R. J. Wainscoat
University of Hawaii
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Featured researches published by R. J. Wainscoat.
The Astrophysical Journal | 2012
John L. Tonry; Christopher W. Stubbs; Keith R. Lykke; Peter Doherty; I. S. Shivvers; W. S. Burgett; Ken Chambers; Klaus-Werner Hodapp; Nick Kaiser; R. P. Kudritzki; E. A. Magnier; Jeffrey S. Morgan; P. A. Price; R. J. Wainscoat
The Pan-STARRS1 survey is collecting multi-epoch, multi-color observations of the sky north of declination –30° to unprecedented depths. These data are being photometrically and astrometrically calibrated and will serve as a reference for many other purposes. In this paper, we present our determination of the Pan-STARRS1 photometric system: g P1, r P1, i P1, z P1, y P1, and w P1. The Pan-STARRS1 photometric system is fundamentally based on the Hubble Space Telescope Calspec spectrophotometric observations, which in turn are fundamentally based on models of white dwarf atmospheres. We define the Pan-STARRS1 magnitude system and describe in detail our measurement of the system passbands, including both the instrumental sensitivity and atmospheric transmission functions. By-products, including transformations to other photometric systems, Galactic extinction, and stellar locus, are also provided. We close with a discussion of remaining systematic errors.
The Astrophysical Journal | 2004
Brian J. Barris; John L. Tonry; Stephane Blondin; Peter M. Challis; Ryan Chornock; Alejandro Clocchiatti; Alexei V. Filippenko; Peter Marcus Garnavich; Stephen T. Holland; Saurabh W. Jha; Robert P. Kirshner; Kevin Krisciunas; Bruno Leibundgut; Weidong Li; Thomas Matheson; Gajus A. Miknaitis; Adam G. Riess; Brian Paul Schmidt; R. Chris Smith; Jesper Sollerman; Jason Spyromilio; Christopher W. Stubbs; Nicholas B. Suntzeff; H. Aussel; K. C. Chambers; Michael S. Connelley; Dominic G. O’Donovan; J. Patrick Henry; Nick Kaiser; Michael C. Liu
We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z = 0.34-1.03, nine of which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, which began in 2001 September and observed a total of 2.5 deg2 to a depth of approximately m ? 25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until 2002 April. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift SNe includes 15 at z ? 0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours that are consistent with the flat universe indicated by the cosmic microwave background (Spergel et al. 2003). Adopting the constraint that ?total = 1.0, we obtain best-fit values of (?m,??) = (0.33, 0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for ?? > 0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z > 1 SNe from the ground.We present photometric and spectroscopic observations of 23 high redshift supernovae spanning a range of z=0.34-1.03, 9 of which are unambiguously classified as Type Ia. These supernovae were discovered during the IfA Deep Survey, which began in September 2001 and observed a total of 2.5 square degrees to a depth of approximately m=25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until April 2002. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift supernovae includes 15 at z>0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours which are consistent with the flat universe indicated by the CMB (Spergel et al. 2003). Adopting the constraint that Omega_total = 1.0, we obtain best-fit values of (Omega_m, Omega_Lambda)=(0.33, 0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for Omega_Lambda > 0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z>1 SNe from the ground.
