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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2506.10700 |
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| _version_ | 1866911143720648704 |
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| author | Gangopadhyay, Anjasha Sollerman, Jesper Tsalapatas, Konstantinos Maeda, Keiichi Dukiya, Naveen Schulze, Steve Fransson, Claes Sarin, Nikhil Pessi, Priscila J. Singh, Mridweeka Wise, Jacob Nakaoka, Tatsuya Singh, Avinash Dastidar, Raya Kawabata, Miho Qing, Yu-Jing Das, Kaustav K. Perley, Daniel Fremling, Christoffer Taguchi, Kenta Hinds, K-Ryan Lunnan, Ragnhild Teja, Rishabh Singh Dubey, Monalisa Ailawadhi, Bhavya Banerjee, Smaranika Kawabata, Koji S Misra, Kuntal Sahu, Devendra K Brennan, Sean J. Kasliwal, Mansi M. Ho, Anna Y. C. Q Bochenek, Aleksandra Rusholme, Ben Laher, Russ R. Smith, Roger Purdum, Josiah Sravan, Niharika |
| author_facet | Gangopadhyay, Anjasha Sollerman, Jesper Tsalapatas, Konstantinos Maeda, Keiichi Dukiya, Naveen Schulze, Steve Fransson, Claes Sarin, Nikhil Pessi, Priscila J. Singh, Mridweeka Wise, Jacob Nakaoka, Tatsuya Singh, Avinash Dastidar, Raya Kawabata, Miho Qing, Yu-Jing Das, Kaustav K. Perley, Daniel Fremling, Christoffer Taguchi, Kenta Hinds, K-Ryan Lunnan, Ragnhild Teja, Rishabh Singh Dubey, Monalisa Ailawadhi, Bhavya Banerjee, Smaranika Kawabata, Koji S Misra, Kuntal Sahu, Devendra K Brennan, Sean J. Kasliwal, Mansi M. Ho, Anna Y. C. Q Bochenek, Aleksandra Rusholme, Ben Laher, Russ R. Smith, Roger Purdum, Josiah Sravan, Niharika |
| contents | We present observations of SN~2023xgo, a transitional Type Ibn/Icn supernova, from $-5.6$ to $+63$~days relative to the $r$-band peak. Early spectra show C~III $λ5696$ emission reminiscent of Type~Icn SNe, which later gives way to Type~Ibn features. The He~I velocities ($1800$--$10{,}000$~km~s$^{-1}$) and pseudo-equivalent widths are among the highest in the Ibn/Icn class. The light curve declines at $0.14$~mag~d$^{-1}$ until $+30$~days, consistent with SNe~Ibn/Icn and slower than fast transients. SN~2023xgo is the faintest in our SN~Ibn sample ($M_r=-17.65\pm0.04$) but shows typical color and host properties. Semi-analytical modeling of the light curve suggests a compact CSM shell ($\sim 10^{12}$--$10^{13}$~cm) and a mass-loss rate of $10^{-4}$--$10^{-3}$~$M_{\odot}$~yr$^{-1}$, with CSM and ejecta masses of $\sim 0.22$ and $0.12$~$M_{\odot}$, respectively. Post-maximum light-curve and spectral modeling favor a $\sim 3$~$M_{\odot}$ helium-star progenitor with extended ($\sim 10^{15}$~cm), stratified CSM (density exponent $n=2.9$) and a mass-loss rate of $0.1$--$2.7$~$M_{\odot}$~yr$^{-1}$. These two mass-loss regimes imply a radially varying CSM, shaped by asymmetry or temporal changes in the progenitor's mass loss. This behavior is compatible with both binary and single-star evolution. We argue that the early Icn-like features arise from hot carbon ionization and fade to Ibn-like signatures as the ejecta and CSM cool, making SN~2023xgo a rare probe of the connection between SNe~Icn, SNe~Ibn, and Ibn events with ejecta signatures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_10700 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | SN 2023xgo: Helium-rich Type Icn or Carbon-Flash Type Ibn supernova? Gangopadhyay, Anjasha Sollerman, Jesper Tsalapatas, Konstantinos Maeda, Keiichi Dukiya, Naveen Schulze, Steve Fransson, Claes Sarin, Nikhil Pessi, Priscila J. Singh, Mridweeka Wise, Jacob Nakaoka, Tatsuya Singh, Avinash Dastidar, Raya Kawabata, Miho Qing, Yu-Jing Das, Kaustav K. Perley, Daniel Fremling, Christoffer Taguchi, Kenta Hinds, K-Ryan Lunnan, Ragnhild Teja, Rishabh Singh Dubey, Monalisa Ailawadhi, Bhavya Banerjee, Smaranika Kawabata, Koji S Misra, Kuntal Sahu, Devendra K Brennan, Sean J. Kasliwal, Mansi M. Ho, Anna Y. C. Q Bochenek, Aleksandra Rusholme, Ben Laher, Russ R. Smith, Roger Purdum, Josiah Sravan, Niharika High Energy Astrophysical Phenomena We present observations of SN~2023xgo, a transitional Type Ibn/Icn supernova, from $-5.6$ to $+63$~days relative to the $r$-band peak. Early spectra show C~III $λ5696$ emission reminiscent of Type~Icn SNe, which later gives way to Type~Ibn features. The He~I velocities ($1800$--$10{,}000$~km~s$^{-1}$) and pseudo-equivalent widths are among the highest in the Ibn/Icn class. The light curve declines at $0.14$~mag~d$^{-1}$ until $+30$~days, consistent with SNe~Ibn/Icn and slower than fast transients. SN~2023xgo is the faintest in our SN~Ibn sample ($M_r=-17.65\pm0.04$) but shows typical color and host properties. Semi-analytical modeling of the light curve suggests a compact CSM shell ($\sim 10^{12}$--$10^{13}$~cm) and a mass-loss rate of $10^{-4}$--$10^{-3}$~$M_{\odot}$~yr$^{-1}$, with CSM and ejecta masses of $\sim 0.22$ and $0.12$~$M_{\odot}$, respectively. Post-maximum light-curve and spectral modeling favor a $\sim 3$~$M_{\odot}$ helium-star progenitor with extended ($\sim 10^{15}$~cm), stratified CSM (density exponent $n=2.9$) and a mass-loss rate of $0.1$--$2.7$~$M_{\odot}$~yr$^{-1}$. These two mass-loss regimes imply a radially varying CSM, shaped by asymmetry or temporal changes in the progenitor's mass loss. This behavior is compatible with both binary and single-star evolution. We argue that the early Icn-like features arise from hot carbon ionization and fade to Ibn-like signatures as the ejecta and CSM cool, making SN~2023xgo a rare probe of the connection between SNe~Icn, SNe~Ibn, and Ibn events with ejecta signatures. |
| title | SN 2023xgo: Helium-rich Type Icn or Carbon-Flash Type Ibn supernova? |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2506.10700 |