Abstract
view Abstract Citations (33) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A VLA Search for Neutral Hydrogen in Cooling Flow Clusters Dwarakanath, K. S. ; van Gorkom, J. H. ; Owen, F. N. Abstract We present a VLA search for neutral hydrogen in three clusters, which are considered to be prime examples of so-called cooling flow clusters: Virgo (Virgo A), Abell 2199 (3C 338), and Abell 780 (Hydra A). We looked for H I in absorption against the central radio sources with a velocity coverage ~2600 km s^-1^ and with a velocity resolution ~87 km s^-1^. We do not detect a spatially extended distribution of cold clouds. Our 3σ optical depth limits are 0.0005 over a typical velocity range of 500 km s^-1^, Assuming the currently popular cooling flow scenarios in which the distribution of the cold gas can be characterized by a core radius of ~100 kpc, our results place an upper limit of 1.2 x 10^10^ M_sun_ to the mass of neutral hydrogen in such a flow for an assumed spin temperature of 100 K. This limit is a factor of 30 below what is expected from the Einstein Solid State Spectrometer observations of cooling flow clusters and is 1-2 orders of magnitude below what is expected from the cooling flow models. The expected large amount of H I is unlikely to exist in these clusters even as optically thick clouds unless their spin temperature is less than 10 K and/or their covering factor is much less than 1. We discuss some physical conditions in which the expected large amounts of H I could have escaped detection. We do, however, find H I absorption against the core of Hydra A. This line is narrow (~50 km s^-1^) and is not seen against the extended radio lobes. The properties of this absorption system are similar to those seen in some other cooling flow clusters and in isolated radio galaxies. We also detect a spiral galaxy in A 2199 with a total mass of 1.8 x 10^9^ M_sun_. Despite this detection of what might be a small H I cloud near the systemic velocity of the core of Hydra A, we do place stringent limits on the existence of such clouds anywhere within the primary beam. The upper limit to H I emission from such clouds ranges from 10^7^ to 10^9^ M_sun_. Publication: The Astrophysical Journal Pub Date: September 1994 DOI: 10.1086/174586 Bibcode: 1994ApJ...432..469D Keywords: Cooling Flows (Astrophysics); Galactic Clusters; H Lines; Hydrogen; Intergalactic Media; Radio Sources (Astronomy); Velocity Distribution; X Ray Absorption; Brightness Distribution; Very Large Array (Vla); X Ray Astronomy; Astrophysics; GALAXIES: COOLING FLOWS; GALAXIES: CLUSTERS: INDIVIDUAL NAME: ABELL 780; GALAXIES: CLUSTERS: INDIVIDUAL NAME: ABELL 2199; GALAXIES: CLUSTERS: INDIVIDUAL NAME: VIRGO A; GALAXIES: CLUSTERS OF; GALAXIES: INTERGALACTIC MEDIUM; RADIO LINES: GENERAL full text sources ADS | data products SIMBAD (6) NED (6)
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