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Date and Time of the Query: 2019-04-19 T12:45:20 PDT
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For refcode 2000MNRAS.318..703B:
Retrieve 1190 NED objects in this reference.
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NED Abstract

Copyright by Royal Astronomical Society. 2000MNRAS.318..703B H{alpha} photometry of Abell 2390 Michael L. Balogh and Simon L. Morris Accepted 2000 May 31. Received 2000 May 31; in original form 2000 January 10 ABSTRACT We present the results of a search for strong H{alpha} emission line galaxies (rest frame equivalent widths greater than 50 A) in the z~0.23 cluster Abell 2390. The survey contains 1189 galaxies over 270 arcmin^2^, and is 50 per cent complete at M_r_ ~ -17.5 + 5 log h. The fraction of galaxies in which H{alpha} is detected at the 2{sigma} level rises from 0.0 in the central regions (excluding the cD galaxy) to 12.5+/-8 per cent at R_200_. For 165 of the galaxies in our catalogue, we compare the H{alpha} equivalent widths with their [O II] {lambda}3727 equivalent widths, from the Canadian Network for Observational Cosmology (CNOC1) spectra. The fraction of strong H{alpha} emission line galaxies is consistent with the fraction of strong [O II] emission galaxies in the CNOC1 sample: only 211 percent have no detectable [O II] emission and yet significant (>2s) H{alpha} equivalent widths. Dust obscuration, non-thermal ionization, and aperture effects are all likely to contribute to this non-correspondence of emission lines. We identify six spectroscopically "secure" k+a galaxies [W_0_(O II) < 5 A and W_0_(H{delta})5 A]; at least two of these show strong signs in H{alpha} of star formation in regions that are covered by the slit from which the spectra were obtained. Thus, some fraction of galaxies classified as k+a based on spectra shortward of 6000 A are likely to be undergoing significant star formation. These results are consistent with a "strangulation" model for cluster galaxy evolution, in which star formation in cluster galaxies is gradually decreased, and is neither enhanced nor abruptly terminated by the cluster environment. Key words: galaxies: clusters: individual: Abell 2390 - galaxies: evolution
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