C. Rojas-Bravo
A5083153486- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- History and Developments in Astronomy
- CCD and CMOS Imaging Sensors
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Advanced Power Generation Technologies
- Methane Hydrates and Related Phenomena
- Particle Detector Development and Performance
- Sensor Technology and Measurement Systems
- Superconducting and THz Device Technology
- Spectroscopy Techniques in Biomedical and Chemical Research
- Advanced Sensor Technologies Research
University of California, Santa Cruz
2017-2024
Universidad de Costa Rica
2016-2017
On 2017 August 17, gravitational waves were detected from a binary neutron star merger, GW170817, along with coincident short gamma-ray burst, GRB170817A. An optical transient source, Swope Supernova Survey 17a (SSS17a), was subsequently identified as the counterpart of this event. We present ultraviolet, and infrared light curves SSS17a extending 10.9 hours to 18 days post-merger. constrain radioactively-powered resulting ejection neutron-rich material. The fast rise curves, subsequent...
On 2017 August 17, the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo interferometer detected gravitational waves emanating from a binary neutron star merger, GW170817. Nearly simultaneously, Fermi INTEGRAL telescopes gamma-ray transient, GRB 170817A. 10.9 hours after wave trigger, we discovered transient fading optical source, Swope Supernova Survey 2017a (SSS17a), coincident with SSS17a is located in NGC 4993, an S0 galaxy at distance of 40 megaparsecs. The precise...
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$_0=73.5\pm1.1$...
Here we present 1701 light curves of 1550 spectroscopically confirmed Type Ia supernovae (SNe Ia) that will be used to infer cosmological parameters as part the Pantheon+ SN analysis and SH0ES (Supernovae H0 for Equation State dark energy) distance-ladder analysis. This effort is one a series works perform an extensive review redshifts, peculiar velocities, photometric calibration, intrinsic-scatter models SNe Ia. The total number curves, which are compiled across 18 different surveys,...
Photons from a gravitational wave event Two neutron stars merging together generate signal and have also been predicted to emit electromagnetic radiation. When the GW170817 was detected, astronomers rushed search for source using conventional telescopes (see Introduction by Smith). Coulter et al. describe how One-Meter Two-Hemispheres (1M2H) collaboration first locate source. Drout present 1M2H measurements of its optical infrared brightness, Shappee report their spectroscopy event, which is...
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 ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early time ( δ t < 2 days) spectra show transient, narrow emission lines from shock ionization confined r 10 15 cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) H i , He i/ii C iv N iii/iv/v the CSM persist on a characteristic timescale IIn ) that marks transition to lower-density emergence Doppler-broadened...
Abstract The merging neutron star gravitational-wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to γ -rays. resulting energetics, variability, and light curves are shown be consistent with originating merger of two stars, in all likelihood followed by prompt gravitational collapse massive remnant. available -ray, X-ray, data provide a clear probe for nature relativistic ejecta non-thermal processes occurring within, while ultraviolet,...
A spectral-energy distribution (SED) model for Type Ia supernovae (SNe Ia) is a critical tool measuring precise and accurate distances across large redshift range constraining cosmological parameters. We present an improved framework, SALT3, which has several advantages over current models including the leading SALT2 (SALT2.4). While SALT3 similar philosophy, it differs from by having estimation of uncertainties, better separation color light-curve stretch, publicly available training code....
ABSTRACT We present observations of ASASSN-19dj, a nearby tidal disruption event (TDE) discovered in the post-starburst galaxy KUG 0810+227 by All-Sky Automated Survey for Supernovae (ASAS-SN) at distance d ≃ 98 Mpc. observed ASASSN-19dj from −21 to 392 relative peak ultraviolet (UV)/optical emission using high-cadence, multiwavelength spectroscopy and photometry. From ASAS-SN g-band data, we determine that TDE began brighten on 2019 February 6.8 first 16 rise was consistent with flux ∝t2...
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 Hubble Space Telescope imaging of a pre-explosion counterpart to SN 2019yvr obtained 2.6 years before its explosion as type Ib supernova (SN Ib). Aligning post-explosion Gemini-S/GSAOI image, we demonstrate that there is single source consistent with being the progenitor system, second candidate after iPTF13bvn. also analyzed Spitzer/IRAC imaging, but do not detect any counterparts at location. was highly reddened, and comparing spectra photometry those other, less extinguished...
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...
We present extensive optical photometry of the afterglow GRB~221009A. Our data cover $0.9 - 59.9$\,days from time \textit{Swift} and \textit{Fermi} GRB detections. Photometry in $rizy$-band filters was collected primarily with Pan-STARRS supplemented by multiple 1- to 4-meter imaging facilities. analyzed Swift X-ray found a single decline rate power-law $f(t) \propto t^{-1.556\pm0.002}$ best describes light curve. In addition high foreground Milky Way dust extinction along this line sight,...
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 Supernova (SN) 2018oh (ASASSN-18bt) is the first spectroscopically confirmed Type Ia supernova (SN Ia) observed in Kepler field. The data revealed an excess emission its early light curve, allowing us to place interesting constraints on progenitor system. Here we present extensive optical, ultraviolet, and near-infrared photometry, as well dense sampling of optical spectra, for this object. SN relatively normal photometric evolution, with a rise time 18.3 ± 0.3 days Δ m 15 ( B ) =...
Abstract We present an analysis of the host-galaxy environment Swope Supernova Survey 2017a (SSS17a), discovery electromagnetic counterpart to a gravitational-wave source, GW170817. SSS17a occurred 1.9 kpc (in projection; 10.″2) from nucleus NGC 4993, S0 galaxy at distance 40 Mpc. Hubble Space Telescope ( HST ) pre-trigger image Magellan optical spectroscopy 4993 and location SSS17a, broadband UV-through-IR photometry 4993. The spectrum spectral-energy distribution indicate that has stellar...
Abstract We present panchromatic observations and modeling of the Calcium-rich supernova (SN) 2019ehk in star-forming galaxy M100 ( d ≈ 16.2 Mpc) starting 10 hr after explosion continuing for ∼300 days. SN shows a double-peaked optical light curve peaking at t = 3 15 The first peak is coincident with luminous, rapidly decaying Swift-XRT–discovered X-ray emission <?CDATA ${L}_{{\rm{x}}}\approx {10}^{41}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$?> days; L x ∝ −3 ), Shane/Kast spectral detection narrow H...
We present and analyse a new tidal disruption event (TDE), AT2017eqx at redshift z=0.1089, discovered by Pan-STARRS ATLAS. The position of the transient is consistent with nucleus its host galaxy; it peaks luminosity $L \approx 10^{44}$ erg s$^{-1}$; spectrum shows persistent blackbody temperature $T \gtrsim 20,000$ K broad H I He II emission. lines are initially centered zero velocity, but 100 days disappear while develops blueshift $\gtrsim 5,000$ km s$^{-1}$. Both early- late-time...
We study the properties of galaxies hosting first 19 tidal disruption events (TDEs) detected with Zwicky Transient Facility (ZTF) within context a carefully constructed, representative host galaxy sample. find that ZTF sample TDE hosts is dominated by compact "green valley" galaxies. After we restrict comparison to similar concentration, as measured Sersic index, this green valley over representation even larger. That is, concentrated red sequence are not producing TDEs at elevated levels....
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 We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee at D = 32 ± 3 Mpc, finding excess flux in first days after explosion, particularly our 10 minutes cadence TESS light curve and Swift UV data. Compared to a few other normal SNe with early flux, SN is redder less luminous. optical spectra 2023bee, including two during period where dominant. At this time, are similar those but weaker Si ii , C ii, Ca absorption lines,...