Showing papers by "Cristina Barbarino published in 2020"
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TL;DR: In this article, the authors present a systematic survey for transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility (ZTF) survey, and find that at least six out of ten events for which a spectrum was obtained within two days of estimated explosion time show evidence for such transient flash lines.
Abstract: Spectroscopic detection of narrow emission lines traces the presence of circumstellar mass distributions around massive stars exploding as core-collapse supernovae. Transient emission lines disappearing shortly after the supernova explosion suggest that the spatial extent of such material is compact, and hence imply an increased mass loss shortly prior to explosion. Here, we present a systematic survey for such transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility (ZTF) survey. We find that at least six out of ten events for which a spectrum was obtained within two days of estimated explosion time show evidence for such transient flash lines. Our measured flash event fraction ($>30\%$ at $95\%$ confidence level) indicates that elevated mass loss is a common process occurring in massive stars that are about to explode as supernovae.
38 citations
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TL;DR: In this paper, the authors used forced-photometry light curves for 196 interacting supernovae (SNe), mostly of Type IIn, detected by the Zwicky Transient Facility between early 2018 and June 2020, to identify and characterize pre-explosion outbursts.
Abstract: Interaction-powered supernovae (SNe) explode within an optically-thick circumstellar medium (CSM) that could be ejected during eruptive events. To identify and characterize such pre-explosion outbursts we produce forced-photometry light curves for 196 interacting SNe, mostly of Type IIn, detected by the Zwicky Transient Facility between early 2018 and June 2020. Extensive tests demonstrate that we only expect a few false detections among the 70,000 analyzed pre-explosion images after applying quality cuts and bias corrections. We detect precursor eruptions prior to 18 Type IIn SNe and prior to the Type Ibn SN2019uo. Precursors become brighter and more frequent in the last months before the SN and month-long outbursts brighter than magnitude -13 occur prior to 25% (5 - 69%, 95% confidence range) of all Type IIn SNe within the final three months before the explosion. With radiative energies of up to $10^{49}\,\text{erg}$, precursors could eject $\sim1\,\text{M}_\odot$ of material. Nevertheless, SNe with detected precursors are not significantly more luminous than other SNe IIn and the characteristic narrow hydrogen lines in their spectra typically originate from earlier, undetected mass-loss events. The long precursor durations require ongoing energy injection and they could, for example, be powered by interaction or by a continuum-driven wind. Instabilities during the neon and oxygen burning phases are predicted to launch precursors in the final years to months before the explosion; however, the brightest precursor is 100 times more energetic than anticipated.
36 citations
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Stockholm University1, INAF2, University of Turku3, University College Dublin4, University of Cádiz5, Spanish National Research Council6, Weizmann Institute of Science7, Xinjiang Astronomical Observatory8, National Central University9, Steward Health Care System10, Tsinghua University11, Chinese Academy of Sciences12, Smithsonian Institution13, University of California, Santa Barbara14, Las Cumbres Observatory Global Telescope Network15, University of California, Davis16, California Institute of Technology17, Space Telescope Science Institute18, European Southern Observatory19
TL;DR: In this article, the results of the first similar to four years of spectroscopic and photometric monitoring of the Type IIn supernova SN 2015da (also known as PSN J13522411+3941286, or iPTF1) were reported.
Abstract: In this paper we report the results of the first similar to four years of spectroscopic and photometric monitoring of the Type IIn supernova SN 2015da (also known as PSN J13522411+3941286, or iPTF1 ...
35 citations
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TL;DR: In this paper, optical, radio, and X-ray observations of SN 2020bvc (ASASSN-20bs, ZTF 20aalxlis) were presented, which is the first double-peaked Ic supernova without a gamma-ray burst (GRB) trigger.