The Astrophysical Journal | 2013
C. Inserra; S. J. Smartt; A. Jerkstrand; S. Valenti; M. Fraser; D. Wright; K. W. Smith; Ting-Wan Chen; R. Kotak; Andrea Pastorello; M. Nicholl; Fabio Bresolin; R. P. Kudritzki; Stefano Benetti; M. T. Botticella; W. S. Burgett; K. C. Chambers; Mattias Ergon; H. Flewelling; J. P. U. Fynbo; S. Geier; Klaus-Werner Hodapp; D. A. Howell; M. E. Huber; Nick Kaiser; G. Leloudas; L. Magill; E. A. Magnier; M. McCrum; N. Metcalfe
We report extensive observational data for five of the lowest redshift Super-Luminous Type Ic Supernovae (SL-SNe Ic) discovered to date, namely PTF10hgi, SN2011ke, PTF11rks, SN2011kf and SN2012il. Photometric imaging of the transients at +50 to +230 days after peak combined with host galaxy subtraction reveals a luminous tail phase for four of these SL-SNe. A high resolution, optical and near infrared spectrum from xshooter provides detection of a broad He I �10830 emission line in the spectrum (+50d) of SN2012il, revealing that at least some SL-SNe Ic are not completely helium free. At first sight, the tail luminosity decline rates that we measure are consistent with the radioactive decay of 56 Co, and would require 1-4 M⊙ of 56 Ni to produce the luminosity. These 56 Ni masses cannot be made consistent with the short diffusion times at peak, and indeed are insufficient to power the peak luminosity. We instead favour energy deposition by newborn magnetars as the power source for these objects. A semi-analytical diffusion model with energy input from the spindown of a magnetar reproduces the extensive lightcurve data well. The model predictions of ejecta velocities and temperatures which are required are in reasonable agreement with those determined from our observations. We derive magnetar energies of 0.4 . E(10 51 erg) . 6.9 and ejecta masses of 2.3 . Mej(M⊙) . 8.6. The sample of five SL-SNe Ic presented here, combined with SN 2010gx - the best sampled SL-SNe Ic so far - point toward an explosion driven by a magnetar as a viable explanation for all SL-SNe Ic. Subject headings: supernovae: general - supernovae: individual (PTF10hgi, SN 2011ke, PTF11rks, SN 2011kf, SN 2012il) - stars: magnetars
The Astrophysical Journal | 2012
Edward F. Schlafly; Douglas P. Finkbeiner; Mario Juric; E. A. Magnier; W. S. Burgett; Ken Chambers; T. Grav; Klaus-Werner Hodapp; Nick Kaiser; R. P. Kudritzki; Nicolas F. Martin; Jeffrey S. Morgan; P. A. Price; H.-W. Rix; Christopher W. Stubbs; John L. Tonry; R. J. Wainscoat
We present a precise photometric calibration of the first 1.5 years of science imaging from the PanSTARRS1 survey (PS1), an ongoing optical survey of the entire sky north of declination −30 ◦ in five bands. Building on the techniques employed by Padmanabhan et al. (2008) in the Sloan Digital Sky Survey (SDSS), we use repeat PS1 observations of stars to perform the relative calibration of PS1 in each of its five bands, solving simultaneously for the system throughput, the atmospheric transparency, and the large-scale detector flat field. Both internal consistency tests and comparison against the SDSS indicate that we achieve relative precision of < 10 mmag in g, r, and iP1, and ∼ 10 mmag in z and yP1. The spatial structure of the differences with the SDSS indicates that errors in both the PS1 and SDSS photometric calibration contribute similarly to the differences. The analysis suggests that both the PS1 system and the Haleakala site will enable < 1% photometry over much of the sky. Subject headings: Surveys: Pan-STARRS1
The Astronomical Journal | 1992
R. J. Wainscoat; Lennox L. Cowie
The K passband (central wavelength 2.2 microns, FWHM 0.4 micron) is the longest wavelength standard near-IR passband through which deep ground-based imaging is possible. Thermal emission from telescope, instrument, and sky limits the depth to which such imaging can reach by producing strongly temperature-dependent backgrounds in the range 11-13.5 mag/sq arcsec. This paper describes how a passband, which is denoted as K-prime, located slightly shortward of the standard K passband (central wavelength 2.1 microns), yet still within the same atmospheric window, leads to a significantly lower thermal component of the background, reducing the background surface brightness by up to 0.9 mag sq arcsec, and thereby allowing deeper imaging to be obtained in the same integration time. The photometric differences between the K-prime filter and the standard K filter are discussed.
