Showing papers by "Takashi J. Moriya published in 2018"
TL;DR: Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2m Subaru telescope on the summit of Maunakea as mentioned in this paper.
Abstract: Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2m Subaru telescope on the summit of Maunakea. A team of scientists from Japan, Taiwan and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg$^2$ in five broad bands ($grizy$), with a $5\,\sigma$ point-source depth of $r \approx 26$. The Deep layer covers a total of 26~deg$^2$ in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg$^2$). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey.
392 citations
TL;DR: In this article, the three major suggested luminosity sources to explain the huge luminosities of superluminous supernovae are introduced, i.e., the nuclear decay of 56Ni, the interaction between supernova ejecta and dense circumstellar media, and the spin down of magnetars.
Abstract: Superluminous supernovae are a new class of supernovae that were recognized about a decade ago. Both observational and theoretical progress has been significant in the last decade. In this review, we first briefly summarize the observational properties of superluminous supernovae. We then introduce the three major suggested luminosity sources to explain the huge luminosities of superluminous supernovae, i.e., the nuclear decay of 56Ni, the interaction between supernova ejecta and dense circumstellar media, and the spin down of magnetars. We compare these models and discuss their strengths and weaknesses.
135 citations
University of Chile1, Millennium Institute2, National Institutes of Natural Sciences, Japan3, European Southern Observatory4, Institute for the Physics and Mathematics of the Universe5, INAF6, University of Concepción7, Pontifical Catholic University of Chile8, University of California, Berkeley9, University of Pittsburgh10, University of Lisbon11, Florida State University12, Austral University of Chile13, University of Turku14, Andrés Bello National University15, University of Copenhagen16, Spanish National Research Council17, Monash University18, Seoul National University19, Liverpool John Moores University20, University College Dublin21, Weizmann Institute of Science22, Queen's University Belfast23, Paris Diderot University24, Max Planck Society25, University of Cambridge26
TL;DR: Forster et al. as mentioned in this paper presented 26 rising optical light curves of SN II candidates discovered shortly after explosion by the High Cadence Transient Survey and derived physical parameters based on hydrodynamical models using a Bayesian approach.
Abstract: Type II supernovae (SNe II) originate from the explosion of hydrogen-rich supergiant massive stars. Their first electromagnetic signature is the shock breakout (SBO), a short-lived phenomenon that can last for hours to days depending on the density at shock emergence. We present 26 rising optical light curves of SN II candidates discovered shortly after explosion by the High Cadence Transient Survey and derive physical parameters based on hydrodynamical models using a Bayesian approach. We observe a steep rise of a few days in 24 out of 26 SN II candidates, indicating the systematic detection of SBOs in a dense circumstellar matter consistent with a mass loss rate of $$\dot M$$
> 10−4M⊙ yr−1 or a dense atmosphere. This implies that the characteristic hour-timescale signature of stellar envelope SBOs may be rare in nature and could be delayed into longer-lived circumstellar material SBOs in most SNe II. The shock breakout (SBO) is the first electromagnetic signature of a supernova (SN) explosion. Forster et al. find that in nearly all type II SNe they survey that the SBO occurs on a timescale of days, indicating that the progenitors were surrounded by thick circumstellar matter when they exploded.
107 citations
California Institute of Technology1, Weizmann Institute of Science2, National Institutes of Natural Sciences, Japan3, University of California, Santa Barbara4, Las Cumbres Observatory Global Telescope Network5, University of Washington6, University of Maryland, College Park7, Goddard Space Flight Center8, University of Oxford9, Stockholm University10, Hebrew University of Jerusalem11, Max Planck Society12, Liverpool John Moores University13, Lawrence Berkeley National Laboratory14, University of California, Berkeley15, University of Nova Gorica16, Carnegie Institution for Science17, University of Southampton18
TL;DR: The discovery of iPTF 14gqr is interpreted as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.
Abstract: Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.2 solar masses) and low kinetic energy (≈2 × 1050 ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.
89 citations
National University of La Plata1, National Scientific and Technical Research Council2, Institute for the Physics and Mathematics of the Universe3, California Institute of Technology4, National University of Río Negro5, National Institutes of Natural Sciences, Japan6, Kyoto University7, University of California, Berkeley8, Goddard Space Flight Center9, University of Maryland, College Park10, Florida State University11, Liverpool John Moores University12, University of Arizona13
TL;DR: The serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day, suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.
Abstract: It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.
88 citations
TL;DR: In this paper, the authors present 26 rising optical light curves of Type II supernovae (SNe) discovered shortly after explosion by the High cadence Transient Survey (HiTS) and derive physical parameters based on hydrodynamical models using a Bayesian approach.
Abstract: Type II supernovae (SNe) originate from the explosion of hydrogen-rich supergiant massive stars. Their first electromagnetic signature is the shock breakout, a short-lived phenomenon which can last from hours to days depending on the density at shock emergence. We present 26 rising optical light curves of SN II candidates discovered shortly after explosion by the High cadence Transient Survey (HiTS) and derive physical parameters based on hydrodynamical models using a Bayesian approach. We observe a steep rise of a few days in 24 out of 26 SN II candidates, indicating the systematic detection of shock breakouts in a dense circumstellar matter consistent with a mass loss rate $\dot{M} > 10^{-4} M_\odot yr^{-1}$ or a dense atmosphere. This implies that the characteristic hour timescale signature of stellar envelope SBOs may be rare in nature and could be delayed into longer-lived circumstellar material shock breakouts in most Type II SNe.
79 citations
TL;DR: In this paper, the authors discuss the role of the Japan Society for the Promotion of Science (JPS) and the Basal Project (BP) in the Millennium Science Initiative (MSI).
Abstract: Japan Society for the Promotion of Science
16H07413
17H02864
Basal Project
PFB-03
Ministry of Economy, Development, and Tourism's Millennium Science Initiative
IC120009
Conicyt through the Programme of International Cooperation
DPI20140090
Korea Astronomy and Space Science Institute under the RD programme
3348-20160002
Monash Centre for Astrophysics via the distinguished visitor programme
Deutsche Forschungsgemeinschaft
GR 1717/5
Yukawa Institute for Theoretical Physics at Kyoto University
YITP-T-16-05
63 citations
TL;DR: In this paper, the authors model the late evolution and mass loss history of rapidly rotating Wolf-Rayet stars in the mass range $5\,\rm{M}_{\odot}\dots 100\,
Abstract: We model the late evolution and mass loss history of rapidly rotating Wolf-Rayet stars in the mass range $5\,\rm{M}_{\odot}\dots 100\,\rm{M}_{\odot}$. We find that quasi-chemically homogeneously evolving single stars computed with enhanced mixing retain very little or no helium and are compatible with Type\,Ic supernovae. The more efficient removal of core angular momentum and the expected smaller compact object mass in our lower mass models lead to core spins in the range suggested for magnetar driven superluminous supernovae. Our more massive models retain larger specific core angular momenta, expected for long-duration gamma-ray bursts in the collapsar scenario. Due to the absence of a significant He envelope, the rapidly increasing neutrino emission after core helium exhaustion leads to an accelerated contraction of the whole star, inducing a strong spin-up, and centrifugally driven mass loss at rates of up to $10^{-2}\,\rm{M}_{\odot}~\rm{yr^{-1}}$ in the last years to decades before core collapse. Since the angular momentum transport in our lower mass models enhances the envelope spin-up, they show the largest relative amounts of centrifugally enforced mass loss, i.e., up to 25\% of the expected ejecta mass. Our most massive models evolve into the pulsational pair-instability regime. We would thus expect signatures of interaction with a C/O-rich circumstellar medium for Type~Ic superluminous supernovae with ejecta masses below $\sim 10\,\rm{M}_{\odot}$ and for the most massive engine-driven explosions with ejecta masses above $\sim 30\,\rm{M}_{\odot}$. Signs of such interaction should be observable at early epochs of the supernova explosion, and may be related to bumps observed in the light curves of superluminous supernovae, or to the massive circumstellar CO-shell proposed for Type~Ic superluminous supernova Gaia16apd.
48 citations
TL;DR: In this paper, the authors model the late evolution and mass loss history of rapidly rotating Wolf-Rayet stars in the mass range $5\,\rm{M}_{\odot}\dots 100\,
Abstract: We model the late evolution and mass loss history of rapidly rotating Wolf-Rayet stars in the mass range $5\,\rm{M}_{\odot}\dots 100\,\rm{M}_{\odot}$. We find that quasi-chemically homogeneously evolving single stars computed with enhanced mixing retain very little or no helium and are compatible with Type\,Ic supernovae. The more efficient removal of core angular momentum and the expected smaller compact object mass in our lower mass models lead to core spins in the range suggested for magnetar driven superluminous supernovae. Our more massive models retain larger specific core angular momenta, expected for long-duration gamma-ray bursts in the collapsar scenario. Due to the absence of a significant He envelope, the rapidly increasing neutrino emission after core helium exhaustion leads to an accelerated contraction of the whole star, inducing a strong spin-up, and centrifugally driven mass loss at rates of up to $10^{-2}\,\rm{M}_{\odot}~\rm{yr^{-1}}$ in the last years to decades before core collapse. Since the angular momentum transport in our lower mass models enhances the envelope spin-up, they show the largest relative amounts of centrifugally enforced mass loss, i.e., up to 25\% of the expected ejecta mass. Our most massive models evolve into the pulsational pair-instability regime. We would thus expect signatures of interaction with a C/O-rich circumstellar medium for Type~Ic superluminous supernovae with ejecta masses below $\sim 10\,\rm{M}_{\odot}$ and for the most massive engine-driven explosions with ejecta masses above $\sim 30\,\rm{M}_{\odot}$. Signs of such interaction should be observable at early epochs of the supernova explosion, and may be related to bumps observed in the light curves of superluminous supernovae, or to the massive circumstellar CO-shell proposed for Type~Ic superluminous supernova Gaia16apd.
46 citations
Max Planck Society1, University of Southampton2, University College Dublin3, National Institutes of Natural Sciences, Japan4, University of California, Berkeley5, Liverpool John Moores University6, Australian National University7, University of New South Wales8, Stockholm University9, European Southern Observatory10, University of California, Santa Cruz11, National Central University12, INAF13, Queen's University Belfast14, University of Turku15, Aalto University16, Spanish National Research Council17, Sapienza University of Rome18, University of Pittsburgh19, Weizmann Institute of Science20, University of Warsaw21, Technical University of Denmark22, Johns Hopkins University23, Space Telescope Science Institute24
TL;DR: In this paper, the authors present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program, showing a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw.
Abstract: We present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program. The redshift z = 0.1086 implies a peak brightness of M g = −21.1 mag, placing the object within the regime of superluminous supernovae. We observe a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw, and finally showing ~2000 km s−1 wide Hα and Hβ emission. Relatively narrow Balmer emission (reminiscent of a SN IIn) is present at all times. We also detect coronal lines, indicative of a dense circumstellar medium. We constrain the progenitor wind velocity to ~50–60 km s−1 based on P-Cygni profiles, which is far slower than those present in Wolf–Rayet stars. This may suggest that the progenitor passed through a luminous blue variable phase, or that the wind is instead from a binary companion red supergiant star. At late times we see the ~2000 km s−1 wide Hα emission persisting at high luminosity (~3 × 1040 erg s−1) for at least 100 day, perhaps indicative of additional mass loss at high velocities that could have been ejected by a pulsational pair instability.
43 citations
TL;DR: In this paper, the authors used the Bayesian light-curve fitting code MOSFiT (Modular Open Source Fitter for Transients) to fit the light curves of 37 hydrogen-poor superluminous supernovae assuming a fallback accretion central engine.
