A5072635130- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- History and Developments in Astronomy
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Planetary Science and Exploration
- Astro and Planetary Science
- Space Science and Extraterrestrial Life
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Influenza Virus Research Studies
- Isotope Analysis in Ecology
- Neutrino Physics Research
- Geophysics and Gravity Measurements
- Historical Astronomy and Related Studies
- Time Series Analysis and Forecasting
- Scientific Research and Discoveries
- Astrophysics and Star Formation Studies
University of Southampton
2020-2025
University of Portsmouth
2022-2025
University of Warwick
2024
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift $z=0.001$ to 2.26. This work features an increased sample size, span, and improved treatment systematic uncertainties comparison original Pantheon results a factor two improvement constraining power. For Flat$\Lambda$CDM model, we find $\Omega_M=0.334\pm0.018$ SNe alone. Flat$w_0$CDM measure $w_0=-0.90\pm0.14$ alone, H$_0=73.5\pm1.1$...
We present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type Ia supernovae discovered by Dark Energy Survey Supernova Program (DES-SN) and used in first DES-SN cosmological analysis. Fitting spectral energy distributions to $griz$ galaxies, we derive stellar masses star-formation rates. For sample, when considering a 5D ($z$, $x_1$, $c$, $α$, $β$) bias correction, find evidence Hubble residual `mass step', where SNe high mass ($>10^{10}...
Type Ia supernovae (SNe Ia) are more precise standardizable candles when measured in the near-infrared (NIR) than optical. With this motivation, from 2012-2017 we embarked on RAISIN program with Hubble Space Telescope (HST) to obtain rest-frame NIR light curves for a cosmologically distant sample of 37 SN ($0.2 \lesssim z 0.6$) discovered by Pan-STARRS and Dark Energy Survey. By comparing higher-$z$ HST data 42 at $z<0.1$ observed Carnegie Supernova Project, construct diagram observations...
We present the full Hubble diagram of photometrically-classified Type Ia supernovae (SNe Ia) from Dark Energy Survey supernova program (DES-SN). DES-SN discovered more than 20,000 SN candidates and obtained spectroscopic redshifts 7,000 host galaxies. Based on light-curve quality, we select 1635 photometrically-identified SNe with redshift 0.10$< z <$1.13, which is largest sample any single survey increases number known $z>0.5$ by a factor five. In companion paper, cosmological results...
Abstract We present the full Hubble diagram of photometrically classified Type Ia supernovae (SNe Ia) from Dark Energy Survey supernova program (DES-SN). DES-SN discovered more than 20,000 SN candidates and obtained spectroscopic redshifts 7000 host galaxies. Based on light-curve quality, we select 1635 identified SNe with redshift 0.10 < z 1.13, which is largest sample any single survey increases number known > 0.5 by a factor 5. In companion paper, cosmological results combined 194...
Analyses of type Ia supernovae (SNe Ia) have found puzzling correlations between their standardised luminosities and host galaxy properties: SNe in high-mass, passive hosts appear brighter than those lower-mass, star-forming hosts. We examine the galaxies Dark Energy Survey three-year spectroscopically-confirmed cosmological sample, obtaining photometry a series "local" apertures centred on SN, for global galaxy. study differences these properties, such as stellar mass rest-frame $U-R$...
Cosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between color and luminosity ($\beta$) do not account for varying host-galaxy dust properties. However, from studies of in large samples galaxies, it is known that attenuation can vary significantly. Here we take advantage state-of-the-art modeling galaxy properties to characterize parameters (dust $A_V$, parameter describing the law slope $R_V$) Dark Energy Survey (DES) SN host galaxies using...
ABSTRACT Future constraints of cosmological parameters from Type Ia supernovae (SNe Ia) will depend on the use photometric samples, those samples without spectroscopic measurements SNe Ia. There is a growing number analyses that show can be utilized for precision studies with minimal systematic uncertainties. To investigate this claim, we perform first analysis combines two separate SDSS and Pan-STARRS, including low-redshift anchor. We evaluate consistency these find they are consistent...
We use a sample of 809 photometrically classified type Ia supernovae (SNe Ia) discovered by the Dark Energy Survey (DES) along with 40415 field galaxies to calculate rate SNe per galaxy in redshift range $0.2 < z <0.6$. recover known correlation between SN and stellar mass across broad scales $8.5 \leq \log(M_*/\mathrm{M}_{\odot}) 11.25$. find that increases as power-law index $0.63 \pm 0.02$, which is consistent previous work. an empirical model assembly estimate average star-formation...
Recent analyses have found intriguing correlations between the colour ($c$) of type Ia supernovae (SNe Ia) and size their 'mass-step', relationship SN host galaxy stellar mass ($M_\mathrm{stellar}$) Hubble residual, suggest that cause this is dust. Using 675 photometrically-classified SNe from Dark Energy Survey 5-year sample, we study differences in residual for a variety global local environmental properties subsamples split by colour. We find $3\sigma$ difference mass-step when comparing...
As part of the cosmology analysis using Type Ia Supernovae (SN Ia) in Dark Energy Survey (DES), we present photometrically identified SN samples multi-band light-curves and host galaxy redshifts. For this analysis, use photometric classification framework SuperNNova (SNN; M\"oller et al. 2019) trained on realistic DES-like simulations. reliable classification, process DES programme (DES-SN) data introduce improvements to classifier architecture, obtaining accuracies more than 98 per cent...
Type Ia supernovae (SNe Ia) are used as standardisable candles to measure cosmological distances, but differences remain in their corrected luminosities which display a magnitude step function of host galaxy properties such stellar mass and rest-frame $U-R$ colour. Identifying the cause these steps is key analyses provides insight into SN physics. Here we investigate effects progenitor ages on light curve using galaxy-based forward model that compare Dark Energy Survey 5-year sample. We...
