Hot Halo Emission Detected at Outskirts of Two Poor Galaxy Groups Using Suzaku
Abstract
We present Suzaku off-center observations of two poor galaxy groups, NGC 3402 and NGC 5129, with temperatures below 1 keV. Through spectral decomposition, we measure their surface brightnesses and temperatures out to 420 and 300 times the critical density of the universe for NGC 3402 and NGC 5129, respectively. These quantities are consistent with extrapolations from existing inner measurements of the two groups. With the refined X-ray luminosities, the two groups prefer LX-T relations without a break in the group regime. Furthermore, we measure the electron number densities and hydrostatic masses at these radii. We find that the electron number density profiles require three β-model components, including one with a flat slope, for both groups. Adding the gas mass measured from the X-ray data and stellar mass from group galaxy members, we measure baryon fractions of fb = 0.120 and 0.116 for NGC 3402 and NGC 5129, respectively. Combining other poor groups with well measured X-ray emission to the outskirts, we find an average baryon fraction of fb,ave = 0.111 for X-ray bright groups with temperatures between 0.8-1.3 keV, extending existing constraints to lower mass systems.
- Publication:
-
American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015
- Bibcode:
- 2015AAS...22543903N