LSQ13ddu: a rapidly evolving stripped-envelope supernova with early circumstellar interaction signatures

This paper describes the rapidly evolving and unusual supernova LSQ13ddu, discovered by the La Silla-QUEST survey. LSQ13ddu displayed a rapid rise of just 4.8 ± 0.9 d to reach a peak brightness of −19.70 ± 0.02 mag in the LSQgr band. Early spectra of LSQ13ddu showed the presence of weak and narrow HeI features arising from interaction with circumstellar material (CSM). These interaction signatures weakened quickly, with broad features consistent with those seen in stripped-envelope SNe becoming dominant around two weeks after maximum. The narrow HeI velocities are consistent with the wind velocities of luminous blue variables but its spectra lack the typically seen hydrogen features. The fast and bright early light curve is inconsistent with radioactive ⁵⁶Ni powering but can be explained through a combination of CSM interaction and an underlying ⁵⁶Ni decay component that dominates the later time behaviour of LSQ13ddu. Based on the strength of the underlying broad features, LSQ13ddu appears deficient in He compared to standard SNe Ib

Carnegie Supernova Project-I and -II: Measurements of H0H_0 using Cepheid, TRGB, and SBF Distance Calibration to Type Ia Supernovae

We present an analysis of Type Ia Supernovae (SNe~Ia) from both the Carnegie Supernova Project~I (CSP-I) and II (CSP-II), and extend the Hubble diagram from the optical to the near-infrared wavelengths ($uBgVriYJH$). We calculate the Hubble constant, $H_0$, using various distance calibrators: Cepheids, Tip of the Red Giant Branch (TRGB), and Surface Brightness Fluctuations (SBF). Combining all methods of calibrations, we derive $\rm H_0=71.76 \pm 0.58 \ (stat) \pm 1.19 \ (sys) \ km \ s^{-1} \ Mpc^{-1}$from$B$-band, and$\rm H_0=73.22 \pm 0.68 \ (stat) \pm 1.28 \ (sys) \ km \ s^{-1} \ Mpc^{-1}$from$H$-band. By assigning equal weight to the Cepheid, TRGB, and SBF calibrators, we derive the systematic errors required for consistency in the first rung of the distance ladder, resulting in a systematic error of$1.2\sim 1.3 \rm \ km \ s^{-1} \ Mpc^{-1}$in$H_0$. As a result, relative to the statistics-only uncertainty, the tension between the late-time$H_0$we derive by combining the various distance calibrators and the early-time$H_0$from the Cosmic Microwave Background is reduced. The highest precision in SN~Ia luminosity is found in the$Y$band ($0.12\pm0.01$mag), as defined by the intrinsic scatter ($\sigma_{int}$). We revisit SN~Ia Hubble residual-host mass correlations and recover previous results that these correlations do not change significantly between the optical and the near-infrared wavelengths. Finally, SNe~Ia that explode beyond 10 kpc from their host centers exhibit smaller dispersion in their luminosity, confirming our earlier findings. Reduced effect of dust in the outskirt of hosts may be responsible for this effect.Comment: Revised calculations are made. Will be resubmitted to Ap

Nebular-phase spectra of Type Ia supernovae from the Las Cumbres Observatory Global Supernova Project