Abstract: The energy liberated by fallback accretion has been suggested as a possible engine to power hydrogen-poor superluminous supernovae. We systematically investigate this model using the Bayesian light-curve fitting code MOSFiT (Modular Open Source Fitter for Transients), fitting the light curves of 37 hydrogen-poor superluminous supernovae assuming a fallback accretion central engine. We find that this model can yield good fits to their light curves, with a fit quality that rivals the popular magnetar engine models. Examining our derived parameters for the fallback model, we find the total energy requirements from the accretion disk are estimated to be 0.002 - 0.7 Msun c^2. If we adopt a typical conversion efficiency ~ 1e-3, the required mass to accrete is thus 2 - 700 Msun. Many superluminous supernovae, therefore, require an unrealistic accretion mass, and so only a fraction of these events could be powered by fallback accretion unless the true efficiency is much greater than our fiducial value. The superluminous supernovae that require the smallest amounts of fallback mass still remain to be the fallback accretion powered supernova candidates, but they are difficult to be distinguished solely by their light curve properties.
TL;DR: In this article, a progenitor mass distribution of core-collapse supernova remnants (CCSNRs) in our Galaxy and the Large and Small Magellanic Clouds was investigated for the first time.
Abstract: We investigate a progenitor mass distribution of core-collapse supernova remnants (CCSNRs) in our Galaxy and the Large and Small Magellanic Clouds, for the first time. We count the number of CCSNRs in three mass ranges divided by the zero-age main-sequence mass, $M_{\rm ZAMS}$; A: $M_{\rm ZAMS} 22.5\ {\rm M}_\odot$. Simple compilation of progenitor masses in the literature yields a progenitor mass distribution of $f_{\rm A}: f_{\rm B}: f_{\rm C} =0.24:0.28:0.48$, where $f$ is the number fraction of the progenitors. The distribution is inconsistent with any standard initial mass functions. We notice, however, that previous mass estimates are subject to large systematic uncertainties because most of the relative abundances (X/Si) are not really good probe for the progenitor masses. Instead, we propose to rely only on the Fe/Si ratio which is sensitive to the CO core mass ($M_{\rm COcore}$) and $M_{\rm ZAMS}$. Comparing Fe/Si ratios in SNRs in the literature with the newest theoretical model, we estimate 33 $M_{\rm COcore}$ and $M_{\rm ZAMS}$, leading to a revised progenitor mass distribution of $f_{\rm A}: f_{\rm B}: f_{\rm C} = 0.47: 0.32 : 0.21$. This is consistent with the standard Salpeter initial mass function. However, the relation between $M_{\rm COcore}$ and $M_{\rm ZAMS}$ could be affected by binary evolution, which is not taken into account in this study and should be considered in the future work to derive a better progenitor mass distribution estimate.
Hiroshima University1, Kyoto University2, Konan University3, University of Tokyo4, Tokyo Institute of Technology5, Subaru6, Saitama University7, Institute for the Physics and Mathematics of the Universe8, Kyoto Sangyo University9, National Institutes of Natural Sciences, Japan10, Nagoya University11, Kagoshima University12
TL;DR: In this paper, optical and near-infrared observations of a low-luminosity Type IIP supernova (SN) 2016bkv from the initial rising phase to the plateau phase are presented.
Abstract: We present optical and near-infrared observations of a low-luminosity Type IIP supernova (SN) 2016bkv from the initial rising phase to the plateau phase. Our observations show that the end of the plateau is extended to $\gtrsim 140$ days since the explosion, indicating that this SN takes one of the longest time to finish the plateau phase. among Type IIP SNe (SNe IIP), including low-luminosity (LL) SNe IIP. The line velocities of various ions at the middle of the plateau phase are as low as 1,000--1,500 km s$^{-1}$, which is the lowest even among LL SNe IIP. These measurements imply that the ejecta mass in SN 2016bkv is larger than that of the well-studied LL IIP SN 2003Z. In the early phase, SN 2016bkv shows a strong bump in the light curve. In addition, the optical spectra in this bump phase exhibit a blue continuum accompanied with a narrow H$\alpha$ emission line. These features indicate an interaction between the SN ejecta and the circumstellar matter (CSM) as in SNe IIn. Assuming the ejecta-CSM interaction scenario, the mass loss rate is estimated to be $\sim 1.7 \times 10^{-2} M_{\odot}$ yr$^{-1}$ within a few years before the SN explosion. This is comparable to or even larger than the largest mass loss rate observed for the Galactic red supergiants ($\sim 10^{-3} M_{\odot}$ yr$^{-1}$ for VY CMa). We suggest that the progenitor star of SN 2016bkv experienced a violent mass loss just before the SN explosion.
