EXPLORING HOT GAS AT JUNCTIONS OF GALAXY FILAMENTS WITHSUZAKU

Abstract

We performed five pointing observations with Suzaku to search for hot gases associated with the junctions of galaxy filaments where no significant diffuse X-ray sources were previously detected. We discovered X-ray sources successfully in all five regions including merging groups of galaxies, Suzaku J0957+2610 and Suzaku J1134+2105, and analyzed two bright sources in each field. Spectral analysis indicates that three sources originate from X-ray diffuse halos associated with optically bright galaxies or groups of galaxies with kT ∼ 0.6-0.8 keV. The three other sources are possibly group-and cluster-scale X-ray halos with temperatures of ∼1 keV and ∼4 keV, respectively while the others are compact object origins such as active galactic nuclei. All of the three observed intracluster media within the junctions of the galaxy filaments previously found are involved in ongoing mergers. Thus, we demonstrate that deep X-ray observations at the filament junctions identified by galaxy surveys are a powerful means to explore previously undetected growing halos in a hierarchical structure.

A Chandra Study of the NGC 7618/UGC 12491 Major Group Merger at Apogee: Multiple Cold Fronts, Boxy Wings, Filaments, and Arc-shaped Slingshot Tails

“…The best-fit heavy element abundances for hot galaxy gas are for the Head1, East Wing1, West Wing1, and Plume1 regions, respectively. These abundances are consistent with each other within their 90% CL uncertainties and are in agreement with Suzaku measurements by Mitsuishi et al (2014). The central value for the metal abundance in the best-fit spectral model for the hot gas in the bright plume (the Plume1 region) is higher than in the other regions.…”

“…This is consistent with the tail being composed of higher abundance stripped or partially stripped galaxy gas viewed through and/or being mixed with the lower abundance group IGM. The measured Fe abundances for UGC 12491 are in agreement, within uncertainties, with Suzaku measurements (Mitsuishi et al 2014). They find abundances of 0.2-0.4 Z e in the central regions of UGC 12491, declining to ∼0.1-0.2 Z e to the southwest, midway between UGC 12491 and NGC 7618.…”

Spatial Distribution of the Milky Way Hot Gaseous Halo Constrained by Suzaku X-Ray Observations

“…Therefore, the high temperature regions might reflect fresh hot gases outflowing from the MW disk. Another possibility is extragalactic hot gas associated with galaxy filaments (Mitsuishi et al 2014). Further observations covering large fractions of the blank X-ray sky are necessary to further examine the origins of these regions.…”

Cluster Physics & Evolution

“…Furthermore, the team measured the hot gas mass fraction in galaxy clusters observed with Chandra out to R 100 . After converting the hot gas fraction to the total baryon (Mitsuishi et al 2014). SDSS spectroscopic identified galaxies (cyan circle) and X-ray contours (white solid lines) are shown.…”

“…To address this issue, Ikuyuki Mitsuishi presented results from the ongoing observational program to search for merging galaxy groups (Kawahara et al 2011, Mitsuishi et al 2014. Using Suzaku X-ray observatory e.g., which possesses both high sensitivity especially in the soft energy band below 1 keV and stable background, the team conducted a search of merging groups in eight fields which are located around junctions of galaxy filaments and three optically-selected groups where an interaction between central and satellite galaxies.…”