M. Childress
A5040317512- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Neutrino Physics Research
- Cancer therapeutics and mechanisms
- CCD and CMOS Imaging Sensors
- Nuclear Physics and Applications
- Geological and Geophysical Studies
- Protein Tyrosine Phosphatases
- Solar and Space Plasma Dynamics
- Cosmology and Gravitation Theories
- Atomic and Subatomic Physics Research
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- High-pressure geophysics and materials
- Infectious Diseases and Mycology
- Beetle Biology and Toxicology Studies
- Scientific Computing and Data Management
University of Southampton
2016-2020
Australian National University
2013-2018
ARC Centre of Excellence for All-sky Astrophysics
2014-2018
University of Missouri
2018
University of California, Berkeley
2009-2015
Lawrence Berkeley National Laboratory
2008-2015
We present cosmological results from a combined analysis of galaxy clustering and weak gravitational lensing, using 1321 deg$^2$ $griz$ imaging data the first year Dark Energy Survey (DES Y1). combine three two-point functions: (i) cosmic shear correlation function 26 million source galaxies in four redshift bins, (ii) angular autocorrelation 650,000 luminous red five (iii) galaxy-shear cross-correlation positions shears. To demonstrate robustness these results, we use independent pairs...
We present photometric and spectroscopic observations of SN 2007if, an overluminous (MV = −20.4), red (B − V 0.16 at B-band maximum), slow-rising (trise 24 days) type Ia supernova (SN Ia) in a very faint (Mg −14.10) host galaxy. A spectrum 5 days past maximum light is direct match to the super-Chandrasekhar-mass candidate 2003fg, showing Si ii C ∼9000 km s−1. high signal-to-noise co-addition spectral time series reveals no Na i D absorption, suggesting negligible reddening galaxy, late-time...
The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and products which are publicly available through ESO archive Data Release 1 (SSDR1). PESSTO uses New Technology Telescope with EFOSC2 SOFI to provide optical NIR spectroscopy imaging. target supernovae transients brighter than 20.5mag for classification. Science targets then selected follow-up based on...
We describe the derivation and validation of redshift distribution estimates their uncertainties for populations galaxies used as weak-lensing sources in Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (bpz) code is to assign four bins between z ≈ 0.2 ≈1.3, produce initial lensing-weighted distributions |$n^i_{\rm PZ}(z)\propto \mathrm{d}n^i/\mathrm{d}z$| members bin i. Accurate determination parameters depends critically on knowledge ni, but...
We introduce redMaGiC, an automated algorithm for selecting Luminous Red Galaxies (LRGs). The was specifically developed to minimize photometric redshift uncertainties in large-scale structure studies. redMaGiC achieves this by self-training the color-cuts necessary produce a luminosity-thresholded LRG sample of constant comoving density. demonstrate that photozs are very nearly as accurate best machine-learning based methods, yet they require minimal spectroscopic training, do not suffer...
The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations used constrain explosion scenarios. We base our discussion on three-dimensional simulations a delayed detonation Chandrasekhar-mass white dwarf violent merger two dwarfs-realizations models appropriate most...
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...
Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, (pseudo-bolometric) peak luminosity log (L) = 43.47 (erg s−1). Its light curves decline slowly over half year after maximum [Δm15(B)true= 0.71], the early-time show secondary maxima, although minima between first second peaks are not very pronounced. The bluer bands exhibit an enhanced fading ∼200 d, which might be caused by...
Supernova (SN) 2009ig was discovered 17 hours after explosion by the Lick Observatory Search, promptly classified as a normal Type Ia SN (SN Ia), peaked at V = 13.5 mag, and equatorial, making it one of foremost supernovae for intensive study in last decade. Here, we present ultraviolet (UV) optical observations 2009ig, starting about 1 day until around maximum brightness. Our data include excellent UV light curves, 25 premaximum spectra, 8 including earliest spectrum ever obtained Ia. is...
We present the results of a search for rapidly evolving transients in Dark Energy Survey Supernova Programme. These events are characterized by fast light-curve evolution (rise to peak ≲10 d and exponential decline ≲30 after peak). discovered 72 events, including 37 with spectroscopic redshift from host galaxy spectral features. The increase total number rapid optical more than factor two. They found at wide range redshifts (0.05 < |$z$| 1.56) brightnesses (−15.75 > Mg −22.25). multiband...
We present the first cosmological parameter constraints using measurements of type Ia supernovae (SNe Ia) from Dark Energy Survey Supernova Program (DES-SN). The analysis uses a subsample 207 spectroscopically confirmed SNe three years DES-SN, combined with low-redshift sample 122 literature. Our "DES-SN3YR" result these 329 is based on series companion analyses and improvements covering SN discovery, spectroscopic selection, photometry, calibration, distance bias corrections, evaluation...