TL;DR: In this article, the authors present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program, and observe a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw, and finally showing ~2000 km s^-1 wide H-alpha and H-beta emission.
Abstract: We present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program. The redshift z=0.1086 implies a peak brightness of M_g=-21.1 mag, placing the object within the regime of superluminous supernovae. We observe a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw, and finally showing ~2000 km s^-1 wide H-alpha and H-beta emission. Relatively narrow Balmer emission (reminiscent of a SN IIn) is present at all times. We also detect coronal lines, indicative of a dense circumstellar medium. We constrain the progenitor wind velocity to ~50-60 km s^-1 based on P-Cygni profiles, which is far slower than those present in Wolf-Rayet stars. This may suggest that the progenitor passed through a luminous blue variable phase, or that the wind is instead from a binary companion red supergiant star. At late times we see the ~2000 km s^-1 wide H-alpha emission persisting at high luminosity (~3x10^40 erg s^-1) for at least 100 day, perhaps indicative of additional mass loss at high velocities that could have been ejected by a pulsational pair instability.
TL;DR: In this paper, the authors investigated the possibility that OGLE-2014-SN-073 is powered by a fallback accretion following the failed explosion of a massive star.
Abstract: We investigate the possibility that the energetic Type II supernova OGLE-2014-SN-073 is powered by a fallback accretion following the failed explosion of a massive star. Taking massive hydrogen-rich supernova progenitor models, we estimate the fallback accretion rate and calculate the light curve evolution of supernovae powered by the fallback accretion. We find that such fallback accretion powered models can reproduce the overall observational properties of OGLE-2014-SN-073. It may imply that some failed supernovae could be observed as energetic supernovae like OGLE-2014-SN-073 instead of faint supernovae as previously proposed.
TL;DR: In this paper, an X-ray micro-calorimeter onboard the Hitomi spacecraft was used to set an upper limit for emission or absorption features from yet undetected thermal plasma in the 2-12 keV range.
Abstract: The Crab nebula originated from a core-collapse supernova (SN) explosion
observed in 1054 A.D. When viewed as a supernova remnant (SNR), it has an
anomalously low observed ejecta mass and kinetic energy for an Fe-core collapse
SN. Intensive searches were made for a massive shell that solves this
discrepancy, but none has been detected. An alternative idea is that the SN1054
is an electron-capture (EC) explosion with a lower explosion energy by an order
of magnitude than Fe-core collapse SNe. In the X-rays, imaging searches were
performed for the plasma emission from the shell in the Crab outskirts to set a
stringent upper limit to the X-ray emitting mass. However, the extreme
brightness of the source hampers access to its vicinity. We thus employed
spectroscopic technique using the X-ray micro-calorimeter onboard the Hitomi
satellite. By exploiting its superb energy resolution, we set an upper limit
for emission or absorption features from yet undetected thermal plasma in the
2-12 keV range. We also re-evaluated the existing Chandra and XMM-Newton data.
By assembling these results, a new upper limit was obtained for the X-ray
plasma mass of <~ 1Mo for a wide range of assumed shell radius, size, and
plasma temperature both in and out of the collisional equilibrium. To compare
with the observation, we further performed hydrodynamic simulations of the Crab
SNR for two SN models (Fe-core versus EC) under two SN environments (uniform
ISM versus progenitor wind). We found that the observed mass limit can be
compatible with both SN models if the SN environment has a low density of <~
0.03 cm-3 (Fe core) or <~ 0.1 cm-3 (EC) for the uniform density, or a
progenitor wind density somewhat less than that provided by a mass loss rate of
10-5 Mo yr-1 at 20 km s-1 for the wind environment.
