Minkowski's Object: A Starburst Triggered by a Radio Jet, Revisited

Creators: Croft, Steve; van Breugel, Wil; de Vries, Wim; Dopita, Mike; Martin, Chris; Morganti, Raffaella; Neff, Susan; Oosterloo, Tom; Schiminovich, David; Stanford, S. A.; Van Gorkom, Jacqueline

Abstract

We present neutral hydrogen, ultraviolet, optical, and near-infrared imaging, and optical spectroscopy, of Minkowski's Object (MO), a star-forming peculiar galaxy near NGC 541. The observations strengthen evidence that star formation in MO was triggered by the radio jet from NGC 541. Key new results are the discovery of a 4.9 × 10^8 M_⊙ double H I cloud straddling the radio jet downstream from MO, where the jet changes direction and decollimates; strong detections of MO, also showing double structure, in UV and Hα; and numerous H II regions and associated clusters in MO. In UV, MO resembles the radio-aligned, rest-frame UV morphologies in many high-redshift radio galaxies (HzRGs), also thought to be caused by jet-induced star formation. MO's stellar population is dominated by a 7.5 Myr old, 1.9 × 10^7 M_⊙ instantaneous burst, with a current star formation rate of 0.52 M_⊙ yr^(-1) (concentrated upstream from where the H I column density is high). This is unlike the jet-induced star formation in Centaurus A, where the jet interacts with preexisting cold gas; in MO, the H I may have cooled out of a warmer, clumpy intergalactic or interstellar medium as a result of jet interaction, followed by the collapse of the cooling clouds and subsequent star formation (consistent with numerical simulations). Since the radio source that triggered star formation in MO is much less luminous, and therefore more common than powerful HzRGs, and because the environment around MO is not particularly special in terms of abundant dense, cold gas, jet-induced star formation in the early universe might be even more prevalent than previously thought.

Additional Information

© 2006 The American Astronomical Society. Received 2006 February 4; accepted 2006 April 26. We thank the staff of the Lick and Siding Spring Observatories for their support. Thanks to Michael Gregg for providing us with Lick PFCam data. We thank the anonymous referee for helpful and constructive suggestions. Data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Work was also based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. GALEX (Galaxy Evolution Explorer) is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the CentreNational d'Etudes Spatiales of France and the Korean Ministry of Science and Technology. The National Radio AstronomyObservatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts. Dopita acknowledges the support of both the Australian National University and the Australian Research Council (ARC) through his ARC Australian Federation Fellowship, and financial support through ARC Discovery project grant DP0208445.Work was performed under the auspices of the US Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract W-7405-Eng-48. S. C. and W.v. B. acknowledge support for radio galaxy studies at the University of California, Merced, including the work reported here, with the Hubble, Spitzer and Chandra space telescopes via NASA grants HST 10127, SST 3482, SST 3329, and Chandra/CXO 06701011.

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