Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh

We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modeling identifies the nuclear burning layers and physical mechanisms that produce the major emission lines, and the diagnostic potential of these. We compare the model calculations with data on the three best observed Type IIb SNe to-date - SN 1993J, SN 2008ax, and SN 2011dh. Oxygen nucleosynthesis depends sensitively on the main-sequence mass of the star and modeling of the [O I] 6300, 6364 lines constrains the progenitors of these three SNe to the M_ZAMS=12-16 M_sun range (ejected oxygen masses 0.3-0.9 M_sun), with SN 2011dh towards the lower end and SN 1993J towards the upper end of the range. The high ejecta masses from M_ZAMS >= 17 M_sun progenitors give rise to brighter nebular phase emission lines than observed. Nucleosynthesis analysis thus supports a scenario of low/moderate mass progenitors for Type IIb SNe, and by implication an origin in binary systems. We demonstrate how oxygen and magnesium recombination lines may be combined to diagnose the magnesium mass in the SN ejecta. For SN 2011dh, a magnesium mass of of 0.02-0.14 M_sun is derived, which gives a Mg/O production ratio consistent with the solar value. Nitrogen left in the He envelope from CNO-burning gives strong [N II] 6548, 6583 emission lines that dominate over H-alpha emission in our models. The hydrogen envelopes of Type IIb SNe are too small and dilute to produce any noticeable H-alpha emission or absorption after ~150 days, and nebular phase emission seen around 6550 A is in many cases likely caused by [N II] 6548, 6583. Finally, the influence of radiative transport on the emergent line profiles is investigated...(abridged)Comment: Published versio

Circumstellar interaction models for the early bolometric light curve of SN 2023ixf

SNe II show growing evidence of interaction with CSM surrounding their progenitor stars as a consequence of enhanced mass loss during the last years of the progenitor's life. We present an analysis of the progenitor mass-loss history of SN2023ixf, a nearby SN II showing signs of interaction. We calculate the early-time bolometric light curve (LC) for SN2023ixf based on the integration of the observed flux covering UV, optical and NIR bands, and black-body extrapolations for the unobserved flux. Our calculations spot the sudden increase to maximum luminosity and temperature, in addition to the subsequent fall, displaying an evident peak. This is the first time that this phase can be precisely estimated for a SN II showing interesting characteristics as: 1) slope changes during the rise to maximum luminosity; and 2) a very sharp peak with a maximum luminosity of $\sim$3$\times$10$^{45}$erg s$^{-1}$. We use the bolometric LC of SN2023ixf to test the calibrations of bolometric corrections against colours from the literature. In addition, we include SN2023ixf into some of the available calibrations to extend their use to earlier epochs. Comparison of the observed bolometric LC to SN II explosion models with CSM interaction suggests a progenitor mass-loss rate of 3$\times$10$^{-3}M_{\odot}$yr$^{-1}$ confined to 12000$R_{\odot}$ and a wind acceleration parameter of $\beta$=5. This model reproduces the early bolometric LC, expansion velocities, and the epoch of disappearance of interacting lines in the spectra. This model indicates that the wind was launched $\sim$80yr before the explosion. If the effect of the wind acceleration is not taken into account, the enhanced wind must have developed over the final months to years prior to the SN, which may not be consistent with the lack of outburst detection in pre-explosion images over the last $\sim$20yr before explosion.Comment: Submitted to A&

Optical photometry and spectroscopy of the 1987A-like supernova 2009mw

We present optical photometric and spectroscopic observations of the 1987A-like supernova (SN) 2009mw. Our $BVRI$ and $g'r'i'z'$ photometry covers 167 days of evolution, including the rise to the light curve maximum, and ends just after the beginning of the linear tail phase. We compare the observational properties of SN 2009mw with those of other SNe belonging to the same subgroup, and find that it shows similarities to several objects. The physical parameters of the progenitor and the SN are estimated via hydrodynamical modelling, yielding an explosion energy of $1$ foe, a pre-SN mass of $19\,{\rm M_{\odot}}$, a progenitor radius as $30\,{\rm R_{\odot}}$ and a $^{56}$Ni mass as $0.062\,{\rm M_{\odot}}$. These values indicate that the progenitor of SN 2009mw was a blue supergiant star, similar to the progenitor of SN 1987A. We examine the host environment of SN 2009mw and find that it emerged from a population with slightly sub-solar metallicty.Comment: 11 pages, 12 figures, accepted for publication in MNRA

The Carnegie Supernova Project I: methods to estimate host-galaxy reddening of stripped-envelope supernovae

We aim to improve upon contemporary methods to estimate host-galaxy reddening of stripped-envelope (SE) supernovae (SNe). To this end the Carnegie Supernova Project (CSP-I) SE SNe photometry data release, consisting of nearly three dozen objects, is used to identify a minimally reddened sub-sample for each traditionally defined spectroscopic sub-types (i.e, SNe~IIb, SNe~Ib, SNe~Ic). Inspection of the optical and near-infrared (NIR) colors and color evolution of the minimally reddened sub-samples reveals a high degree of homogeneity, particularly between 0d to +20d relative to B-band maximum. This motivated the construction of intrinsic color-curve templates, which when compared to the colors of reddened SE SNe, yields an entire suite of optical and NIR color excess measurements. Comparison of optical/optical vs. optical/NIR color excess measurements indicates the majority of the CSP-I SE SNe suffer relatively low amounts of reddening and we find evidence for different R_(V)^(host) values among different SE SN. Fitting the color excess measurements of the seven most reddened objects with the Fitzpatrick (1999) reddening law model provides robust estimates of the host visual-extinction A_(V)^(host) and R_(V)^(host). In the case of the SE SNe with relatively low amounts of reddening, a preferred value of R_(V)^(host) is adopted for each sub-type, resulting in estimates of A_(V)^(host) through Fitzpatrick (1999) reddening law model fits to the observed color excess measurements. Our analysis suggests SE SNe reside in galaxies characterized by a range of dust properties. We also find evidence SNe Ic are more likely to occur in regions characterized by larger R_(V)^(host) values compared to SNe IIb/Ib and they also tend to suffer more extinction. These findings are consistent with work in the literature suggesting SNe Ic tend to occur in regions of on-going star formation.Comment: Abstract abridged to fit allowed limit. Resubmitted to A&A, 34 pages, 19 figures, 6 tables. Constructive comments welcome

