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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.14437 |
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| _version_ | 1866917494422241280 |
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| author | Rojas-Bravo, César Sun, Ning-Chen Smith, Mathew Chen, Chun Chen, Xiaohan Niu, Zexi Wang, Anyu Wang, Zi-Yang Zhao, Yi-Han Liu, Jifeng |
| author_facet | Rojas-Bravo, César Sun, Ning-Chen Smith, Mathew Chen, Chun Chen, Xiaohan Niu, Zexi Wang, Anyu Wang, Zi-Yang Zhao, Yi-Han Liu, Jifeng |
| contents | Early-time flux excesses in Type Ia supernovae (SNe~Ia) offer a unique insight into their progenitor systems and explosion mechanisms. Although individual early-excess events and larger searches have been reported, demographic studies remain limited by sample size. We present a systematic search for early-time excess emission in a volume-limited sample ($z<0.06$) of SNe~Ia based on the Zwicky Transient Facility Data Release 2 (ZTF DR2). Using ZTF $g$- and $r$-band light curves, we identify candidates showing early-excesses shortly after the explosion time, and we apply conservative coverage and quality requirements to build reliable ``excess'' and ``no-excess'' bump and no-bump catalogs. From an initial sample of 1547 SNe~Ia, our final catalogs contain 42 early-excess and 110 no-excess events. We compare the two populations using SN and host environment parameters from ZTF DR2 and quantify the differences using two-sample statistical tests. We find the strongest differences are in SN light-curve properties: early-excess events have larger SALT2 stretch $x_1$ ($7.91σ$) and larger $r$-band secondary-maximum flux $\mathcal{F}_{r_2}$ ($6.25σ$), while differences in SALT2 color $c$ are weak ($0.57σ$). Early-excess events also favor bluer $(g-z)_{\rm local}$ ($3.41σ$) and lower $\log_{10} (M_*/M_\odot)_{\rm local}$ ($2.73σ$). Our results connect early excesses with SNe~Ia diversity, and motivate further analyses of upcoming larger samples. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_14437 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Not All Who Wander Are Lost: Early Excess Demographics in the Volume-limited ZTF DR2 SN Ia Sample Rojas-Bravo, César Sun, Ning-Chen Smith, Mathew Chen, Chun Chen, Xiaohan Niu, Zexi Wang, Anyu Wang, Zi-Yang Zhao, Yi-Han Liu, Jifeng High Energy Astrophysical Phenomena Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies Solar and Stellar Astrophysics Early-time flux excesses in Type Ia supernovae (SNe~Ia) offer a unique insight into their progenitor systems and explosion mechanisms. Although individual early-excess events and larger searches have been reported, demographic studies remain limited by sample size. We present a systematic search for early-time excess emission in a volume-limited sample ($z<0.06$) of SNe~Ia based on the Zwicky Transient Facility Data Release 2 (ZTF DR2). Using ZTF $g$- and $r$-band light curves, we identify candidates showing early-excesses shortly after the explosion time, and we apply conservative coverage and quality requirements to build reliable ``excess'' and ``no-excess'' bump and no-bump catalogs. From an initial sample of 1547 SNe~Ia, our final catalogs contain 42 early-excess and 110 no-excess events. We compare the two populations using SN and host environment parameters from ZTF DR2 and quantify the differences using two-sample statistical tests. We find the strongest differences are in SN light-curve properties: early-excess events have larger SALT2 stretch $x_1$ ($7.91σ$) and larger $r$-band secondary-maximum flux $\mathcal{F}_{r_2}$ ($6.25σ$), while differences in SALT2 color $c$ are weak ($0.57σ$). Early-excess events also favor bluer $(g-z)_{\rm local}$ ($3.41σ$) and lower $\log_{10} (M_*/M_\odot)_{\rm local}$ ($2.73σ$). Our results connect early excesses with SNe~Ia diversity, and motivate further analyses of upcoming larger samples. |
| title | Not All Who Wander Are Lost: Early Excess Demographics in the Volume-limited ZTF DR2 SN Ia Sample |
| topic | High Energy Astrophysical Phenomena Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2605.14437 |