A5016550371- Optical Systems and Laser Technology
- Gamma-ray bursts and supernovae
- Integrated Circuits and Semiconductor Failure Analysis
- Advancements in Semiconductor Devices and Circuit Design
- Astrophysics and Cosmic Phenomena
- Semiconductor materials and devices
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Neutrino Physics Research
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Pulsed Power Technology Applications
- Non-Destructive Testing Techniques
- Vacuum and Plasma Arcs
- Nuclear Physics and Applications
- Adaptive optics and wavefront sensing
- Cosmology and Gravitation Theories
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Radiation Detection and Scintillator Technologies
- Particle accelerators and beam dynamics
- Advanced Optical Sensing Technologies
Humboldt-Universität zu Berlin
2015-2024
Lawrence Berkeley National Laboratory
2012-2023
Freie Universität Berlin
2019-2020
University of California, Berkeley
2012-2018
Max Planck Institute for Astrophysics
2016
Stockholm University
2008-2011
AlbaNova
2009-2011
The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides 47 deg2 field of view and 8 s readout time, yielding more than an order magnitude improvement in speed relative to its predecessor survey, Factory. We describe design implementation observing system. ZTF data system at Infrared Processing Analysis Center near-real-time reduction identify moving varying objects. outline analysis...
We report on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts. Light curves, including signal-to-noise Hubble Space Telescope data, and spectra six SNe that were discovered during 2001, are presented. Additionally, for two with z > 1, we present ground-based J-band photometry from Gemini Very Large Telescope. These among most distant which near-IR observations have been obtained. add these together other data sets recently become available in...
The Zwicky Transient Facility (ZTF), a public-private enterprise, is new time domain survey employing dedicated camera on the Palomar 48-inch Schmidt telescope with 47 deg$^2$ field of view and 8 second readout time. It well positioned in development astronomy, offering operations at 10% scale style Large Synoptic Survey Telescope (LSST) single 1-m class telescope. public surveys will cover observable northern sky every three nights g r filters visible Galactic plane night r. Alerts...
Previously we used the Nearby Supernova Factory sample to show that Type Ia supernovae (SNe Ia) having locally star-forming environments are dimmer than SNe passive environments. Here use Constitution together with host galaxy data from GALEX independently confirm result. The effect is seen using both SALT2 and MLCS2k2 lightcurve fitting standardization methods, brightness differences of 0.094 ± 0.037 mag for 0.155 0.041 RV = 2.5. When combined our previous measurement 0.025 SALT2. If ratio...
Abstract We present a public catalog of transients from the Zwicky Transient Facility (ZTF) Bright Survey, magnitude-limited ( m < 19 mag in either g or r filter) survey for extragalactic ZTF stream. introduce cuts on coverage, sky visibility around peak light, and other properties unconnected to nature transient, show that resulting statistical sample is spectroscopically 97% complete at <18 mag, 93% <18.5 75% <19 mag. summarize fundamental this population, identifying distinct...
As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization Type Ia supernovae (SNIa) cosmology, we have statistically classified a large sample nearby SNeIa into those located predominantly younger or older environments. This classification is based on specific star formation rate measured within projected distance 1kpc from each SN location (LsSFR). important refinement compared using local directly as it provides normalization relative...
The origins of the high-energy cosmic neutrino flux remain largely unknown. Recently, one was associated with a tidal disruption event (TDE). Here we present AT2019fdr, an exceptionally luminous TDE candidate, coincident another neutrino. Our observations, including bright dust echo and soft late-time x-ray emission, further support origin this flare. probability finding two such events by chance is just 0.034%. We evaluate several models for production show that AT2019fdr capable producing...
Abstract We present a search for extragalactic fast blue optical transients (FBOTs) during Phase I of the Zwicky Transient Facility (ZTF). identify 38 candidates with durations above half-maximum light 1 day < t 1/2 12 days, which 28 have ( g − r ≲ −0.2 mag) colors at peak light. Of (28 FBOTs), 19 (13) can be spectroscopically classified as core-collapse supernovae (SNe): 11 (8) H- or He-rich (Type II/IIb/Ib) SNe, 6 (4) interacting IIn/Ibn) and 2 (1) H&He-poor Ic/Ic-BL) SNe. Two FBOTs...
Abstract Narrow transient emission lines (flash-ionization features) in early supernova (SN) spectra trace the presence of circumstellar material (CSM) around massive progenitor stars core-collapse SNe. The disappear within days after SN explosion, suggesting that this is spatially confined, and originates from enhanced mass loss shortly (months to a few years) prior explosion. We performed systematic survey H-rich (Type II) SNe discovered less than 2 explosion during first phase Zwicky...
Abstract The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is scheduled to be launched geostationary orbit in 2027. It will carry a telescope with an unprecedentedly large field of view (204 deg 2 ) and near-ultraviolet (NUV; 230–290 nm) sensitivity (22.5 mag, 5 σ , at 900 s). ULTRASAT conduct the first wide-field survey transient variable NUV sources revolutionize our ability study hot Universe. explore new parameter space energy timescale (months-long light curves minutes cadence),...