Detection of the Gravitational Lens Magnifying a Type Ia Supernova

Objects of known brightness, like Type Ia supernovae (SNIa), can be used to measure distances. If a massive object warps spacetime to form multiple images of a background SNIa, a direct test of cosmic expansion is also possible. However, these lensing events must first be distinguished from other rare phenomena. Recently, a supernova was found to shine much brighter than normal for its distance, which resulted in a debate: was it a new type of superluminous supernova or a normal SNIa magnified by a hidden gravitational lens? Here we report that a spectrum obtained after the supernova faded away shows the presence of a foreground galaxy--the first found to strongly magnify a SNIa. We discuss how more lensed SNIa may be found than previously predicted.Comment: 32 pages, 10 figures. Accepted for publication in Scienc

HYDRODYNAMICAL MODELS OF TYPE II-P SUPERNOVA LIGHT CURVES

RESUMEN Presentamos los progresos en el modelado de curvas de luz de supernovas de tipo II plateau (SNe II-P) obtenidos a partir de un código hidrodinámico unidimensional que recientemente hemos desarrollado. Usando modelos iniciales simples (polítropas) reprodujimos el comportamiento global de las curvas de luz observadas y analizamos la sensibilidad de la curva de luz a la variación de los parámetros libres. ABSTRACT We present progress in light curve models of type II-P supernovae (SNe II-P) obtained using a newly developed, one-dimensional hydrodynamic code. Using simple initial models (polytropes), we reproduced the global behavior of the observed light curves and we analyzed the sensitivity of the light curves to the variation of free parameters

Properties of Newly Formed Dust Grains in The Luminous Type IIn Supernova 2010jl

Supernovae (SNe) have been proposed to be the main production sites of dust grains in the Universe. Our knowledge on their importance to dust production is, however, limited by observationally poor constraints on the nature and amount of dust particles produced by individual SNe. In this paper, we present a spectrum covering optical through near-Infrared (NIR) light of the luminous Type IIn supernova (SN IIn) 2010jl around one and half years after the explosion. This unique data set reveals multiple signatures of newly formed dust particles. The NIR portion of the spectrum provides a rare example where thermal emission from newly formed hot dust grains is clearly detected. We determine the main population of the dust species to be carbon grains at a temperature of ~1,350 - 1,450K at this epoch. The mass of the dust grains is derived to be ~(7.5 - 8.5) x 10^{-4} Msun. Hydrogen emission lines show wavelength-dependent absorption, which provides a good estimate on the typical size of the newly formed dust grains (~0.1 micron, and most likely <~0.01 micron). We attribute the dust grains to have been formed in a dense cooling shell as a result of a strong SN-circumstellar media (CSM) interaction. The dust grains occupy ~10% of the emitting volume, suggesting an inhomogeneous, clumpy structure. The average CSM density is required to be >~3 x 10^{7} cm^{-3}, corresponding to a mass loss rate of >~0.02 Msun yr^{-1} (for a mass loss wind velocity of ~100 km s^{-1}). This strongly supports a scenario that SN 2010jl and probably other luminous SNe IIn are powered by strong interactions within very dense CSM, perhaps created by Luminous Blue Variable (LBV)-like eruptions within the last century before the explosion.Comment: 18 pages, 11 figures. Accepted by ApJ on 30 July 2013. The accepted version was submitted on 8 July 2013, and the original version was submitted on 3 March 201

Human variants in the Neuronal Basic Helix-Loop-Helix/ Per-Arnt-Sim (bHLH/PAS) transcription factor complex NPAS4/ARNT2 disrupt function

Neuronal Per-Arnt-Sim homology (PAS) Factor 4 (NPAS4) is a neuronal activity-dependent transcription factor which heterodimerises with ARNT2 to regulate genes involved in inhibitory synapse formation. NPAS4 functions to maintain excitatory/inhibitory balance in neurons, while mouse models have shown it to play roles in memory formation, social interaction and neurodegeneration. NPAS4 has therefore been implicated in a number of neuropsychiatric or neurodegenerative diseases which are underpinned by defects in excitatory/inhibitory balance. Here we have explored a broad set of non-synonymous human variants in NPAS4 and ARNT2 for disruption of NPAS4 function. We found two variants in NPAS4 (F147S and E257K) and two variants in ARNT2 (R46W and R107H) which significantly reduced transcriptional activity of the heterodimer on a luciferase reporter gene. Furthermore, we found that NPAS4.F147S was unable to activate expression of the NPAS4 target gene BDNF due to reduced dimerisation with ARNT2. Homology modelling predicts F147 in NPAS4 to lie at the dimer interface, where it appears to directly contribute to protein/protein interaction. We also found that reduced transcriptional activation by ARNT2 R46W was due to disruption of nuclear localisation. These results provide insight into the mechanisms of NPAS4/ARNT dimerisation and transcriptional activation and have potential implications for cognitive phenotypic variation and diseases such as autism, schizophrenia and dementia.David C. Bersten, John B. Bruning, Daniel J. Peet, Murray L. Whitela