C. L. Ransome
A5003143355- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Neutrino Physics Research
- Atmospheric Ozone and Climate
- Influenza Virus Research Studies
- SAS software applications and methods
- Isotope Analysis in Ecology
- Geophysics and Gravity Measurements
- Nuclear Physics and Applications
- Astro and Planetary Science
- Spectroscopy Techniques in Biomedical and Chemical Research
- Advanced X-ray Imaging Techniques
Pennsylvania State University
2022-2024
Center for Astrophysics Harvard & Smithsonian
2024
Liverpool John Moores University
2021-2022
Isaac Newton Group
2022
Abstract We present UV and/or optical observations and models of SN 2023ixf, a type II supernova (SN) located in Messier 101 at 6.9 Mpc. Early time ( flash ) spectroscopy obtained primarily Lick Observatory, reveals emission lines H i , He i/ii C iv N iii/iv/v with narrow core broad, symmetric wings arising from the photoionization dense, close-in circumstellar material (CSM) around progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for ∼8 days...
Abstract We present preexplosion optical and infrared (IR) imaging at the site of type II supernova (SN II) 2023ixf in Messier 101 6.9 Mpc. astrometrically registered a ground-based image SN to archival Hubble Space Telescope (HST), Spitzer (Spitzer), near-IR images. A single point source is detected position consistent with wavelengths ranging from HST R band 4.5 μ m. Fitting blackbody red supergiant (RSG) spectral energy distributions (SEDs), we find that anomalously cool significant...
We present the Young Supernova Experiment Data Release 1 (YSE DR1), comprised of processed multi-color Pan-STARRS1 (PS1) griz and Zwicky Transient Facility (ZTF) gr photometry 1975 transients with host-galaxy associations, redshifts, spectroscopic/photometric classifications, additional data products from 2019 November 24 to 2021 December 20. YSE DR1 spans discoveries observations young fast-rising supernovae (SNe) that persist for over a year, redshift distribution reaching z~0.5. relative...
Abstract The nearby type II supernova, SN 2023ixf in M101 exhibits signatures of early time interaction with circumstellar material the first week postexplosion. This may be consequence prior mass loss suffered by progenitor, which possibly manifested form a detectable presupernova outburst. We present an analysis long-baseline preexplosion photometric data g , w r i z and y filters from Pan-STARRS as part Young Supernova Experiment, spanning ∼5000 days. find no significant detections light...
Abstract We present optical photometry and spectroscopy of the Type IIn supernova (SN) 2021qqp. Its unusual light curve is marked by a long precursor for ≈300 days, rapid increase in brightness ≈60 then sharp ≈1.6 mag only few days to first peak M r ≈ −19.5 mag. The declines rapidly until it rebrightens second distinct −17.3 centered at ≈335 after peak. spectra are dominated Balmer lines with complex morphology, including narrow component width ≈1300 km s −1 (first peak) ≈2500 (second that...
We present optical and near-infrared (NIR) observations of the Type Icn supernova (SN Icn) 2022ann, fifth member its newly identified class SNe. Its early spectra are dominated by narrow carbon oxygen P-Cygni features with absorption velocities 800 km/s; slower than other SNe indicative interaction a dense, H/He-poor circumstellar medium (CSM) that is outflowing typical Wolf-Rayet wind velocity $>$1000 km/s. identify helium in NIR obtained two weeks after maximum at three weeks,...
ABSTRACT A growing number of supernovae (SNe) are now known to exhibit evidence for significant interaction with a dense, pre-existing, circumstellar medium (CSM). SNe Ibn comprise one such class that can be characterized by both rapidly evolving light curves and persistent narrow He i lines. The origin dense CSM in these systems remains pressing question, specifically concerning the progenitor system mass-loss mechanism. In this paper, we present multiwavelength data Type SN 2020nxt,...
Type IIn supernovae (SNe\,IIn) are an uncommon and highly heterogeneous class of SN where the ejecta interact with pre-existing circumstellar media (CSM). Previous studies have found a mass ladder in terms association location H$\alpha$ emission progenitor masses classes. In this paper, we present largest environmental study SNe\,IIn. We analyse environments 77 type using continuum subtracted images. use pixel statistics technique, normalised cumulative ranking (NCR), to associate pixels...
Type IIn supernovae (SNe IIn) are a relatively infrequently observed subclass of SNe whose photometric and spectroscopic properties varied. A common thread among the complex multiple-component hydrogen Balmer lines. Owing to heterogeneity IIn, online databases contain some outdated, erroneous, or even contradictory classifications. SN classification is further complicated by impostors contamination from underlying HII regions. We have compiled catalogue systematically classified nearby...
