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Foreground Contamination in Interferometric Measurements of the Redshifted 21 cm Power Spectrum
Judd D. Bowman, Miguel F. Morales, Jacqueline N. Hewitt
Subtraction of astrophysical foreground contamination from "dirty" sky maps produced by simulated measurements of the Murchison Widefield Array (MWA) has been performed by fitting…
Toward Empirical Constraints on the Global Redshifted 21 cm Brightness Temperature During the Epoch of Reionization
Judd D. Bowman, Alan E. E. Rogers, Jacqueline N. Hewitt
Preliminary results are presented from a simple, single-antenna experiment designed to measure the all-sky radio spectrum between 100 and 200 MHz. The system used an internal compa…
Low frequency radio astronomy from the moon: cosmic reionization and more
C. L. Carilli, J. N. Hewitt, A. Loeb
We discuss low frequency radio astronomy from the moon, predominantly in the context of studying the neutral intergalactic medium during cosmic reionization using the HI 21cm line…
Report of the Dark Energy Task Force
Andreas Albrecht, Gary Bernstein, Robert Cahn +10
Dark energy appears to be the dominant component of the physical Universe, yet there is no persuasive theoretical explanation for its existence or magnitude. The acceleration of th…
The Extragalactic Lens VLBI Imaging Survey (ELVIS). I. A Search for the Central Image in the Gravitational Lens PMN J1838-3427
Edward R. Boyce, Joshua N. Winn, Jacqueline N. Hewitt +1
The Extragalactic Lens VLBI Imaging Survey (ELVIS) searches for central images of lensed radio quasars, in order to measure the central density profiles of distant galaxies. Here w…
Constraints on Fundamental Cosmological Parameters with Upcoming Redshifted 21 cm Observations
Judd D. Bowman, Miguel F. Morales, Jacqueline N. Hewitt
Constraints on cosmological parameters from upcoming measurements with the Mileura Widefield Array-Low Frequency Demonstrator (MWA-LFD) of the redshifted 21 cm power spectrum are f…
A Search for Radio Gravitational Lenses, Using the Sloan Digital Sky Survey and the Very Large Array
Edward R. Boyce, Judd D. Bowman, Adam S. Bolton +2
We report on a novel search for radio gravitational lenses. Using the Very Large Array, we imaged ten candidates with both dual redshifts in Sloan Digital Sky Survey spectra and 1.…
Improving Foreground Subtraction in Statistical Observations of 21 cm Emission from the Epoch of Reionization
Miguel F. Morales, Judd D. Bowman, Jacqueline N. Hewitt
Statistical observations of the Epoch of Reionization using the 21 cm line of neutral hydrogen have the potential to revolutionize our understanding of structure formation and the…
The Sensitivity of First Generation Epoch of Reionization Observatories and Their Potential for Differentiating Theoretical Power Spectra
Judd D. Bowman, Miguel F. Morales, Jacqueline N. Hewitt
Statistical observations of the epoch of reionization (EOR) power spectrum provide a rich data set for understanding the transition from the cosmic "dark ages" to the ionized unive…
Gravitational Lensing Signatures of Supermassive Black Holes in Future Radio Surveys
Judd D. Bowman, Jacqueline N. Hewitt, James R. Kiger
Observational measurements of the relationship between supermassive black holes (SMBHs) and the properties of their host galaxies are an important method for probing theoretical hi…
The Design of Radio Telescope Array Configurations using Multiobjective Optimization: Imaging Performance versus Cable Length
Babak E. Cohanim, Jacqueline N. Hewitt, Olivier de Weck
The next generation of radio telescope interferometric arrays requires careful design of the array configuration to optimize the performance of the overall system. We have develope…
Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
Miguel F. Morales, Jacqueline Hewitt
This paper explores the potential for statistical epoch of reionization (EOR) measurements using wide field radio observations. New developments in low frequency radio instrumentat…
PMN J0134-0931: A gravitationally lensed quasar with an unusual radio morphology
Joshua N. Winn, James E. J. Lovell, Hsiao-Wen Chen +4
The radio-loud quasar PMN J0134-0931 was discovered to have an unusual morphology during our search for gravitational lenses. In VLA and MERLIN images, there are 5 compact componen…
PMN J1632-0033: A new gravitationally lensed quasar
Joshua N. Winn, Nicholas D. Morgan, Jacqueline N. Hewitt +6
We report the discovery of a gravitationally lensed quasar resulting from our survey for lenses in the southern sky. Radio images of PMN J1632-0033 with the VLA and ATCA exhibit tw…
Further Investigation of the Time Delay, Magnification Ratios, and Variability in the Gravitational Lens 0218+357
A. S. Cohen, J. N. Hewitt, C. B. Moore +1
High precision VLA flux density measurements for the lensed images of 0218+357 yield a time delay of 10.1(+1.5-1.6)days (95% confidence). This is consistent with independent measur…
PMN J1838-3427: A new gravitationally lensed quasar
Joshua N. Winn, Jacqueline N. Hewitt, Paul L. Schechter +11
We report the discovery of a new double-image quasar that was found during a search for gravitational lenses in the southern sky. Radio source PMN J1838-3427 is composed of two fla…
A nearly symmetric double-image gravitational lens
Joshua N. Winn, Jacqueline N. Hewitt, Alok R. Patnaik +5
We report the discovery of a new double-image gravitational lens resulting from our search for lenses in the southern sky. Radio source PMN J2004-1349 is composed of two compact co…
A multipole-Taylor expansion for the potential of gravitational lens MG J0414+0534
Catherine S. Trotter, Joshua N. Winn, Jacqueline N. Hewitt
We employ a multipole-Taylor expansion to investigate how tightly the gravitational potential of the quadruple-image lens MG J0414+0534 is constrained by recent VLBI observations.…
A southern VLA-based gravitational lens search
Joshua N. Winn, Jacqueline N. Hewitt, Paul L. Schechter
We present a status report on our search for multiple-image QSOs among southern radio sources. Our goal is to identify new lenses for use in studies of cosmology and galaxy structu…
The Radio Wavelength Time Delay of Gravitational Lens 0957+561
Deborah B. Haarsma, Jacqueline N. Hewitt, Joseph Lehár +1
The gravitational lens 0957+561 was monitored with the Very Large Array from 1979 to 1997. The 6 cm light curve data from 1995-1997 and the 4 cm data from 1990-1997 are reported he…
15 GHz Monitoring of the Gravitational Lens MG 0414+0534
Christopher B. Moore, Jacqueline N. Hewitt
We report the results of monitoring the four images of the gravitational lens MG 0414+0534 at 15 GHz. In 35 VLA maps spanning 180 days, we measure root-mean-square variations in th…
The Quadruple Gravitational Lens PG1115+080: Time Delays and Models
P. L. Schechter, C. D. Bailyn, R. Barr +24
Optical photometry is presented for the quadruple gravitational lens PG1115+080. A preliminary reduction of data taken from November 1995 to June 1996 gives component ``C'' leading…
The 6 cm Light Curves of B0957+561, 1979-1994: New Features and Implications for the Time Delay
Deborah B. Haarsma, Jacqueline N. Hewitt, Joseph Lehár +1
We report on 15 years of VLA monitoring of the gravitational lens B0957+561 at 6 cm. Since our last report in 1992, there have been 32 additional observations, in which both images…
A 23 GHz Survey of GRB Error Boxes
J. N. Hewitt, C. A. Katz, S. D. Barthelmy +11
The Haystack 37-meter telescope was used in a pilot project in May 1995 to observe GRB error boxes at 23~GHz. Seven BATSE error boxes and two IPN arcs were scanned by driving the b…