Constraining the Physical State of the Hot Gas Halos in NGC 4649 and NGC 5846

Abstract

We present results of a joint \textit{Chandra}/\textit{XMM-Newton} analysis of the early-type galaxies NGC 4649 and NGC 5846 aimed at investigating differences between mass profiles derived from X-ray data and those from optical data, to probe the state of the hot ISM in these galaxies. If the hot ISM is at a given radius in hydrostatic equilibrium (HE) the X-ray data can be used to measure the total enclosed mass of the galaxy. Differences from optically-derived mass distributions therefore yield information about departures from HE in the hot halos. The X-ray mass profiles in different angular sectors of NGC 4649 are generally smooth with no significant azimuthal asymmetries within \(12\) kpc. Extrapolation of these profiles beyond this scale yields results consistent with the optical estimate. However, in the central region (\(r < 3\) kpc) the X-ray data underpredict the enclosed mass, when compared with the optical mass profiles. Consistent with previous results we estimate a non-thermal pressure component accounting for \(30\%\) of the gas pressure, likely linked to nuclear activity. In NGC 5846 the X-ray mass profiles show significant azimuthal asymmetries, especially in the NE direction. Comparison with optical mass profiles in this direction suggests significant departures from HE, consistent with bulk gas compression and decompression due to sloshing on \(\sim 15\) kpc scales; this effect disappears in the NW direction where the emission is smooth and extended. In this sector we find consistent X-ray and optical mass profiles, suggesting that the hot halo is not responding to strong non-gravitational forces.

38 pages, 26 figures, accepted for publication on ApJ

References in corpus (12)

• Shocks and cold fronts in galaxy clusters
• The origin of cold fronts in the cores of relaxed galaxy clusters
• Measuring the non-thermal pressure in early type galaxy atmospheres: A comparison of X-ray and optical potential profiles in M87 and NGC1399
• The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files
• Small scatter and nearly-isothermal mass profiles to four half-light radii from two-dimensional stellar dynamics of early-type galaxies
• Stripped elliptical galaxies as probes of ICM physics: II. Stirred, but mixed? Viscous and inviscid gas stripping of the Virgo elliptical M89
• Stripped elliptical galaxies as probes of ICM physics: I. Tails, wakes, and flow patterns in and around stripped ellipticals
• Weighing the Quiescent Central Black Hole in an Elliptical Galaxy with X-ray Emitting Gas
• A discrete chemo-dynamical model of the giant elliptical galaxy NGC 5846: dark matter fraction, internal rotation and velocity anisotropy out to six effective radii
• Reconciling optical and X-ray mass estimates: the case of the elliptical galaxy NGC3379
• A SLUGGS and Gemini/GMOS combined study of the elliptical galaxy M60: wide-field photometry and kinematics of the globular cluster system
• Probing the kinematics of early-type galaxy halos using planetary nebulae

Cited by in corpus (11)

• Dust growth and evolution in protoplanetary disks
• Simulating the dynamics and non-thermal emission of relativistic magnetised jets I. Dynamics
• A Black-Hole Feedback Valve in Massive Galaxies
• Correlations between supermassive black holes, hot atmospheres, and the total masses of early type galaxies
• Probing multiphase gas in local massive elliptical galaxies via multiwavelength observations
• Study of gravitational fields and globular cluster systems of early-type galaxies
• X-ray Constraints on the Hot Gas Content of Early-type Galaxies in Virgo
• The dynamics of three nearby E0 galaxies in refracted gravity
• The Hot Interstellar Medium
• Refracted Gravity Solutions from Small to Large Scales
• An XMM-Newton Early-type Galaxy Atlas