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Journal article
Multi-Wavelength Analysis of AT 2023sva: a Luminous Orphan Afterglow With Evidence for a Structured Jet
Monthly notices of the Royal Astronomical Society, v 538(1), pp 351-372
18 Feb 2025
Abstract
We present multi-wavelength analysis of ZTF23abelseb (AT 2023sva), an optically discovered fast-fading (Δmr = 2.2 mag in Δt = 0.74 days), luminous (Mr ∼ −30.0 mag) and red (g − r = 0.50 mag) transient at z = 2.28 with accompanying luminous radio emission. AT 2023sva does not possess a γ-ray burst (GRB) counterpart to an isotropic equivalent energy limit of Eγ, iso < 1.6 × 1052 erg, determined through searching γ-ray satellite archives between the last non-detection and first detection, making it the sixth example of an optically-discovered afterglow with a redshift measurement and no detected GRB counterpart. We analyze AT 2023sva’s optical, radio, and X-ray observations to characterize the source. From radio analyses, we find the clear presence of strong interstellar scintillation (ISS) 72 days after the initial explosion, allowing us to place constraints on the source’s angular size and bulk Lorentz factor. When comparing the source sizes derived from ISS of orphan events to those of the classical GRB population, we find orphan events have statistically smaller source sizes. We also utilize Bayesian techniques to model the multi-wavelength afterglow. Within this framework, we find evidence that AT 2023sva possesses a shallow power-law structured jet viewed slightly off-axis (θv = 0.07 ± 0.02) just outside of the jet’s core opening angle (θc = 0.06 ± 0.02). We determine this is likely the reason for the lack of a detected GRB counterpart, but also investigate other scenarios. AT 2023sva’s evidence for possessing a structured jet stresses the importance of broadening orphan afterglow search strategies to a diverse range of GRB jet angular energy profiles, to maximize the return of future optical surveys.
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Details
- Title
- Multi-Wavelength Analysis of AT 2023sva: a Luminous Orphan Afterglow With Evidence for a Structured Jet
- Creators
- Gokul P Srinivasaragavan (Corresponding Author) - University of Maryland, College ParkDaniel A Perley - Liverpool John Moores UniversityAnna Y Q Ho - Cornell UniversityBrendan O’Connor - Carnegie Mellon UniversityAntonio de Ugarte PostigoNikhil Sarin - Stockholm UniversityS Bradley Cenko - Joint Space Science InstituteJesper Sollerman - Stockholm UniversityLauren Rhodes - Space Science InstituteDavid A GreenDmitry S Svinkin - Ioffe InstituteVarun Bhalerao - Indian Institute of Technology BombayGaurav Waratkar - Indian Institute of Technology BombayA J Nayana - National Centre for Radio AstrophysicsPoonam Chandra - National Centre for Radio AstrophysicsM Coleman Miller - University of Maryland, College ParkDaniele B Malesani - DAWN Center for Independent LivingGeoffrey Ryan - Perimeter InstituteSuryansh Srijan - Indian Institute of Technology BombayEric C Bellm - University of WashingtonEric Burns - Louisiana State UniversityDavid J TitteringtonMaria B Stone - University of TurkuJosiah Purdum - California Institute of TechnologyTomás Ahumada - California Institute of TechnologyG C Anupama - Indian Institute of AstrophysicsSudhanshu Barway - Indian Institute of AstrophysicsMichael W Coughlin - University of MinnesotaAndrew Drake - California Institute of TechnologyRob Fender - University of OxfordJosé F Agüí Fernández - Calar Alto ObservatoryDmitry D Frederiks - Ioffe InstituteStefan Geier - Gran Telescopio CanariasMatthew J Graham - California Institute of TechnologyMansi M Kasliwal - California Institute of TechnologyS R Kulkarni - California Institute of TechnologyHarsh Kumar - Center for Astrophysics Harvard & SmithsonianMaggie L Li - California Institute of TechnologyRuss R Laher - Infrared Processing and Analysis CenterAlexandra L Lysenko - Ioffe InstituteGopal Parwani - Indian Institute of Technology BombayRichard A Perley - National Radio Astronomy ObservatoryAnna V Ridnaia - Ioffe InstituteAnirudh Salgundi - Indian Institute of Technology BombayRoger Smith - California Institute of TechnologyNiharika Sravan - Drexel UniversityVishwajeet Swain - Indian Institute of Technology BombayChristina C Thöne - Czech Academy of Sciences, Astronomical InstituteAnastasia E Tsvetkova - Ioffe InstituteMikhail V Ulanov - Ioffe InstituteJada Vail - Cornell UniversityJacob L Wise - Liverpool John Moores UniversityAvery Wold - Infrared Processing and Analysis Center
- Publication Details
- Monthly notices of the Royal Astronomical Society, v 538(1), pp 351-372
- Publisher
- Oxford University Press
- Number of pages
- 22
- Grant note
- NASA: 80NSSC23K1155 NASA: PHY-2308862, PHY-2117997 National Science Foundation: 00231098 Finnish Cultural FoundationFinnish Centre for Astronomy with ESO (FINCA) grantIndian National Science AcademyINSA Senior Scientist ProgrammeDavid and Lucille Packard FoundationMcWilliams Postdoctoral Fellowship at Carnegie Mellon UniversityASI-INAF Accordo Attuativo HERMES
GPS thanks Isiah Holt for useful discussions on nested sampling techniques, Tony Piro for reading the paper on request, and Simi Bhullar for her moral support through out the paper-writing process. AYQH was supported in part by NASA grant number 80NSSC23K1155. MWC acknowledges support from the National Science Foundation with grant numbers PHY-2308862 and PHY-2117997. MBS acknowledges the Finnish Cultural Foundation grant number 00231098 and Finnish Centre for Astronomy with ESO (FINCA) grant. GCA thanks the Indian National Science Academy for support under the INSA Senior Scientist Programme. MMK acknowledges generous support from the David and Lucille Packard Foundation. BO is supported by the McWilliams Postdoctoral Fellowship at Carnegie Mellon University. AT acknowledges the financial support from 'ASI-INAF Accordo Attuativo HERMES Pathinder operazioni n.2022-25-HH.0'.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:001437680800001
- Scopus ID
- 2-s2.0-86000163710
- Other Identifier
- 991022028142804721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics