M. L. Graham
A5076800283- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Optical Systems and Laser Technology
- Integrated Circuits and Semiconductor Failure Analysis
- Particle Accelerators and Free-Electron Lasers
- Solar and Space Plasma Dynamics
- Neutrino Physics Research
- Adaptive optics and wavefront sensing
- Radio Astronomy Observations and Technology
- Nuclear Physics and Applications
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Non-Destructive Testing Techniques
- Distributed and Parallel Computing Systems
- Astrophysics and Star Formation Studies
- Geological and Geophysical Studies
- History and Developments in Astronomy
- Spectroscopy Techniques in Biomedical and Chemical Research
University of Washington
2016-2024
City University of Seattle
2020-2024
Vera C. Rubin Observatory
2024
University of Wisconsin–Madison
2016-2023
Wisconsin Department of Agriculture Trade and Consumer Protection
2023
Imperial College London
2021
California Institute of Technology
2016-2020
Large Synoptic Survey Telescope Corporation
2019
University of California, Berkeley
2013-2018
Seattle University
2017
Las Cumbres Observatory Global Telescope (LCOGT) is a young organization dedicated to time-domain observations at optical and (potentially) near-IR wavelengths. To this end, LCOGT constructing worldwide network of telescopes, including the two 2 m Faulkes as many 17 × 1 23 40 cm telescopes. These telescopes initially will be outfitted for imaging (excepting telescopes) spectroscopy wavelengths between atmospheric UV cutoff roughly 1-μm limit silicon detectors. Since first LCOGT's are now...
We combine high redshift Type Ia supernovae from the first 3 years of Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample 472 SNe (123 low-$z$, 93 SDSS, 242 SNLS, and 14 {\it Hubble Space Telescope}). SN data alone require cosmic acceleration >99.9% confidence, including systematic effects. For dark energy equation state parameter (assumed constant out least $z=1.4$) in flat universe, we find $w =...
We present photometric properties and distance measurements of 252 high redshift Type Ia supernovae (0.15 < z 1.1) discovered during the first three years Supernova Legacy Survey (SNLS). These events were detected their multi-colour light curves measured using MegaPrime/MegaCam instrument at Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in bands. Follow-up spectroscopy was performed VLT, Gemini Keck telescopes to confirm nature measure redshifts....
We present observational constraints on the nature of dark energy using Supernova Legacy Survey three-year sample (SNLS3) Guy et al. and Conley use 472 Type Ia supernovae (SNe Ia) in this sample, accounting for recently discovered correlations between SN luminosity host galaxy properties, include effects all identified systematic uncertainties directly cosmological fits. Combining SNLS3 data with full WMAP7 power spectrum, Sloan Digital Sky luminous red a prior Hubble constant H0 from SHOES,...
High-quality collections of Type II supernova (SN) light curves are scarce because they evolve for hundreds days, making follow-up observations time consuming and often extending over multiple observing seasons. In these difficulties, the diversity SNe is not fully understood. Here we present ultraviolet optical photometry 12 monitored by Las Cumbres Observatory Global Telescope Network during 2013 to 2014, compare them with previously studied having well-sampled curves. We explore SN...
In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around strong gravitational lens could be used to measure the rate of cosmic expansion. We report discovery such system. Hubble Space Telescope imaging, we have found four images single forming an Einstein cross configuration redshift z=0.54 elliptical galaxy in MACS J1149.6+2223 cluster. The cluster's potential also creates z=1.49 spiral host galaxy, and future appearance elsewhere cluster field is expected....
We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies all superluminous supernovae (SLSNe) discovered by Palomar Transient Factory prior to 2013, derive measurements their luminosities, star-formation rates, stellar masses, gas-phase metallicities. find that Type I (hydrogen-poor) SLSNe are found almost exclusively in low-mass (M < 2x10^9 M_sun) metal-poor (12+log[O/H] 8.4) galaxies. compare mass metallicity distributions our sample nearby galaxy...
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...
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...
While a white dwarf is, from theoretical perspective, the most plausible primary star in Type Ia supernova (SN Ia), many other candidates have not been formally ruled out. Shock energy deposited envelope of any exploding contributes to early SN brightness and, since this radiation is degraded by expansion after explosion, diffusive luminosity depends on initial radius. We present new non-detection limit nearby 2011fe, obtained what appears be just 4 hours allowing us directly constrain...
