Alexander Gagliano
A5056166141- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Advanced Vision and Imaging
- Cardiac Arrest and Resuscitation
- Computational Physics and Python Applications
- Anomaly Detection Techniques and Applications
- Distributed and Parallel Computing Systems
- Neutrino Physics Research
- Data Stream Mining Techniques
- Seismology and Earthquake Studies
- Geophysics and Gravity Measurements
- Radio, Podcasts, and Digital Media
- Methane Hydrates and Related Phenomena
- Particle Detector Development and Performance
- Historical Geography and Cartography
- Advanced Fluorescence Microscopy Techniques
- Remote Sensing in Agriculture
- Dark Matter and Cosmic Phenomena
Center for Astrophysics Harvard & Smithsonian
2024
The NSF AI Institute for Artificial Intelligence and Fundamental Interactions
2023-2024
Massachusetts Institute of Technology
2024
National Center for Supercomputing Applications
2021-2023
University of Illinois Urbana-Champaign
2021-2023
Flatiron Health (United States)
2023
Flatiron Institute
2023
Virginia Tech
2018
Los Alamos National Laboratory
2018
Cerro Tololo Inter-American Observatory
2018
We present panchromatic observations and modeling of supernova (SN) 2020tlf, the first normal type II-P/L SN with confirmed precursor emission, as detected by Young Supernova Experiment transient survey Pan-STARRS1 telescope. Pre-explosion emission was in $riz-$bands at 130 days prior to 2020tlf persisted relatively constant flux until light. Soon after discovery, "flash" spectroscopy revealed prominent narrow symmetric lines ($v_w < 300$ km s$^{-1}$) that resulted from photo-ionization...
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...
Time domain science has undergone a revolution over the past decade, with tens of thousands new supernovae (SNe) discovered each year. However, several observational domains, including SNe within days or hours explosion and faint, red transients, are just beginning to be explored. Here, we present Young Supernova Experiment (YSE), novel optical time-domain survey on Pan-STARRS telescopes. Our is designed obtain well-sampled $griz$ light curves for transient events up $z \approx 0.2$. This...
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...
The modern study of astrophysical transients has been transformed by an exponentially growing volume data. Within the last decade, transient discovery rate increased a factor ~20, with associated survey data, archival and metadata also increasing number discoveries. To manage data at this rate, we require new tools. Here present YSE-PZ, management platform that ingests multiple live streams alerts, identifies host galaxies those transients, downloads coincident retrieves photometry spectra...
Abstract We present photometric and spectroscopic observations of Supernova 2020oi (SN 2020oi), a nearby (∼17 Mpc) type-Ic supernova Ic) within the grand-design spiral M100. undertake comprehensive analysis to characterize evolution SN constrain its progenitor system. detect flux in excess fireball rise model δ t ≈ 2.5 days from date explosion multiband optical UV photometry Las Cumbres Observatory Neil Gehrels Swift Observatory, respectively. The derived bolometric luminosity is consistent...
Abstract Substantial effort has been devoted to the characterization of transient phenomena from photometric information. Automated approaches this problem have taken advantage complete phase coverage an event, limiting their use for triggering rapid follow-up ongoing phenomena. In work, we introduce a neural network with single recurrent layer designed explicitly early classification supernovae (SNe). Our algorithm leverages transfer learning account model misspecification, host-galaxy...
Abstract We present UV–optical–near-infrared observations and modeling of supernova (SN) 2024ggi, a type II (SN II) located in NGC 3621 at 7.2 Mpc. Early-time (“flash”) spectroscopy SN 2024ggi within +0.8 days discovery shows emission lines H i , He C iii N with narrow core broad, symmetric wings (i.e., “IIn-like”) arising from the photoionized, optically thick, unshocked circumstellar material (CSM) that surrounded progenitor star shock breakout (SBO). By next spectral epoch +1.5 days,...
We present observations of SN 2020fqv, a Virgo-cluster Type II core-collapse supernova (CCSN) with high temporal resolution light curve from the Transiting Exoplanet Survey Satellite (TESS) covering time explosion; ultraviolet (UV) spectroscopy Hubble Space Telescope (HST) starting 3.3 days post-explosion; ground-based spectroscopic 1.1~days along extensive photometric observations. Massive stars have complicated mass-loss histories leading up to their death as CCSNe, creating circumstellar...