TL;DR: In this article, the authors proposed that massive Thorne-Zytkow objects can explode and the explosion energy depends on when the accretion is suppressed, and the maximum possible explosion energy is ~ 1e52 erg and such a high-energy explosion could be observed as an energetic Type II supernova or a superluminous supernova.
Abstract: We propose that massive Thorne-Zytkow objects can explode. A Thorne-Zytkow object is a theoretically predicted star that has a neutron core. When nuclear reactions supporting a massive Thorne-Zytkow object terminate, a strong accretion occurs towards the central neutron core. The accretion rate is large enough to sustain a super-Eddington accretion towards the neutron core. The neutron core may collapse to a black hole after a while. A strong large-scale outflow or a jet can be launched from the super-Eddington accretion disk and the collapsing Thorne-Zytkow object can be turned into an explosion. The ejecta have about 10 Msun but the explosion energy depends on when the accretion is suppressed. We presume that the explosion energy could be as low as ~ 1e47 erg and such a low-energy explosion could be observed like a failed supernova. The maximum possible explosion energy is ~ 1e52 erg and such a high-energy explosion could be observed as an energetic Type II supernova or a superluminous supernova. Explosions of Thorne-Zytkow objects may provide a new path to spread lithium and other heavy elements produced through the irp process such as molybdenum in the Universe.
TL;DR: In this article, the effect of including a magnetar on the light curves of supernovae with H-rich progenitors was explored, and it was shown that bright and long rising morphologies are possible even assuming RSG structures.
Abstract: Context: It has been suggested that some supernovae (SNe) may be powered by a magnetar formed at the moment of the explosion. While this scenario has mostly been applied to hydrogen-free events, it may be possible also for hydrogen-rich objects. Aims: We explore the effect of including a magnetar on the light curves of supernovae with H-rich progenitors. Methods: We have applied a version of our one-dimensional LTE radiation hydrodynamics code that takes into account the relativistic motion of the ejecta caused by the extra energy provided by the magnetar. For a fixed red supergiant (RSG) progenitor, we have obtained a set of light curves that corresponds to different values of the magnetar initial rotation energy and the spin-down timescale. The model is applied to SN~2004em and OGLE-2014-SN-073, two peculiar Type II SNe with long-rising SN1987A-like light curves, although with much larger luminosities. Results: The presence of a plateau phase in either normal or superluminous supernovae is one possible outcome, even if a magnetar is continuously injecting energy into the this http URL other cases, the light curve shows a peak but not a plateau. Also, there are intermediate events with a first peak followed by a slow decline and a late break of the declining slope. Our models show that bright and long rising morphologies are possible even assuming RSG structures. Conclusions: A large number of supernova discoveries per year reveal unexpected new types of explosions. According to our results, SLSNe II-P are to be expected, as well as a variety of light curve morphologies that can all be possible signs of a newly born magnetar.
TL;DR: In this paper, the authors used the Bayesian light-curve fitting code MOSFiT (Modular Open Source Fitter for Transients) to fit the light curves of 37 hydrogen-poor superluminous supernovae assuming a fallback accretion central engine.
Abstract: The energy liberated by fallback accretion has been suggested as a possible engine to power hydrogen-poor superluminous supernovae. We systematically investigate this model using the Bayesian light-curve fitting code MOSFiT (Modular Open Source Fitter for Transients), fitting the light curves of 37 hydrogen-poor superluminous supernovae assuming a fallback accretion central engine. We find that this model can yield good fits to their light curves, with a fit quality that rivals the popular magnetar engine models. Examining our derived parameters for the fallback model, we find the total energy requirements from the accretion disk are estimated to be 0.002 - 0.7 Msun c^2. If we adopt a typical conversion efficiency ~ 1e-3, the required mass to accrete is thus 2 - 700 Msun. Many superluminous supernovae, therefore, require an unrealistic accretion mass, and so only a fraction of these events could be powered by fallback accretion unless the true efficiency is much greater than our fiducial value. The superluminous supernovae that require the smallest amounts of fallback mass still remain to be the fallback accretion powered supernova candidates, but they are difficult to be distinguished solely by their light curve properties.
