Color Me Intrigued: The Discovery of iPTF 16fnm, an SN 2002cx-like Object
Abstract
Modern wide-field, optical time-domain surveys must solve a basic optimization problem: maximize the number of transient discoveries or minimize the follow-up needed for the new discoveries. Here, we describe the Color Me Intrigued experiment, the first from the intermediate Palomar Transient Factory (iPTF) to search for transients simultaneously in the g PTF and R PTF bands. During the course of this experiment, we discovered iPTF 16fnm, a new member of the 02cx-like subclass of Type Ia supernovae (SNe). iPTF 16fnm peaked at {M}{g{PTF}}=-15.09+/- 0.17 {mag}, making it the second-least-luminous known SN Ia. iPTF 16fnm exhibits all the hallmarks of the 02cx-like class: (I) low luminosity at peak, (II) low ejecta velocities, and (III) a non-nebular spectrum several months after peak. Spectroscopically, iPTF 16fnm exhibits a striking resemblance to two other low-luminosity 02cx-like SNe: SN 2007qd and SN 2010ae. iPTF 16fnm and SN 2005hk decline at nearly the same rate, despite a 3 mag difference in brightness at peak. When considering the full subclass of 02cx-like SNe, we do not find evidence for a tight correlation between peak luminosity and decline rate in either the g‧ or r‧ band. We measure the relative rate of 02cx-like SNe to normal SNe Ia and find {r}{N02{cx}/{N}{Ia}}={33}-25+158 % . We further examine the g‧ - r‧ evolution of 02cx-like SNe and find that their unique color evolution can be used to separate them from 91bg-like and normal SNe Ia. This selection function will be especially important in the spectroscopically incomplete Zwicky Transient Facility/Large Synoptic Survey Telescope (LSST) era. Finally, we close by recommending that LSST periodically evaluate, and possibly update, its observing cadence to maximize transient science.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2017
- DOI:
- 10.3847/1538-4357/aa8c7e
- arXiv:
- arXiv:1703.07449
- Bibcode:
- 2017ApJ...848...59M
- Keywords:
-
- methods: observational;
- surveys;
- supernovae: general;
- supernovae: individual: SN 2002cx;
- SN 2005hk;
- iPTF 16fnm;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 13 pages, 8 figures, 3 table - submitted to ApJ