Current and future cosmological analyses with Type Ia Supernovae (SNe Ia) face three critical challenges: i) measuring redshifts from the supernova or its host galaxy; ii) classifying SNe without spectra; iii) accounting for correlations between properties of their galaxies. We present here a novel approach that addresses each challenge. In context Dark Energy Survey (DES), we analyze SNIa sample galaxies in redMaGiC galaxy catalog, selection Luminous Red Galaxies. Photo-$z$ estimates these...
Dwarf novae are a crucial astrophysical laboratory for probing the nature of accretion, binary mass transfer, and evolution -- yet their diverse observational characteristics continue to challenge our theoretical understanding. We here present discovery of, subsequent observing campaign on GOTO065054+593624 (hereafter GOTO0650), dwarf nova WZ Sge type, discovered in real-time by citizen scientists via Kilonova Seekers science project. An extensive dataset charts photometric spectroscopic...
The Time Domain Extragalactic Survey (TiDES) conducted on the 4-metre Multi-Object Spectroscopic Telescope (4MOST) will perform spectroscopic follow-up of extragalactic transients discovered in era NSF-DOE Vera C. Rubin Observatory. TiDES conduct a 5-year survey, covering ${>}14\,000\,\mathrm{square\, degrees}$, and use around 250 000 fibre hours to address three main science goals: (i) observations ${>}30 000$ live transients, (ii) comprehensive ${>}200 host galaxies obtain redshift...
Abstract The present state of cosmology is facing a crisis where there fundamental disagreement in measurements the Hubble constant (H0), with significant tension between early and late universe methods. Type Ia supernovae (SNe Ia) are important to measuring H0 through astronomical distance ladder. However, remains potential better standardise SN light curves by using known dependencies on host galaxy properties after standard curve width colour corrections have been applied peak...
Abstract Using 1533 type Ia supernovae (SNe Ia) from the five-year sample of Dark Energy Survey (DES), we investigate relationship between projected galactocentric separation SNe and their host galaxies light curves standardization. We show, for first time, that difference in SN post-standardization brightnesses high low-mass hosts reduces 0.078 ± 0.011 mag full to 0.036 0.018 located outer regions galaxies, while increasing 0.100 0.014 inner regions. The size mass step is 0.064 0.023 mag....
The analysis of current and future cosmological surveys type Ia supernovae (SNe Ia) at high-redshift depends on the accurate photometric classification SN events detected. Generating realistic simulations constitutes an essential step for training testing algorithms, correcting biases introduced by selection effects contamination arising from core collapse SNe in samples. We use published time-series spectrophotometric templates, rates, luminosity functions empirical relationships between...
Cosmological analyses of samples photometrically-identified Type Ia supernovae (SNe Ia) depend on understanding the effects 'contamination' from core-collapse and peculiar SN events. We employ a rigorous analysis state-of-the-art simulations photometrically identified determine cosmological biases due to such 'non-Ia' contamination in Dark Energy Survey (DES) 5-year sample. As part analysis, we test our DES performance SuperNNova, photometric classifier based recurrent neural networks....
Abstract While many studies have shown a correlation between properties of the light curves SNe Ia and their host galaxies, it remains unclear what is driving these correlations. We introduce new direct method to study correlations by analyzing “parent” galaxies that multiple “siblings.” Here, we search Dark Energy Survey SN sample, one largest samples discovered SNe, find eight hosted two likely Ia. Comparing light-curve recovered distances from curves, no better agreement in same galaxy as...
Rapidly evolving transients (RETs), also termed fast blue optical (FBOTs), are a distinct class of astrophysical event. They characterised by lightcurves that decline much faster than common classes supernovae (SNe), span vast ranges in peak luminosity and can be seen to redshifts greater 1. Their evolution on timescales has hindered high quality follow-up observations, thus their origin explosion/emission mechanism remains unexplained. In this paper we define the largest sample RETs date,...
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift $z=0.001$ to 2.26. This work features an increased sample size, span, and improved treatment systematic uncertainties comparison original Pantheon results a factor two improvement constraining power. For Flat$Λ$CDM model, we find $Ω_M=0.334\pm0.018$ SNe alone. Flat$w_0$CDM measure $w_0=-0.90\pm0.14$ alone, H$_0=73.5\pm1.1$ km...
An intensive monitoring campaign aimed at detecting rotation periods in a set of bright T Tauri and Herbig Ae/Be stars was undertaken during the 1985/86 Milky Way season. Between 85 200 V magnitude measurements were made for each star on program. In addition to period found Tau, basis these data (Herbst et al. 1986) we find probable SU Aur 1.55 or 2.73 ± 0.03 days, ambiguity arising because sampling frequency (1 day)<SUP>-1</SUP>, possible RY Tau 5.6 days. Z CMa displayed remarkably regular...
ABSTRACT We use stacked spectra of the host galaxies photometrically identified Type Ia supernovae (SNe Ia) from Dark Energy Survey (DES) to search for correlations between Hubble diagram residuals and spectral properties galaxies. Utilizing full spectrum fitting techniques on binned by residual, we find no evidence trends that rely absorption features (&lt;1.3σ), such as stellar population age, metallicity, mass-to-light ratio. However, significant strengths [O ii] (4.4σ) Balmer...
Context. Type Ia supernovae (SNe Ia) are useful distance indicators in cosmology, provided their luminosity is standardized by applying empirical corrections based on light-curve properties. One factor behind these dust extinction, which accounted for the color–luminosity relation of standardization. This usually assumed to be universal, can potentially introduce systematics into The “mass step” observed SN Hubble residuals has been suggested as one such systematic. Aims. We seek obtain a...