Examinando por Autor "Maeda, Keiichi"

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    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.
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    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.
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    DISAPPEARANCE OF THE PROGENITOR OF SUPERNOVA iPTF13bvn
    (IOP PUBLISHING, 2016-07) Folatelli, Gastón; Van Dyk, Schuyler D.; Kuncarayakti, Hanindyo; Maeda, Keiichi; Bersten, Melina C.; Nomoto, Ken'ichi; Pignata, Giuliano; Hamuy, Mario; Quimby, Robert M.; Zheng, WeiKang; Filippenko, Alexei V.; Clubb, Kelsey I.; Smith, Nathan; Elias-Rosa, Nancy; Foley, Ryan J.; Miller, Adam A.
    Supernova (SN) iPTF13bvn in NGC 5806 was the first Type Ib SN to have been tentatively associated with a progenitor in pre-explosion images. We performed deep ultraviolet (UV) and optical Hubble Space Telescope observations of the SN site similar to 740 days after explosion. We detect an object in the optical bands that is fainter than the pre-explosion object. This dimming is likely not produced by dust absorption in the ejecta; thus, our finding confirms the connection of the progenitor candidate with the SN. The object in our data is likely dominated by the fading SN, implying that the pre-SN flux is mostly due to the progenitor. We compare our revised pre-SN photometry with previously proposed models. Although binary progenitors are favored, models need to be refined. In particular, to comply with our deep UV detection limit, any companion star must be less luminous than a late-O star or substantially obscured by newly formed dust. A definitive progenitor characterization will require further observations to disentangle the contribution of a much fainter SN and its environment.
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    First Release of High-redshift Superluminous Supernovae from the Subaru HIgh-Z SUpernova CAmpaign (SHIZUCA). II. Spectroscopic Properties
    (Astrophysical Journal, Supplement Series, 2019-04) Curtin, Chris; Cooke, Jeff; Curtin, Chris; Cooke, Jeff; Moriya, Takashi J.; Tanaka, Masayuki; Quimby, Robert M.; Bernard, Stephanie R.; Galbany, Lluís; Jiang, Ji-an; Lee, Chien-Hsiu; Maeda, Keiichi; Morokuma, Tomoki; Nomoto, Ken’ichi; Pignata, Giuliano; Pritchard, Tyler; Suzuki, Nao; Takahashi, Ichiro; Tanaka, Masaomi; Tominaga, Nozomu; Yamaguchi, Masaki; Yasuda, Naoki
    We present Keck spectroscopic observations of three probable high-redshift superluminous supernovae (SLSNe) from the Subaru HIgh-Z sUpernova CAmpaign (SHIZUCA), confirming redshifts of 1.851, 1.965, and 2.399. The host galaxies were selected for transient monitoring from multiband photometric redshifts. The supernovae are detected during their rise, and the classically scheduled spectra are collected near maximum light. The rest-frame far-ultraviolet (∼1000-2500 ) spectra include a significant host galaxy flux contribution, and we compare our host-galaxy-subtracted spectra to UV-luminous SNe from the literature. While the signal-to-noise ratios of the spectra presented here are sufficient for redshift confirmation, supernova spectroscopic type confirmation remains inconclusive. The success of the first SHIZUCA Keck spectroscopic follow-up program demonstrates that campaigns such as SHIZUCA are capable of identifying high-redshift SLSNe with sufficient accuracy, speed, and depth for rapid, well-cadenced, and informative follow-up.
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    A study of the color diversity around maximum light in Type Ia supernovae
    (2011) Cartier, Regis; Foster, Francisco; Coppi, Paolo; Hamuy, Mario; Maeda, Keiichi; Pignata, Guiliano; Folatelli, Gastón
    From a sample of 12 well-observed Type Ia supernovae, we find clear evidence of correlations between early phase (U − B), (V − R), and (V − I) colors and the velocity shifts of the [Fe II] λ7155 and [Ni II] λ7378 nebular lines measured from late-phase spectra. As these lines are thought to trace the ashes of the initial deflagration process, our findings provide additional support to the new paradigm of off-center explosions in Type Ia supernovae, and we interpret these correlations as viewing angle effects in the observed colors. We also show that the nebular velocity shifts are related to the strength and width of the Ca II H&K and IR-triplet lines near-maximum light. The evidence presented here implies that the viewing angle must be taken into account when deriving extinction values and distances in future cosmological studies based on Type Ia supernovae.
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    The Highly Energetic Expansion of SN2010bh Associated with GRB100316D
    (2012) Bufano, Filomena; Pian, Elena; Sollerman, Jesper; Benetti, Stefano; Pignata, Giuliano; Valenti, Stefano; Covino, Stefano; D’Avanzo, Paolo; Malesani, Daniele; Enrico, Cappellaro; Della Valle, Massimo; Fynbo, Johan; Hjorth, Jens; Mazzali, Paolo A.; Reichart, Daniel E.; Starling, Rhaana L. C.; Turatto, Massimo; Vergani, Susanna D.; Wiersema, Klass; Amati, Lorenzo; Bersier, David; Campana, Sergio; Cano, Zach; Castro-Tirado, Alberto J.; Chincarini, Guido; D’Elia, Valerio; de Ugarte, Antonio; Postigo, Deng, Jinsong; Ferrero, Patrizia; Alexei V., Filippenko; Goldoni, Paolo; Gorosabel, Javier; Greiner, Jochen; Hammer, Francois; Jakobsson, Pall; Kaper, Lex; Kawabata, Koji S.; Klose, Sylvio; Levan, Andrew J.; Maeda, Keiichi; Masetti, Nicola; Milvang-Jensen, Bo; Mirabel, Felix I.; Moller, Palle; Nomoto, Ken’ichi; Palazzi, Eliana; Piranomonte, Silvia; Salvaterra, Ruben; Stratta, Giulia; Tagliaferri, Gianpiero; Tanaka, Masaomi; Tanvir, Nial R.; Wijers, Ralph A.M.J.