Examinando por Autor "Chandra, Poonam"

Mostrando 1 - 2 de 2
  • No hay miniatura disponible
    Ítem
    A Multiwavelength View of the Rapidly Evolving SN 2018ivc: An Analog of SN IIb 1993J but Powered Primarily by Circumstellar Interaction
    (Institute of Physics, 2023-01-01) Maeda, Keiichi; Chandra, Poonam; Moriya, Takashi J.; Reguitti, Andrea; Ryder, Stuart; Matsuoka, Tomoki; Michiyama, Tomonari; Pignata, Giuliano; Hiramatsu, Daichi; Bostroem, K. Azalee; Kundu, Esha; Kuncarayakti, Hanindyo; Bersten, Melina C.; Pooley, David; Lee, Shiu-Hang; Patnaude, Daniel; Rodríguez, Ósmar; Folatelli, Gaston
    SN 2018ivc is an unusual Type II supernova (SN II). It is a variant of SNe IIL, which might represent a transitional case between SNe IIP with a massive H-rich envelope and SNe IIb with only a small amount of the H-rich envelope. However, SN 2018ivc shows an optical light-curve evolution more complicated than that of canonical SNe IIL. In this paper, we present the results of prompt follow-up observations of SN 2018ivc with the Atacama Large Millimeter/submillimeter Array. Its synchrotron emission is similar to that of SN IIb 1993J, suggesting that it is intrinsically an SN IIb-like explosion of an He star with a modest (∼0.5-1M ⊙) extended H-rich envelope. Its radio, optical, and X-ray light curves are explained primarily by the interaction between the SN ejecta and the circumstellar material (CSM); we thus suggest that it is a rare example (and the first involving the “canonical” SN IIb ejecta) for which the multiwavelength emission is powered mainly by the SN-CSM interaction. The inner CSM density, reflecting the progenitor activity in the final decade, is comparable to that of SN IIb 2013cu, which shows a flash spectral feature. The outer CSM density, and therefore the mass-loss rate in the final ∼200 yr, is higher than that of SN 1993J by a factor of ∼5. We suggest that SN 2018ivc represents a missing link between SNe IIP and SNe IIb/Ib/Ic in the binary evolution scenario. © 2022. The Author(s). Published by the American Astronomical Society.
  • No hay miniatura disponible
    Ítem
    Bridging between Type IIb and Ib Supernovae: SN IIb 2022crv with a Very Thin Hydrogen Envelope
    (Institute of Physics, 2023-11) Gangopadhyay, Anjasha; Maeda, Keiichi; Singh, Avinash; Nayana A.J.; Nakaoka, Tatsuya; Kawabata, Koji S.; Taguchi, Kenta; Singh, Mridweeka; Chandra, Poonam; Ryder, Stuart D.; Dastidar, Raya; Yamanaka, Masayuki; Kawabata, Miho; Alsaberi, Rami Z. E.; Dukiya, Naveen; Teja, Rishabh Singh; Ailawadhi, Bhavya; Dutta, Anirban; Sahu, D.K.; Moriya, Takashi J.; Misra, Kuntal; Tanaka, Masaomi; Chevalier, Roger; Tominaga, Nozomu; Uno, Kohki; Imazawa, Ryo; Hamada, Taisei; Hori, Tomoya; Isogai, Keisuke
    We present optical, near-infrared, and radio observations of supernova (SN) SN IIb 2022crv. We show that it retained a very thin H envelope and transitioned from an SN IIb to an SN Ib; prominent Hα seen in the pre-maximum phase diminishes toward the post-maximum phase, while He i lines show increasing strength. SYNAPPS modeling of the early spectra of SN 2022crv suggests that the absorption feature at 6200 Å is explained by a substantial contribution of Hα together with Si ii, as is also supported by the velocity evolution of Hα. The light-curve evolution is consistent with the canonical stripped-envelope SN subclass but among the slowest. The light curve lacks the initial cooling phase and shows a bright main peak (peak M V = −17.82 ± 0.17 mag), mostly driven by radioactive decay of 56Ni. The light-curve analysis suggests a thin outer H envelope (M env ∼ 0.05 M ⊙) and a compact progenitor (R env ∼ 3 R ⊙). An interaction-powered synchrotron self-absorption model can reproduce the radio light curves with a mean shock velocity of 0.1c. The mass-loss rate is estimated to be in the range of (1.9−2.8) × 10−5 M ⊙ yr−1 for an assumed wind velocity of 1000 km s−1, which is on the high end in comparison with other compact SNe IIb/Ib. SN 2022crv fills a previously unoccupied parameter space of a very compact progenitor, representing a beautiful continuity between the compact and extended progenitor scenario of SNe IIb/Ib.