Abstract: We present optical, radio, and X-ray observations of SN 2020bvc (=ASASSN-20bs, ZTF 20aalxlis), a nearby ($z=0.0252;$ d = 114 Mpc) broad-line (BL) Type Ic supernova (SN) and the first double-peaked Ic-BL discovered without a gamma-ray burst (GRB) trigger. Our observations show that SN 2020bvc shares several properties in common with the Ic-BL SN 2006aj, which was associated with the low-luminosity gamma-ray burst (LLGRB) 060218. First, the 10 GHz radio luminosity (${L}_{\mathrm{radio}}\approx {10}^{37}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$) is brighter than ordinary core-collapse SNe but fainter than LLGRB SNe such as SN 1998bw (associated with LLGRB 980425). We model our VLA observations (spanning 13–43 days) as synchrotron emission from a mildly relativistic (v gsim 0.3c) forward shock. Second, with Swift and Chandra, we detect X-ray emission (LX ≈ 1041 erg ${{\rm{s}}}^{-1}$) that is not naturally explained as inverse Compton emission or part of the same synchrotron spectrum as the radio emission. Third, high-cadence (6× night–1) data from the Zwicky Transient Facility (ZTF) show a double-peaked optical light curve, the first peak from shock cooling of extended low-mass material (mass ${M}_{e}\lt {10}^{-2}\,{M}_{\odot }$ at radius Re > 1012 cm) and the second peak from the radioactive decay of ${}^{56}\mathrm{Ni}$. SN 2020bvc is the first double-peaked Ic-BL SN discovered without a GRB trigger, so it is noteworthy that it shows X-ray and radio emission similar to LLGRB SNe. For four of the five other nearby (z lesssim 0.05) Ic-BL SNe with ZTF high-cadence data, we rule out a first peak like that seen in SN 2006aj and SN 2020bvc, i.e., that lasts ≈1 day and reaches a peak luminosity M ≈ −18. Follow-up X-ray and radio observations of Ic-BL SNe with well-sampled early optical light curves will establish whether double-peaked optical light curves are indeed predictive of LLGRB-like X-ray and radio emission.
25 citations
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TL;DR: In this article, the authors reported the discovery and panchromatic followup observations of the young Type Ic supernova, SN2020oi, in M100, a grand design spiral galaxy at a mere distance of $14$ Mpc.
Abstract: We report the discovery and panchromatic followup observations of the young Type Ic supernova, SN2020oi, in M100, a grand design spiral galaxy at a mere distance of $14$ Mpc We followed up with observations at radio, X-ray and optical wavelengths from only a few days to several months after explosion The optical behaviour of the supernova is similar to those of other normal Type Ic supernovae The event was not detected in the X-ray band but our radio observation revealed a bright mJy source ($L_{
u} \approx 12 \times 10^{27} {\rm erg\,s}^{-1} {\rm Hz}^{-1}$) Given, the relatively small number of stripped envelope SNe for which radio emission is detectable, we used this opportunity to perform a detailed analysis of the comprehensive radio dataset we obtained The radio emitting electrons initially experience a phase of inverse Compton cooling which leads to steepening of the spectral index of the radio emission Our analysis of the cooling frequency points to a large deviation from equipartition at the level of $\epsilon_e/\epsilon_B \gtrsim 200$, similar to a few other cases of stripped envelope SNe Our modeling of the radio data suggests that the shockwave driven by the SN ejecta into the circumstellar matter (CSM) is moving at $\sim 3\times 10^{4}\,{\rm km\,s}^{-1}$ Assuming a constant mass-loss from the stellar progenitor, we find that the mass-loss rate is $\dot{M} \approx 14\times 10^{-4}\,{M}_{\odot}\,{\rm yr}^{-1}$, for an assumed wind velocity of $1000\,{\rm km\,s}^{-1}$ The temporal evolution of the radio emission suggests a radial CSM density structure steeper than the standard $r^{-2}$
18 citations
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TL;DR: In this article, photometry and spectroscopy of four hydrogen-poor luminous supernovae discovered during the 2-month long science commissioning and early operations of the Zwicky Transient Facility (ZTF) survey are presented.
Abstract: We present photometry and spectroscopy of four hydrogen-poor luminous supernovae discovered during the 2-month long science commissioning and early operations of the Zwicky Transient Facility (ZTF) survey. Three of these objects, SN 2018bym (ZTF18aapgrxo), SN 2018avk (ZTF18aaisyyp), and SN 2018bgv (ZTF18aavrmcg), resemble typical SLSN-I spectroscopically, while SN 2018don (ZTF18aajqcue) may be an object similar to SN 2007bi experiencing considerable host galaxy reddening, or an intrinsically long-lived, luminous, and red SN Ic. We analyze the light curves, spectra, and host galaxy properties of these four objects and put them in context of the population of SLSN-I. SN 2018bgv stands out as the fastest-rising SLSN-I observed to date, with a rest-frame g-band rise time of just 10 days from explosion to peak—if it is powered by magnetar spin-down, the implied ejecta mass is only sime1 M⊙. SN 2018don also displays unusual properties—in addition to its red colors and comparatively massive host galaxy, the light curve undergoes some of the strongest light-curve undulations postpeak seen in an SLSN-I, which we speculate may be due to interaction with circumstellar material. We discuss the promises and challenges of finding SLSNe in large-scale surveys like ZTF given the observed diversity in the population.
