HCG 80 (z=0.03). The system is a spiral-only group composed of four late-type galaxies, and has a high-velocity dispersion of 309 km/s. With high-sensitivity Chandra observations, we searched for diffuse X-ray emission from the intragroup medium (IGM); however, no significant emission was detected. We place a severe upper limit on the luminosity of the diffuse gas as LX < 6e40 erg/s. On the other hand, significant emission from three of the four members were detected. In particular, we discovered huge halo emission from HCG 80a that extends on a scale of ~30 kpc perpendicular to the galactic disk, whose X-ray temperature and luminosity were measured to be ~0.6 keV and ~4e40 erg/s in the 0.5-2 keV band, respectively. It is most likely to be an outflow powered by intense starburst activity. Based on the results, we discuss possible reasons for the absence of diffuse X-ray emission in the HCG 80 group, suggesting that the system is subject to galaxy interactions, and is possibly at an early stage of IGM evolution.

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Naomi Ota, Umeyo Morita, Tetsu Kitayama, Takaya Ohashi. 2004-10-18. Chandra Observation of a Group of Galaxies HCG 80: Does the Spiral-Only Group Have Hot Intragroup Gas?. https://doi.org/10.1093/pasj%2F56.5.753

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