Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 75) Show all publications
Schulze, S., Fransson, C., Jerkstrand, A., Sollerman, J., Omand, C. M. B., Sarin, N., . . . Pessi, P. J. (2024). 1100 days in the life of the supernova 2018ibb The best pair-instability supernova candidate, to date. Astronomy and Astrophysics, 683, Article ID A223.
Open this publication in new window or tab >>1100 days in the life of the supernova 2018ibb The best pair-instability supernova candidate, to date
Show others...
2024 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 683, article id A223Article in journal (Refereed) Published
Abstract [en]

Stars with zero-age main sequence masses between 140 and 260 M are thought to explode as pair-instability supernovae (PISNe). During their thermonuclear runaway, PISNe can produce up to several tens of solar masses of radioactive nickel, resulting in luminous transients similar to some superluminous supernovae (SLSNe). Yet, no unambiguous PISN has been discovered so far. SN 2018ibb is a hydrogen-poor SLSN at z = 0.166 that evolves extremely slowly compared to the hundreds of known SLSNe. Between mid 2018 and early 2022, we monitored its photometric and spectroscopic evolution from the UV to the near-infrared (NIR) with 2–10 m class telescopes. SN 2018ibb radiated > 3 × 1051 erg during its evolution, and its bolometric light curve reached > 2 × 1044 erg s−1 at its peak. The long-lasting rise of > 93 rest-frame days implies a long diffusion time, which requires a very high total ejected mass. The PISN mechanism naturally provides both the energy source (56Ni) and the long diffusion time. Theoretical models of PISNe make clear predictions as to their photometric and spectroscopic properties. SN 2018ibb complies with most tests on the light curves, nebular spectra and host galaxy, and potentially all tests with the interpretation we propose. Both the light curve and the spectra require 25–44 M of freshly nucleosynthesised 56Ni, pointing to the explosion of a metal-poor star with a helium core mass of 120–130 M at the time of death. This interpretation is also supported by the tentative detection of [Co II] λ 1.025 μm, which has never been observed in any other PISN candidate or SLSN before. We observe a significant excess in the blue part of the optical spectrum during the nebular phase, which is in tension with predictions of existing PISN models. However, we have compelling observational evidence for an eruptive mass-loss episode of the progenitor of SN 2018ibb shortly before the explosion, and our dataset reveals that the interaction of the SN ejecta with this oxygen-rich circumstellar material contributed to the observed emission. That may explain this specific discrepancy with PISN models. Powering by a central engine, such as a magnetar or a black hole, can be excluded with high confidence. This makes SN 2018ibb by far the best candidate for being a PISN, to date.

Keywords
supernovae: individual: SN 2018ibb, supernovae: individual: ATLAS18unu, supernovae: individual: Gaia19cvo supernovae, individual: PS19crg, supernovae: individual: ZTF18acenqto
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-229343 (URN)10.1051/0004-6361/202346855 (DOI)001190051800002 ()2-s2.0-85193033597 (Scopus ID)
Available from: 2024-05-24 Created: 2024-05-24 Last updated: 2024-11-13Bibliographically approved
Chen, P., Gal-Yam, A., Sollerman, J., Schulze, S., Post, R. S., Liu, C., . . . Yan, L. (2024). A 12.4-day periodicity in a close binary system after a supernova. Nature, 625(7994), 253-258
Open this publication in new window or tab >>A 12.4-day periodicity in a close binary system after a supernova
Show others...
2024 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 625, no 7994, p. 253-258Article in journal (Refereed) Published
Abstract [en]

