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We present the first Hubble diagram of superluminous supernovae (SLSNe) out to a redshift of two, together with constraints on the matter density, ωM, and the dark energy equation-of-state parameter, w(p/ρ). We build a sample of 20 cosmologically useful SLSNe I based on light curve and spectroscopy quality cuts. We confirm the robustness of the peak-decline SLSN I standardization relation with a larger data set and improved fitting techniques than previous works. We then solve the SLSN model based on the above standardization via minimization of the χ2 computed from a covariance matrix that includes statistical and systematic uncertainties. For a spatially flat Λ cold dark matter (ΛCDM) cosmological model, we find $\Omega{\rm M}=0.38^{+0.24}_{-0.19}$, with an rms of 0.27 mag for the residuals of the distance moduli. For a w0waCDM cosmological model, the addition of SLSNe I to a 'baseline' measurement consisting of Planck temperature together with Type Ia supernovae, results in a small improvement in the constraints of w0 and wa of 4 per cent. We present simulations of future surveys with 868 and 492 SLSNe I (depending on the configuration used) and show that such a sample can deliver cosmological constraints in a flat ΛCDM model with the same precision (considering only statistical uncertainties) as current surveys that use Type Ia supernovae, while providing a factor of 2-3 improvement in the precision of the constraints on the time variation of dark energy, w0 and wa. This paper represents the proof of concept for superluminous supernova cosmology, and demonstrates they can provide an independent test of cosmology in the high-redshift (z > 1) universe.

We present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is CCv=9.10-1.27+1.56× 10-5SNe yr-1Mpc-3, h703 at za = 0.028, and the SESN volumetric rate is SEv=2.41-0.64+0.81× 10-5SNe yr-1Mpc-3, h703. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z ≤ 0.2 of SLSN-Iv=35-13+25 SNe yr-1Gpc-3, h703, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of ∼1/810+1500-94, and of SLSN-I to all CCSN types of ∼1/3500+2800-720. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM∗ < 9.5 M·) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of 1/300+380-170 and 1/1700+1800-720 for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass.

We present a sample of 21 hydrogen-free superluminous supernovae (SLSNe-I) and one hydrogen-rich SLSN (SLSN-II) detected during the five-year Dark Energy Survey (DES). These SNe, located in the redshift range 0.220 < z < 1.998, represent the largest homogeneously selected sample of SLSN events at high redshift. We present the observed g, r, i, z light curves for these SNe, which we interpolate using Gaussian processes. The resulting light curves are analysed to determine the luminosity function of SLSNe-I, and their evolutionary timescales. The DES SLSN-I sample significantly broadens the distribution of SLSN-I light-curve properties when combined with existing samples from the literature. We fit a magnetar model to our SLSNe, and find that this model alone is unable to replicate the behaviour of many of the bolometric light curves. We search the DES SLSN-I light curves for the presence of initial peaks prior to the main light-curve peak. Using a shock breakout model, our Monte Carlo search finds that 3 of our 14 events with pre-max data display such initial peaks. However, 10 events show no evidence for such peaks, in some cases down to an absolute magnitude of

We present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is CCv=9.10-1.27+1.56× 10-5SNe yr-1Mpc-3, h703 at za = 0.028, and the SESN volumetric rate is SEv=2.41-0.64+0.81× 10-5SNe yr-1Mpc-3, h703. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z ≤ 0.2 of SLSN-Iv=35-13+25 SNe yr-1Gpc-3, h703, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of ∼1/810+1500-94, and of SLSN-I to all CCSN types of ∼1/3500+2800-720. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM∗ < 9.5 M·) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of 1/300+380-170 and 1/1700+1800-720 for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass.

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 of1500 km s-1, and the light curve shows an initial peak that fades after 50 d before slowly rebrightening over a further 100 d to reach an absolute brightness of Mr ∼-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 56Co, 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 56Ni production of 0.075 M· from an ∼15 M· red supergiant progenitor typical of other SNe II, or (ii) a relatively compact ∼40 M· star, explosion energy of 1 foe, and 0.08 M· of 56Ni. Both scenarios require additional energy input to explain the late-time light curve, which is consistent with fallback accretion at a rate of ∼0.5 × 10-8 M· s-1.