The intermediate Palomar Transient Factory reports our discovery of a young supernova, iPTF13bvn, in the nearby galaxy, NGC 5806 (22.5 Mpc). Our spectral sequence optical and infrared suggests Type Ib classification. We identify blue progenitor candidate deep pre-explosion imaging within 2σ error circle 80 mas (8.7 pc). has an MB luminosity −5.52 ± 0.39 mag B − I color 0.25 mag. If confirmed by future observations, this would be first direct detection for Ib. Fitting power law to early light...
Abstract We present early photometric and spectroscopic observations of SN 2013ej, a bright Type IIP supernova (SN) in M74. 2013ej is one the closest SNe ever discovered. The available archive images discovery help to constrain nature its progenitor. earliest detection this explosion was on 2013 July 24.125 ut our monitoring with FLOYDS spectrographs began 27.7 ut, continuing almost daily for two weeks. Daily optical achieved 1 m telescopes Las Cumbres Observatory Global Telescope (LCOGT)...
The supernova (SN) PTF11iqb was initially classified as a Type IIn event caught very early after explosion. It showed narrow Wolf–Rayet (WR) spectral features on day 2 (as in SN 1998S and 2013cu), but the emission weakened quickly spectrum morphed to resemble Types II-L II-P. At late times, Hα exhibited complex, multipeaked profile reminiscent of 1998S. In terms spectroscopic evolution, we find that near twin 1998S, although with somewhat weaker interaction circumstellar material (CSM) at...
Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe) are perhaps the best-studied class SNe, yet progenitor systems these explosions largely remain a mystery. A rare subclass SNe show evidence strong interaction with circumstellar medium (CSM), and in particular, hydrogen-rich CSM; we refer them as Ia-CSM. In first systematic search such systems, have identified 16 Ia-CSM, here present new spectra 13 them. Six Ia-CSM been well-studied previously, three...
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...
The Large Synoptic Survey Telescope is designed to provide an unprecedented optical imaging dataset that will support investigations of our Solar System, Galaxy and Universe, across half the sky over ten years repeated observation. However, exactly how LSST observations be taken (the observing strategy or "cadence") not yet finalized. In this dynamically-evolving community white paper, we explore detailed performance anticipated science expected depend on small changes strategy. Using...
A key tracer of the elusive progenitor systems Type Ia supernovae (SNe Ia) is detection narrow blueshifted time-varying Na i D absorption lines, interpreted as evidence circumstellar material surrounding system. The origin this controversial, but simplest explanation that it results from previous mass-loss in a system containing white dwarf and non-degenerate companion star. We present new single-epoch intermediate-resolution spectra 17 low-redshift SNe taken with XShooter on European...
ABSTRACT We report evidence for excess blue light from the Type Ia supernova (Sn Ia) SN 2012cg at 15 and 16 days before maximum B -band brightness. The emission is consistent with predictions impact of on a non-degenerate binary companion. This first companion to normal Ia. Sixteen light, <?CDATA $B-V$?> <?MML <mml:math> <mml:mi>B</mml:mi> <mml:mo>−</mml:mo> <mml:mi>V</mml:mi> </mml:math>?> color 0.2 mag bluer than other At later times, this has typical curve, extinction-corrected...
We present observations of two new hydrogen-poor superluminous supernovae (SLSN-I), iPTF15esb and iPTF16bad, showing late-time H-alpha emission with line luminosities (1-3)e+41 erg/s velocity widths (4000-6000) km/s. Including the previously published iPTF13ehe, this makes up a total three such events to date. iPTF13ehe is one most luminous slowest evolving SLSNe-I, whereas other are less fast decliners. interpret as result ejecta running into neutral H-shell located at radius ~ 1.0e+16cm....
Torques acting on galaxies lead to physical alignments, but the resulting ellipticity correlations are difficult predict. As they constitute a major contaminant for cosmic shear studies, it is important constrain intrinsic alignment signal observationally. We measured alignments of satellite within 90 massive galaxy clusters in redshift range 0.05 <z< 0.55 and quantified their impact signal. combined sample 38 104 with spectroscopic redshifts high-quality data from Canada-France-Hawaii...
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...
Vera C. Rubin Observatory is a ground-based astronomical facility under construction, joint project of the National Science Foundation and U.S. Department Energy, designed to conduct multi-purpose 10-year optical survey southern hemisphere sky: Legacy Survey Space Time. Significant flexibility in strategy remains within constraints imposed by core science goals probing dark energy matter, cataloging Solar System, exploring transient sky, mapping Milky Way. The survey's massive data...