15 citations
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TL;DR: In this paper, the authors investigated the presence of CSM interaction with previously ejected material, a phenomenon that is unusual among SE SNe, and they used their follow-up photometry and spectroscopy for these supernovae to demonstrate the presence and properties of the CSM, and discuss why the signals are so different for the two objects.
Abstract: Context. We present observations of SN 2019tsf (ZTF19ackjszs) and SN 2019oys (ZTF19abucwzt). These two stripped envelope (SE) Type Ib supernovae (SNe) suddenly showed a (re-)brightening in their late light curves. We investigate this in the context of circumstellar material (CSM) interaction with previously ejected material, a phenomenon that is unusual among SE SNe.
Aims. We use our follow-up photometry and spectroscopy for these supernovae to demonstrate the presence of CSM interaction, estimate the properties of the CSM, and discuss why the signals are so different for the two objects.
Methods. We present and analyze observational data, consisting of optical light curves and spectra. For SN 2019oys, we also have detections in radio as well as limits from UV and X-rays.
Results. Both light curves show spectacular re-brightening after about 100 days. In the case of SN 2019tsf, the re-brightening is followed by a new period of decline, and the spectra never show signs of narrow emission lines that would indicate CSM interaction. On the contrary, SN 2019oys made a spectral makeover from a Type Ib to a spectrum clearly dominated by CSM interaction at the light curve brightening phase. Deep Keck spectra reveal a plethora of narrow high-ionization lines, including coronal lines, and the radio observations show strong emission.
Conclusions. The rather similar light curve behavior – with a late linear re-brightening – of these two Type Ib SE SNe indicate CSM interaction as the powering source. For SN 2019oys the evidence for a phase where the ejecta hit H-rich material, likely ejected from the progenitor star, is conspicuous. We observe strong narrow lines of H and He, but also a plethora of high-ionization lines, including coronal lines, revealing shock interaction. Spectral simulations of SN 2019oys show two distinct density components, one with density ≳10⁹ cm⁻³, dominated by somewhat broader, low-ionization lines of H I, He I, Na I, and Ca II, and one with narrow, high-ionization lines at a density ∼10⁶ cm⁻³. The former is strongly affected by electron scattering, while the latter is unaffected. The evidence for CSM interaction in SN 2019oys is corroborated by detections in radio. On the contrary, for SN 2019tsf, we find little evidence in the spectra for any CSM interaction.
14 citations
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Trinity College, Dublin1, European Southern Observatory2, Stockholm University3, University of California, Davis4, University of California, Santa Barbara5, Las Cumbres Observatory Global Telescope Network6, Queen's University Belfast7, University College Dublin8, University of Granada9, University of Warsaw10, University of Southampton11, Cardiff University12, Liverpool John Moores University13, University of Turku14, Max Planck Society15, University of Birmingham16, University of Edinburgh17, INAF18
TL;DR: In this article, the authors present the data and analysis of SN 2018gjx, an unusual low-luminosity transient with three distinct spectroscopic phases, including a hot blue spectrum with signatures of ionized circumstellar material (CSM), broad features, consistent with those seen in a Type IIb supernova at maximum light, and Phase III is that of a supernova interacting with helium-rich CSM, similar to a Type Ibn supernova.
Abstract: We present the data and analysis of SN 2018gjx, an unusual low-luminosity transient with three distinct spectroscopic phases. Phase I shows a hot blue spectrum with signatures of ionized circumstellar material (CSM), Phase II has the appearance of broad SN features, consistent with those seen in a Type IIb supernova at maximum light, and Phase III is that of a supernova interacting with helium-rich CSM, similar to a Type Ibn supernova. This event provides an apparently rare opportunity to view the inner workings of an interacting supernova. The observed properties can be explained by the explosion of a star in an aspherical CSM. The initial light is emitted from an extended CSM (∼4000 R⊙), which ionizes the exterior unshocked material. Some days after, the SN photosphere envelops this region, leading to the appearance of a SN IIb. Over time, the photosphere recedes in velocity space, revealing interaction between the supernova ejecta and the CSM that partially obscures the supernova nebular phase. Modelling of the initial spectrum reveals a surface composition consistent with compact H-deficient Wolf–Rayet and Luminous Blue Variable (LBV) stars. Such configurations may not be unusual, with SNe IIb being known to have signs of interaction so at least some SNe IIb and SNe Ibn may be the same phenomena viewed from different angles, or possibly with differing CSM configurations.