We present a sample of 21 hydrogen-free superluminous supernovae (SLSNe-I) and one hydrogen-rich SLSN (SLSN-II) detected during the five-year Dark Energy Survey (DES). These SNe, located in the redshift range 0.220 < z < 1.998, represent the largest homogeneously selected sample of SLSN events at high redshift. We present the observed g, r, i, z light curves for these SNe, which we interpolate using Gaussian processes. The resulting light curves are analysed to determine the luminosity function of SLSNe-I, and their evolutionary timescales. The DES SLSN-I sample significantly broadens the distribution of SLSN-I light-curve properties when combined with existing samples from the literature. We fit a magnetar model to our SLSNe, and find that this model alone is unable to replicate the behaviour of many of the bolometric light curves. We search the DES SLSN-I light curves for the presence of initial peaks prior to the main light-curve peak. Using a shock breakout model, our Monte Carlo search finds that 3 of our 14 events with pre-max data display such initial peaks. However, 10 events show no evidence for such peaks, in some cases down to an absolute magnitude of

We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift z ≊ 2. DES16C2nm was discovered by the Dark Energy Survey (DES) Supernova Program, with follow-up photometric data from the Hubble Space Telescope, Gemini, and the European Southern Observatory Very Large Telescope supplementing the DES data. Spectroscopic observations confirm DES16C2nm to be at z = 1.998, and spectroscopically similar to Gaia16apd (a SLSN-I at z = 0.102), with a peak absolute magnitude of U = -22.26 ± 0.06. The high redshift of DES16C2nm provides a unique opportunity to study the ultraviolet (UV) properties of SLSNe-I. Combining DES16C2nm with 10 similar events from the literature, we show that there exists a homogeneous class of SLSNe-I in the UV (λrest ≊ 2500 Å), with peak luminosities in the (rest-frame) U band, and increasing absorption to shorter wavelengths. There is no evidence that the mean photometric and spectroscopic properties of SLSNe-I differ between low (z < 1) and high redshift (z > 1), but there is clear evidence of diversity in the spectrum at λrest < 2000 Å, possibly caused by the variations in temperature between events. No significant correlations are observed between spectral line velocities and photometric luminosity. Using these data, we estimate that SLSNe-I can be discovered to z = 3.8 by DES. While SLSNe-I are typically identified from their blue observed colors at low redshift (z < 1), we highlight that at z > 2 these events appear optically red, peaking in the observer-frame z-band. Such characteristics are critical to identify these objects with future facilities such as the Large Synoptic Survey Telescope, Euclid, and the Wide-field Infrared Survey Telescope, which should detect such SLSNe-I to z = 3.5, 3.7, and 6.6, respectively.

Quasi-periodic eruptions (QPEs) are luminous bursts of soft X-rays from the nuclei of galaxies, repeating on timescales of hours to weeks 1-5 . The mechanism behind these rare systems is uncertain, but most theories involve accretion disks around supermassive black holes (SMBHs) undergoing instabilities 6-8 or interacting with a stellar object in a close orbit 9-11 . It has been suggested that this disk could be created when the SMBH disrupts a passing star 8,11 , implying that many QPEs should be preceded by observable tidal disruption events (TDEs). Two known QPE sources show long-term decays in quiescent luminosity consistent with TDEs 4,12 and two observed TDEs have exhibited X-ray flares consistent with individual eruptions 13,14 . TDEs and QPEs also occur preferentially in similar galaxies 15 . However, no confirmed repeating QPEs have been associated with a spectroscopically confirmed TDE or an optical TDE observed at peak brightness. Here we report the detection of nine X-ray QPEs with a mean recurrence time of approximately 48 h from AT2019qiz, a nearby and extensively studied optically selected TDE 16 . We detect and model the X-ray, ultraviolet (UV) and optical emission from the accretion disk and show that an orbiting body colliding with this disk provides a plausible explanation for the QPEs., (© 2024. The Author(s).)

Background: Arrhythmia-induced cardiomyopathy (AIC) is characterized by improvement in left ventricular ejection fraction (LVEF) following arrhythmia treatment. Predictors of recovery in LVEF are not well understood., Objective: We evaluated predictors of AIC recovery in a large multicenter cohort., Methods: In total, 243 patients (age 65 ± 11, 73% male) with AIC caused by atrial fibrillation (49%), atrial tachycardia (20%), and premature ventricular contractions (PVCs; 31%) were treated and included. LVEF was assessed before and after treatment. Patients were stratified by arrhythmia duration (known [KN, n = 132] vs. unknown [UKN, n = 111]), arrhythmia type, LVEF, and presence of structural heart disease (SHD)., Results: Arrhythmia treatment was rhythm control in 95%. Median arrhythmia duration in the KN group was 47 months (25-75th percentile, 24-80 months). Post treatment LVEF was higher in KN group (55.9 ± 7 vs. 46.2 ± 12%; p < .0001) but the degree of LVEF improvement was similar (21.2 ± 9 vs. 19.4 ± 11; p = .16). Comparing highest quartile (longest arrhythmia duration) versus the rest of the KN group, the extent of LVEF improvement was similar (21.5 ± 8 vs. 21 ± 9%; p = .1). Patients in lowest index LVEF quartile (n = 74) had more PVC-induced AIC, greater EF improvement after treatment (24 ± 17 vs. 19 ± 7%; p < .0001) but lower post treatment EF (45 ± 14 vs. 54 ± 8%; p < .0001) versus other patients. Patients with SHD had lower index EF (28 ± 8 vs. 34 ± 8%; p < .0001) and lower final EF (47 ± 12 vs. 56 ± 7; p ≪ .0001). In multivariate regression, low index LVEF predicted myocardial recovery (odds ratio, 11.4; p < .005)., Conclusions: In this AIC cohort, LVEF improved regardless of arrhythmia duration or type but those with PVCs had lower index LVEF and had less recovery. Low index LVEF predicted LVEF recovery following arrhythmia treatment., (© 2021 Wiley Periodicals LLC.)

