Examinando por Autor "Baron, E."

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    SN 2021fxy: mid-ultraviolet flux suppression is a common feature of Type Ia supernovae
    (Oxford University Press, 2023-07-01) DerKacy, J.M.; Paugh, S.; Baron, E.; Brown, P.J.; Ashall, C.; Burns, C.R.; Hsiao, E.Y.; Kumar, S.; Lu, J.; Morrell, N.; Phillips, M.M.; Shahbandeh, M.; Shappee, B.J.; Stritzinger, M.D.; Tucker, M.A.; Yarbrough, Z.; Boutsia, K.; Hoeflich, P.; Wang, L.; Galbany, L.; Karamehmetoglu, E.; Krisciunas, K.; Mazzali, P.; Piro, A.L.; Suntzeff, N.B.; Fiore, A.; Gutiérrez, C.P.; Lundqvist, P.; Reguitti, A.
    We present ultraviolet (UV) to near-infrared (NIR) observations and analysis of the nearby Type Ia supernova SN 2021fxy. Our observations include UV photometry from Swift/UVOT, UV spectroscopy from HST/STIS, and high-cadence optical photometry with the Swope 1-m telescope capturing intranight rises during the early light curve. Early B − V colours show SN 2021fxy is the first 'shallow-silicon' (SS) SN Ia to follow a red-to-blue evolution, compared to other SS objects which show blue colours from the earliest observations. Comparisons to other spectroscopically normal SNe Ia with HST UV spectra reveal SN 2021fxy is one of several SNe Ia with flux suppression in the mid-UV. These SNe also show blueshifted mid-UV spectral features and strong high-velocity Ca II features. One possible origin of this mid-UV suppression is the increased effective opacity in the UV due to increased line blanketing from high velocity material, but differences in the explosion mechanism cannot be ruled out. Among SNe Ia with mid-UV suppression, SNe 2021fxy and 2017erp show substantial similarities in their optical properties despite belonging to different Branch subgroups, and UV flux differences of the same order as those found between SNe 2011fe and 2011by. Differential comparisons to multiple sets of synthetic SN Ia UV spectra reveal this UV flux difference likely originates from a luminosity difference between SNe 2021fxy and 2017erp, and not differing progenitor metallicities as suggested for SNe 2011by and 2011fe. These comparisons illustrate the complicated nature of UV spectral formation, and the need for more UV spectra to determine the physical source of SNe Ia UV diversity. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
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    Two transitional type Ia supernovae located in the Fornax cluster member NGC 1404: SN 2007on and SN 2011iv
    (EDP Sciences, 2018-03) Gall, C.; Stritzinger, M.D.; Ashall, C.; Baron, E.; Burns, C.R.; Hoeflich, P.; Hsiao, E.Y.; Mazzali, P.A.; Phillips, M.M.; Filippenko, A.V.; Anderson, J.P.; Benetti, S.; Brown, P.J.; Campillay, A.; Challis, P.; Contreras, C.; Elias De La Rosa, N.; Folatelli, G.; Foley, R.J.; Fraser, M.; Holmbo, S.; Marion, G.H.; Morrell, N.; Pan, Y.-C.; Pignata, G.; Suntzeff, N.B.; Taddia, F.; Robledo, S.T.; Valenti, S.
    We present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band light curves of SN 2007on and SN 2011iv are characterised by Δm 15 (B) decline-rate values of 1.96 mag and 1.77 mag, respectively. Although they have similar decline rates, their peak B- and H-band magnitudes differ by ~ 0.60 mag and ~0.35 mag, respectively. After correcting for the luminosity vs. decline rate and the luminosity vs. colour relations, the peak B-band and H-band light curves provide distances that differ by ~ 14% and ~ 9%, respectively. These findings serve as a cautionary tale for the use of transitional SNe Ia located in early-type hosts in the quest to measure cosmological parameters. Interestingly, even though SN 2011iv is brighter and bluer at early times, by three weeks past maximum and extending over several months, its B - V colour is 0.12 mag redder than that of SN 2007on. To reconcile this unusual behaviour, we turn to guidance from a suite of spherical one-dimensional Chandrasekhar-mass delayed-detonation explosion models. In this context, 56 Ni production depends on both the so-called transition density and the central density of the progenitor white dwarf. To first order, the transition density drives the luminosity-width relation, while the central density is an important second-order parameter. Within this context, the differences in the B - V colour evolution along the Lira regime suggest that the progenitor of SN 2011iv had a higher central density than SN 2007on. © ESO 2018.