13 citations
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University of Southampton1, National University of La Plata2, National Scientific and Technical Research Council3, University of Tokyo4, Cardiff University5, European Southern Observatory6, National Institutes of Natural Sciences, Japan7, University of Granada8, Lawrence Berkeley National Laboratory9, University of Copenhagen10, Stockholm University11, Max Planck Society12, University of Queensland13, University of California, Santa Cruz14, University College Dublin15, University of Portsmouth16, University of Lisbon17, University of Warsaw18, University of Turku19, Carnegie Institution for Science20, University of Sydney21, Trinity College, Dublin22, University of Birmingham23, Australian National University24, University of São Paulo25, Fermilab26, Autonomous University of Madrid27, Institut d'Astrophysique de Paris28, Pierre-and-Marie-Curie University29, University College London30, Stanford University31, University of Illinois at Urbana–Champaign32, University of Trieste33, Indian Institute of Technology, Hyderabad34, California Institute of Technology35, University of Arizona36, Spanish National Research Council37, University of Michigan38, Ohio State University39, Harvard University40, Lowell Observatory41, Macquarie University42, University of Pennsylvania43, Princeton University44, Brandeis University45, Oak Ridge National Laboratory46, Ludwig Maximilian University of Munich47, University of Sussex48
TL;DR: DES16C3cje as mentioned in this paper is a unique type II supernova with very narrow photospheric lines corresponding to very low expansion velocities of ≲1500 km/s−1, and the light curve shows an initial peak that fades after 50-d before slowly rebrightening over a further 100-d to reach an absolute brightness of −15.5
Abstract: We present DES16C3cje, a low-luminosity, long-lived type II supernova (SN II) at redshift 0.0618, detected by the Dark Energy Survey (DES). DES16C3cje is a unique SN. The spectra are characterized by extremely narrow photospheric lines corresponding to very low expansion velocities of ≲1500 km s−1, and the light curve shows an initial peak that fades after 50 d before slowly rebrightening over a further 100 d to reach an absolute brightness of Mr ∼ −15.5 mag. The decline rate of the late-time light curve is then slower than that expected from the powering by radioactive decay of 56Co, but is comparable to that expected from accretion power. Comparing the bolometric light curve with hydrodynamical models, we find that DES16C3cje can be explained by either (i) a low explosion energy (0.11 foe) and relatively large 56Ni production of 0.075 M⊙ from an ∼15 M⊙ red supergiant progenitor typical of other SNe II, or (ii) a relatively compact ∼40 M⊙ star, explosion energy of 1 foe, and 0.08 M⊙ of 56Ni. Both scenarios require additional energy input to explain the late-time light curve, which is consistent with fallback accretion at a rate of ∼0.5 × 10−8 M⊙ s−1.
9 citations
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TL;DR: In this article, a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) in the Ultra-Violet (UV) and visible light is presented.
Abstract: We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) in the Ultra-Violet (UV) and visible light. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical circumstellar material (CSM), we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% on the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common - consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modelling of these events.
9 citations
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Hebrew University of Jerusalem1, Stockholm University2, University of Manchester3, Spanish National Research Council4, Commonwealth Scientific and Industrial Research Organisation5, University of Sydney6, Weizmann Institute of Science7, University of Oxford8, California Institute of Technology9, University of Washington10, University of Cambridge11, University of California, Santa Barbara12, Northwestern University13, Adler Planetarium14, Victoria University of Wellington15
TL;DR: In this article, the authors reported the discovery and panchromatic followup observations of the young Type Ic supernova, SN2020oi, in M100, a grand design spiral galaxy at a mere distance of $14$ Mpc.