TL;DR: In this paper, a progenitor mass distribution of core-collapse supernova remnants (CCSNRs) in our Galaxy and the Large and Small Magellanic Clouds was investigated for the first time.
Abstract: We investigate a progenitor mass distribution of core-collapse supernova remnants (CCSNRs) in our Galaxy and the Large and Small Magellanic Clouds, for the first time. We count the number of CCSNRs in three mass ranges divided by the zero-age main-sequence mass, $M_{\rm ZAMS}$; A: $M_{\rm ZAMS} 22.5\ {\rm M}_\odot$. Simple compilation of progenitor masses in the literature yields a progenitor mass distribution of $f_{\rm A}: f_{\rm B}: f_{\rm C} =0.24:0.28:0.48$, where $f$ is the number fraction of the progenitors. The distribution is inconsistent with any standard initial mass functions. We notice, however, that previous mass estimates are subject to large systematic uncertainties because most of the relative abundances (X/Si) are not really good probe for the progenitor masses. Instead, we propose to rely only on the Fe/Si ratio which is sensitive to the CO core mass ($M_{\rm COcore}$) and $M_{\rm ZAMS}$. Comparing Fe/Si ratios in SNRs in the literature with the newest theoretical model, we estimate 33 $M_{\rm COcore}$ and $M_{\rm ZAMS}$, leading to a revised progenitor mass distribution of $f_{\rm A}: f_{\rm B}: f_{\rm C} = 0.47: 0.32 : 0.21$. This is consistent with the standard Salpeter initial mass function. However, the relation between $M_{\rm COcore}$ and $M_{\rm ZAMS}$ could be affected by binary evolution, which is not taken into account in this study and should be considered in the future work to derive a better progenitor mass distribution estimate.
National Institutes of Natural Sciences, Japan1, Tohoku University2, Institute for the Physics and Mathematics of the Universe3, University of Tokyo4, Kyoto University5, San Diego State University6, Konan University7, University of Melbourne8, Swinburne University of Technology9, University of Pittsburgh10, University of Lisbon11, Millennium Institute12, Andrés Bello National University13, Graduate University for Advanced Studies14, Princeton University15
TL;DR: Curtin et al. as discussed by the authors reported the discovery of three supernovae at spectroscopically-confirmed redshifts of 2.399 (HSC16adga), 1.965(HSC17auzg), and 1.851 (hSC17dbpf).
Abstract: We report our first discoveries of high-redshift supernovae from the Subaru HIgh-Z sUpernova CAmpaign (SHIZUCA), a transient survey using Subaru/Hyper Suprime-Cam. We report the discovery of three supernovae at spectroscopically-confirmed redshifts of 2.399 (HSC16adga), 1.965 (HSC17auzg), and 1.851 (HSC17dbpf), and two supernova candidates with host-galaxy photometric redshifts of 3.2 (HSC16apuo) and 4.2 (HSC17dsid), respectively. In this paper, we present their photometric properties and the spectroscopic properties of the confirmed high-redshift supernovae are presented in the accompanying paper Curtin et al. (2018). The supernovae with the confirmed redshifts of z ~ 2 have rest ultraviolet peak magnitudes of around -21 mag, which make them superluminous supernovae. The discovery of three supernovae at z ~ 2 roughly corresponds to an event rate of ~ 900 Gpc-3 yr-1, which is already consistent with the total superluminous supernova rate estimated by extrapolating the local rate based on the cosmic star-formation history. Adding unconfirmed superluminous supernova candidates would increase the event rate. Our superluminous supernova candidates at the redshifts of around 3 and 4 indicate minimum superluminous supernova rates of ~ 400 Gpc-3 yr-1 (z ~ 3) and ~ 500 Gpc-3 yr-1 (z ~ 4). Because we have only performed a pilot search for high-redshift supernovae so far and have not completed selecting all the high-redshift supernova candidates, these rates are lower limits. Our initial results demonstrate the amazing capability of Hyper Suprime-Cam to discover high-redshift supernovae.