The Astrophysical Journal | 2014
Armin Rest; D. Scolnic; Ryan J. Foley; M. Huber; Ryan Chornock; Gautham S. Narayan; John L. Tonry; Edo Berger; Alicia M. Soderberg; Christopher W. Stubbs; Adam G. Riess; Robert P. Kirshner; S. J. Smartt; Edward F. Schlafly; Steven A. Rodney; M. T. Botticella; D. Brout; Peter M. Challis; Ian Czekala; Maria Rebecca Drout; Michael J. Hudson; R. Kotak; C. Leibler; R. Lunnan; G. H. Marion; M. McCrum; D. Milisavljevic; Andrea Pastorello; Nathan Edward Sanders; K. W. Smith
We present griz P1 light curves of 146 spectroscopically confirmed Type Ia supernovae (SNe Ia; 0.03 < z < 0.65) discovered during the first 1.5 yr of the Pan-STARRS1 Medium Deep Survey. The Pan-STARRS1 natural photometric system is determined by a combination of on-site measurements of the instrument response function and observations of spectrophotometric standard stars. We find that the systematic uncertainties in the photometric system are currently 1.2% without accounting for the uncertainty in the Hubble Space Telescope Calspec definition of the AB system. A Hubble diagram is constructed with a subset of 113 out of 146 SNe Ia that pass our light curve quality cuts. The cosmological fit to 310 SNe Ia (113 PS1 SNe Ia + 222 light curves from 197 low-z SNe Ia), using only supernovae (SNe) and assuming a constant dark energy equation of state and flatness, yields . When combined with BAO+CMB(Planck)+H 0, the analysis yields and including all identified systematics. The value of w is inconsistent with the cosmological constant value of –1 at the 2.3σ level. Tension endures after removing either the baryon acoustic oscillation (BAO) or the H 0 constraint, though it is strongest when including the H 0 constraint. If we include WMAP9 cosmic microwave background (CMB) constraints instead of those from Planck, we find , which diminishes the discord to <2σ. We cannot conclude whether the tension with flat ΛCDM is a feature of dark energy, new physics, or a combination of chance and systematic errors. The full Pan-STARRS1 SN sample with ~three times as many SNe should provide more conclusive results.
The Astrophysical Journal | 2010
Andrea Pastorello; S. J. Smartt; M. T. Botticella; K. Maguire; M. Fraser; K. W. Smith; R. Kotak; L. Magill; S. Valenti; D. R. Young; S. Gezari; Fabio Bresolin; R.-P. Kudritzki; Dale Andrew Howell; Armin Rest; N. Metcalfe; Seppo Mattila; E. Kankare; Kuiyun Huang; Yuji Urata; W. S. Burgett; K. C. Chambers; T. Dombeck; H. Flewelling; T. Grav; J. N. Heasley; K. W. Hodapp; N. Kaiser; Gerard A. Luppino; Robert H. Lupton
Recent searches by unbiased, wide-field surveys have uncovered a group of extremely luminous optical transients. The initial discoveries of SN 2005ap by the Texas Supernova Search and SCP-06F6 in a deep Hubble pencil beam survey were followed by the Palomar Transient Factory confirmation of host redshifts for other similar transients. The transients share the common properties of high optical luminosities (peak magnitudes ~-21 to -23), blue colors, and a lack of H or He spectral features. The physical mechanism that produces the luminosity is uncertain, with suggestions ranging from jet-driven explosion to pulsational pair instability. Here, we report the most detailed photometric and spectral coverage of an ultra-bright transient (SN 2010gx) detected in the Pan-STARRS 1 sky survey. In common with other transients in this family, early-time spectra show a blue continuum and prominent broad absorption lines of O II. However, about 25 days after discovery, the spectra developed type Ic supernova features, showing the characteristic broad Fe II and Si II absorption lines. Detailed, post-maximum follow-up may show that all SN 2005ap and SCP-06F6 type transients are linked to supernovae Ic. This poses problems in understanding the physics of the explosions: there is no indication from late-time photometry that the luminosity is powered by 56Ni, the broad light curves suggest very large ejected masses, and the slow spectral evolution is quite different from typical Ic timescales. The nature of the progenitor stars and the origin of the luminosity are intriguing and open questions.
The Astrophysical Journal | 1994
L. L. Cowie; J.P. Gardner; Esther M. Hu; Antoinette Songaila; K.-W. Hodapp; R. J. Wainscoat
We present the results of a very deep K-band survey with a 5 sigma total galaxy magnitude limit of K = 21.9 in the deepest field. A 5 sigma K-band-selected sample of 123 galaxies is presented, together with their optical colors. Only three galaxies in this sample are not detected at the 1 sigma level in Kron-Cousins I band. At K less than or = 20 the reddest (I-K) color is 5.1 +/- 0.4, and 15 of the 123 objects in the deep field sample have (I-K) greater than 4. In the blue, the galaxies show a rapid blueward trend at magnitudes beyond K = 19, dropping from a median (B-K) = 6 at K = 18 to a median (B-K) of only 4.2 at K = 21.5. The surface density of (I-K) greater than 4 objects is interpreted to imply either that there is a significant evolution toward later types in the colors of the normal galaxy population beyond z = 11 or that galaxies have faded by that redshift.
