Examinando por Autor "Pan, Yen-Chen"

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    Observational Properties of a Bright Type lax SN 2018cni and a Faint Type Iax SN 2020kyg
    (Institute of Physics, 2023-08) Singh, Mridweeka; Sahu, Devendra. K.; Dastidar, Raya; Barna, Barnabás; Misra, Kuntal; Gangopadhyay, Anjasha; Howell, D. Andrew; Jha, Saurabh W.; Im, Hyobin; Taggart, Kirsty; Andrews, Jennifer; Hiramatsu, Daichi; Teja, Rishabh Singh; Pellegrino, Craig; Foley, Ryan J.; Joshi, Arti; Anupama G.C.; Bostroem, K. Azalee; Burke, Jamison; Camacho-Neves, Yssavo; Dutta, Anirban; Kwok, Lindsey A. i; McCully, Curtis; Pan, Yen-Chen; Siebert, Matt; Srivastav, Shubham; Szalai, Tamás; Swift, Jonathan J.; Yang, Grace; Zhou, Henry; DiLullo, Nico; Scheer, Jackson
    We present the optical photometric and spectroscopic analysis of two Type Iax supernovae (SNe), 2018cni and 2020kyg. SN 2018cni is a bright Type Iax SN (M V,peak = −17.81 ± 0.21 mag), whereas SN 2020kyg (M V,peak = −14.52 ± 0.21 mag) is a faint one. We derive 56Ni mass of 0.07 and 0.002 M ⊙and ejecta mass of 0.48 and 0.14 M ⊙ for SNe 2018cni and 2020kyg, respectively. A combined study of the bright and faint Type Iax SNe in R/r-band reveals that the brighter objects tend to have a longer rise time. However, the correlation between the peak luminosity and decline rate shows that bright and faint Type Iax SNe exhibit distinct behavior. Comparison with standard deflagration models suggests that SN 2018cni is consistent with the deflagration of a CO white dwarf, whereas the properties of SN 2020kyg can be better explained by the deflagration of a hybrid CONe white dwarf. The spectral features of both the SNe point to the presence of similar chemical species but with different mass fractions. Our spectral modeling indicates stratification at the outer layers and mixed inner ejecta for both of the SNe. © 2023. The Author(s). Published by the American Astronomical Society.
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    Ultraviolet diversity of Type Ia Supernovae
    (OXFORD UNIV PRESS, 2016-06) Foley, Ryan J.; Pan, Yen-Chen; Brown, P.; Filippenko, A. V.; Fox, O. D.; Hillebrandt, W.; Kirshner, R. P.; Marion, G. H.; Milne, P. A.; Parrent, J. T.; Pignata, G.; Stritzinger, M. D.
    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 angstrom. We focus on spectra taken within 5 d of maximum brightness. Our sample of 10 SNe Ia spans, the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 angstrom (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich.
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    Ultraviolet diversity of type Ia supernovae
    (Oxford University Press, 2016-09) Foley, Ryan J.; Pan, Yen-Chen; Brown, P.; Filippenko, A.V.; Fox, O.D.; Hillebrandt, W.; Kirshner, R.P.; Marion, G.H.; Milne, P.A.; Parrent, J.T.; Pignata, G.; Stritzinger, M.D.
    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 Å. We focus on spectra taken within 5 d of maximum brightness. Our sample of 10 SNe Ia spans, the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 Å (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich. Key words: supernovae: general – supernovae: individual: SN 1992A, SN 2009ig, SN 2011by, SN 2011fe, SN 2011iv, SN 2012cg, SN 2013dy, SN 2014J, ASASSN-14lp, SN 2015F – ultraviolet: stars.