TL;DR: In this article, a series of three-dimensional hydrodynamical simulations was performed to investigate how CCSN explosions affect their binary companion, and they found that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta, strongly increases with decreasing binary separation and increasing explosion energy.
Abstract: The progenitors of many core-collapse supernovae (CCSNe) are expected to be in binary systems. By performing a series of three-dimensional hydrodynamical simulations, we investigate how CCSN explosions affect their binary companion. We find that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta, strongly increases with decreasing binary separation and increasing explosion energy. Also, it is foud that the impact effects of CCSN ejecta on the structure of main-sequence (MS) companions, and thus their long term post-explosion evolution, is in general not be dramatic.
Posted Content•
TL;DR: The results of workshop 8 (supernovae) held during the IAU Symposium 339 "Southern Horizons in Time-Domain Astronomy" at Stellenbosch University, South Africa are presented in this article.
Abstract: This contribution presents the results of workshop 8 (supernovae) held during the IAU Symposium 339 "Southern Horizons in Time-Domain Astronomy" at Stellenbosch University, South Africa. Workshop 8 covered a cornucopia of topics with each one having a short presentation by a pre-determined participant followed by a round table discussion. During the first of two sessions, G. Hosseinzadeh and H. Kuncarayakti presented results of their recent works on interacting supernovae. This includes both the intriguing Type Ibn supernova subclass, as well as SN 2017dio, which appears to be the first Type Ic supernova to exhibit signatures of hydrogen-rich circumstellar interaction at all phases. During the second session, M. Sullivan provided an excellent summary related to the future of transient science in the era of Big Data, and the participants discussed strategies to determine which targets and fields should be selected for spectroscopic followup. Workshop 8 concluded with a rather heated discussion regarding the need for the IAU supernova working group to consider to modify the current criteria for a confirmed supernova to receive an official IAU designation.
California Institute of Technology1, Weizmann Institute of Science2, National Institutes of Natural Sciences, Japan3, University of California, Santa Barbara4, Las Cumbres Observatory Global Telescope Network5, University of Washington6, Goddard Space Flight Center7, University of Maryland, College Park8, University of Oxford9, Stockholm University10, Hebrew University of Jerusalem11, Max Planck Society12, Liverpool John Moores University13, University of California, Berkeley14, Lawrence Berkeley National Laboratory15, University of Nova Gorica16, Carnegie Institution for Science17, University of Southampton18
TL;DR: This paper reported the discovery of iPTF 14gqr (SN 2014ft), a Type Ic supernova with a fast evolving light curve indicating an extremely low ejecta mass and low kinetic energy.
Abstract: Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a Type Ic supernova with a fast evolving light curve indicating an extremely low ejecta mass ($\approx 0.2$ solar masses) and low kinetic energy ($\approx 2 \times 10^{50}$ ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended He-rich envelope, likely ejected in an intense pre-explosion mass loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.
01 Aug 2018
TL;DR: In this article, a series of three-dimensional hydrodynamical simulations was performed to investigate how CCSN explosions affect their binary companion, and they found that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta, strongly increases with decreasing binary separation and increasing explosion energy.
Abstract: The progenitors of many core-collapse supernovae (CCSNe) are expected to be in binary systems. By performing a series of three-dimensional hydrodynamical simulations, we investigate how CCSN explosions affect their binary companion. We find that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta, strongly increases with decreasing binary separation and increasing explosion energy. Also, it is foud that the impact effects of CCSN ejecta on the structure of main-sequence (MS) companions, and thus their long term post-explosion evolution, are in general not dramatic.