Mitchell Karmen
A5011089656- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Neutrino Physics Research
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Computational Physics and Python Applications
- Anomaly Detection Techniques and Applications
- Astrophysics and Star Formation Studies
- Time Series Analysis and Forecasting
- Galaxies: Formation, Evolution, Phenomena
- Superconducting Materials and Applications
Johns Hopkins University
2024
Lawrence Berkeley National Laboratory
2022-2023
Abstract JWST has now revealed a population of broad-line active galactic nuclei (AGN) at z ≳ 4 characterized by distinctive spectral energy distribution shape, with very red rest-frame optical and blue UV continuum. While the continuum is thought to originate from accretion disk, origin been largely unclear. We report detection strong emission lines C iii ] λλ 1907, 1909 iv 1549, 1551 in “little dot” AGN, COS-66964. Spectroscopically confirmed = 7.0371, COS-66964 exhibits broad H α (FWHM ∼...
Abstract We present James Webb Space Telescope (JWST) NIRCam and NIRSpec observations of a Type Ic supernova (SN Ic) its host galaxy (JADES-GS+53.13533-27.81457) at z = 2.83. This SN (named 2023adta) was identified in deep JWST/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Follow-up with JWST/NIRSpec provided spectroscopic redshift 2.83 classification as an Ic-BL. The light curve 2023adta matches well other stripped-envelope SNe, we find high peak...
Abstract We present the James Webb Space Telescope (JWST) discovery of SN 2023adsy, a transient object located in host galaxy JADES-GS+53.13485−27.82088 with spectroscopic redshift 2.903 ± 0.007. The was identified deep (JWST)/NIRCam imaging from JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and follow-up NIRCam NIRSpec, respectively, confirm yield UV-NIR light-curve, NIR color, information all consistent Type Ia classification. Despite its classification as likely Ia,...
Abstract We present a new empirical Type Ia supernova (SN Ia) model with three chromatic flux variation templates: one phase dependent and two independent. No underlying dust extinction or patterns of intrinsic variability are assumed. Implemented S tan trained using spectrally binned Nearby Supernova Factory spectrophotometry, we examine this model's 2D, phase-independent space motivated basis representations. In both, the first template captures that appears dust-like, while second...
Abstract We present the most comprehensive catalog to date of Type I Superluminous Supernovae (SLSNe), a class stripped envelope supernovae (SNe) characterized by exceptionally high luminosities. have compiled sample 262 SLSNe reported through 2022 December 31. verified spectroscopic classification each SLSN and collated an exhaustive data set UV, optical IR photometry totaling over 30,000 photometric detections. Using these we derive observational parameters such as peak absolute...
Transient astronomy in the early, high-redshift (z>3) Universe is an unexplored regime that offers possibility of probing first stars and Epoch Reionization. During Cycles 1 2 James Webb Space Telescope (JWST), JWST Advanced Deep Extragalactic Survey (JADES) program enabled one searches for transients deep images (~ $30$ AB mag) over a relatively wide area ($25$ arcmin$^2$). One transient, AT 2023adsv, was discovered with F200W magnitude $28.04$ mag, subsequent observations revealed...
Abstract The James Webb Space Telescope (JWST) is opening new frontiers of transient discovery and follow-up at high redshift. Here we present the a spectroscopically confirmed Type Ia supernova (SN Ia; SN 2023aeax) z = 2.15 with JWST, including NIRCam multiband light curve. 2023aeax lands edge traditional low- cosmology cuts because its blue color (peak rest-frame B − V ∼ −0.3) but normal decline rate (Δ m 15 ( ) 1.25), applying fiducial standardization BayeSN model find luminosity distance...
We apply the color-magnitude intercept calibration method (CMAGIC) to Nearby Supernova Factory SNe Ia spectrophotometric dataset. The currently existing CMAGIC parameters are slope and of a straight line fit first linear region in diagram, which occurs over span approximately 30 days after maximum brightness. define new parameter, $\omega_{XY}$, size ``bump'' feature near brightness for arbitrary filters $X$ $Y$. find significant correlation between region, $\beta_{XY, 1}$, diagram...
Abstract We construct a physically parameterized probabilistic autoencoder (PAE) to learn the intrinsic diversity of Type Ia supernovae (SNe Ia) from sparse set spectral time series. The PAE is two-stage generative model, composed an that interpreted probabilistically after training using normalizing flow. demonstrate learns low-dimensional latent space captures nonlinear range features exists within population and can accurately model evolution SNe across full wavelength observation times...
We present the JWST discovery of SN 2023adsy, a transient object located in host galaxy JADES-GS$+53.13485$$-$$27.82088$ with spectroscopic redshift $2.903\pm0.007$. The was identified deep James Webb Space Telescope (JWST)/NIRCam imaging from Advanced Deep Extragalactic Survey (JADES) program. Photometric and followup NIRCam NIRSpec, respectively, confirm yield UV-NIR light-curve, NIR color, information all consistent Type Ia classification. Despite its classification as likely Ia, 2023adsy...
We present JWST NIRCam and NIRSpec observations of a Type Ic supernova (SN Ic) its host galaxy (JADES-GS+53.13533-27.81457) at $z = 2.83$. This SN (named 2023adta) was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the Advanced Deep Extragalactic Survey (JADES) Program. Follow-up with JWST/NIRSpec provided spectroscopic redshift 2.83$ classification as Ic-BL. The light curve 2023adta matches well other stripped envelope supernovae we find high peak luminosity, $M_V...
We present the most comprehensive catalog to date of Type I Superluminous Supernovae (SLSNe), a class stripped envelope supernovae (SNe) characterized by exceptionally high luminosities. have compiled sample 262 SLSNe reported through 2022 December 31. verified spectroscopic classification each SLSN and collated an exhaustive data set UV, optical IR photometry from both publicly available our own FLEET observational follow-up program, totaling over 30,000 photometric detections. Using these...
JWST has now revealed a population of broad-line AGN at $z>4$ characterized by distinctive SED shape, with very red rest-frame optical and blue UV continuum. While the continuum is thought to originate from accretion disk, origin been largely unclear. We report detection strong emission lines CIII]$\lambda\lambda$1907,1909 CIV$\lambda\lambda$1549,1551 in "little dot" AGN, COS-66964. Spectroscopically confirmed $z=7.0371$, COS-66964 exhibits broad H$\alpha$ (FWHM $\sim 2000$ km s$^{-1}$),...
Type-I Superluminous Supernovae (SLSNe) are an exotic class of core-collapse SN (CCSN) that can be up to 100 times brighter and more slowly-evolving than normal CCSNe. SLSNe represent the end-stages most massive stripped stars, thought powered by spin-down energy a millisecond magnetar. Studying them measuring their physical parameters help us better understand stellar mass-loss, evolution, explosions. Moreover, thanks high luminosities, seen greater distances, allowing explore how physics...