Aims: Permanent pacemaker placement (PPM) is often required after valvular surgery and is especially common following tricuspid valve surgery [tricuspid valve repair or replacement (TVR)]. Literature suggests that surgical intervention for isolated tricuspid valve disease is becoming more prevalent. Predictors of PPM dependency following TVR are currently unknown and would be clinically useful from a prognostication standpoint., Methods and Results: We conducted a multicentre, retrospective study to assess perioperative factors of TVR that predispose to PPM placement and long-term PPM dependency from 2008 to 2014. Regression analysis was used to determine independent predictors of PPM implantation. A total of 237 patients (age 66 ± 15 years, 29% male) were studied, and the incidence of PPM placement following TVR was 27% (65/237). No significant differences were observed between those who received PPM and those who did not in age (P = 0.092), gender (P = 0.359), and co-morbidities. Regression analysis identified cross-clamp time >60 min (OR 4.1, 95% CI 1.3-12.9, P = 0.015) and concomitant mitral valve surgery (OR 3.8, 95% CI 1.2-12.2, P = 0.026) as independent risk factors for PPM following TVR. Long-term PPM dependency data were only available in 28 patients who received PPM with 14 of these patients developing long-term dependence. The only statistically significant difference noted was an increased frequency of coronary artery disease in the long-term dependent group vs. the non-dependent group (64% vs. 14%, P = 0.018)., Conclusion: Cross-clamp time >60 min and concomitant mitral valve surgery were independent predictors of PPM implantation following TVR. Long-term PPM dependency is more prevalent after TVR than other types of valvular surgery., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Gravitational waves were discovered with the detection of binary black-hole mergers and they should also be detectable from lower-mass neutron-star mergers. These are predicted to eject material rich in heavy radioactive isotopes that can power an electromagnetic signal. This signal is luminous at optical and infrared wavelengths and is called a kilonova. The gravitational-wave source GW170817 arose from a binary neutron-star merger in the nearby Universe with a relatively well confined sky position and distance estimate. Here we report observations and physical modelling of a rapidly fading electromagnetic transient in the galaxy NGC 4993, which is spatially coincident with GW170817 and with a weak, short γ-ray burst. The transient has physical parameters that broadly match the theoretical predictions of blue kilonovae from neutron-star mergers. The emitted electromagnetic radiation can be explained with an ejected mass of 0.04 ± 0.01 solar masses, with an opacity of less than 0.5 square centimetres per gram, at a velocity of 0.2 ± 0.1 times light speed. The power source is constrained to have a power-law slope of -1.2 ± 0.3, consistent with radioactive powering from r-process nuclides. (The r-process is a series of neutron capture reactions that synthesise many of the elements heavier than iron.) We identify line features in the spectra that are consistent with light r-process elements (atomic masses of 90-140). As it fades, the transient rapidly becomes red, and a higher-opacity, lanthanide-rich ejecta component may contribute to the emission. This indicates that neutron-star mergers produce gravitational waves and radioactively powered kilonovae, and are a nucleosynthetic source of the r-process elements.

Aims: To estimate the cost-effectiveness and resourcing implications of universal alcohol screening and brief intervention (SBI) programmes in primary care in England., Methods: This was a health economic model, combining evidence of the effectiveness and health care resource requirements of SBI activities with existing epidemiological modelling of the relationship between alcohol consumption and health harms., Results: Screening patients on registration with a family doctor would steadily capture ~40% of the population over a 10-year programme; screening patients at next primary care consultation would capture 96% of the population over the same period, but with high resourcing needs in the first year. The registration approach, delivered by a practice nurse, provides modest cost savings to the health care system of £120 m over 30 years. Health gains over the same period amount to 32,000 quality-adjusted life years (QALYs). This SBI programme still appears cost-effective (at £6900 per QALY gained) compared with no programme, under pessimistic effectiveness assumptions. Switching to a consultation approach, delivered by a doctor, would incur an incremental net cost of £108 m, with incremental health gains equivalent to 92,000 QALYs, giving an incremental cost-effectiveness ratio of £1175 per QALY gained compared with current practice., Conclusion: A universal programme of alcohol SBI in primary care is estimated to be cost-effective, under all but the most pessimistic assumptions for programme costs and effectiveness. Policymakers should ensure that SBI programmes are routinely evaluated and followed up, given the substantial uncertainty over the effects of many of the implementation details.