The Merger Dynamics of the Galaxy Cluster Abell 1775: New Insights from Chandra and XMM-Newton for a Cluster Simultaneously Hosting a WAT and a NAT Radio Sources

Abstract

We present a new study of the merger dynamics of Abell~1775 by analyzing the high-quality Chandra and XMM-Newton archival data. We confirm/identify an arc-shaped edge (i.e., the head) at $\sim 48$~kpc west of the X-ray peak, a split cold gas tail that extends eastward to $\sim 163$~kpc, and a plume of spiral-like X-ray excess (within about $81-324$~kpc northeast of the cluster core) that connects to the end of the tail. The head, across which the projected gas temperature rises outward from $3.39_{-0.18}^{+0.28}$~keV to $5.30_{-0.43}^{+0.54}$~keV, is found to be a cold front with a Mach number of $\mathcal{M}\sim 0.79$. Along the surfaces of the cold front and tail, typical KHI features (noses and wings, etc.) are found and are used to constrain the upper limit of the magnetic field ($\sim 11.2\mu$G) and the viscosity suppression factor ($\sim 0.01$). Combining optical and radio evidence we propose a two-body merger (instead of systematic motion in a large-scale gas environment) scenario and have carried out idealized hydrodynamic simulations to verify it. We find that the observed X-ray emission and temperature distributions can be best reproduced with a merger mass ratio of 5 after the first pericentric passage. The NAT radio galaxy is thus more likely to be a single galaxy falling into the cluster center at a relative velocity of 2800~$\mathrm{km}{\mathrm{s}}^{-1}$, a speed constrained by its radio morphology. The infalling subcluster is expected to have a relatively low gas content, because only a gas-poor subcluster can cause central-only disturbances as observed in such an off-axis merger.

12 figures, 5 tables, accepted for publication in the ApJ

References in corpus (33)

• Shocks and cold fronts in galaxy clusters
• Chandra temperature profiles for a sample of nearby relaxed galaxy clusters
• A Catalog of Galaxy Clusters Observed by XMM-Newton
• The origin of cold fronts in the cores of relaxed galaxy clusters
• The impact of mergers on relaxed X-ray clusters - I. Dynamical evolution and emergent transient structures
• Scaling Properties of a Complete X-ray Selected Galaxy Group Sample
• A deeper X-ray study of the core of the Perseus galaxy cluster: the power of sound waves and the distribution of metals and cosmic rays
• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• The speed of the `bullet' in the merging galaxy cluster 1E0657-56
• Contour binning: a new technique for spatially-resolved X-ray spectroscopy applied to Cassiopeia A
• The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files
• Chandra's View of the Ram Pressure Stripped Galaxy M86
• Chandra observation of two shock fronts in the merging galaxy cluster Abell 2146
• Stripped elliptical galaxies as probes of ICM physics: II. Stirred, but mixed? Viscous and inviscid gas stripping of the Virgo elliptical M89
• The Effect of Anisotropic Viscosity on Cold Fronts in Galaxy Clusters
• Deep Chandra observations of NGC 1404: cluster plasma physics revealed by an infalling early-type galaxy
• A systematic search for X-ray cavities in galaxy clusters, groups, and elliptical galaxies
• Abundance and temperature distributions in the hot intra-cluster gas of Abell 4059
• Radio morphology and spectral analysis of cD galaxies in rich and poor galaxy clusters
• An azimuthally resolved study of the cold front in Abell 3667
• The Shape of X-ray Cavities in Galaxy Clusters: Probing Jet Properties and Viscosity
• Narrow head-tail radio galaxies at very high resolution
• The bow shock, cold fronts and disintegrating cool core in the merging galaxy group RXJ0751.3+5012
• The relation between the turbulent Mach number and observed fractal dimensions of turbulent clouds
• A very deep Chandra observation of Abell 1795: The Cold Front and Cooling Wake
• Building a cluster: shocks, cavities, and cooling filaments in the group-group merger NGC 6338
• How Much Can We Learn From A Merging Cold Front Cluster? : Insights From X-ray Temperature and Radio Maps of Abell 3667
• Chandra Observation of the Cluster Environment of a WAT Radio Source in Abell 1446
• Collision of Merger and Accretion Shocks: Formation of Mpc-scale Contact Discontinuity in the Perseus Cluster
• A Simple Physical Model for the Gas Distribution in Galaxy Clusters
• 3C 40 in Abell 194: can tail radio galaxies exist in a quiescent cluster?
• A Study of Gas Entropy Profiles of 47 Galaxy Clusters and Groups Out to the Virial Radius
• Revealing A Head-on Major Merger in the Nearby NGC 6338 Group with Chandra and VLA observations

Cited by in corpus (5)

• Gas sloshing and cold fronts in pre-merging galaxy cluster Abell 98
• Indications of an offset merger in Abell 3667
• The Glow of Axion Quark Nugget Dark Matter: (II) Galaxy Clusters
• A Semi-Analytical Model for the Formation and Evolution of Radio Relics in Galaxy Clusters
• A Chandra view of SPT-CL J0217-5014: a massive galaxy cluster at a cosmic intersection at z=0.53