2006A&A...454..125E -
Astronomy and Astrophysics, volume 454, 125-135 (2006/7-4)
Timescales of merger, starburst and AGN activity in radio galaxy B2 0648+27.
EMONTS B.H.C., MORGANTI R., TADHUNTER C.N., HOLT J., OOSTERLOO T.A., VAN DER HULST J.M. and WILLS K.A.
Abstract (from CDS):
We use neutral hydrogen (HI) and optical spectroscopic observations to compare the timescales of a merger event, starburst episode and radio-AGN activity in the radio galaxy
B2 0648+27. We detect a large ring-like structure of HI in emission around the early-type host galaxy of
B2 0648+27 (M
HI=8.5x10
9M
☉, diameter=190kpc). We interpret this as the result of a major merger that occurred >1.5Gyr ago. From modelling optical long-slit spectra we find that a young stellar population of 0.3Gyr, indicative of a past starburst event, dominates the stellar light throughout the galaxy. The off-set in time between the merger event and the starburst activity in
B2 0648+27 suggests that the starburst was triggered in an advanced stage of the merger, which can be explained if the gas-rich progenitor galaxies contained a bulge. Although the exact age of the radio source remains uncertain, there appears to be a significant time-delay between the merger/starburst event and the current episode of radio-AGN activity. We also observe an outflow of emission-line gas in this system, which is likely related to superwinds driven by the stars that formed during the starburst event. We argue that the radio galaxy
B2 0648+27 is a link in the evolutionary sequence between Ultra-Luminous Infrared Galaxies (ULIRGs) and genuine early-type galaxies.
Abstract Copyright:
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Journal keyword(s):
galaxies: individual: B2 0648+27 - galaxies: interactions - galaxies: starburst - galaxies: active - galaxies: evolution - ISM: kinematics and dynamics
Nomenclature:
Table 1: [MOC2003] JHHMM+DDMM N=14 added.
CDS comments:
Paragraph 2 calibration star D191-B2B is G 191-B2B in Simbad.
Simbad objects:
25
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