TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Aune, Taylor
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fleischhack, H.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gotthelf, Eric V.
A1  - Grube, J.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Huang, K.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Huetten, M.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Pandel, Dirk
A1  - Park, Nahee
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, Alexis
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rousselle, J.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Vassiliev, V. V.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Zitzer, B.
T1  - A Very High Energy gamma-Ray Survey toward the Cygnus Region of the Galaxy
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present results from deep observations toward the Cygnus region using 300 hr of very high energy (VHE)gamma-ray data taken with the VERITAS Cerenkov telescope array and over 7 yr of high-energy.-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse gamma-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130) and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL J2021.0+4031e (the Gamma Cygni supernova remnant) was examined, and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE gamma-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula flux. We interpret these observations in a multiwavelength context and present the most detailed gamma-ray view of the region to date.
KW  - acceleration of particles
KW  - cosmic rays
KW  - gamma rays: general
KW  - ISM: supernova remnants
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aac4a2
SN  - 0004-637X
SN  - 1538-4357
VL  - 861
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Heintz, Kasper Elm
A1  - Watson, D.
A1  - Jakobsson, P.
A1  - Fynbo, J. P. U.
A1  - Bolmer, J.
A1  - Arabsalmani, M.
A1  - Cano, Zach
A1  - Covino, S.
A1  - Gomboc, A.
A1  - Japelj, J.
A1  - Kaper, L.
A1  - Krogager, J. -K.
A1  - Pugliese, G.
A1  - Sanchez-Ramirez, R.
A1  - Selsing, J.
A1  - Sparre, Martin
A1  - Tanvir, N. R.
A1  - Thone, C. C.
A1  - de Ugarte Postigo, A.
A1  - Vergani, S. D.
T1  - Highly ionized metals as probes of the circumburst gas in the natal regions of gamma-ray bursts
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present here a survey of high-ionization absorption lines in the afterglow spectra of long-duration gamma-ray bursts (GRBs) obtained with the VLT/X-shooter spectrograph. Our main goal is to investigate the circumburst medium in the natal regions of GRBs. Our primary focus is on the N vλλ 1238, 1242 line transitions, but we also discuss other high-ionization lines such as O vi, C iv, and Si iv. We find no correlation between the column density of N v and the neutral gas properties such as metallicity, H i column density, and dust depletion; however, the relative velocity of N v, typically a blueshift with respect to the neutral gas, is found to be correlated with the column density of H i. This may be explained if the N v gas is part of an H ii region hosting the GRB, where the region’s expansion is confined by dense, neutral gas in the GRB’s host galaxy. We find tentative evidence (at 2σ significance) that the X-ray derived column density, NH, X, may be correlated with the column density of N v, which would indicate that both measurements are sensitive to the column density of the gas located in the vicinity of the GRB. We investigate the scenario where N v (and also O vi) is produced by recombination after the corresponding atoms have been stripped entirely of their electrons by the initial prompt emission, in contrast to previous models where highly ionized gas is produced by photoionization from the GRB afterglow.
KW  - gamma-ray bursts: general
KW  - ISM: abundances
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty1447
SN  - 0035-8711
SN  - 1365-2966
VL  - 479
IS  - 3
SP  - 3456
EP  - 3476
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - de Jong, S.
A1  - Kukreja, R.
A1  - Trabant, C.
A1  - Pontius, N.
A1  - Chang, C. F.
A1  - Kachel, T.
A1  - Beye, Martin
A1  - Sorgenfrei, Nomi
A1  - Back, C. H.
A1  - Braeuer, B.
A1  - Schlotter, W. F.
A1  - Turner, J. J.
A1  - Krupin, O.
A1  - Doehler, M.
A1  - Zhu, D.
A1  - Hossain, M. A.
A1  - Scherz, A. O.
A1  - Fausti, D.
A1  - Novelli, F.
A1  - Esposito, M.
A1  - Lee, W. S.
A1  - Chuang, Y. D.
A1  - Lu, D. H.
A1  - Moore, R. G.
A1  - Yi, M.
A1  - Trigo, M.
A1  - Kirchmann, P.
A1  - Pathey, L.
A1  - Golden, M. S.
A1  - Buchholz, Marcel
A1  - Metcalf, P.
A1  - Parmigiani, F.
A1  - Wurth, W.
A1  - Föhlisch, Alexander
A1  - Schuessler-Langeheine, Christian
A1  - Duerr, H. A.
T1  - Speed limit of the insulator-metal transition in magnetite
JF  - Nature materials
N2  - As the oldest known magnetic material, magnetite (Fe3O4) has fascinated mankind for millennia. As the first oxide in which a relationship between electrical conductivity and fluctuating/localized electronic order was shown(1), magnetite represents a model system for understanding correlated oxides in general. Nevertheless, the exact mechanism of the insulator-metal, or Verwey, transition has long remained inaccessible(2-8). Recently, three- Fe- site lattice distortions called trimeronswere identified as the characteristic building blocks of the low-temperature insulating electronically ordered phase(9). Here we investigate the Verwey transition with pump- probe X- ray diffraction and optical reflectivity techniques, and show how trimerons become mobile across the insulator-metal transition. We find this to be a two- step process. After an initial 300 fs destruction of individual trimerons, phase separation occurs on a 1.5 +/- 0.2 ps timescale to yield residual insulating and metallic regions. This work establishes the speed limit for switching in future oxide electronics(10).
Y1  - 2013
U6  - https://doi.org/10.1038/NMAT3718
SN  - 1476-1122
SN  - 1476-4660
VL  - 12
IS  - 10
SP  - 882
EP  - 886
PB  - Nature Publ. Group
CY  - London
ER  -