Abstract Evaluating the accuracy and calibration of redshift posteriors produced by photometric (photo- z ) estimators is vital for enabling precision cosmology extragalactic astrophysics with modern wide-field surveys. photo- on a per-galaxy basis difficult, however, as real galaxies have true but not posterior. We introduce PZFlow, Python package probabilistic forward modeling galaxy catalogs normalizing flows. For simulated there natural notion “true” that can be used validation. use...
Abstract We present a new photometric pipeline for the detection of pre-supernova (pre-SN) emission in Young Supernova Experiment (YSE) sky survey. The method described is applied to SN 2020tlf, type II with precursor last ~100 days before first light. re-analyze YSE griz -band light curves 2020tlf and provide revised pre-explosion photometry that includes robust list confident limiting magnitudes. Compared results W. V. Jacobson-Galán et al., this analysis yields fewer total r / i z pre-SN...
As we observe a rapidly growing number of astrophysical transients, learn more about the diverse host galaxy environments in which they occur. Host information can be used to purify samples cosmological Type Ia supernovae, uncover progenitor systems individual classes, and facilitate low-latency follow-up rare peculiar explosions. In this work, develop novel data-driven methodology simulate time-domain sky that includes detailed modeling probability density function for multiple transient...
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...
Abstract We present the Keck Infrared Transient Survey, a NASA Key Strategic Mission Support program to obtain near-infrared (NIR) spectra of astrophysical transients all types, and its first data release, consisting 105 NIR 50 transients. Such set is essential as we enter new era IR astronomy with James Webb Space Telescope (JWST) upcoming Nancy Grace Roman (Roman). spectral templates will be search JWST images for stellar explosions stars plan an effective SN Ia cosmology survey, both key...
We present UV/optical observations and models of supernova (SN) 2023ixf, a type II 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 photo-ionization dense, close-in circumstellar material (CSM) around progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for $\sim$8 days respect...
We present observations of a peculiar hydrogen- and helium-poor stripped-envelope (SE) supernova (SN) 2020wnt, primarily in the optical near-infrared (near-IR). Its peak absolute bolometric magnitude -20.9 mag rise time 69~days are reminiscent hydrogen-poor superluminous SNe (SLSNe~I), luminous transients potentially powered by spinning-down magnetars. Before main peak, there is brief lasting <10 days post-explosion, likely caused interaction with circumstellar medium (CSM) ejected ~years...
Abstract The large-scale distribution of globular clusters in the central region Coma cluster galaxies is derived through analysis Hubble Space Telescope /Advanced Camera for Surveys data. Data from three different HST observing programs are combined order to obtain a full surface density map core Coma. A total 22,426 Globular candidates were selected detailed morphological inspection and their magnitude colors two wavebands, F475W (Sloan g ) F814W ( I ). spatial defines main overdensities...
Abstract We present DELIGHT, or Deep Learning Identification of Galaxy Hosts Transients, a new algorithm designed to automatically and in real time identify the host galaxies extragalactic transients. The proposed receives as input compact, multiresolution images centered at position transient candidate outputs two-dimensional offset vectors that connect with center its predicted host. consists set same number pixels, but progressively larger pixel sizes fields view. A sample 16,791 visually...
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...
We present multi-band ATLAS photometry for SN 2019tsf, a stripped-envelope Type Ib supernova (SESN). The shows triple-peaked light curve and late (re-)brightening, making it unique among systems. re-brightening observations represent the latest photometric measurements of multi-peaked to date. As late-time spectroscopy suggest no hydrogen, potential circumstellar material (CSM) must be H-poor. Moreover, (>150 days) spectra show signs narrow emission lines, further disfavouring CSM...
We present the Keck Infrared Transient Survey (KITS), a NASA Key Strategic Mission Support program to obtain near-infrared (NIR) spectra of astrophysical transients all types, and its first data release, consisting 105 NIR 50 transients. Such set is essential as we enter new era IR astronomy with James Webb Space Telescope (JWST) upcoming Nancy Grace Roman (Roman). spectral templates will be search JWST images for stellar explosions stars plan an effective Roma} SN Ia cosmology survey, both...
We present LAISS (Lightcurve Anomaly Identification and Similarity Search), an automated pipeline to detect anomalous astrophysical transients in real-time data streams. deploy our anomaly detection model on the nightly ZTF Alert Stream via ANTARES broker, identifying a manageable $\sim$1-5 candidates per night for expert vetting coordinating follow-up observations. Our method leverages statistical light-curve contextual host-galaxy features within random forest classifier, tagging of rare...