Abstract: We report the discovery and panchromatic followup observations of the young Type Ic supernova, SN2020oi, in M100, a grand design spiral galaxy at a mere distance of $14$ Mpc. We followed up with observations at radio, X-ray and optical wavelengths from only a few days to several months after explosion. The optical behaviour of the supernova is similar to those of other normal Type Ic supernovae. The event was not detected in the X-ray band but our radio observation revealed a bright mJy source ($L_{
u} \approx 1.2 \times 10^{27} {\rm erg\,s}^{-1} {\rm Hz}^{-1}$). Given, the relatively small number of stripped envelope SNe for which radio emission is detectable, we used this opportunity to perform a detailed analysis of the comprehensive radio dataset we obtained. The radio emitting electrons initially experience a phase of inverse Compton cooling which leads to steepening of the spectral index of the radio emission. Our analysis of the cooling frequency points to a large deviation from equipartition at the level of $\epsilon_e/\epsilon_B \gtrsim 200$, similar to a few other cases of stripped envelope SNe. Our modeling of the radio data suggests that the shockwave driven by the SN ejecta into the circumstellar matter (CSM) is moving at $\sim 3\times 10^{4}\,{\rm km\,s}^{-1}$. Assuming a constant mass-loss from the stellar progenitor, we find that the mass-loss rate is $\dot{M} \approx 1.4\times 10^{-4}\,{M}_{\odot}\,{\rm yr}^{-1}$, for an assumed wind velocity of $1000\,{\rm km\,s}^{-1}$. The temporal evolution of the radio emission suggests a radial CSM density structure steeper than the standard $r^{-2}$.
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Stockholm University1, Aarhus University2, Weizmann Institute of Science3, University of Turku4, University of Washington5, California Institute of Technology6, Hebrew University of Jerusalem7, Claude Bernard University Lyon 18, Humboldt University of Berlin9, Liverpool John Moores University10, Lawrence Berkeley National Laboratory11, University of Manchester12
TL;DR: In this paper, the discovery and study of SN 2020bqj (ZTF20aalrqbu), a supernova with a long-duration peak plateau lasting 40 days and hosted by a faint low-mass galaxy is presented.
Abstract: Context: Type Ibn supernovae are a rare class of stripped envelope supernovae interacting with a helium-rich CSM. The majority of the SNe Ibn reported display a surprising homogeneity in their fast lightcurves and starforming hosts. Aims: We present the discovery and study of SN 2020bqj (ZTF20aalrqbu), a SN Ibn with a long-duration peak plateau lasting 40 days and hosted by a faint low-mass galaxy. We aim to explain its peculiar properties using an extensive data set. Methods: We compare the evolution of SN 2020bqj with SNe Ibn from the literature. We fit the bolometric and multi-band lightcurves with different powering mechanism models. Results: The risetime, peak magnitude and spectral features of SN 2020bqj are consistent with those of most SNe Ibn, but the SN is a clear outlier based on its bright, long-lasting peak plateau and low host mass. We show through modeling that the lightcurve can be powered predominantly by shock heating from the interaction of the SN ejecta and a dense CSM. The peculiar Type Ibn SN 2011hw is a close analog to SN 2020bqj, suggesting a similar progenitor and CSM scenario. In this scenario a very massive progenitor star in the transitional phase between a luminous blue variable and a compact Wolf-Rayet star undergoes core-collapse, embedded in a dense helium-rich CSM with an elevated opacity compared to normal SNe Ibn, due to the presence of residual hydrogen. This scenario is consistent with the observed properties of SN 2020bqj and the modeling results. Conclusions: SN 2020bqj is a compelling example of a transitional SN Ibn/IIn based on not only its spectral features, but also its lightcurve, host galaxy properties and the inferred progenitor properties. The strong similarity with SN 2011hw suggests this subclass may be the result of a progenitor in a stellar evolution phase that is distinct from those of progenitors of regular SNe Ibn.
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TL;DR: In this article, the authors analyzed the spectral properties of two stripped envelope Type Ib supernovae and found evidence for CSM interaction with previously ejected material, a phenomenon that is unusual among SE SNe.
Abstract: We present SN 2019tsf (ZTF19ackjszs) and SN 2019oys (ZTF19abucwzt). These two stripped envelope Type Ib supernovae suddenly showed a (re-)brightening in their late light curves. We investigate this in the context of circumstellar material (CSM) interaction with previously ejected material, a phenomenon that is unusual among SE SNe. We analyse observational data, consisting of optical light curves and spectra. For SN 2019oys we also have detections in radio as well as limits from UV and X-rays. Both light curves show spectacular re-brightening after about 100 days. In the case of SN 2019tsf, the re-brightening is followed by a new period of decline, and the spectra never show signs of narrow emission lines that would indicate CSM interaction. On the contrary, SN 2019oys made a spectral makeover from a Type Ib to a spectrum clearly dominated by CSM interaction at the light curve brightening phase. Deep spectra reveal a plethora of narrow high ionization lines, including coronal lines, and the radio observations show strong emission. The rather similar light curve behaviour indicate CSM interaction as the powering source. For SN 2019oys the evidence for a phase where the ejecta hit H-rich material, likely ejected from the progenitor star, is conspicuous. We observe strong narrow lines of H and He, but also a plethora of high ionization lines, including coronal lines, revealing shock interaction. Spectral simulations of SN 2019oys show two distinct density components, one with density > 1e9/cm3, dominated by somewhat broader, low ionization lines of H I, He I, Na I and Ca II, and one with narrow, high ionization lines at a density about 1e6 /cm3. The former is strongly affected by electron scattering. The evidence for CSM interaction in SN 2019oys is corroborated by detections in radio. On the contrary, for SN 2019tsf, we find little evidence in the spectra for any CSM interaction.
