The Near-IR Luminosity Function and Bimodal Surface Brightness Distribution of Virgo Cluster Galaxies - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: We have acquired deep, H-band, imaging for a sample of 286 Virgo clustergalaxies with B <= 16 mag and extracted surface photometry from optical g,r,i,zSloan Digital Sky Survey images of 742 Virgo Cluster Catalog galaxies,including those with H-band images. We confirm the detection of a dip in theluminosity function indicative of a discontinuity in the cluster galaxypopulation; the dip is more pronounced at redder wavelengths. We find, inagreement with earlier works of Tully and Verheijen and ours for Ursa Majorcluster galaxies, a clear dichotomy between high and low surface brightnessgalaxy disks. The difference between the low and high brightness peaks of Virgodisk galaxies is ~2 H-mag arcsec^-2, significantly larger than any systematicerrors. The high surface brightness disk galaxies have two distinct classes ofhigh and low concentration bulges, while low surface brightness galaxies haveonly low concentration bulges. Early-type galaxies exhibit a similar structuralbimodality though offset from that of the spiral galaxies towards highersurface brightnesses. Both the early- and late-type structural bimodalities areuncorrelated with colour or any other structural parameter except, possibly,circular velocity. The structural bimodality may be linked to dynamicalproperties of galaxies. Low angular momentum systems may collapse to formdynamically important disks with high surface brightness, while high angularmomentum systems would end up as low surface brightness galaxies dominated bythe dark halo at all radii. The confirmation of structural bimodality forgas-rich and gas-poor galaxies in the high-density Virgo cluster as well as thelow-density UMa cluster suggests that this phenomenon is independent ofenvironment.



Autor: Michael McDonald, Stephane Courteau, R. Brent Tully

Fuente: https://arxiv.org/







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