The observed diversity in Type Ia supernovae (SNe Ia) – the thermonuclear explosions of carbon–oxygen white dwarf stars used as cosmological standard candles – is currently met with a variety of explosion models and progenitor scenarios. To help improve our understanding of whether and how often different models contribute to the occurrence of SNe Ia and their assorted properties, we present a comprehensive analysis of seven nearby SNe Ia. We obtained one to two epochs of optical spectra with Gemini Observatory during the nebular phase (>200 d past peak) for each of these events, all of which had time series of photometry and spectroscopy at early times (the first ∼8 weeks after explosion). We use the combination of early- and late-time observations to assess the predictions of various models for the explosion (e.g. double-detonation, off-centre detonation, stellar collisions), progenitor star (e.g. ejecta mass, metallicity), and binary companion (e.g. another white dwarf or a non-degenerate star). Overall, we find general consistency in our observations with spherically symmetric models for SN Ia explosions, and with scenarios in which the binary companion is another degenerate star. We also present an in-depth analysis of SN 2017fzw, a member of the subgroup of SNe Ia which appear to be transitional between the subluminous ‘91bg-like’ events and normal SNe Ia, and for which nebular-phase spectra are rare.The international Gemini Observatory, a program of NSF’s NOIRLab, is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). The observations were made under Gemini programs GS-2018A-Q-315, GS-2018B-Q-209, and GN-2018B-Q-213 (optical spectra), and GS-2018B-Q-218 (NIR spectrum). The data and calibration files were obtained from the Gemini Observatory Archive at NSF’s NOIRLab, and processed using the Gemini IRAF package. This work makes use of observations from the Las Cumbres Observatory global telescope network. The Las Cumbres Observatory team is supported by NSF grants AST-1911225 and AST-1911151. We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team. MLG and TDK acknowledge support from the DIRAC Institute in the Department of Astronomy at the University of Washington. The DIRAC Institute is supported through generous gifts from the Charles and Lisa Simonyi Fund for Arts and Sciences, and the Washington Research Foundation. MLG and TDK thank Brigitta Sipőcz for assistance with implementing the Bayesian Information Criterion. Time domain research by DJS is supported by NSF grants AST-1821987, 1813466, and 1908972, and by the Heising–Simons Foundation under grant #2020-1864. LG acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 and from the Spanish MICIU project PID2020-115253GA-I00. XW is supported by the National Science Foundation of China (NSFC grants 12033003 and 11633002), the Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002), and the Tencent XPLORER Prize.Peer reviewe

LSQ13ddu: a rapidly evolving stripped-envelope supernova with early circumstellar interaction signatures

This paper describes the rapidly evolving and unusual supernova LSQ13ddu, discovered by the La Silla-QUEST survey. LSQ13ddu displayed a rapid rise of just 4.8 +/- 0.9 d to reach a peak brightness of -19.70 +/- 0.02 mag in the LSQgr band. Early spectra of LSQ13ddu showed the presence of weak and narrow He I features arising from interaction with circumstellar material (CSM). These interaction signatures weakened quickly, with broad features consistent with those seen in stripped-envelope SNe becoming dominant around two weeks after maximum. The narrow He I velocities are consistent with the wind velocities of luminous blue variables but its spectra lack the typically seen hydrogen features. The fast and bright early light curve is inconsistent with radioactive Ni-56 powering but can be explained through a combination of CSM interaction and an underlying Ni-56 decay component that dominates the later time behaviour of LSQ13ddu. Based on the strength of the underlying broad features, LSQ13ddu appears deficient in He compared to standard SNe Ib

Red and Reddened: Ultraviolet through Near-infrared Observations of Type Ia Supernova 2017erp

We present space-based ultraviolet/optical photometry and spectroscopy with the Swift Ultra-Violet/Optical Telescope and Hubble Space Telescope (HST), respectively, along with ground-based optical photometry and spectroscopy and near-infrared spectroscopy of supernova SN 2017erp. The optical light curves and spectra are consistent with a normal SN Ia. Compared to previous photometric samples in the near-ultraviolet (NUV), SN 2017erp has UV colors that are redder than NUV-blue SNe Ia corrected to similar optical colors. The chromatic difference between SNe 2011fe and 2017erp is dominated by the intrinsic differences in the UV rather than the expected dust reddening. This chromatic difference is similar to the SALT2 color law, derived from rest-frame ultraviolet photometry of higher redshift SNe Ia. Differentiating between intrinsic UV diversity and dust reddening can have important consequences for determining cosmological distances with rest-frame ultraviolet photometry. This ultraviolet spectroscopic series is the first from HST of a normal, albeit reddened, NUV-red SN Ia and is important for analyzing SNe Ia with intrinsically redder NUV colors. We show model comparisons suggesting that metallicity could be the physical difference between NUV-blue and NUV-red SNe Ia, with emission peaks from reverse fluorescence near 3000 Å implying a factor of ~10 higher metallicity in the upper layers of SN 2017erp compared to SN 2011fe. Metallicity estimates are very model dependent, however, and there are multiple effects in the UV. Further models and UV spectra of SNe Ia are needed to explore the diversity of SNe Ia, which show seemingly independent differences in the near-UV peaks and mid-UV flux levels.NASA from the Space Telescope Science Institute [14665]; NASA [NAS 5-26555, NNG17PX03C]; NASA's Astrophysics Data Analysis Program [NNX13AF35G]; NSF [AST 1313484, AST-1821967, 1821987, 1813708, 1813466]; Gemini Observatory [GS-2017A-Q-33]; US Department of Energy [DE-SC0011636]; Australian Research Council [CE110001020, FT170100243]; Chinese Academy of Sciences President's International Fellowship Initiative grant [2016PM014]; National Science Foundation [AST-1613472]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Carnegie Supernova Project-II: Near-infrared Spectroscopic Diversity of Type II Supernovae

