Constraining the role of Type Ia and Type II supernovae in galaxy groups by spatially resolved analysis of ROSAT and ASCA observations

Abstract

We present the results of modelling the distribution of gas properties in the galaxy groups HCG 51, HCG 62 and NGC 5044, and in the poor cluster AWM 7, using both ASCA SIS and ROSAT data. The spectral quality of the ASCA data allows the radial distribution in the abundances of several elements to be resolved. In all systems apart from HCG 51, we see both central cooling flows and a general decline in metal abundances with radius. The ratio of iron to α‐element abundances varies significantly, and, in comparison with theoretical supernova yields, indicates a significant contribution to the metal abundance of the intergalactic medium from Type Ia supernovae. This is seen both within the groups and throughout much of the cluster AWM 7. The total energy input into the IGM from supernovae can be calculated from our results, and is typically 20‐‐40 per cent of the thermal energy of the gas, mostly from Type II supernovae. Our results support the idea that the SN II ejecta have been more widely distributed in the IGM, probably owing to the action of galaxy winds, and the lower iron mass‐to‐light ratio in groups suggests that some of this enriched gas has been lost altogether from the shallower potential wells of the smaller systems.

Chandra and XMM-Newton Observations of the Group of Galaxies HCG 62

“…This is because the hot component dominates the surface brightness. For the 1-T model, the temperature rises from kT = 0.7 keV at the center to kT = 1.4 keV at larger radii, which is consistent with the previous deprojection analysis for the ASCA data (Finoguenov & Ponman 1999) and the ROSAT temperature profile by Buote (2000a). This profile in r < 2 ′ is also seen in the temperature map calculated from the HR (figure 6).…”

“…It also indicates a flatter profile, though significance is low due to the low abundance of oxygen. The decline of Fe, Si, and Mg abundances with radius previously reported by Finoguenov & Ponman (1999) with ASCA, is also confirmed with Chandra and XMM-Newton. Our result shows that Fe, Si, and Mg abundances are 1-2 solar at the center and drop to about 0.1 solar at r ∼ 10 ′ .…”

“…This situation corresponds to the case of 1-T fit, and the 2-T model tends to shift the temperature away from such a high emissivity position. The ASCA spectra of HGG 62 are fitted with the 1-T Mekal model by Finoguenov & Ponman (1999), and the present results for Fe, Si, and Mg with 1-T fits are in good agreement with the ASCA deprojection results within the 90% confidence limit at r > 1 ′ ,…”

“…The temperature with the 1-T model drops again at r > 8 ′ from the intermediate level of kT = 1.4 keV, as shown in figure 9. The temperature drop in our data is much steeper than those reported by Finoguenov & Ponman (1999) with ASCA and by Buote (2000a) with ROSAT. The ROSAT temperature at r > 8 ′ is kT = 0.9-1.0 keV, while ours is kT = 0.66 ± 0.03 keV.…”

“…HCG 62 is the brightest group of galaxies in the X-ray band, and the extended X-ray emission was first discovered by Ponman & Bertram (1993) from the ROSAT PSPC observation. Based on the ASCA observation, Fukazawa et al (2001) detected excess hard X-ray emission, and Finoguenov & Ponman (1999) report strong central concentration of iron. Using the high resolution image of Chandra, Vrtilek et al (2001Vrtilek et al ( ,2002 detected two ghost cavities, which is the first report of cavities in groups of galaxies.…”