arXiv subjects

M. C. Bersten

Publications and source records attributed to M. C. Bersten.

16 recordsLinked to original sources

arXiv2025

Hydrodynamical modeling of SN 2025kg associated with the Fast X-ray Transient EP250108a

Supernovae (SNe) associated with X-Ray Flashes (XRFs) are extremely rare. Therefore, the discovery of each new object in this class offers a unique opportunity to improve our understanding about their origins and potential connection with other high-energy phenomena. SN 2025kg is one of the most recent events discovered in this category, and exhibits a double-peaked light curve, with an initial cooling phase followed by the main peak. Here, we investigate the possible mechanisms powering its bolometric light curve and expansion velocities, using numerical calculations to simulate the explosion. We found that low ejecta masses (Mej ~ 2 Msun) and moderate explosion energies (E ~ 2e51 erg) are required to reproduce the data. Our models also show that a large amount of nickel (M_Ni = 0.85 Msun) is needed to achieve the high luminosity of SN 2025kg, which makes this scenario difficult to sustain. As an alternative, we explore a model in which a millisecond magnetar serves as the primary energy source. A magnetar with a spin period of 3 ms, approximately, and a magnetic field of 28e14 G gives an adequate match to the data. To account for the early cooling phase, we assume the presence of a dense circumstellar material surrounding the progenitor, with a mass of 0.27 Msun and an extension of 500 Rsun. A comparison and modeling of a select group of SNe--SN 2006aj, SN 2020bvc and SN 2023pel--is also presented. A remarkable similarity emerges between SN 2025kg and SN 2023pel. As SN 2023pel was recently proposed to be powered by a magnetar, this further supports the magnetar scenario for SN 2025kg.

astro-ph.HE↗

arXiv2025

The nebular phase of SN 2024ggi: a low-mass progenitor with no signs of interaction

Context: SN 2024ggi is a Type II supernova (SN) discovered in the nearby galaxy NGC 3621 (D $\approx6.7\pm0.d$ Mpc) on 2024 April 03.21 UT. Its proximity enabled a detailed investigation of the SN's properties and its progenitor star. This work focuses on the optical evolution of SN 2024ggi at the nebular phase. Aims: We investigate the progenitor properties and possible asymmetries in the ejecta by studying the nebular phase evolution between days 287 and 400 after the explosion. Methods: We present optical photometry and spectroscopy of SN 2024ggi during the nebular phase, obtained with the Las Campanas and Gemini South Observatories. Four nebular spectra were taken at 287, 288, 360, and 396 days post-explosion, supplemented by late-time $uBVgri$-band photometry spanning $320-400$ days. The analysis of the nebular emission features is performed to probe ejecta asymmetries. Based on the [O I] flux and [O I]/[Ca II] ratio, and comparisons with spectra models from the literature, we arrive to an estimate of the progenitor mass. Additionally, we construct the bolometric light curve from optical photometry and near-infrared data to derive the synthesized nickel mass. Results: Our analysis suggests a progenitor zero-age-main-sequence mass between $12-15 M_\odot$. The late-time bolometric light curve is consistent with a synthesized $^{56}$Ni mass of $0.05-0.06 M_\odot$. The line profiles exhibit only minor changes over the observed period and suggest a roughly symmetrical ejecta, with a possible clump of oxygen-rich material moving towards the observer. No signatures of circumstellar material interaction are detected up to 400 days after the explosion.

astro-ph.SR↗

arXiv2025

A magnetar powers the luminous supernova 2023pel, associated with a long gamma-ray burst

We explore SN 2023pel, the most recent event associated with gamma-ray bursts (GRBs), specifically GRB 230812B. SN 2023pel has a high luminosity and low expansion velocities compared to other GRB-SNe. These properties seem difficult to reconcile with a single nickel power source. We searched for models that can explain the properties of this event. We calculated a grid of hydrodynamic models based on pre-SN structures derived from evolutionary calculations. We compared our models with observations of SN~2023pel and selected our preferred model using statistical analysis, taking both light curves and expansion velocities into account. This allowed us to derive a set of physical properties for SN~2023pel. Our models suggest that the most probable scenario involves a millisecond magnetar as the primary power source, supplemented by energy from radioactive decay. Our preferred model has a spin period of P = 3.2 ms, a magnetic field of B = 28 x 10^14 G, an explosion energy of 2.3 foe, a nickel mass of M_Ni= 0.24 solar masses, and an ejected mass of 3.4 solar masses. Alternatively, we find that a purely nickel-powered model also provides a good match with the observations, though M_Ni > 0.8 solar masses are always required. However, the combination of such high values of M_Ni and low M_ej is difficult to reconcile, indicating that this scenario is less probable. We have also identified a specific region within the peak luminosity-velocity plane where an additional energy source beyond nickel may be necessary to power SNe with characteristics similar to SN~2023pel. Our study indicates that an additional energy source beyond radioactive decay is essential to explain the high brightness and relatively low expansion velocities of SN 2023pel. A magnetar-powered model, similar to the models proposed for the very luminous GRB-SN 2011kl, aligns well with these characteristics.

