Timescales of merger, starburst and AGN activity in radio galaxy B2 0648+27

B. H. C. Emonts, R. Morganti, C. N. Tadhunter, J. Holt, T. A. V Oosterloo, J. M. van der Hulst, K. A. Wills

Research output: Contribution to journalArticleAcademicpeer-review

49 Citations (Scopus)
175 Downloads (Pure)

Abstract

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 = 8.5 x 10(9) M-circle dot, diameter = 190 kpc). We interpret this as the result of a major merger that occurred greater than or similar to 1.5 Gyr ago. From modelling optical long-slit spectra we find that a young stellar population of 0.3 Gyr, 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.

Original languageEnglish
Pages (from-to)125-135
Number of pages11
JournalAstronomy and astrophysics
Volume454
Issue number1
DOIs
Publication statusPublished - Jul-2006

Keywords

  • galaxies : individual : B2 0648+27
  • galaxies : interactions
  • galaxies : starburst
  • galaxies : active
  • galaxies : evolution
  • ISM : kinematics and dynamics
  • H-I
  • STELLAR POPULATIONS
  • GALACTIC NUCLEI
  • HOST GALAXIES
  • BLACK-HOLES
  • INFRARED GALAXIES
  • ELLIPTIC GALAXIES
  • COMPLETE SAMPLE
  • MAJOR MERGERS
  • MOLECULAR GAS

Cite this