Browsing by Author "Metzger, Brian D."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    SN 2019tsf: Evidence for Extended Hydrogen-poor CSM in the Three-peaked Light Curve of Stripped Envelope of a Type Ib Supernova
    (2025) Zenati, Yossef; Wang, Qinan; Bobrick, Alexey; DeMarchi, Lindsay; Glanz, Hila; Rozner, Mor; Jencson, Jacob E.; Rest, Armin; Metzger, Brian D.; Margutti, Raffaella; Gómez, Sebastián; Smith, Nathan; Toonen, Silvia; Bright, Joe S.; Norman, Colin; Foley, Ryan J.; Gagliano, Alexander; Krolik, Julian H.; Smartt, Stephen J.; Villar, Ashley V.; Narayan, Gautham; Fox, Ori; Auchettl, Katie; Brethauer, Daniel; Clocchiatti, Alejandro; Coelln, Sophie V.; Coppejans, Deanne L.; Dimitriadis, Georgios; Dorozsmai, Andris; Drout, Maria; Jacobson-Galan, Wynn; Gao, Bore; Ridden-Harper, Ryan; Kilpatrick, Charles Donald; Laskar, Tanmoy; Matthews, David; Smith, Ken W.; Stauffer, Candice McKenzie; Rest, Sofia; Stroh, Michael C.; Strolger, Louis-Gregory; Terreran, Giacomo; Pierel, Justin D. R.; Piro, Anthony L.
    We present multiband ATLAS and ZTF photometry for SN 2019tsf, a Type Ib stripped-envelope supernova (SESN). The slow spectral evolution could be associated with an uncommon explosion mechanism specific to this SN. Possible explanations include fallback accretion onto a compact remnant or a long-lived central engine, both of which could provide extended energy injection responsible for the late-time rebrightening and unusual spectral features. The rebrightening observations represent the latest photometric measurements of a multipeaked Type Ib SN. As late-time photometry and spectroscopy suggest no hydrogen, the potential circumstellar material (CSM) must be H-poor. The absence of a nebular phase and the lack of narrow emission lines in the late-time spectra (>142 days) of the SNe suggest that any CSM interaction is likely asymmetric and enveloped by the SN ejecta. However, an extended CSM structure is evident through a follow-up radio campaign with the Karl G. Jansky Very Large Array (VLA), indicating a source of bright optically thick radio emission at late times, which is highly unusual among H-poor SESNe. We attribute this phenomenology to an interaction of the supernova ejecta with asymmetric CSM, potentially disk-like, and we present several models that may explain the origin of this rare Type Ib supernova. We propose a warped disk model in which a tertiary companion—commonly present around massive stars—perturbs the progenitor's CSM, producing density enhancements that may explain the observed multipeaked SN 2019tsf light curve. This SN 2019tsf is a unique SN Type Ib among the recently discovered class of SNe that undergo mass transfer at the moment of explosion....
  • No Thumbnail Available
    Item
    The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star-Black Hole Merger GW190814
    (2021) Kilpatrick, Charles D.; Coulter, David A.; Arcavi, Iair; Brink, Thomas G.; Dimitriadis, Georgios; Filippenko, Alexei, V; Foley, Ryan J.; Howell, D. Andrew; Jones, David O.; Kasen, Daniel; Makler, Martin; Piro, Anthony L.; Rojas-Bravo, Cesar; Sand, David J.; Swift, Jonathan J.; Tucker, Douglas; Zheng, WeiKang; Allam, Sahar S.; Annis, James T.; Antilen, Juanita; Bachmann, Tristan G.; Bloom, Joshua S.; Bom, Clecio R.; Bostroem, K. Azalee; Brout, Dillon; Burke, Jamison; Butler, Robert E.; Butner, Melissa; Campillay, Abdo; Clever, Karoli E.; Conselice, Christopher J.; Cooke, Jeff; Dage, Kristen C.; de Carvalho, Reinaldo R.; de Jaeger, Thomas; Desai, Shantanu; Garcia, Alyssa; Garcia-Bellido, Juan; Gill, Mandeep S. S.; Girish, Nachiket; Hallakoun, Na'ama; Herner, Kenneth; Hiramatsu, Daichi; Holz, Daniel E.; Huber, Grace; Kawash, Adam M.; McCully, Curtis; Medallon, Sophia A.; Metzger, Brian D.; Modak, Shaunak; Morgan, Robert; Munoz, Ricardo R.; Munoz-Elgueta, Nahir; Murakami, Yukei S.; Felipe Olivares, E.; Palmese, Antonella; Patra, Kishore C.; Pereira, Maria E. S.; Pessi, Thallis L.; Pineda-Garcia, J.; Quirola-Vasquez, Jonathan; Ramirez-Ruiz, Enrico; Rembold, Sandro Barboza; Rest, Armin; Rodriguez, Osmar; Santana-Silva, Luidhy; Sherman, Nora F.; Siebert, Matthew R.; Smith, Carli; Smith, J. Allyn; Soares-Santos, Marcelle; Stacey, Holland; Stahl, Benjamin E.; Strader, Jay; Strasburger, Erika; Sunseri, James; Tinyanont, Samaporn; Tucker, Brad E.; Ulloa, Natalie; Valenti, Stefano; Vasylyev, Sergiy S.; Wiesner, Matthew P.; Zhang, Keto D.
    We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and Thacher Telescope of the LIGO/Virgo gravitational wave (GW) signal from the neutron star-black hole (NSBH) merger GW190814. We searched the GW190814 localization region (19 deg(2) for the 90th percentile best localization), covering a total of 51 deg(2) and 94.6% of the two-dimensional localization region. Analyzing the properties of 189 transients that we consider as candidate counterparts to the NSBH merger, including their localizations, discovery times from merger, optical spectra, likely host galaxy redshifts, and photometric evolution, we conclude that none of these objects are likely to be associated with GW190814. Based on this finding, we consider the likely optical properties of an electromagnetic counterpart to GW190814, including possible kilonovae and short gamma-ray burst afterglows. Using the joint limits from our follow-up imaging, we conclude that a counterpart with an r-band decline rate of 0.68 mag day(-1), similar to the kilonova AT 2017gfo, could peak at an absolute magnitude of at most -17.8 mag (50% confidence). Our data are not constraining for "red" kilonovae and rule out "blue" kilonovae with M > 0.5 M (circle dot) (30% confidence). We strongly rule out all known types of short gamma-ray burst afterglows with viewing angles <17 degrees assuming an initial jet opening angle of similar to 5.degrees 2 and explosion energies and circumburst densities similar to afterglows explored in the literature. Finally, we explore the possibility that GW190814 merged in the disk of an active galactic nucleus, of which we find four in the localization region, but we do not find any candidate counterparts among these sources.