51 results found
Schmit CJ, Pritchard JR, 2018, Emulation of reionization simulations for Bayesian inference of astrophysics parameters using neural networks, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 475, Pages: 1213-1223, ISSN: 0035-8711
Burns JO, Bradley R, Tauscher K, et al., 2017, A Space-based Observational Strategy for Characterizing the First Stars and Galaxies Using the Redshifted 21cm Global Spectrum, ASTROPHYSICAL JOURNAL, Vol: 844, ISSN: 0004-637X
Watkinson CA, Majumdar S, Pritchard JR, et al., 2017, A fast estimator for the bispectrum and beyond - a practical method for measuring non-Gaussianity in 21-cm maps, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 472, Pages: 2436-2446, ISSN: 0035-8711
Harker GJA, Mirocha J, Burns JO, et al., 2016, Parametrizations of the 21-cm global signal and parameter estimation from single-dipole experiments, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 455, Pages: 3829-3840, ISSN: 0035-8711
Liu A, Pritchard JR, Allison R, et al., 2016, Eliminating the optical depth nuisance from the CMB with 21 cm cosmology, PHYSICAL REVIEW D, Vol: 93, ISSN: 2470-0010
Pritchard J, 2015, Reionization and the SKA, ASTRONOMY & GEOPHYSICS, Vol: 56, ISSN: 1366-8781
Watkinson CA, Mesinger A, Pritchard JR, et al., 2015, 21-cm signatures of residual H I inside cosmic H II regions during reionization, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 449, Pages: 3202-3211, ISSN: 0035-8711
Watkinson CA, Pritchard JR, 2015, The impact of spin-temperature fluctuations on the 21-cm moments, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 454, Pages: 1416-1431, ISSN: 0035-8711
Glover SCO, Chluba J, Furlanetto SR, et al., 2014, Atomic, Molecular, and Optical Physics in the Early Universe: From Recombination to Reionization, Editors: Arimondo, Berman, Lin, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 135-270, ISBN: 978-0-12-800129-5
Koopmans LVE, Pritchard J, Mellema G, et al., 2014, The cosmic dawn and epoch of reionization with the square kilometre array
© Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. Concerted effort is currently ongoing to open up the Epoch of Reionization (z ∼15-6) for studies with IR and radio telescopes. Whereas IR detections have been made of sources (Lyman-a emitters, quasars and drop-outs) in this redshift regime in relatively small fields of view, no direct detection of neutral hydrogen, via the redshifted 21-cm line, has yet been established. Such a direct detection is expected in the coming years, with ongoing surveys, and could open up the entire universe from z ∼6-200 for astrophysical and cosmological studies, opening not only the Epoch of Reionization, but also its preceding Cosmic Dawn (z ∼30-15) and possibly even the later phases of the Dark Ages (z ∼200-30). All currently ongoing experiments attempt statistical detections of the 21-cm signal during the Epoch of Reionization, with limited signal-to-noise. Direct imaging, except maybe on the largest (degree) scales at lower redshifts, as well as higher redshifts will remain out of reach. The Square Kilometre Array (SKA) will revolutionize the field, allowing direct imaging of neutral hydrogen from scales of arc-minutes to degrees over most of the redshift range z ∼6-28 with SKA1-LOW, and possibly even higher redshifts with the SKA2-LOW. In this SKA will be unique, and in parallel provide enormous potential of synergy with other upcoming facilities (e.g. JWST). In this chapter we summarize the physics of 21-cm emission, the different phases the universe is thought to go through, and the observables that the SKA can probe, referring where needed to detailed chapters in this volume. This is done within the framework of the current SKA1 baseline design and a nominal CD/EoR straw-man survey, consisting of a shallow, medium-deep and deep survey, the latter probing down to ∼1mK brightness temperature on arc-minute scales at the end of reion
Pritchard J, Masters K, Allen J, et al., 2014, Asking gender questions, ASTRONOMY & GEOPHYSICS, Vol: 55, Pages: 8-12, ISSN: 1366-8781
Watkinson CA, Pritchard JR, 2014, Distinguishing models of reionization using future radio observations of 21-cm 1-point statistics, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 443, Pages: 3090-3106, ISSN: 0035-8711
Liu A, Pritchard JR, Tegmark M, et al., 2013, Global 21 cm signal experiments: A designer's guide, PHYSICAL REVIEW D, Vol: 87, ISSN: 1550-7998
Mellema G, Koopmans LVE, Abdalla FA, et al., 2013, Reionization and the Cosmic Dawn with the Square Kilometre Array, EXPERIMENTAL ASTRONOMY, Vol: 36, Pages: 235-318, ISSN: 0922-6435
Pritchard JR, Loeb A, 2013, Evolution of the 21cm signal throughout cosmic history, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 78, ISSN: 1089-4918
The potential use of the redshifted 21 cm line from neutral hydrogen for probing the epoch of reionization is motivating the construction of several low-frequency interferometers. There is also much interest in the possibility of constraining the initial conditions from inflation and the nature of the dark matter and dark energy by probing the power spectrum of density perturbations in three dimensions and on smaller scales than probed by the microwave background anisotropies. Theoretical understanding of the 21 cm signal has been fragmented into different regimes of physical interest. In this paper, we make the first attempt to describe the full redshift evolution of the 21 cm signal between 0<z<300. We include contributions to the 21 cm signal from fluctuations in the gas density, temperature, and neutral fraction, as well as the Lyα flux, and allow for a post-reionization signal from damped Lyα systems. Our comprehensive analysis provides a useful foundation for optimizing the design of future arrays whose goal is to separate the particle physics from the astrophysics, either by probing the peculiar velocity distortion of the 21 cm power spectrum, or by extending the 21 cm horizon to z≳25 before the first galaxies had formed, or to z≲6 when the residual pockets of hydrogen trace large-scale structure.