astro-ph.HE↗

arXiv2025

SN 2024ggi: another year, another striking Type II supernova

SN 2024ggi is a Type II supernova that exploded in the nearby galaxy NGC 3621 at a distance of approximately 7 Mpc, making it one of the closest supernovae of the decade. This SN shows clear signs of interaction with a dense circumstellar material, and several studies have investigated the properties of its possible progenitor star using pre-explosion data. In this work we aim to constrain the progenitor properties of SN 2024ggi by performing hydrodynamical modeling of its bolometric light curve and expansion velocities. We present photometric and spectroscopic observations of SN 2024ggi obtained in the Complejo Astronómico El Leoncito, in Las Campanas Observatory, and in Las Cumbres Observatory Global Telescope Network, spanning from 2 to 106 days after explosion. We constructed its bolometric light curve and we characterize it by calculating its morphological parameters. Then, we computed a grid of one dimensional explosion models for evolved stars with varying masses and estimated the properties of the progenitor star of SN 2024ggi by comparing the models to the observations. The observed bolometric luminosity and expansion velocities are well-matched by a model involving the explosion of a star in the presence of a close circumstellar material (CSM), with a zero-age main sequence mass of $\mathrm{M_{ZAMS}}$ = 15 $M_{\odot}$, a pre-SN mass and radius of 14.1 $M_{\odot}$ and 517 $R_{\odot}$, respectively, an explosion energy of $1.3\times10^{51}$ erg, and a nickel mass below 0.035 $M_{\odot}$. Our analysis suggests that the progenitor suffered a mass-loss rate of $4 \times 10^{-3}$ $M_{\odot}$yr$^{-1}$, confined to a distance of 3000 $R_{\odot}$. The CSM distribution is likely a two-component structure that consists of a compact core and an extended tail. This analysis represents the first hydrodynamical model of SN 2024ggi with a complete coverage of the plateau phase.

astro-ph.HE↗

arXiv2023

The progenitor of SN 2023ixf from hydrodynamical modelling

Context: Supernova (SN) 2023ixf is among the most nearby Type II SNe in the last decades. As such, there is a wealth of observational data of both the event itself and of the associated object identified in pre-explosion images. This allows to perform a variety of studies that aim at determining the SN properties and the nature of the putative progenitor star. Modelling of the light curve is a powerful method to derive physical properties independently of direct progenitor analyses. Aims: To investigate the physical nature of SN 2023ixf based on hydrodynamical modelling of its bolometric light curve and expansion velocities during the complete photospheric phase. Methods: A grid of one dimensional explosions was calculated for evolved stars of different masses. We derived properties of SN 2023ixf and its progenitor by comparing our models with the observations. Results: The observations are well reproduced by the explosion of a star with zero age main sequence mass of f $M_\mathrm{ZAMS} = 12 M_\odot$ , an explosion energy of $1.2 \times 10^{51}$ erg, and a nickel production of 0.05M . This indicates that SN 2023ixf was a normal event. Our modelling suggests a limit of $M_\mathrm{ZAMS} < 15 M_\odot$ and therefore favours the low mass range among the results from pre-explosion observations.

astro-ph.SR↗

arXiv2023

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 $β$=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.

