Difference: TransientWGSedM (1 vs. 12)

Lead: Yi Yang, Steve Schulze, Avishay Gal-Yam

[Abstract]: The dawn of deep, high-cadence, wide-field surveys opens up the opportunity to study one of the final frontiers in supernova (SN) science: the first hours after the single star or binary system exploded. The early evolution is highly sensitive to circumstellar material in the proximity of the SN progenitor (pCSM), the elusive final evolutionary history of progenitor just before the explosion, and how the star exploded. After a few days, these signatures get wiped out by the expanding SN ejecta (Gal-Yam, et al. 2014; Yaron, et al. 2017). The high-cadence experiment of the Zwicky Transient Facility (ZTF) plays a distinct role in this frontier field. ZTF can detect one-day old SNe every week. Such infant SNe can be identified based on their rise time of a few tenths of a mag every 3-4 hours, faster than most known transients. However, spectroscopic observations are needed to confirm candidates and secure spectroscopic information of this elusive phase. We propose to secure spectroscopy and photometry of up to ~53 infant SNe with SEDM during the first six months of ZTF. These data will allow us to answer key questions not only why but also how stars explode as SNe.

[File]: https://www.dropbox.com/s/gtidp6bmc7jom3b/Weizmann-Infant_SNe.pdf?dl=0

https://www.dropbox.com/s/wmmsf81xyx5g6n5/whitepaperSEDmIbc_2nofigures.pdf?dl=0

and here the same text with additional with figures (4.5 pages): https://www.dropbox.com/s/4q4cnungm2ql14m/whitepaperSEDmIbc_2.pdf?dl=0

Lead: S. Kulkarni

[Abstract]. We propose a flux limited transient survey based on the MSIP all sky survey. The standard in this field is set by ASAS-SN (T. Holoien, PhD thesis; OSU; several papers by T. Holoien) which is, contrary to the claims, complete to less than 17 mag. The experimental goal of the proposed ZTF project is to classify transients (which are mostly SN) to a peak flux, m_p of about 18 mag. In practice, this means classifying transients which are a few tenths mag fainter. Flux limited surveys serve many purposes such as rates. We have a specific novel goal: use SN of type Ia to evaluate the red-shift completeness factor (RCF) of catalog(s) of nearby (<200 Mpc). In anticipation of this project we undertook analysis of the ASAS-SN flux limited samples for 2014 and 2015 (Kulkarni, Perley & Miller 2017: http://adsabs.harvard.edu/abs/2017arXiv171004223K). The "missing fraction" is 70% (to within binomial errors). We present a histogram of "missing galaxies" ordered by mass (K-band) and star-formation rate (UV/NUV). The expected improvement in the precision of RCF and other returns from this survey can be found in this paper also.

We aim to seek contribution of SEDM time from the Caltech TAC. It is our intention to rapidly release the classifications to the community (via ATEL). This is a large project with significant combined SEDM time (in the vicinity of 40%). The project is envisaged to include members from partnership and also astronomers not within the partnership (members of the Caltech proposal. We are developing a detailed management & publication plan. We hope to post a full 2-page proposal in about a week's time.

Lead: S. Kulkarni, B. Cenko, A. Ho, D. Perley, A. Miller

During ZTF, we plan to use SEDM as part of our procedure for filtering out false positives in the search for afterglows to relativistic explosions. In our iPTF archival search, we found a ratio of GRB afterglows to false positives (M-dwarf flares) of roughly 1/10. In all cases, the M dwarf could be identified from its red counterpart in WISE and PanSTARRS. During ZTF, we expect 1-3 events per month and 3-4 triggers per object and will refine our criteria as we develop experience during the survey.

1) SED machine to observe stripped-envelope supernovae from ZTF

Lead: J. Sollerman, F. Taddia, C. Barbarino, L. Tartaglia.

We want to study stripped-envelope supernovae (SE SNe) to understand their properties and therefore their progenitors. Following the approach we adopted in iPTF, we will study single interesting events, in particular nearby and very young supernovae, as well as large samples of SE SNe discovered before peak. The SED machine can be used for both of these studies starting from the first 6 months of ZTF observations between January and June 2018.

For nearby (associated to hosts at < 80 Mpc), very young (same night or night before) SE SNe we want to acquire early SED spectra to secure the information about the early color evolution and the composition of the external layers. Like in the cases of iPTF13bvn and iPTF15dtg, a very early spectrum would be crucial to constrain the progenitor radius, the Ni mixing and/or the presence of a powering magnetar or the interaction with a companion star.

For all the SE SNe discovered before peak, which we want to follow-up to build a large sample, the SED machine will be useful to secure at least a classification spectrum around peak, which will allow us to reach a good degree of completeness for our SE SN samples.

In about 8 years PTF found about 100 SNe Ib,Ic and Ic-BL caught before peak. If we assume that ZTF will be 10 times more efficient, during the first 6 month ZTF will find about 60 SE SNe to follow up. Based on the iPTF results, about 20 of these SNe will have peak magnitude brighter than 19 mag and can be observed with the SEDm to obtain a good spectrum around peak. About 3 objects will be brighter than 17 mag at peak (these are the SNe within 80 Mpc, assuming average peak magnitude -17.5) and can be studied also at very early epochs (when they are at at least 19 mag, i.e. at least 2 mag below peak). Since we require S/N>=10 around the central part of the spectrum, and most of the SNe will be between 18 and 19 mag at peak, about 23 hrs of SED machine observations (1 hr per spectrum) will be enough to secure the spectra we need for this project.