ORIGIN OF MULTIPLE NUCLEI IN ULTRALUMINOUS INFRARED GALAXIES

Journal Article · Fri Feb 10 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/746/1/26· OSTI ID:22011847

Matsui, Hidenori; Makino, Junichiro; Tomisaka, Kohji; Kokubo, Eiichiro ^[1]; Saitoh, Takayuki R ^[2]; Wada, Keiichi ^[3]; Daisaka, Hiroshi ^[4]; Okamoto, Takashi ^[5]; Yoshida, Naoki ^[6]

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1. Center for Computational Astrophysics, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
2. Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
3. Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan)
4. Graduate School of Commerce and Management, Hitotsubashi University, Naka 2-1 Kunitachi, Tokyo 186-8601 (Japan)
5. Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)
6. Institute for the Physics and Mathematics of the Universe, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

Ultraluminous infrared galaxies (ULIRGs) with multiple ({>=}3) nuclei are frequently observed. It has been suggested that these nuclei are produced by multiple major mergers of galaxies. The expected rate of such mergers is, however, too low to reproduce the observed number of ULIRGs with multiple nuclei. We have performed high-resolution simulations of the merging of two gas-rich disk galaxies. We found that extremely massive and compact star clusters form from the strongly disturbed gas disks after the first or second encounter between the galaxies. The mass of such clusters reaches {approx}10{sup 8} M{sub Sun} and their half-mass radii are 20-30 pc. Since these clusters consist of young stars, they appear as several bright cores in the galactic central region ({approx}kpc). The peak luminosity of these clusters reaches {approx}10% of the total luminosity of the merging galaxy. These massive and compact clusters are consistent with the characteristics of the observed multiple nuclei in ULIRGs. Multiple mergers are not necessary to explain multiple nuclei in ULIRGs.

• OSTI ID: 22011847
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 746; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPUTERIZED SIMULATION
GALACTIC EVOLUTION
GALAXIES
LUMINOSITY
STAR CLUSTERS
STARS