Presently, a >3σ tension exists between values of the Hubble constant H0 derived from analysis fluctuations in cosmic microwave background by Planck, and local measurements expansion using calibrators Type Ia supernovae (SNe Ia). We perform blinded re-analysis Riess et al. (2011) to measure low-redshift SNe Ia, calibrated Cepheid variables geometric distances including NGC 4258. This paper is demonstration techniques be applied (2016) data. Our end-to-end starts available Harvard...
We present two hydrogen-rich superluminous supernovae (SLSNe), namely SN2013hx and PS15br. These objects, together with SN2008es are the only SLSNe showing a distinct, broad Halpha feature during photospheric phase also do not show any sign of strong interaction between fast-moving ejecta circumstellar shells in their early spectra. Despite PS15br peak luminosity is fainter than other spectrophotometric evolution similar to different supernova space. group all them as II hence distinct from...
OzDES is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim to measure redshifts of approximately 2,500 Type Ia supernovae host galaxies over redshift range 0.1 < z 1.2, and derive reverberation-mapped black hole masses for 500 active galactic nuclei quasars 0.3 4.5. This treasure trove data forms major part follow-up Dark Energy Survey which we are also targeting cluster galaxies, radio strong lenses, unidentified transients, as well measuring...
We describe catalog-level simulations of Type Ia supernova (SN~Ia) light curves in the Dark Energy Survey Supernova Program (DES-SN), and low-redshift samples from Center for Astrophysics (CfA) Carnegie Project (CSP). These are used to model biases selection effects curve analysis, determine bias corrections SN~Ia distance moduli that measure cosmological parameters. To generate realistic curves, simulation uses a detailed model, incorporates information observations (PSF, sky noise, zero...
We present a sample of 21 hydrogen-free superluminous supernovae (SLSNe-I), and one hydrogen-rich SLSN (SLSN-II) detected during the five-year Dark Energy Survey (DES). These SNe, located in redshift range 0.220<z<1.998, represent largest homogeneously-selected events at high redshift. observed g,r, i, z light curves for these which we interpolate using Gaussian Processes. The resulting are analysed to determine luminosity function SLSN-I, their evolutionary timescales. DES SLSN-I...
Abstract We present griz light curves of 251 SNe Ia from the first 3 years Dark Energy Survey Supernova Program’s (DES-SN) spectroscopically classified sample. The photometric pipeline described in this paper produces calibrated fluxes and associated uncertainties used cosmological parameter analysis by employing a scene modeling approach that simultaneously models variable transient flux temporally constant host galaxy. inject artificial point sources onto DECam images to test accuracy our...
We employ 76 type Ia supernovae with optical spectrophotometry within 2.5 days of B-band maximum light obtained by the Nearby Supernova Factory to derive impact Si and Ca features on intrinsic luminosity determine a dust reddening law. use equivalent width II {\lambda}4131 in place curve stretch account for first-order variability. The resultant empirical spectral law exhibits strong associated {\lambda}6355. After applying correction based H&K we find consistent Cardelli extinction Using...
We present a new atmospheric extinction curve for Mauna Kea spanning 3200--9700 \AA. It is the most comprehensive to date, being based on some 4285 standard star spectra obtained 478 nights spread over period of 7 years by Nearby SuperNova Factory using Integral Field Spectrograph. This mean and its dispersion can be used as an aid in calibrating spectroscopic or imaging data from Kea, estimating calibration uncertainty associated with use curve. Our method decomposing into physical...
We present a new method to standardize type Ia supernova (SN Ia) luminosities 0.13 mag using flux ratios from single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for that correlate with SN luminosity. After developing the and selecting best training sample, verified results on separate validation sample data literature. identified multiple whose correlations luminosity are stronger than those light curve shape...
The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by Kepler mission. In order to determine black hole mass in from H-beta reverberation mapping, we have carried out nightly observations with Kast Spectrograph at Lick 3m telescope during dark runs June through December 2010, obtaining 54 spectroscopic total. We also obtained V-band imaging Katzman Automatic Imaging Telescope Observatory and 0.9m Brigham Young University West Mountain over same period....
We present multi-band ultraviolet and optical light curves, as well visual-wavelength near-infrared spectroscopy of the Type II linear (IIL) supernova (SN) 2013by. show that SN 2013by other SNe IIL in literature, after their decline phase start maximum, have a sharp curve similar to seen plateau (IIP) supernovae. This feature has rarely been observed due relative rarity intrinsic faintness this particular curve. suggest presence drop could be used physical parameter distinguish between...
We present results for the first three years of OzDES, a six year programme to obtain redshifts objects in Dark Energy Survey (DES) supernova fields using 2dF fibre positioner and AAOmega spectrograph on Anglo-Australian Telescope. OzDES is multi-object spectroscopic survey targeting multiple types targets at epochs over multiyear baseline one surveys dynamically include transients into target list soon after their discovery. At end years, has spectroscopically confirmed almost 100...