The Astrophysical Journal | 2014
R. Lunnan; Ryan Chornock; Edo Berger; Tanmoy Laskar; William. Fong; Armin Rest; Nathan Edward Sanders; Peter M. Challis; Maria Rebecca Drout; Ryan J. Foley; M. E. Huber; Robert P. Kirshner; C. Leibler; G. H. Marion; M. McCrum; D. Milisavljevic; Gautham S. Narayan; D. Scolnic; S. J. Smartt; K. W. Smith; Alicia M. Soderberg; John L. Tonry; W. S. Burgett; K. C. Chambers; H. Flewelling; Klaus-Werner Hodapp; Nick Kaiser; E. A. Magnier; P. A. Price; R. J. Wainscoat
We present optical spectroscopy and optical/near-IR photometry of 31 host galaxies of hydrogen-poor superluminous supernovae (SLSNe), including 15 events from the Pan-STARRS1 Medium Deep Survey. Our sample spans the redshift range 0.1 ~ -17.3 mag), low stellar mass ( ~ 2 x 10^8 M_sun) population, with a high median specific star formation rate ( ~ 2 Gyr^-1). The median metallicity of our spectroscopic sample is low, 12 + log(O/H}) ~ 8.35 ~ 0.45 Z_sun, although at least one host galaxy has solar metallicity. The host galaxies of H-poor SLSNe are statistically distinct from the hosts of GOODS core-collapse SNe (which cover a similar redshift range), but resemble the host galaxies of long-duration gamma-ray bursts (LGRBs) in terms of stellar mass, SFR, sSFR and metallicity. This result indicates that the environmental causes leading to massive stars forming either SLSNe or LGRBs are similar, and in particular that SLSNe are more effectively formed in low metallicity environments. We speculate that the key ingredient is large core angular momentum, leading to a rapidly-spinning magnetar in SLSNe and an accreting black hole in LGRBs.
The Astrophysical Journal | 2011
Laura Chomiuk; Ryan Chornock; Alicia M. Soderberg; Edo Berger; Roger A. Chevalier; Ryan J. Foley; M. E. Huber; Gautham S. Narayan; Armin Rest; S. Gezari; Robert P. Kirshner; Adam G. Riess; Steven A. Rodney; S. J. Smartt; Christopher W. Stubbs; John L. Tonry; William Michael Wood-Vasey; W. S. Burgett; K. C. Chambers; Ian Czekala; H. Flewelling; K. Forster; N. Kaiser; R.-P. Kudritzki; E. A. Magnier; D. C. Martin; Jeffrey S. Morgan; James D. Neill; P. A. Price; Kathy Roth
We present the discovery of two ultraluminous supernovae (SNe) at z ≈ 0.9 with the Pan-STARRS1 Medium Deep Survey. These SNe, PS1-10ky and PS1-10awh, are among the most luminous SNe ever discovered, comparable to the unusual transients SN 2005ap and SCP 06F6. Like SN 2005ap and SCP 06F6, they show characteristic high luminosities (M_(bol) ≈ –22.5 mag), blue spectra with a few broad absorption lines, and no evidence for H or He. We have constructed a full multi-color light curve sensitive to the peak of the spectral energy distribution in the rest-frame ultraviolet, and we have obtained time series spectroscopy for these SNe. Given the similarities between the SNe, we combine their light curves to estimate a total radiated energy over the course of explosion of (0.9-1.4) × 10^(51) erg. We find photospheric velocities of 12,000-19,000 km s^(–1) with no evidence for deceleration measured across ~3 rest-frame weeks around light curve peak, consistent with the expansion of an optically thick massive shell of material. We show that, consistent with findings for other ultraluminous SNe in this class, radioactive decay is not sufficient to power PS1-10ky, and we discuss two plausible origins for these events: the initial spin-down of a newborn magnetar in a core-collapse SN, or SN shock breakout from the dense circumstellar wind surrounding a Wolf-Rayet star.