Chandra and XMM-Newton Observations of a Group of Galaxies, HCG 62

Abstract

We present results from Chandra and XMM-Newton observations of a bright group of galaxies, HCG 62. There are two cavities at about $30{}^{\prime\prime}$ northeast and $20{}^{\prime\prime}$ southwest of the central galaxy in the Chandra image. The energy spectrum shows no significant change in the cavity compared with that in the surrounding region. The radial X-ray profile is described by the sum of the 3-$\beta$ components with core radii of about 2, 10, and 160 kpc. We studied the radial distributions of the temperature and the metal abundance with a joint spectral fit for both data; two temperatures were required in the inner $r< 2'$ (36 kpc) region. A sharp drop of the temperature at $r \sim 5'$ implies a gravitational mass density even lower than the gas density, suggesting that the gas may not be in hydrostatic equilibrium. The Fe and Si abundances are 1–2 solar at the center, and drop to about 0.1 solar at $r \sim 10'$. The O abundance is less than 0.5 solar, and shows a flatter profile. The observed metal distribution supports the view that iron and silicon are produced by type Ia supernova (SN Ia) in the central galaxy, while galactic winds by SN II have caused a wide distribution of oxygen. The supporting mechanism of the cavity is discussed. The pressure for the sum of electrons and the magnetic field is too low to displace the hot group gas, and the required pressure due to high-energy protons is nearly 700-times higher than the electron pressure. This leaves the origin of the cavities a puzzle; we also discuss other possible origins of the cavities.

Suzaku observations of clusters of galaxies

“…The observed O and Mg abundances are mostly consistent with those derived from Chandra and XMM-Newton (Buote, 2002;Morita et al 2006;Hayakawa et al 2006). Due to the better sensitivity to O and Mg lines, the XIS results are significantly better than those from other satellites, especially at low surface brightness.…”

Constraining the Nature of X‐Ray Cavities in Clusters and Galaxies

“…Chandra and XMM-Newton observations (e.g., McNamara et al 2000) have revealed the existence of giant cavities in clusters, which are often associated with radio emission from ongoing jet activity of the central AGN, actively inflating these ''bubbles.'' This direct link has also been observed on the smaller group (e.g., Morita et al 2006) and galaxy scales (e.g., Finoguenov & Jones 2001;Diehl & Statler 2007, 2008a, 2008b. AGN outbursts have been shown to have potentially more than sufficient energy to offset cooling in a large fraction of clusters (Bîrzan et al 2004), and even in normal elliptical galaxies and groups (Best et al 2005(Best et al , 2006.…”

The Infrared Properties of Hickson Compact Groups

“…This result is consistent with what is seen in brightest cluster galaxies in clusters without strong cooling flows by Egami et al (2006). Those clusters frequently have evidence for AGN activity that apparently injects energy into the ICM and prevents cooling; the large X-ray bubbles in HCG 62 indicate similar activity (e.g., Morita et al 2006). …”