Burns JO, Lazio J, Bale S, et al., 2012, Probing the first stars and black holes in the early Universe with the Dark Ages Radio Explorer (DARE), ADVANCES IN SPACE RESEARCH, Vol: 49, Pages: 433-450, ISSN: 0273-1177
Harker GJA, Pritchard JR, Burns JO, et al., 2012, An MCMC approach to extracting the global 21-cm signal during the cosmic dawn from sky-averaged radio observations, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 419, Pages: 1070-1084, ISSN: 0035-8711
Loeb A, Pritchard J, 2012, The missing reel, NEW SCIENTIST, Vol: 216, Pages: 30-33, ISSN: 0262-4079
Pritchard JR, Loeb A, 2012, 21 cm cosmology in the 21st century, REPORTS ON PROGRESS IN PHYSICS, Vol: 75, ISSN: 0034-4885
We describe the use of the high redshift 21 cm signal to probe the very first galaxies to appear in the Universe. Using fast large volume simulations of the pre-Reionization epoch we have shown that the Lyman alpha radiation emitted from these young galaxies makes a strong contribution to the 21cm signal on large scales at z∼20. With the current setup the Square Kilometre Array (SKA) should be able to measure this signal, therefore making it probably the only telescope capable of giving us detailed information about the radiation emitted by the first stars and characterizing their host galaxies. SKA-pathfinders with ∼10%of the full collecting area should be capable of making a statistical detection of the 21cm power spectrum at redshifts z < 20.We then discuss the use of the redshift space distortions as a way to further constrain the Lyman alpha signal and demonstrate that they can be used as a model independent way to extract this signature with the SKA. © Springer-Verlag Berlin Heidelberg 2012.
Silva MB, Santos MG, Pritchard JR, et al., 2012, Probing the Very First Galaxies with the SKA, Joint European and National Astronomy Meeting (JENAM)/18th Annual Meeting of the European-Astronomical-Society/20th Annual Portuguese Meeting of Astronomy and Astrophysics/Symposium 7 - Square Kilometre Array (SKA), Publisher: SPRINGER, Pages: 101-116, ISSN: 1570-6591
Abazajian KN, Calabrese E, Cooray A, et al., 2011, Cosmological and astrophysical neutrino mass measurements, ASTROPARTICLE PHYSICS, Vol: 35, Pages: 177-184, ISSN: 0927-6505
Adshead P, Easther R, Pritchard J, et al., 2011, Inflation and the scale dependent spectral index: prospects and strategies, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516
Lidz A, Furlanetto SR, Oh SP, et al., 2011, INTENSITY MAPPING WITH CARBON MONOXIDE EMISSION LINES AND THE REDSHIFTED 21 cm LINE, ASTROPHYSICAL JOURNAL, Vol: 741, ISSN: 0004-637X
Pritchard JR, Loeb A, 2011, 21-cm cosmology, Rep. Prog. Phys., Vol: 75
Imaging the Universe during the first hundreds of millions of years remainsone of the exciting challenges facing modern cosmology. Observations of theredshifted 21 cm line of atomic hydrogen offer the potential of opening a newwindow into this epoch. This would transform our understanding of the formationof the first stars and galaxies and of the thermal history of the Universe. Anew generation of radio telescopes is being constructed for this purpose withthe first results starting to trickle in. In this review, we detail the physicsthat governs the 21 cm signal and describe what might be learnt from upcomingobservations. We also generalize our discussion to intensity mapping of otheratomic and molecular lines.
Santos MG, Silva MB, Pritchard JR, et al., 2011, Probing the first galaxies with the Square Kilometer Array, ASTRONOMY & ASTROPHYSICS, Vol: 527, ISSN: 0004-6361
Pritchard J, Loeb A, 2010, COSMOLOGY Hydrogen was not ionized abruptly, NATURE, Vol: 468, Pages: 772-773, ISSN: 0028-0836
Pritchard JR, Loeb A, 2010, Constraining the unexplored period between the dark ages and reionization with observations of the global 21 cm signal, PHYSICAL REVIEW D, Vol: 82, ISSN: 1550-7998
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