astro-ph.SR↗

arXiv2023

SN 2021gno: a Calcium-rich transient with double-peaked light curves

We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN)~2021gno by the "Precision Observations of Infant Supernova Explosions" (POISE) project, starting less than two days after the explosion. Given its intermediate luminosity, fast photometric evolution, and quick transition to the nebular phase with spectra dominated by [Ca~II] lines, SN~2021gno belongs to the small family of Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared with only four other Calcium-rich events. The projected distance from the center of the host galaxy is not as large as other objects in this family. The initial optical light-curve peaks coincide with a very quick decline of the UV flux, indicating a fast initial cooling phase. Through hydrodynamical modelling of the bolometric light curve and line velocity evolution, we found that the observations are compatible with the explosion of a highly-stripped massive star with an ejecta mass of $0.8\,M_\odot$ and a $^{56}$Ni mass of $0.024~M_{\odot}$. The initial cooling phase (first light curve peak) is explained by the presence of an extended circumstellar material comprising $\sim$$10^{-2}\,M_{\odot}$ with an extension of $1100\,R_{\odot}$. We discuss if hydrogen features are present in both maximum-light and nebular spectra, and its implications in terms of the proposed progenitor scenarios for Calcium-rich transients.

astro-ph.HE↗

arXiv2022

Type II supernovae from the Carnegie Supernova Project-I. III. Understanding SN II diversity through correlations between physical and observed properties

SNe II show great photometric and spectroscopic diversity which is attributed to the varied physical characteristics of their progenitor and explosion properties. In this study, the third of a series of papers where we analyse a sample of SNe II observed by the Carnegie Supernova Project-I, we present correlations between their observed and physical properties. Our analysis shows that explosion energy is the physical property that correlates with the highest number of parameters. We recover previously suggested relationships between the hydrogen-rich envelope mass and the plateau duration, and find that more luminous SNe II with higher expansion velocities, faster declining light curves, and higher Ni masses are consistent with higher energy explosions. In addition, faster declining SNe II are also compatible with more concentrated Ni in the inner regions of the ejecta. Positive trends are found between the initial mass, explosion energy, and Ni mass. While the explosion energy spans the full range explored with our models, the initial mass generally arises from a relatively narrow range. Observable properties were measured from our grid of models to determine the effect of each physical parameter on the observed SN II diversity. We argue that explosion energy is the physical parameter causing the greatest impact on SN II diversity, when assuming standard single-star evolution as in the models used in this study. The inclusion of pre-SN models assuming higher mass loss produces a significant increase in the strength of some correlations, particularly those between the progenitor hydrogen-rich envelope mass and the plateau and optically thick phase durations. These differences clearly show the impact of having different treatments of stellar evolution, implying that changes in the assumption of standard single-star evolution are necessary for a complete understanding of SN II diversity.

astro-ph.SR↗

arXiv2022

Type II supernovae from the Carnegie Supernova Project-I. II. Physical parameter distributions from hydrodynamical modelling

Linking supernovae to their progenitors is a powerful method for furthering our understanding of the physical origin of their observed differences, while at the same time testing stellar evolution theory. In this second study of a series of three papers where we characterise SNe II to understand their diversity, we derive progenitor properties (initial and ejecta masses, and radius), explosion energy, $^{56}$Ni mass, and its degree of mixing within the ejecta for a large sample of SNe II. This dataset was obtained by the Carnegie Supernova Project-I and is characterised by a high cadence of their optical and NIR light curves and optical spectra that were homogeneously observed and processed. A large grid of hydrodynamical models and a fitting procedure based on MCMC methods were used to fit the bolometric light curve and the evolution of the photospheric velocity of 53 SNe II. We infer ejecta masses between 7.9 and 14.8 $M_{\odot}$, explosion energies between 0.15 and 1.40 foe, and $^{56}$Ni masses between 0.006 and 0.069 $M_{\odot}$. We define a subset of 24~SNe (the `gold sample') with well-sampled bolometric light curves and expansion velocities for which we consider the results more robust. Most SNe~II in the gold sample ($\sim$88%) are found with ejecta masses in the range of $\sim$8-10 $M_{\odot}$, coming from low zero-age main-sequence masses (9-12 $M_{\odot}$). The modelling of the initial-mass distribution of the gold sample gives an upper mass limit of 21.3$^{+3.8}_{-0.4}$ $M_{\odot}$ and a much steeper distribution than that for a Salpeter massive-star IMF. This IMF incompatibility is due to the large number of low-mass progenitors found -- when assuming standard stellar evolution. This may imply that high-mass progenitors lose more mass during their lives than predicted. However, a deeper analysis of all stellar evolution assumptions is required to test this hypothesis.

astro-ph.SR↗

arXiv2021

Type II supernovae from the Carnegie Supernova Project-I. I. Bolometric light curves of 74 SNe II using uBgVriYJH photometry

The present study is the first of a series of three papers where we characterise the type II supernovae (SNe~II) from the Carnegie Supernova Project-I to understand their diversity in terms of progenitor and explosion properties. In this first paper, we present bolometric light curves of 74 SNe~II. We outline our methodology to calculate the bolometric luminosity, which consists of the integration of the observed fluxes in numerous photometric bands ($uBgVriYJH$) and black-body (BB) extrapolations to account for the unobserved flux at shorter and longer wavelengths. BB fits were performed using all available broadband data except when line blanketing effects appeared. Photometric bands bluer than $r$ that are affected by line blanketing were removed from the fit, which makes near-infrared (NIR) observations highly important to estimate reliable BB extrapolations to the infrared. BB fits without NIR data produce notably different bolometric light curves, and therefore different estimates of SN~II progenitor and explosion properties when data are modelled. We present two methods to address the absence of NIR observations: (a) colour-colour relationships from which NIR magnitudes can be estimated using optical colours, and (b) new prescriptions for bolometric corrections as a function of observed SN~II colours. Using our 74 SN~II bolometric light curves, we provide a full characterisation of their properties based on several observed parameters. We measured magnitudes at different epochs, as well as durations and decline rates of different phases of the evolution. An analysis of the light-curve parameter distributions was performed, finding a wide range and a continuous sequence of observed parameters which is consistent with previous analyses using optical light curves.

astro-ph.SR↗

arXiv2021

The Blue Supergiant Progenitor of the Supernova Imposter AT~2019krl

Extensive archival \textit{Hubble Space Telescope}, \textit{Spitzer Space Telescope}, and Large Binocular Telescope imaging of the recent intermediate-luminosity transient, AT~2019krl in M74, reveal a bright optical and mid-infrared progenitor star. While the optical peak of the event was missed, a peak was detected in the infrared with an absolute magnitude of $M_{4.5\,μ{\rm m}} = -18.4$ mag, leading us to infer a visual-wavelength peak absolute magnitude of $-$13.5 to $-$14.5. The pre-discovery light curve indicated no outbursts over the previous 16\,yr. The colors, magnitudes, and inferred temperatures of the progenitor best match a 13--14 M$_{\sun}$ yellow or blue supergiant (BSG), if only foreground extinction is taken into account, or a hotter and more massive star, if any additional local extinction is included. A pre-eruption spectrum of the star reveals strong H$α$ and [N~{\sc ii}] emission with wings extending to $\pm 2000$\,km\,s$^{-1}$. The post-eruption spectrum is fairly flat and featureless with only H$α$, \ion{Na}{1}~D, [\ion{Ca}{2}], and the \ion{Ca}{2} triplet in emission. As in many previous intermediate-luminosity transients, AT~2019krl shows remarkable observational similarities to luminous blue variable (LBV) giant eruptions, SN~2008S-like events, and massive-star mergers. However, the information about the pre-eruption star favors either a relatively unobscured BSG or a more extinguished LBV with $M > 20$\,M$_{\sun}$ likely viewed pole-on.

astro-ph.SR↗

arXiv2021

The double-peaked type Ic Supernova 2019cad: another SN 2005bf-like object

We present the photometric and spectroscopic evolution of supernova (SN) 2019cad during the first $\sim100$ days from explosion. Based on the light curve morphology, we find that SN 2019cad resembles the double-peaked type Ib/c SN 2005bf and the type Ic PTF11mnb. Unlike those two objects, SN 2019cad also shows the initial peak in the redder bands. Inspection of the g-band light curve indicates the initial peak is reached in $\sim8$ days, while the r band peak occurred $\sim15$ days post-explosion. A second and more prominent peak is reached in all bands at $\sim45$ days past explosion, followed by and fast decline from $\sim60$ days. During the first 30 days, the spectra of SN 2019cad show the typical features of a type Ic SN, however, after 40 days, a blue continuum with prominent lines of Si II $λ6355$ and C II $λ6580$ is observed again. Comparing the bolometric light curve to hydrodynamical models, we find that SN 2019cad is consistent with a pre-SN mass of 11 M$_{\odot}$, and an explosion energy of $3.5\times 10^{51}$ erg. The light curve morphology can be reproduced either by a double-peaked $^{56}$Ni distribution with an external component of 0.041 M$_{\odot}$ and an internal component of 0.3 M$_{\odot}$ or a double-peaked $^{56}$Ni distribution plus magnetar model (P $\sim11$ ms and B $\sim26\times 10^{14}$ G). If SN 2019cad were to suffer from significant host reddening (which cannot be ruled out), the $^{56}$Ni model would require extreme values, while the magnetar model would still be feasible.