Neutron stars and stellar-mass black holes are the remnants of massive star explosions1. Most massive stars reside in close binary systems2, and the interplay between the companion star and the newly formed compact object has been theoretically explored3, but signatures for binarity or evidence for the formation of a compact object during a supernova explosion are still lacking. Here we report a stripped-envelope supernova, SN 2022jli, which shows 12.4-day periodic undulations during the declining light curve. Narrow Hα emission is detected in late-time spectra with concordant periodic velocity shifts, probably arising from hydrogen gas stripped from a companion and accreted onto the compact remnant. A new Fermi-LAT γ-ray source is temporally and positionally consistent with SN 2022jli. The observed properties of SN 2022jli, including periodic undulations in the optical light curve, coherent Hα emission shifting and evidence for association with a γ-ray source, point to the explosion of a massive star in a binary system leaving behind a bound compact remnant. Mass accretion from the companion star onto the compact object powers the light curve of the supernova and generates the γ-ray emission.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-226987 (URN)10.1038/s41586-023-06787-x (DOI)001143579000018 ()38200292 (PubMedID)2-s2.0-85181900770 (Scopus ID)
Available from: 2024-03-04 Created: 2024-03-04 Last updated: 2024-03-04Bibliographically approved
Solar, M., Michałowski, M. J., Nadolny, J., Galbany, L., Hjorth, J., Zapartas, E., . . . Wróblewski, R. (2024). Binary progenitor systems for Type Ic supernovae. Nature Communications, 15(1), Article ID 7667.
Open this publication in new window or tab >>Binary progenitor systems for Type Ic supernovae
Show others...
2024 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 15, no 1, article id 7667Article in journal (Refereed) Published
Abstract [en]

Core-collapse supernovae are explosions of massive stars at the end of their evolution. They are responsible for metal production and for halting star formation, having a significant impact on galaxy evolution. The details of these processes depend on the nature of supernova progenitors, but it is unclear if Type Ic supernovae (without hydrogen or helium lines in their spectra) originate from core-collapses of very massive stars (>30 M⊙) or from less massive stars in binary systems. Here we show that Type II (with hydrogen lines) and Ic supernovae are located in environments with similar molecular gas densities, therefore their progenitors have comparable lifetimes and initial masses. This supports a binary interaction for most Type Ic supernova progenitors, which explains the lack of hydrogen and helium lines. This finding can be implemented in sub-grid prescriptions in numerical cosmological simulations to improve the feedback and chemical mixing.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-236973 (URN)10.1038/s41467-024-51863-z (DOI)39227590 (PubMedID)2-s2.0-85203005876 (Scopus ID)
Available from: 2024-12-10 Created: 2024-12-10 Last updated: 2024-12-10Bibliographically approved
Schady, P., Yates, R. M., Christensen, L., De Cia, A., Rossi, A., D'Elia, V., . . . Wiseman, P. (2024). Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at z =2-4 using JWST. Monthly notices of the Royal Astronomical Society, 529(3), 2807-2831
Open this publication in new window or tab >>Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at z =2-4 using JWST
Show others...
2024 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 529, no 3, p. 2807-2831Article in journal (Refereed) Published
Abstract [en]

Much of what is known of the chemical composition of the universe is based on emission line spectra from star-forming galaxies. Emission-based inferences are, nevertheless, model-dependent and they are dominated by light from luminous star-forming regions. An alternative and sensitive probe of the metallicity of galaxies is through absorption lines imprinted on the luminous afterglow spectra of long gamma ray bursts (GRBs) from neutral material within their host galaxy. We present results from a JWST/NIRSpec programme to investigate for the first time the relation between the metallicity of neutral gas probed in absorption by GRB afterglows and the metallicity of the star-forming regions for the same host galaxy sample. Using an initial sample of eight GRB host galaxies at z = 2.1–4.7, we find a tight relation between absorption and emission line metallicities when using the recently proposed 𝑅^ metallicity diagnostic (±0.2 dex). This agreement implies a relatively chemically homogeneous multiphase interstellar medium and indicates that absorption and emission line probes can be directly compared. However, the relation is less clear when using other diagnostics, such as R23 and R3. We also find possible evidence of an elevated N/O ratio in the host galaxy of GRB 090323 at z = 4.7, consistent with what has been seen in other z > 4 galaxies. Ultimate confirmation of an enhanced N/O ratio and of the relation between absorption and emission line metallicities will require a more direct determination of the emission line metallicity via the detection of temperature-sensitive auroral lines in our GRB host galaxy sample.

Keywords
gamma-ray burst: general, ISM: abundances, galaxies: abundances, galaxies: high-redshift, galaxies: ISM, quasars: absorption lines
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-228652 (URN)10.1093/mnras/stae677 (DOI)001188770300012 ()2-s2.0-85188705507 (Scopus ID)
Available from: 2024-04-26 Created: 2024-04-26 Last updated: 2024-04-26Bibliographically approved
Sarin, N. & Schulze, S. (2024). Heavy-element production in a compact object merger observed by JWST. Nature, 626, 737-741
Open this publication in new window or tab >>Heavy-element production in a compact object merger observed by JWST
2024 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 626, p. 737-741Article in journal (Refereed) Published
Abstract [en]

The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs)1, sources of high-frequency gravitational waves (GWs)2 and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process)3. Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers4,5,6 and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs. 7,8,9,10,11,12). We obtained James Webb Space Telescope (JWST) mid-infrared imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns, which we interpret as tellurium (atomic mass A = 130) and a very red source, emitting most of its light in the mid-infrared owing to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy-element nucleosynthesis across the Universe.

National Category
Atom and Molecular Physics and Optics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-227416 (URN)10.1038/s41586-023-06759-1 (DOI)001169196100001 ()37879361 (PubMedID)2-s2.0-85182219102 (Scopus ID)
Available from: 2024-03-14 Created: 2024-03-14 Last updated: 2024-04-29Bibliographically approved
Das, K. K., Kasliwal, M. M., Sollerman, J., Fremling, C., Irani, I., Leung, S.-C., . . . Zolkower, J. (2024). Probing Presupernova Mass Loss in Double-peaked Type Ibc Supernovae from the Zwicky Transient Facility. Astrophysical Journal, 972(1), Article ID 91.
Open this publication in new window or tab >>Probing Presupernova Mass Loss in Double-peaked Type Ibc Supernovae from the Zwicky Transient Facility
Show others...
2024 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 972, no 1, article id 91Article in journal (Refereed) Published
Abstract [en]

Eruptive mass loss of massive stars prior to supernova (SN) explosion is key to understanding their evolution and end fate. An observational signature of pre-SN mass loss is the detection of an early, short-lived peak prior to the radioactive-powered peak in the lightcurve of the SN. This is usually attributed to the SN shock passing through an extended envelope or circumstellar medium. Such an early peak is common for double-peaked Type IIb SNe with an extended hydrogen envelope but uncommon for normal Type Ibc SNe with very compact progenitors. In this paper, we systematically study a sample of 14 double-peaked Type Ibc SNe out of 475 Type Ibc SNe detected by the Zwicky Transient Facility. The rate of these events is ∼3%-9% of Type Ibc SNe. A strong correlation is seen between the peak brightness of the first and the second peak. We perform a holistic analysis of this sample’s photometric and spectroscopic properties. We find that six SNe have ejecta mass less than 1.5 M ⊙. Based on the nebular spectra and lightcurve properties, we estimate that the progenitor masses for these are less than ∼12 M ⊙. The rest have an ejecta mass >2.4 M ⊙ and a higher progenitor mass. This sample suggests that the SNe with low progenitor masses undergo late-time binary mass transfer. Meanwhile, the SNe with higher progenitor masses are consistent with wave-driven mass loss or pulsation-pair instability-driven mass-loss simulations.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-237867 (URN)10.3847/1538-4357/ad595f (DOI)001299545000001 ()2-s2.0-85202564173 (Scopus ID)
Available from: 2025-01-15 Created: 2025-01-15 Last updated: 2025-01-15Bibliographically approved
Sarin, N., Hübner, M., Omand, C. M. B., Setzer, C. N., Schulze, S., Adhikari, N., . . . Lin, E.-T. (2024). REDBACK: a Bayesian inference software package for electromagnetic transients. Monthly notices of the Royal Astronomical Society, 531(1), 1203-1227
Open this publication in new window or tab >>REDBACK: a Bayesian inference software package for electromagnetic transients
Show others...
2024 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 531, no 1, p. 1203-1227Article in journal (Refereed) Published
Abstract [en]

Fulfilling the rich promise of rapid advances in time-domain astronomy is only possible through confronting our observations with physical models and extracting the parameters that best describe what we see. Here, we introduce REDBACK; a Bayesian inference software package for electromagnetic transients. REDBACK provides an object-orientated PYTHON interface to over 12 different samplers and over 100 different models for kilonovae, supernovae, gamma-ray burst afterglows, tidal disruption events, engine-driven transients among other explosive transients. The models range in complexity from simple analytical and semi-analytical models to surrogates built upon numerical simulations accelerated via machine learning. REDBACK also provides a simple interface for downloading and processing data from various catalogues such as Swift and FINK. The software can also serve as an engine to simulate transients for telescopes such as the Zwicky Transient Facility and Vera Rubin with realistic cadences, limiting magnitudes, and sky coverage or a hypothetical user-constructed survey or a generic transient for target-of-opportunity observations with different telescopes. As a demonstration of its capabilities, we show how REDBACK can be used to jointly fit the spectrum and photometry of a kilonova, enabling a more powerful, holistic probe into the properties of a transient. We also showcase general examples of how REDBACK can be used as a tool to simulate transients for realistic surveys, fit models to real, simulated, or private data, multimessenger inference with gravitational waves, and serve as an end-to-end software toolkit for parameter estimation and interpreting the nature of electromagnetic transients.

Keywords
black hole–neutron star mergers, gamma-ray bursts, neutron star mergers, software: data analysis, transients: supernovae, transients: tidal disruption events
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-235659 (URN)10.1093/mnras/stae1238 (DOI)001228290700002 ()2-s2.0-85193978793 (Scopus ID)
Available from: 2024-11-18 Created: 2024-11-18 Last updated: 2024-11-18Bibliographically approved
Brennan, S. J., Schulze, S., Lunnan, R., Sollerman, J., Yan, L., Fransson, C., . . . Rodriguez, H. (2024). SN 2021adxl: A luminous nearby interacting supernova in an extremely low-metallicity environment. Astronomy and Astrophysics, 690, Article ID A259.
Open this publication in new window or tab >>SN 2021adxl: A luminous nearby interacting supernova in an extremely low-metallicity environment
Show others...
2024 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 690, article id A259Article in journal (Refereed) Published
Abstract [en]

SN 2021adxl is a slowly evolving, luminous, Type IIn supernova with asymmetric emission line profiles, similar to the well-studied SN 2010jl. We present extensive optical, near-ultraviolet, and near-infrared photometry and spectroscopy covering ~1.5 years post discovery. SN 2021adxl occurred in an unusual environment, atop a vigorously star-forming region that is offset from its host galaxy core. The appearance of Lyα and O ii, as well as the compact core, would classify the host of SN 2021adxl as a “Blueberry” galaxy, analogous to higher redshift, low-metallicity, star-forming dwarf “Green Pea” galaxies. Using several abundance indicators, we find a metallicity of the explosion environment of only [Formula Presented], the lowest reported metallicity for a Type IIn SN environment. SN 2021adxl reaches a peak magnitude of Mr ≈ −20.2 mag and since discovery, SN 2021adxl has faded by only ~4 magnitudes in the r band with a cumulative radiated energy of ~1.5 × 1050 erg over 18 months. SN 2021adxl shows strong signs of interaction with a complex circumstellar medium, seen by the detection of X-rays, revealed by the detection of coronal emission lines, and through multicomponent hydrogen and helium profiles. In order to further understand this interaction, we model the Hα profile using a Monte Carlo electron scattering code. The blueshifted high-velocity component is consistent with emission from a radially thin spherical shell resulting in the broad emission components due to electron scattering. Using the velocity evolution of this emitting shell, we find that the SN ejecta collide with circumstellar material of at least [Formula Presented] assuming a steady-state mass-loss rate of ~4−6 × 10−3 M yr−1 for the first ~200 days of evolution. SN 2021adxl was last observed to be slowly declining at ~0.01 mag d−1, and if this trend continues, SN 2021adxl will remain observable after its current solar conjunction. Continuing the observations of SN 2021adxl may reveal signatures of dust formation or an infrared excess, similar to that seen for SN 2010jl.

Keywords
circumstellar matter, HII regions, ISM: abundances, supernovae: general
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-237231 (URN)10.1051/0004-6361/202349036 (DOI)2-s2.0-85207930344 (Scopus ID)
Available from: 2025-01-09 Created: 2025-01-09 Last updated: 2025-01-09Bibliographically approved
Irani, I., Chen, P., Morag, J., Schulze, S., Gal-Yam, A., Strotjohann, N. L., . . . Medford, M. S. (2024). SN 2022oqm-A Ca-rich Explosion of a Compact Progenitor Embedded in C/O Circumstellar Material. Astrophysical Journal, 962(2), Article ID 109.
Open this publication in new window or tab >>SN 2022oqm-A Ca-rich Explosion of a Compact Progenitor Embedded in C/O Circumstellar Material
Show others...
2024 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 962, no 2, article id 109Article in journal (Refereed) Published
Abstract [en]

We present the discovery and analysis of SN 2022oqm, a Type Ic supernova (SN) detected <1 day after the explosion. The SN rises to a blue and short-lived (2 days) initial peak. Early-time spectral observations of SN 2022oqm show a hot (40,000 K) continuum with high ionization C and O absorption features at velocities of 4000 km s−1, while its photospheric radius expands at 20,000 km s−1, indicating a pre-existing distribution of expanding C/O material. After ∼2.5 days, both the spectrum and light curves evolve into those of a typical SN Ic, with line velocities of ∼10,000 km s−1, in agreement with the evolution of the photospheric radius. The optical light curves reach a second peak at t ≈ 15 days. By t = 60 days, the spectrum of SN 2022oqm becomes nearly nebular, displaying strong Ca ii and [Ca ii] emission with no detectable [O i], marking this event as Ca-rich. The early behavior can be explained by 10−3M of optically thin circumstellar material (CSM) surrounding either (1) a massive compact progenitor such as a Wolf–Rayet star, (2) a massive stripped progenitor with an extended envelope, or (3) a binary system with a white dwarf. We propose that the early-time light curve is powered by both the interaction of the ejecta with the optically thin CSM and shock cooling (in the massive star scenario). The observations can be explained by CSM that is optically thick to X-ray photons, is optically thick in the lines as seen in the spectra, and is optically thin to visible-light continuum photons that come either from downscattered X-rays or from the shock-heated ejecta. Calculations show that this scenario is self-consistent.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-226985 (URN)10.3847/1538-4357/ad04d7 (DOI)001159919400001 ()2-s2.0-85184936369 (Scopus ID)
Available from: 2024-03-05 Created: 2024-03-05 Last updated: 2024-03-05Bibliographically approved
Gkini, A., Lunnan, R., Schulze, S., Dessart, L., Brennan, S. J., Sollerman, J., . . . Young, D. R. (2024). SN2020zbf: A fast-rising hydrogen-poor superluminous supernova with strong carbon lines. Astronomy and Astrophysics, 685, Article ID A20.
Open this publication in new window or tab >>SN2020zbf: A fast-rising hydrogen-poor superluminous supernova with strong carbon lines
Show others...
2024 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 685, article id A20Article in journal (Refereed) Published
Abstract [en]

SN 2020zbf is a hydrogen-poor superluminous supernova (SLSN) at z = 0.1947 that shows conspicuous C II features at early times, in contrast to the majority of H-poor SLSNe. Its peak magnitude is Mg = −21.2 mag and its rise time (≲26.4 days from first light) places SN 2020zbf among the fastest rising type I SLSNe. We used spectra taken from ultraviolet (UV) to near-infrared wavelengths to identify spectral features. We paid particular attention to the C II lines as they present distinctive characteristics when compared to other events. We also analyzed UV and optical photometric data and modeled the light curves considering three different powering mechanisms: radioactive decay of 56Ni, magnetar spin-down, and circumstellar medium (CSM) interaction. The spectra of SN 2020zbf match the model spectra of a C-rich low-mass magnetar-powered supernova model well. This is consistent with our light curve modeling, which supports a magnetar-powered event with an ejecta mass Mej = 1.5 M. However, we cannot discard the CSM-interaction model as it may also reproduce the observed features. The interaction with H-poor, carbon-oxygen CSM near peak light could explain the presence of C II emission lines. A short plateau in the light curve around 35–45 days after peak, in combination with the presence of an emission line at 6580 Å, can also be interpreted as being due to a late interaction with an extended H-rich CSM. Both the magnetar and CSM-interaction models of SN 2020zbf indicate that the progenitor mass at the time of explosion is between 2 and 5 M. Modeling the spectral energy distribution of the host galaxy reveals a host mass of 108.7 M, a star formation rate of 0.24−0.12+0.41 M yr−1, and a metallicity of ∼0.4 Z.

Keywords
supernovae: general, supernovae: individual: SN 2020zbf
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-231531 (URN)10.1051/0004-6361/202348166 (DOI)001231008100002 ()2-s2.0-85192368350 (Scopus ID)
Available from: 2024-07-23 Created: 2024-07-23 Last updated: 2024-07-23Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6797-1889

Search in DiVA

Show all publications