Abstract We present the photometric and spectroscopic evolution of SN 2022oqm, a nearby multipeaked hydrogen- helium-weak calcium-rich transient (CaRT). 2022oqm was detected 13.1 kpc from its host galaxy, face-on spiral galaxy NGC 5875. Extensive coverage reveals an early hot ( T ≥ 40,000 K) continuum carbon features observed ∼1 day after discovery, Ic-like photospheric-phase spectra, strong forbidden calcium emission starting 38 days discovery. has relatively high peak luminosity M B = −17...
We present optical photometry and spectroscopy of the Type IIn supernova (SN) 2021qqp. Its unusual light curve is marked by a long precursor for $\approx300$ days, rapid increase in brightness $\approx60$ then sharp $\approx1.6$ mag only few days to first peak $M_r \approx -19.5$ mag. The declines rapidly until it re-brightens second distinct -17.3$ centered at $\approx335$ after peak. spectra are dominated Balmer lines with complex morphology, including narrow component width $\approx 1300$...
We present the photometric and spectroscopic evolution of SN 2022oqm, a nearby multi-peaked hydrogen- helium-weak calcium-rich transient (CaRT). 2022oqm was detected 13.1 kpc from its host galaxy, face-on spiral galaxy NGC 5875. Extensive coverage reveals an early hot (T >= 40,000 K) continuum carbon features observed $\sim$1~day after discovery, Ic-like photospheric-phase spectra, strong forbidden calcium emission starting 38 days discovery. has relatively high peak luminosity (MB = -17...
A growing number of supernovae (SNe) are now known to exhibit evidence for significant interaction with a dense, pre-existing, circumstellar medium (CSM). SNe Ibn comprise one such class that can be characterised by both rapidly evolving light curves and persistent narrow He I lines. The origin dense CSM in these systems remains pressing question, specifically concerning the progenitor system mass-loss mechanism. In this paper, we present multi-wavelength data Type SN 2020nxt, including...
The nearby type II supernova, SN2023ixf in M101 exhibits signatures of early-time interaction with circumstellar material the first week post-explosion. This may be consequence prior mass loss suffered by progenitor which possibly manifested form a detectable pre-supernova outburst. We present an analysis long-baseline pre-explosion photometric data $g$, $w$, $r$, $i$, $z$ and $y$ filters from Pan-STARRS as part Young Supernova Experiment, spanning $\sim$5,000 days. find no significant...
We present a comprehensive analysis of the photometric and spectroscopic evolution SN~2021foa, unique among class transitional supernovae for repeatedly changing its appearance from hydrogen-to-helium-to-hydrogen-dominated (IIn-to-Ibn-to-IIn) within 50 days past peak brightness. The spectra exhibit multiple narrow ($\approx$ 300--600~km~s$^{-1}$) absorption lines hydrogen, helium, calcium iron together with broad helium emission full-width-at-half-maximum (FWHM) $\sim 6000$~km~s$^{-1}$. For...
We present multi-wavelength data of SN2020acct, a double-peaked stripped-envelope supernova (SN) in NGC2981 at ~150 Mpc. The two peaks are temporally distinct, with maxima separated by 58 rest-frame days, and factor 20 reduction flux between. first is luminous (M$_{r}$ = -18.00 $\pm$ 0.02 mag), blue (g - r 0.27 0.03 displays spectroscopic signatures interaction hydrogen-free circumstellar material. second peak fainter -17.29 spectroscopically similar to an evolved SNe, strong blended...
Abstract We present a comprehensive analysis of the photometric and spectroscopic evolution SN 2021foa, unique among class transitional supernovae for repeatedly changing its appearance from hydrogen-to-helium-to-hydrogen dominated (IIn-to-Ibn-to-IIn) within 50 days past peak brightness. The spectra exhibit multiple narrow (≈300–600 km s −1 ) absorption lines hydrogen, helium, calcium, iron together with broad helium emission full width at half-maximum (FWHM) ∼6000 . For steady, wind...
Abstract We present multiwavelength data of SN 2020acct, a double-peaked stripped-envelope supernova (SN) in NGC 2981 at ∼150 Mpc. The two peaks are temporally distinct, with maxima separated by 58 rest-frame days and factor 20 reduction flux between. first is luminous ( M r = −18.00 ± 0.02 mag) blue g − 0.27 0.03 displays spectroscopic signatures interaction hydrogen-free circumstellar material. second peak fainter −17.29 has some similarities to an evolved SN, strong forbidden [Ca ii ] [O...
We present pre-explosion optical and infrared (IR) imaging at the site of type II supernova (SN II) 2023ixf in Messier 101 6.9 Mpc. astrometrically registered a ground-based image SN to archival Hubble Space Telescope (HST), Spitzer (Spitzer), near-IR images. A single point source is detected position consistent with wavelengths ranging from HST $R$-band 4.5 $μ$m. Fitting blackbody red supergiant (RSG) spectral-energy distributions (SEDs), we find that anomalously cool significant mid-IR...