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Calcium-rich gap transients in the remote outskirts of galaxies

Kasliwal, Mansi M. and Kulkarni, S. R. and Bhalerao, Varun B. and Horesh, Assaf and Quimby, Robert M. (2012) Calcium-rich gap transients in the remote outskirts of galaxies. Astrophysical Journal, 755 (2). Art. No. 161. ISSN 0004-637X. doi:10.1088/0004-637X/755/2/161.

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From the first two seasons of the Palomar Transient Factory, we identify three peculiar transients (PTF09dav, PTF10iuv, PTF11bij) with five distinguishing characteristics: peak luminosity in the gap between novae and supernovae (M_R ≈ - 15.5 to -16.5), rapid photometric evolution (t_(rise) ≈12-15 days), large photospheric velocities (≈6000 to 11000 km s^(-1)), early spectroscopic evolution into nebular phase (≈1 to 3 months) and peculiar nebular spectra dominated by Calcium. We also culled the extensive decade-long Lick Observatory Supernova Search database and identified an additional member of this group, SN 2007ke. Our choice of photometric and spectroscopic properties was motivated by SN 2005E (Perets et al. 2010). To our surprise, as in the case of SN 2005E, all four members of this group are also clearly offset from the bulk of their host galaxy. Given the well-sampled early and late-time light curves, we derive ejecta masses in the range of 0.4--0.7 M_⊙. Spectroscopically, we find that there may be a diversity in the photospheric phase, but the commonality is in the unusual nebular spectra. Our extensive follow-up observations rule out standard thermonuclear and standard core-collapse explosions for this class of "Calcium-rich gap" transients. If the progenitor is a white dwarf, we are likely seeing a detonation of the white dwarf core and perhaps, even shock-front interaction with a previously ejected nova shell. In the less likely scenario of a massive star progenitor, a very non-standard channel specific to a low-metallicity environment needs to be invoked (e.g., ejecta fallback leading to black hole formation). Detection (or lack thereof) of a faint underlying host (dwarf galaxy, cluster) will provide a crucial and decisive diagnostic to choose between these alternatives.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kasliwal, Mansi M.0000-0002-5619-4938
Kulkarni, S. R.0000-0001-5390-8563
Bhalerao, Varun B.0000-0002-6112-7609
Horesh, Assaf0000-0002-5936-1156
Quimby, Robert M.0000-0001-9171-5236
Additional Information:© 2012 American Astronomical Society. Received 2011 November 28; accepted 2012 June 19; published 2012 August 7. We thank Chuck Steidel and Ryan Trainor for target of opportunity observations of PTF 11bij with Keck I. We are grateful to the staff of the Expanded Very Large Array for efficiently executing target of opportunity triggers. Excellent assistance was provided by the staffs of the various observatories where we obtained data (Lick, Keck, Palomar, WHT, and EVLA). M.M.K. acknowledges support from the Hubble Fellowship and Carnegie-Princeton Fellowship. E.O.O. is supported by an Einstein Fellowship. H.B.P. is a CfA and Bikura prize fellow. The Weizmann Institute’s participation in PTF is supported by grants to AGY from the Israel Science Foundation, the US-Israel Binational Science Foundation and the Minerva/ARCHES Prize. A.V.F. and his group at UC Berkeley acknowledge generous financial assistance from Gary and Cynthia Bengier, the Richard and Rhoda Goldman Fund, the TABASGO Foundation, and National Science Foundation (NSF) grant AST-0908886. KAIT was constructed and supported by donations from Sun Microsystems, Inc., the Hewlett-Packard Company, AutoScope Corporation, Lick Observatory, the NSF, the University of California, the Sylvia and Jim Katzman Foundation, and the TABASGO Foundation. Computational resources and data storage were contributed by NERSC, supported by U.S, DOE contract DE-AC02-05CH11231. P.E.N. acknowledges support from the U.S. DOE contract DE-FG02-06ER06-04. J.S.B. acknowledges support of an NSF-CDI grant 0941742, “Real-time Classification of Massive Time-series Data Streams.” M.S. acknowledges support from the Royal Society. L.B. acknowledges NSF grants PHY-11-25915 and AST-11-09174. D.C.L. acknowledges NSF grant AST-1009571. Some of the data presented herein 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; it was made possible by the generous financial support of the W. M. Keck Foundation. The Expanded Very Large Array is operated by the National Radio Astronomy Observatory, a facility of the NSF operated under cooperative agreement by Associated Universities, Inc. The WHT is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. All spectra are available in digital form at WISEREP (Yaron & Gal-Yam 2012;
Group:Space Radiation Laboratory, Palomar Transient Factory
Funding AgencyGrant Number
Hubble FellowshipUNSPECIFIED
Carnegie-Princeton FellowshipUNSPECIFIED
Einstein FellowshipUNSPECIFIED
Israeli Science FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
Gary and Cynthia BengierUNSPECIFIED
Richard and Rhoda Goldman FundUNSPECIFIED
Sun Microsystems, Inc.UNSPECIFIED
Hewlett-Packard CompanyUNSPECIFIED
AutoScope CorporationUNSPECIFIED
Lick ObservatoryUNSPECIFIED
Sylvia and Jim Katzman FoundationUNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
Department of Energy (DOE)DE-FG02-06ER06-04
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: clusters: general; Galaxy: halo; novae, cataclysmic variables; supernovae: individual (SN2005E, SN2007ke, PTF09dav, PTF10iuv, PTF11bij); surveys; white dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:20111216-133850759
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28493
Deposited By: Tony Diaz
Deposited On:13 Apr 2012 18:28
Last Modified:09 Nov 2021 16:57

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