We present 81 near-infrared (NIR) spectra of 30 Type II supernovae (SNe II) from the Carnegie Supernova Project-II (CSP-II), the largest such data set published to date. We identify a number of NIR features and characterize their evolution over time. The NIR spectroscopic properties of SNe II fall into two distinct groups. This classification is first based on the strength of the He i λ1.083 μm absorption during the plateau phase; SNe II are either significantly above (spectroscopically strong) or below 50 Å (spectroscopically weak) in pseudo equivalent width. However, between the two groups other properties, such as the timing of CO formation and the presence of Sr ii, are also observed. Most surprisingly, the distinct weak and strong NIR spectroscopic classes correspond to SNe II with slow and fast declining light curves, respectively. These two photometric groups match the modern nomenclature of SNe IIP, which show a long duration plateau, and IIL, which have a linear declining light curve. Including NIR spectra previously published, 18 out of 19 SNe II follow this slow declining-spectroscopically weak and fast declining-spectroscopically strong correspondence. This is in apparent contradiction to the recent findings in the optical that slow and fast decliners show a continuous distribution of properties. The weak SNe II show a high-velocity component of helium that may be caused by a thermal excitation from a reverse shock created by the outer ejecta interacting with the red supergiant wind, but the origin of the observed dichotomy is not understood. Further studies are crucial in determining whether the apparent differences in the NIR are due to distinct physical processes or a gap in the current data set.Fil: Davis, Scott. Florida State University; Estados UnidosFil: Hsiao, Eric. Florida State University; Estados UnidosFil: Ashall, Chris. Florida State University; Estados UnidosFil: Hoeflich, Peter. Florida State University; Estados UnidosFil: Phillips, Mark. Florida State University; Estados Unidos. Las Campanas Observatory; ChileFil: Marion, G. H.. University of Texas at Austin; Estados UnidosFil: Kirshner, Robert. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Gordon and Betty Moore Foundation; Estados UnidosFil: Morrell, Nidia Irene. Las Campanas Observatory; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Sand, David. University of Arizona; Estados UnidosFil: Burns, Christopher R.. Carnegie Institution for Science; Estados UnidosFil: Contreras Velásquez, Carlos. Las Campanas Observatory; ChileFil: Stritzinger, Maximilian. University Aarhus; DinamarcaFil: Anderson, Joseph. European Southern Observatory Chile; ChileFil: Baron, Edward. University Aarhus; Dinamarca. Oklahoma State University; Estados Unidos. Universitat Hamburg; AlemaniaFil: Diamond, Tiara. National Aeronautics and Space Administration; Estados UnidosFil: Gutiérrez, C. P.. University of Southampton; Reino UnidoFil: Hamuy, Mario. Universidad de Chile; ChileFil: Holmbo, S.. University Aarhus; DinamarcaFil: Kasliwal, Mansi. California Institute of Technology; Estados UnidosFil: Krisciunas, Kevin. Texas A&M University; Estados UnidosFil: Kumar, Sahana. Florida State University; Estados UnidosFil: Lu, J.. Florida State University; Estados UnidosFil: Pessi, Priscila Jael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Piro, Anthony. Carnegie Institution for Science; Estados UnidosFil: Prieto Katunaric, Jose Luis. Universidad Diego Portales; ChileFil: Shahbandeh, Melissa. Florida State University; Estados UnidosFil: Suntzeff, Nicholas B.. Texas A&M University; Estados Unido

Near-infrared and Optical Nebular-phase Spectra of Type Ia Supernovae SN 2013aa and SN 2017cbv in NGC 5643

