Physical Sciences and Mathematics Commons^™

A Search For Correlations Between Gamma-Ray Burst Variability And Afterglow Onset, Sarah A. Yost

Physics Faculty Publications

We compared the time (or time limit) of onset for optical afterglow emission to the γ-ray variability V in 76 gamma-ray bursts with redshifts. In the subset (25 cases) with the rise evident in the data, we fit the shape of the onset peak as well and compared the rising and decaying indices to V. We did not find any evidence for any patterns between these properties and there is no statistical support for any correlations. This indicates a lack of connection between irregularities of the prompt γ-ray emission and the establishment of the afterglow phase. In the ordinary …

A Determination Of The Gamma-Ray Flux And Photon Spectral Index Distributions Of Blazars From The Fermi-Lat 3lac, Jack Singal

Physics Faculty Publications

We present a determination of the distributions of gamma-ray photon flux – the so-called LogN–LogS relation – and photon spectral index for blazars, based on the third extragalactic source catalogue of the Fermi Gamma-ray Space Telescope's Large Area Telescope, and considering the photon energy range from 100 MeV to 100 GeV. The data set consists of the 774 blazars in the so-called Clean sample detected with a greater than approximately 7σ detection threshold and located above ±20° Galactic latitude. We use non-parametric methods verified in previous works to reconstruct the intrinsic distributions from the observed ones …

Spectroscopic Needs For Imaging Dark Energy Experiments, Jeffrey A. Newman, Alexandra Abate, Filipe B. Abdalla, Sahar Allam, Steven W. Allen, Réza Ansari, Stephen Bailey, Wayne A. Barkhouse, Timothy C. Beers, Michael R. Blanton, Mark Brodwin, Joel R. Brownstein, Robert J. Brunner, Matias Carrasco Kind, Jorge L. Cervantes-Cota, Elliott Cheu, Nora Elisa Chisari, Matthew Colless, Johan Comparat, Jean Coupon, Carlos E. Cunha, Axel De La Macorra, Ian P. Dell'antonio, Brenda L. Frye, Eric J. Gawiser, Neil Gehrels, Kevin Grady, Alex Hagen, Patrick B. Hall, Andrew P. Hearin, Hendrik Hildebrandt, Christopher M. Hirata, Shirley Ho, Klaus Honscheid, Dragan Huterer, Željko Ivezić, Jean-Paul Kneib, Jeffrey W. Kruk, Ofer Lahav, Rachel Mandelbaum, Jennifer L. Marshall, Daniel J. Matthews, Brice Ménard, Ramon Miquel, Marc Moniez, H. W. Moos, John Moustakas, Adam D. Myers, Casey Popovich, John A. Peacock, Changbom Park, Mubdi Rahman, Jason Rhodes, Jean-Stephane Ricol, Iftach Sadeh, Anže Slozar, Samuel J. Schmidt, Daniel K. Stern, J. Anthony Tyson, Anja Von Der Linden, Risa H. Wechsler, W. M. Wood-Vasey, Andrew R. Zentner

Physics Faculty Publications

Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments.

Hence, to achieve their full potential, imaging-based experiments …

Precision Measurements Of Aⁿ1 In The Deep Inelastic Regime, D. S. Parno, D. Flay, M. Posik, M. Canan, C. Hyde, The Jefferson Lab Hall A Collaboration

Physics Faculty Publications

We have performed precision measurements of the double-spin virtual-photon asymmetry A₁ on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized ³He target. Our data cover a wide kinematic range 0.277 <= x <= 0.548 at an average Q² value of 3.078(GeV/c)², doubling the available high-precision neutron data in this xrange. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. Our data are consistent with …

First Measurement Of The Polarization Observable E In The P→ (Ɣ→, Π+) In Reaction Up To 2.25 Gev, S. Strauch, W. J. Briscoe, M. Döring, E. Klempt, V. A. Nikonov, E. Pasyuk, D. Rönchen, A.V. Sarantsev, I. Strakovsky, R. Workman, K. P. Adhikari, D. Adikaram, L. El Fassi

Physics Faculty Publications

First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction ɣ^→p^→→π+n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been …