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Title: Color Me Intrigued: the Discovery of iPTF 16fnm, a Supernova 2002cx-like Object

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 $$g_\mathrm{PTF}$$- and $$R_\mathrm{PTF}$$-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 $$M_{g_\mathrm{PTF}} = -15.09 \pm 0.17 \; \mathrm{mag}$$, making it the second least-luminous known type Ia SN. 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 spectra several months after peak. Spectroscopically, iPTF$$\,$$16fnm exhibits a striking resemblence to 2 other low-luminosity 02cx-like SNe: SNe 2007qd and 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 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 type Ia SNe. This selection function will be especially important in the spectroscopically incomplete Zwicky Transient Facility/Large Synoptic Survey Telescope era. We measure the relative rate of 02cx-like SNe to normal SNe Ia and find $$r_{N_{02cx}/N_{Ia}} = 25^{+75}_{-18.5}\%$$. Finally, we close by recommending that LSST periodically evaluate, and possibly update, its observing cadence to maximize transient science.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [6] ;  [2] ;  [7] ;  [8] ;  [4] ;  [9] ;  [10] ;  [4] ;  [4] ;  [6]
  1. Northwestern Univ., Evanston, IL (United States); Adler Planetarium, Chicago, IL (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States)
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  3. Univ. of Washington, Seattle, WA (United States)
  4. AlbaNova, Stockholm (Sweden)
  5. Weizmann Inst. of Science, Rehovot (Israel)
  6. California Inst. of Technology (CalTech), Pasadena, CA (United States
  7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  8. Univ. of Copenhagen (Denmark). The Niels Bohr Inst.; Liverpool John Moores Univ. (United Kingdom)
  9. San Diego State Univ., CA (United States)
  10. California Inst. of Technology (CalTech), La Canada Flintridge, CA (United States). Jet Propulsion Lab.
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 848; Journal Issue: 1; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
Country of Publication:
United States
OSTI Identifier: