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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. Type Ic supernovae (SNe) originate either from the core collapse of very massive stars or from less massive stars in binary systems. Here, the authors show that progenitors of Type II and Ic SNe have comparable lifetimes and initial masses, which supports binary interaction for most Type Ic SNe progenitors.

A black hole can launch a powerful relativistic jet after it tidally disrupts a star. If this jet fortuitously aligns with our line of sight, the overall brightness is Doppler boosted by several orders of magnitude. Consequently, such on-axis relativistic tidal disruption events have the potential to unveil cosmological (redshift z > 1) quiescent black holes and are ideal test beds for understanding the radiative mechanisms operating in super-Eddington jets. Here we present multiwavelength (X-ray, UV, optical and radio) observations of the optically discovered transient AT 2022cmc at z = 1.193. Its unusual X-ray properties, including a peak observed luminosity of ≳1048 erg s−1, systematic variability on timescales as short as 1,000 s and overall duration lasting more than 30 days in the rest frame, are traits associated with relativistic tidal disruption events. The X-ray to radio spectral energy distributions spanning 5–50 days after discovery can be explained as synchrotron emission from a relativistic jet (radio), synchrotron self-Compton (X-rays) and thermal emission similar to that seen in low-redshift tidal disruption events (UV/optical). Our modelling implies a beamed, highly relativistic jet akin to blazars but requires extreme matter domination (that is, a high ratio of electron-to-magnetic-field energy densities in the jet) and challenges our theoretical understanding of jets.By modelling the radio, optical, UV and X-ray data of the unusually bright cosmological explosion AT 2022cmc, Pasham et al. argue for the presence of a highly collimated jet moving at ≳99.99% the speed of light.

Type Ia supernovae are thermonuclear explosions of white dwarf stars. They play a central role in the chemical evolution of the Universe and are an important measure of cosmological distances. However, outstanding questions remain about their origins. Despite extensive efforts to obtain natal information from their earliest signals, observations have thus far failed to identify how the majority of them explode. Here, we present infant-phase detections of SN 2018aoz from a very low brightness of −10.5 AB absolute magnitude, revealing a hitherto unseen plateau in the B band that results in a rapid redward colour evolution between 1.0 and 12.4 hours after the estimated epoch of first light. The missing B -band flux is best explained by line-blanket absorption from Fe-peak elements in the outer 1% of the ejected mass. The observed B  −  V colour evolution of the supernova also matches the prediction from an over-density of Fe-peak elements in the same outer 1% of the ejected mass, whereas bluer colours are expected from a purely monotonic distribution of Fe-peak elements. The presence of excess nucleosynthetic material in the extreme outer layers of the ejecta points to enhanced surface nuclear burning or extended subsonic mixing processes in some normal type Ia SN explosions. Very early observations of a type Ia supernova—from within one hour of explosion—show a red colour that develops and rapidly disappears. These data provide information on the initial explosion mechanism: surface nuclear burning on the white dwarf or extreme mixing of the nuclear burning process.

. Bright and homogeneous, thermonuclear, or type Ia, supernovae (SNeIa) are our best extragalactic distance indicators. Since the 60s, SNeIa have been used as cosmological tools, initially, to estimate the current expansion rate of the Universe, the Hubble constant. Decades ago SNeIa were discovered by chance, in many cases by amateurs. Advances in the instrumentation, techniques and new observational strategies allowed in the 80s to discover SNe in scheduled surveys. Moreover, through calibration relations, a high precision in extragalactic distance determinations was achieved, allowing SNIa observations to reveal the dynamics of the Universe. The Nobel prize in Physics in 2011 was awarded to the leaders of two independent teams “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae”. This is a brief and incomplete story of SNeIa as cosmological tools. In the Madrasah of Granada (Spain), built in 1349 by the Nasrid monarch Yosuf the 1st, Astronomy was one of the disciplines included in the studies. On the Madrasah walls, a calligraphic decoration reads: “make study shine like stars”. It is a good motto for our 4th Azarquiel School of Astronomy.

Dust associated with various stellar sources in galaxies at all cosmic epochs remains a controversial topic, particularly whether supernovae play an important role in dust production. We report evidence of dust formation in the cold, dense shell behind the ejecta–circumstellar medium (CSM) interaction in the Type Ia-CSM supernova (SN) 2018evt three years after the explosion, characterized by a rise in mid-infrared emission accompanied by an accelerated decline in the optical radiation of the SN. Such a dust-formation picture is also corroborated by the concurrent evolution of the profiles of the Hα emission line. Our model suggests enhanced CSM dust concentration at increasing distances from the SN as compared to what can be expected from the density profile of the mass loss from a steady stellar wind. By the time of the last mid-infrared observations at day +1,041, a total amount of 1.2 ± 0.2 × 10 −2   M ⊙ of new dust has been formed by SN 2018evt, making SN 2018evt one of the most prolific dust factories among supernovae with evidence of dust formation. The unprecedented witness of the intense production procedure of dust may shed light on the perceptions of dust formation in cosmic history. By day 1,041 after explosion, SN Ia-CSM 2018evt had produced an estimated 0.01 solar masses of dust in the cold, dense shell behind the supernova ejecta–circumstellar medium interaction, ranking it as one of the most prolific dust-producing supernovae ever recorded.

We present three studies that use supernova (SN) environments within host galaxies (HGs) to constrain SNe properties. These studies are ordered from an indirect approximation to a direct determination of the environmental parameters of the SN. We find correlations between the galactocentric distance and several parameters measured from both the SN light-curve (LC) and the host galaxy spectroscopy. We are able to recover and strength previous results pointing to a sequence on the progenitor mass of different SN types. We also confirm no significant difference in the elemental abundances of the environment where different SN types exploded, measured with a more powerful technique such as Integral Field Spectroscopy (IFS).

We present a Principal Component Analysis (PCA) of the V band light-curves of a sample of more than 100 nearby Core collapse supernovae (CC SNe) from [Anderson et al. (2014)]. We used different reference epochs in order to extract the common properties of these light-curves and searched for correlations to some physical parameters such as the burning of 56Ni, and morphological light-curve parameters such as the length of the plateau, the stretch of the light-curve, and the decrements in brightness after maximum and after the plateau. We also used these similarities to create SNe II light-curve templates that will be used in the future for standardize these objects and determine cosmological distances.

This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg2 area along the celestial equator. This data release is comprised of all transient sources brighter than r 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN Ia sample and assuming a flat ΛCDM cosmology, we determine M = 0.315 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7 .

We report the discovery of a peculiar X-ray transient, EP240408a, by Einstein Probe (EP) and follow-up studies made with EP , Swift , NICER , GROND, ATCA and other ground-based multiwavelength telescopes. The new transient was first detected with Wide-field X-ray Telescope (WXT) on board EP on April 8th, 2024, manifested in an intense yet brief X-ray flare lasting for 12 s. The flare reached a peak flux of 3.9 × 10 −9 erg cm −2 s −1 in 0.5–4 keV, ∼300 times brighter than the underlying X-ray emission detected throughout the observation. Rapid and more precise follow-up observations by EP /FXT, Swift and NICER confirmed the finding of this new transient. Its X-ray spectrum is non-thermal in 0.5–10 keV, with apower-law photon index varying within 1.8–2.5. The X-ray light curve shows a plateau lasting for ∼4 d, followed by a steep decay till becoming undetectable ∼10 d after the initial detection. Based on its temporal property and constraints from previous EP observations, an unusual timescale in the range of 7–23 d is found for EP240408a, which is intermediate between the commonly found fast and long-term transients. No counterparts have been found in optical and near-infrared, with the earliest observation at 17 h after the initial X-ray detection, suggestive of intrinsically weak emission in these bands. We demonstrate that the remarkable properties of EP240408a are inconsistent with any of the transient types known so far, by comparison with, in particular, jetted tidal disruption events, gamma-ray bursts, X-ray binaries and fast blue optical transients. The nature of EP240408a thus remains an enigma. We suggest that EP240408a may represent a new type of transients with intermediate timescales of the order of ∼10 d. The detection and follow-ups of more of such objects are essential for revealing their origin.

This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg² area along the celestial equator. This data release is comprised of all transient sources brighter than r ≃ 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN Ia sample and assuming a flat ΛCDM cosmology, we determine ΩM  = 0.315 ± 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7σ.