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Stockholm University1, University of Turku2, Liverpool John Moores University3, University of Washington4, California Institute of Technology5, University of Maryland, College Park6, Weizmann Institute of Science7, University of California, Santa Cruz8, Claude Bernard University Lyon 19, Lawrence Berkeley National Laboratory10
TL;DR: In this article, the authors discuss the outcomes of the follow-up campaign of SN 2018ijp, discovered as part of the Zwicky Transient Facility survey for optical transients.
Abstract: In this paper, we discuss the outcomes of the follow-up campaign of SN 2018ijp, discovered as part of the Zwicky Transient Facility survey for optical transients. Its first spectrum shows similarities to broad-lined Type Ic supernovae around maximum light, whereas later spectra display strong signatures of interaction between rapidly expanding ejecta and a dense H-rich circumstellar medium, coinciding with a second peak in the photometric evolution of the transient. This evolution, along with the results of modeling of the first light curve peak, suggests a scenario where a stripped star exploded within a dense circumstellar medium. The two main phases in the evolution of the transient could be interpreted as a first phase dominated by radioactive decays, and an later interaction-dominated phase where the ejecta collide with a pre-existing shell. We therefore discuss SN 2018jp within the context of a massive star depleted of its outer layers exploding within a dense H-rich circumstellar medium.
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Lawrence Berkeley National Laboratory1, Weizmann Institute of Science2, University of California, Berkeley3, Goddard Space Flight Center4, University of Maryland, College Park5, Stockholm University6, Liverpool John Moores University7, California Institute of Technology8, University of Washington9, University of Turku10, Duke University11, Kavli Institute for Theoretical Physics12, Northwestern University13, Adler Planetarium14, University of Auvergne15
TL;DR: In this article, the authors present a survey of the early evolution of 12 Type IIn supernovae at ultraviolet and visible light wavelengths, and use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity.
Abstract: We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) at ultraviolet and visible light wavelengths. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical CSM, we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher-luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% for the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common—consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modeling of these events.
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TL;DR: In this article, the authors presented an analysis of 44 spectroscopically normal Type Ic supernovae, with focus on the light curves and confirmed the correlation between the rise parameter Delta m{-10} and the decline parameter Deltam{-15}.
Abstract: Type Ic supernovae represent the explosions of the most stripped massive stars, but their progenitors and explosion mechanisms remain unclear. Larger samples of observed supernovae can help characterize the population of these transients. We present an analysis of 44 spectroscopically normal Type Ic supernovae, with focus on the light curves. The photometric data were obtained over 7 years with the Palomar Transient Factory (PTF) and its continuation, the intermediate Palomar Transient Factory (iPTF). This is the first homogeneous and large sample of SNe Ic from an untargeted survey, and we aim to estimate explosion parameters for the sample. We present K-corrected Bgriz light curves of these SNe, obtained through photometry on template-subtracted images. We performed an analysis on the shape of the $r$-band light curves and confirmed the correlation between the rise parameter Delta m_{-10} and the decline parameter Delta m_{15}. Peak r-band absolute magnitudes have an average of -17.71 +- 0.85 mag. To derive the explosion epochs, we fit the r-band lightcurves to a template derived from a well-sampled light curve. We computed the bolometric light curves using r and g band data, g-r colors and bolometric corrections. Bolometric light curves and Fe II lambda 5169 velocities at peak were used to fit to the Arnett semianalytic model in order to estimate the ejecta mass M_{ej}, the explosion energy E_{K} and the mass of radioactive nickel (M(56) Ni) for each SN. Including 41 SNe, we find average values of =4.50 +-0.79 msun, =1.79 +- 0.29 x10^{51} erg, and = 0.19 +- 0.03 msun. The explosion-parameter distributions are comparable to those available in the literature, but our large sample also includes some transients with narrow and very broad light curves leading to more extreme ejecta masses values.