ABSTRACT The origin of cosmic high-energy neutrinos remains largely unexplained. For neutrino alerts from IceCube, a coincidence with time-variable emission has been seen for three different types accreting black holes: (1) gamma-ray flare blazar (TXS 0506+056), (2) an optical transient following stellar tidal disruption event (TDE; AT2019dsg), and (3) outburst active galactic nucleus (AGN; AT2019fdr). the latter two sources, infrared follow-up observations revealed powerful reverberation...
Context. As type Ia supernova cosmology transitions from a statistics-dominated to systematics-dominated era, it is crucial understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming astrophysical biases. Type supernovae are standardisable candles whose absolute magnitude reaches scatter of typically 0.15 mag when empirical correlations with light-curve stretch and colour environmental properties accounted for. Aims. We investigate dependence...
Context. Type Ia supernova (SN Ia) cosmology studies will soon be dominated by systematic, uncertainties, rather than statistical ones. Thus, it is crucial to understand the unknown phenomena potentially affecting their luminosity that may remain, such as astrophysical biases. For accurate application in studies, SN magnitudes need standardised; namely, they must corrected for correlation with light-curve width and colour. Aims. Here, we investigate how standardisation procedure used reduce...
We present 32 epochs of optical (3300-9700 \AA) spectrophotometric observations the nearby quintessential "normal" type Ia supernova (SN Ia) SN 2011fe in galaxy M101, extending from -15 to +97 d with respect B-band maximum, obtained by Nearby Supernova Factory collaboration. is closest (\mu = 29.04) and brightest (Bmax 9.94 mag) observed since advent modern large scale programs for intensive periodic followup supernovae. Both synthetic light curve measurements spectral feature analysis...
We present an analysis of the host galaxy dependences Type Ia Supernovae (SNe Ia) from full three year sample SDSS-II Supernova Survey. re-discover, to high significance, strong correlation between type and width observed SN light curve, i.e., fainter, quickly declining SNe favor passive galaxies, while brighter, slowly Ia's star-forming galaxies. also find evidence (at 2σ 3σ) that are ≃0.1 ± 0.04 mag brighter in galaxies than hosts, after curves have been standardized using light-curve...
Abstract The Zwicky Transient Facility (ZTF) is performing a three-day cadence survey of the visible northern sky (∼3 π ) with newly found transient candidates announced via public alerts. ZTF Bright Survey (BTS) large spectroscopic campaign to complement photometric survey. BTS endeavors spectroscopically classify all extragalactic transients m peak ≤ 18.5 mag in either g or r filters, and publicly announce said classifications. discoveries are predominantly supernovae (SNe), making this...
We present a sample of normal Type Ia supernovae (SNe Ia) from the Nearby Supernova Factory data set with spectrophotometry at sufficiently late phases to estimate ejected mass using bolometric light curve. measure 56Ni masses peak luminosity, then compare luminosity in 56Co-decay tail expected rate radioactive energy release ejecta given mass. infer Bayesian context semi-analytic model ejecta, incorporating constraints contemporary numerical models as priors on density structure and...
Current time domain facilities are discovering hundreds of new galactic and extra-galactic transients every week. Classifying the ever-increasing number is challenging, yet crucial to further our understanding their nature, discover classes, or ensuring sample purity, for instance, Supernova Ia cosmology. The Zwicky Transient Facility one example such a survey. In addition, it has dedicated very-low resolution spectrograph, SEDMachine, operating on Palomar 60-inch telescope. This...
This paper describes the data release of Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, ancillary are presented for 10,258 variable transient sources discovered through repeat ugriz imaging SDSS Stripe 82, a 300 deg2 area along celestial equator. is comprised all brighter than r~22.5 mag with no history variability prior to 2004. Dedicated spectroscopic observations were performed on subset 889 transients, as...
(Abridged) We study the host galaxy regions in close proximity to Type Ia supernovae (SNe Ia) analyze relations between properties of SN events and environments most similar where their progenitors formed. focus on local H\alpha\ emission as an indicator young environments. The Nearby Supernova Factory has obtained flux-calibrated spectral timeseries for SNe using integral field spectroscopy, allowing simultaneous measurement its immediate vicinity. For 89 we measure tracing ongoing star...
We present spectroscopic observations of the host galaxies 82 low-redshift Type Ia supernovae (SNe Ia) discovered by Palomar Transient Factory. determine star formation rates, gas-phase/stellar metallicities, and stellar masses ages these objects. As expected, strong correlations between SN light-curve width (stretch) age/mass/metallicity are found: fainter, faster declining events tend to be hosted older/massive/metal-rich galaxies. There is some evidence that redder SNe explode in higher...
The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use data set by taking advantage temporal nature data, further combining it with other sets. start initial steps separating bogus candidates from real ones, stars galaxies, go on classification objects into classes. Besides usual methods (e.g., based features...
Early-time observations of Type Ia supernovae (SNe Ia) are essential to constrain their progenitor properties. In this paper, we present high-quality light curves 127 SNe discovered by the Zwicky Transient Facility (ZTF) in 2018. We describe our method perform forced point spread function (PSF) photometry, which can be applied other types extragalactic transients. With a planned cadence six per night ($3g+3r$), all detected both $g$ and $r$ band more than 10\,d (in rest frame) prior epoch...