We present multiwavelength time-series spectroscopy of SN 2013aa and SN 2017cbv, two Type Ia supernovae (SNe Ia) on the outskirts of the same host galaxy, NGC 5643. This work utilizes new nebular-phase near-infrared (NIR) spectra obtained by the Carnegie Supernova Project-II, in addition to previously published optical and NIR spectra. Using nebular-phase [Fe ii ] lines in the optical and NIR, we examine the explosion kinematics and test the efficacy of several common emission-line-fitting techniques. The NIR [Fe ii ] 1.644 μ m line provides the most robust velocity measurements against variations due to the choice of the fit method and line blending. The resulting effects on velocity measurements due to choosing different fit methods, initial fit parameters, continuum and line profile functions, and fit region boundaries were also investigated. The NIR [Fe ii ] velocities yield the same radial shift direction as velocities measured using the optical [Fe ii ] λ 7155 line, but the sizes of the shifts are consistently and substantially lower, pointing to a potential issue in optical studies. The NIR [Fe ii ] 1.644 μ m emission profile shows a lack of significant asymmetry in both SNe, and the observed low velocities elevate the importance for correcting for any velocity contribution from the host galaxy’s rotation. The low [Fe ii ] velocities measured in the NIR at nebular phases disfavor progenitor scenarios in close double-degenerate systems for both SN 2013aa and SN 2017cbv. The time evolution of the NIR [Fe ii ] 1.644 μ m line also indicates moderately high progenitor white dwarf central density and potentially high magnetic fields

Carnegie Supernova Project-II: Extending the Near-infrared Hubble Diagram for Type Ia Supernovae to z ∼ 0.1

The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year program to obtain optical and near-infrared observations of a "Cosmology" sample of ∼100 Type Ia supernovae located in the smooth Hubble flow (0.03 ≲ z ≲ 0.10). Light curves were also obtained of a "Physics" sample composed of 90 nearby Type Ia supernovae at z ≤ 0.04 selected for near-infrared spectroscopic timeseries observations. The primary emphasis of the CSP-II is to use the combination of optical and near-infrared photometry to achieve a distance precision of better than 5%. In this paper, details of the supernova sample, the observational strategy, and the characteristics of the photometric data are provided. In a companion paper, the near-infrared spectroscopy component of the project is presented.Fil: Phillips, Mark. Las Campanas Observatory; ChileFil: Contreras Velásquez, Carlos. Las Campanas Observatory; ChileFil: Hsiao, Eric. Las Campanas Observatory; Chile. University Aarhus; Dinamarca. Florida State University; Estados UnidosFil: Morrell, Nidia Irene. Las Campanas Observatory; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Burns, Christopher R.. Observatories of the Carnegie Institution for Science; Estados UnidosFil: Stritzinger, Maximilian. University Aarhus; DinamarcaFil: Ashall, Chris. Florida State University; Estados UnidosFil: Freedman, Wendy L.. Observatories of the Carnegie Institution for Science; Estados Unidos. University of Chicago; Estados UnidosFil: Hoeflich, Peter. Florida State University; Estados UnidosFil: Persson, S. E.. Observatories of the Carnegie Institution for Science; Estados UnidosFil: Piro, Anthony. Observatories of the Carnegie Institution for Science; Estados UnidosFil: Suntzeff, Nicholas B.. Texas A&M University; Estados UnidosFil: Uddin, Syed A.. Observatories of the Carnegie Institution for Science; Estados UnidosFil: Anais, Jorge. Las Campanas Observatory; ChileFil: Baron, Edward. Oklahoma State University; Estados UnidosFil: Busta, Luis. Las Campanas Observatory; ChileFil: Campillay, Abdo. Las Campanas Observatory; Chile. Universidad de La Serena; ChileFil: Castellón, Sergio. Las Campanas Observatory; ChileFil: Corco, Carlos. Las Campanas Observatory; Chile. Soar Telescope; ChileFil: Diamond, Tiara. Florida State University; Estados Unidos. Laboratory of Observational Cosmology; Estados UnidosFil: Gall, Christa. University Aarhus; Dinamarca. Universidad de Copenhagen; DinamarcaFil: Gonzalez, Consuelo. Las Campanas Observatory; ChileFil: Holmbo, Simon. University Aarhus; DinamarcaFil: Krisciunas, Kevin. Texas A&M University; Estados UnidosFil: Roth, Miguel. Las Campanas Observatory; Chile. GMTO Corporation; ChileFil: Serón, Jacqueline. Las Campanas Observatory; Chile. Cerro Tololo Inter American Observatory; ChileFil: Taddia, F.. Stockholms Universitet; SueciaFil: Torres, Simón. Soar Telescope; ChileFil: Anderson, Joseph. European Southern Observatory Chile; ChileFil: Folatelli, Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentin