Two New Calcium-rich Gap Transients in Group and Cluster Environments

Journal Article · Fri Feb 10 00:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/836/1/60· OSTI ID:22869393

Lunnan, R.; Kasliwal, M. M.; Cao, Y.; Kupfer, T.; Kulkarni, S. R. ^[1]; Hangard, L.; Fremling, C. ^[2]; Yaron, O.; Gal-Yam, A. ^[3]; Parrent, J. T.; Ben-Ami, S. ^[4]; McCully, C.; Howell, D. A. ^[5]; Mulchaey, J. S. ^[6]; Filippenko, A. V.; Nugent, P. E. ^[7]; Fruchter, A. S. ^[8]; Koda, J. ^[9]; Laher, R. ^[10]; others, and

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1. Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
2. Oskar Klein Centre, Physics Department, Stockholm University, SE-106 91 Stockholm (Sweden)
3. Benoziyo Center for Astrophysics and the Helen Kimmel Center for Planetary Science, Weizmann Institute of Science, 76100 Rehovot (Israel)
4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
5. Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States)
6. The Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States)
7. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
8. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
9. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)
10. Spitzer Science Center, California Institute of Technology, MS 314-6, Pasadena, CA 91125 (United States)

We present the Palomar Transient Factory discoveries and the photometric and spectroscopic observations of PTF11kmb and PTF12bho. We show that both transients have properties consistent with the class of calcium-rich gap transients, specifically lower peak luminosities and rapid evolution compared to ordinary supernovae, and a nebular spectrum dominated by [Ca ii] emission. A striking feature of both transients is their host environments: PTF12bho is an intracluster transient in the Coma Cluster, while PTF11kmb is located in a loose galaxy group, at a physical offset ∼150 kpc from the most likely host galaxy. Deep Subaru imaging of PTF12bho rules out an underlying host system to a limit of M{sub R}>−8.0 mag, while Hubble Space Telescope imaging of PTF11kmb reveals a marginal counterpart that, if real, could be either a background galaxy or a globular cluster. We show that the offset distribution of Ca-rich gap transients is significantly more extreme than that seen for SNe Ia or even short-hard gamma-ray bursts (sGRBs). Thus, if the offsets are caused by a kick, they require higher kick velocities and/or longer merger times than sGRBs. We also show that almost all Ca-rich transients found to date are in group and cluster environments with elliptical host galaxies, indicating a very old progenitor population; the remote locations could partially be explained by these environments having the largest fraction of stars in the intragroup/intracluster light following galaxy–galaxy interactions.

• OSTI ID: 22869393
• Journal Information: Astrophysical Journal, Vol. 836, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CALCIUM
COMPARATIVE EVALUATIONS
COSMIC GAMMA BURSTS
DISTRIBUTION
EMISSION
GALAXIES
LUMINOSITY
SPACE
SPECTRA
SUPERNOVAE
TELESCOPES