_version_ 1866911185002037248
author Terwel, Jacco H.
Maguire, Kate
Brennan, Seán J.
Galbany, Lluís
Reusch, Simeon
Schulze, Steve
Koivisto, Niilo
Pursimo, Tapio
Sørensen, Samuel Grund
Teodori, María Alejandra Díaz
Theil, Astrid Guldberg
Turkki, Mikael
Müller-Bravo, Tomás E.
Burgaz, Umut
Kim, Young-Lo
Bloom, Joshua S.
Graham, Matthew J.
Kasliwal, Mansi M.
Kulkarni, Shri R.
Masci, Frank J.
Purdum, Josiah
Pyshna, Oleksandra
Wold, Avery
author_facet Terwel, Jacco H.
Maguire, Kate
Brennan, Seán J.
Galbany, Lluís
Reusch, Simeon
Schulze, Steve
Koivisto, Niilo
Pursimo, Tapio
Sørensen, Samuel Grund
Teodori, María Alejandra Díaz
Theil, Astrid Guldberg
Turkki, Mikael
Müller-Bravo, Tomás E.
Burgaz, Umut
Kim, Young-Lo
Bloom, Joshua S.
Graham, Matthew J.
Kasliwal, Mansi M.
Kulkarni, Shri R.
Masci, Frank J.
Purdum, Josiah
Pyshna, Oleksandra
Wold, Avery
contents The nature of Type Ia supernova (SN Ia) progenitor systems and the mechanisms that lead up to their explosions are still widely debated. In rare cases the SN ejecta interact with circumstellar material (CSM) that was ejected from the progenitor system prior to the SN. The unknown distance between the CSM and SN explosion site makes it impossible to predict when the interaction will start. If the time between the SN and start of CSM interaction is of the order of months to years the SN has generally faded and is not actively followed up anymore, making it even more difficult to detect the interaction while it happens. Here we report on a real-time monitoring program which ran between 13-11-2023 and 09-07-2024, monitoring 6914 SNe Ia for signs of late-time rebrightening using the Zwicky Transient Facility (ZTF). Flagged candidates were rapidly followed up with photometry and spectroscopy to confirm the late-time excess and its position. We report the discovery of a $\sim50$ day rebrightening event in SN 2020qxz around 1200 days after the peak of its light curve. SN 2020qxz had signs of early CSM interaction but faded from view over 2 years before its reappearance. Follow-up spectroscopy revealed 4 emission lines that faded shortly after the end of the ZTF detected rebrightening. Our best match for these emission lines are H$β$ (blue shifted by $\sim5900$ km s$^{-1}$) and CaII$_{\lambda8542}$, NI$_{\lambda8567}$, and KI$_{λλ8763, 8767}$, all blue shifted by 5100 km s$^{-1}$ (although we note that these identifications are uncertain). This shows that catching and following up on late-time interactions as they occur can give new clues about the nature of the progenitor systems that produce these SNe by putting constraints on the possible type of donor star, and the only way to do this systematically is to use large sky surveys such as ZTF to monitor a large sample of objects.
format Preprint
id arxiv_https___arxiv_org_abs_2508_04782
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A real-time search for Type Ia Supernovae with late-time CSM interaction in ZTF
Terwel, Jacco H.
Maguire, Kate
Brennan, Seán J.
Galbany, Lluís
Reusch, Simeon
Schulze, Steve
Koivisto, Niilo
Pursimo, Tapio
Sørensen, Samuel Grund
Teodori, María Alejandra Díaz
Theil, Astrid Guldberg
Turkki, Mikael
Müller-Bravo, Tomás E.
Burgaz, Umut
Kim, Young-Lo
Bloom, Joshua S.
Graham, Matthew J.
Kasliwal, Mansi M.
Kulkarni, Shri R.
Masci, Frank J.
Purdum, Josiah
Pyshna, Oleksandra
Wold, Avery
High Energy Astrophysical Phenomena
The nature of Type Ia supernova (SN Ia) progenitor systems and the mechanisms that lead up to their explosions are still widely debated. In rare cases the SN ejecta interact with circumstellar material (CSM) that was ejected from the progenitor system prior to the SN. The unknown distance between the CSM and SN explosion site makes it impossible to predict when the interaction will start. If the time between the SN and start of CSM interaction is of the order of months to years the SN has generally faded and is not actively followed up anymore, making it even more difficult to detect the interaction while it happens. Here we report on a real-time monitoring program which ran between 13-11-2023 and 09-07-2024, monitoring 6914 SNe Ia for signs of late-time rebrightening using the Zwicky Transient Facility (ZTF). Flagged candidates were rapidly followed up with photometry and spectroscopy to confirm the late-time excess and its position. We report the discovery of a $\sim50$ day rebrightening event in SN 2020qxz around 1200 days after the peak of its light curve. SN 2020qxz had signs of early CSM interaction but faded from view over 2 years before its reappearance. Follow-up spectroscopy revealed 4 emission lines that faded shortly after the end of the ZTF detected rebrightening. Our best match for these emission lines are H$β$ (blue shifted by $\sim5900$ km s$^{-1}$) and CaII$_{\lambda8542}$, NI$_{\lambda8567}$, and KI$_{λλ8763, 8767}$, all blue shifted by 5100 km s$^{-1}$ (although we note that these identifications are uncertain). This shows that catching and following up on late-time interactions as they occur can give new clues about the nature of the progenitor systems that produce these SNe by putting constraints on the possible type of donor star, and the only way to do this systematically is to use large sky surveys such as ZTF to monitor a large sample of objects.
title A real-time search for Type Ia Supernovae with late-time CSM interaction in ZTF
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2508.04782