The BLOBs: Enigmatic Diffuse Ionized Gas Structures in a Cluster of Galaxies near Cosmic Noon

Abstract

We explore the massive cluster XMMXCS J2215.9-1738 at z about 1.46 with MUSE and KMOS integral field spectroscopy. Using MUSE spectroscopy we traced the kinematics of the ionized gas using [OII] in the central 500x500 square kpc area of the cluster, which contains 28 spectroscopically identified cluster galaxies. We detected [OII] emission lines in the integrated spectra of 21 galaxies. The remaining seven are passive galaxies. Six of these passive galaxies lie in the central part of the cluster, which has a diameter of 200 kpc and which contains no star-forming objects. In this place star-formation in galaxies is quenched. An interesting discovery in this central area of the cluster are three diffuse ionized [OII] gas structures, which we refer to as [OII] blobs. They extend over areas of some hundred square kpc. The ionization source of one of the gaseous structures that displays two prominent filamentary patterns indicating outflow of gas is an active galactic nucleus (AGN). The KMOS data enabled us to use the BPT diagram to identify this object as a type 2 AGN. The other two diffuse ionized oxygen gaseous structures are more enigmatic. They are located between the stellar components of passive cluster galaxies. One of these blobs lacks a stellar counterpart in the HST optical and near-infrared data, and the other blob has only a very faint counterpart. Ram-pressure stripping of photoionized gas or AGN feedback might be an explanation. Additionally, the galaxy velocity distribution in this high-redshift cluster is bimodal, which indicates that the cluster is probably not fully virialized and that recent and ongoing merging events that produced shocks might provide photoionization sources for the two enigmatic [OII] blobs.

Accepted for publication in Astronomy & Astrophysics; version after language editor corrections

References in corpus (27)

• Star Formation in Galaxies Along the Hubble Sequence
• Stellar Masses and Star Formation Histories for 10^5 Galaxies from the Sloan Digital Sky Survey
• Evolution since z = 0.5 of the Morphology-Density relation for Clusters of Galaxies
• The Evolution of the Global Stellar Mass Density at 0 < z < 3
• The Data Processing Pipeline for the MUSE Instrument
• ZAP -- Enhanced PCA Sky Subtraction for Integral Field Spectroscopy
• The stellar mass function of galaxies to z ~ 5 in the Fors Deep and GOODS-S fields
• The XMM Cluster Survey: A Massive Galaxy Cluster at z=1.45
• On the origin of the faint-end of the red sequence in high density environments
• MASSIV: Mass Assembly Survey with SINFONI in VVDS - II. Kinematics and close environment classification
• The XMM Cluster Survey: Active Galactic Nuclei and Starburst Galaxies in XMMXCS J2215.9-1738 at z=1.46
• Galaxy Mergers Drive Shocks: an Integral Field Study of GOALS galaxies
• The XMM Cluster Survey: The build up of stellar mass in Brightest Cluster Galaxies at high redshift
• Solar oxygen abundance
• The XMM Cluster Survey: Galaxy Morphologies and the Color-Magnitude Relation in XMMXCS J2215.9-1738 at z=1.46
• Molecular gas reservoirs in cluster galaxies at z=1.46
• Galaxy evolution in protoclusters
• The KMOS Cluster Survey (KCS) I: The fundamental plane and the formation ages of cluster galaxies at redshift $1.4<z<1.6$
• Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7
• Evolutionary phases of gas-rich galaxies in a galaxy cluster at z=1.46
• Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z~0.2
• ALMA pin-points a strong over-density of U/LIRGs in the massive cluster XCS J2215 at z=1.46
• Cluster induced quenching of galaxies in the massive cluster XMMXCSJ2215.9-1738 at z~1.5 traced by enhanced metallicities inside half R200
• A study of the ionized gas in Stephan's Quintet from integral field spectroscopy observations
• First Systematic Search for Oxygen-Line Blobs at High Redshift: Uncovering AGN Feedback and Star-Formation Quenching
• Star-formation quenching of cluster galaxies as traced by metallicity, presence of active galactic nuclei, and galactic conformity
• Systematic Survey for [OII], [OIII], and H$\alpha$ Blobs at $z=0.1-1.5$: The Implication for Evolution of Galactic-Scale Outflow