astro-ph.HE↗

arXiv2020

Progenitor properties of type II supernovae: fitting to hydrodynamical models using Markov chain Monte Carlo methods

The progenitor and explosion properties of type II supernovae (SNe II) are fundamental to understand the evolution of massive stars. Special interest has been given to the range of initial masses of their progenitors, but despite the efforts made, it is still uncertain. Direct imaging of progenitors in pre-explosion images point out an upper initial mass cutoff of $\sim$18$M_{\odot}$. However, this is in tension with previous studies in which progenitor masses inferred by light curve modelling tend to favour high-mass solutions. Moreover, it has been argued that light curve modelling alone cannot provide a unique solution for the progenitor and explosion properties of SNe II. We develop a robust method which helps us to constrain the physical parameters of SNe II by fitting simultaneously their bolometric light curve and the evolution of the photospheric velocity to hydrodynamical models using statistical inference techniques. Pre-supernova red supergiant models were created using the stellar evolution code MESA, varying the initial progenitor mass. The explosion of these progenitors was then processed through hydrodynamical simulations, where the explosion energy, synthesised nickel mass, and the latter's spatial distribution within the ejecta were changed. We compare to observations via Markov chain Monte Carlo methods. We apply this method to a well-studied set of SNe with an observed progenitor in pre-explosion images and compare with results in the literature. Progenitor mass constraints are found to be consistent between our results and those derived by pre-SN imaging and the analysis of late-time spectral modelling. We have developed a robust method to infer progenitor and explosion properties of SN II progenitors which is consistent with other methods in the literature, which suggests that hydrodynamical modelling is able to accurately constrain physical properties of SNe II.

astro-ph.SR↗

arXiv2020

DES16C3cje: A low-luminosity, long-lived supernova

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 $\lesssim1500$ km s$^{-1}$, and the light curve shows an initial peak that fades after 50 days before slowly rebrightening over a further 100 days to reach an absolute brightness of M$_r\sim -15.5$ mag. The decline rate of the late-time light curve is then slower than that expected from the powering by radioactive decay of $^{56}$Co 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 $^{56}$Ni production of 0.075 M$_{\odot}$ from a $\sim15$ M$_{\odot}$ red supergiant progenitor typical of other SNe II, or ii) a relatively compact $\sim40$ M$_{\odot}$ star, explosion energy of 1 foe, and 0.08 M$_{\odot}$ of $^{56}$Ni. Both scenarios require additional energy input to explain the late-time light curve, which is consistent with fallback accretion at a rate of $\sim0.5\times{10^{-8}}$ M$_{\odot}$ s$^{-1}$.

hep-ph↗

arXiv2018

A surge of light at the birth of a supernova

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.

astro-ph.HE↗

arXiv2015

Nebular phase observations of the type-Ib supernova iPTF13bvn favour a binary progenitor

Aims. We present and analyse late-time observations of the type-Ib supernova with possible pre-supernova progenitor detection, iPTF13bvn, taken at $\sim$300 days after the explosion, and discuss these in the context of constraints on the supernova's progenitor. Previous studies have proposed two possible natures for the progenitor of the supernova, i.e. a massive Wolf-Rayet star or a lower-mass star in close binary system. Methods. Our observations show that the supernova has entered the nebular phase, with the spectrum dominated by Mg~I]$λλ$4571, [O~I]$λλ$6300, 6364, and [Ca~II]$λλ$7291, 7324 emission lines. We measured the emission line fluxes to estimate the core oxygen mass and compare the [O~I]/[Ca~II] line ratio with other supernovae. Results. The core oxygen mass of the supernova progenitor was estimated to be $\lesssim$0.7 M$_\odot$, which implies initial progenitor mass not exceeding $\sim$15 -- 17 M$_\odot$. Since the derived mass is too small for a single star to become a Wolf-Rayet star, this result lends more support to the binary nature of the progenitor star of iPTF13bvn. The comparison of [O~I]/[Ca~II] line ratio with other supernovae also shows that iPTF13bvn appears to be in close association with the lower-mass progenitors of stripped-envelope and type-II supernovae.

astro-ph.HE↗