44871
2016
2016
eng
12
594
article
EDP Sciences
Les Ulis
Veritas Collaboration
1
--
--
--
Very high energy outburst of Markarian 501 in May 2009
The very high energy (VHE; E > 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54 938-54 956), 2009, as part of an extensive multiwavelength campaign from radio to VHE. Strong VHE yray activity was detected on May 1st with Whipple and VERITAS, when the flux (E > 400 GeV) increased to 10 times the preflare baseline flux (3.9 x 10(-11) ph cm(-2) s(-1)), reaching five times the flux of the Crab Nebula. This coincided with a decrease in the optical polarization and a rotation of the polarization angle by 15. This VHE flare showed a fast flux variation with an increase of a factor similar to 4 in 25 min, and a falling time of similar to 50 min. We present the observations of the quiescent state previous to the flare and of the high state after the flare, focusing on the flux and spectral variability from Whipple, VERITAS, Fermi-LAT, RXTE, and Swift combined with optical and radio data.
Physical chemistry, chemical physics : a journal of European Chemical Societies
10.1051/0004-6361/201628744
1432-0746
wos2016:2019
A76
WOS:000385832200085
Pichel, A (reprint author), Inst Astron & Fis Espacio, Casilla Correo 67,Sucursal 28,C1428ZAA, Buenos Aires, DF, Argentina., anapichel@iafe.uba.ar
US Department of Energy Office of Science; US National Science Foundation; Smithsonian Institution; NSERC in Canada; South African Research Chairs Initiative (SARChI) by National Research Foundation; Department of Science and Technology of South Africa
importub
2020-03-22T13:48:01+00:00
filename=package.tar
9eac71db8d99b6f78ad5d64f40931fa9
E. Aliu
S. Archambault
A. Archer
T. Arlen
T. Aune
Anna Barnacka
B. Behera
M. Beilicke
W. Benbow
K. Berger
R. Bird
Markus Böttcher
A. Bouvier
M. Buchovecky
J. H. Buckley
V. Bugaev
J. V. Cardenzana
M. Cerruti
A. Cesarini
Xuhui Chen
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
J. Dumm
J. D. Eisch
A. Falcone
Simone Federici
Q. Feng
J. P. Finley
H. Fleischhack
P. Fortin
L. Fortson
A. Furniss
N. Galante
D. Gall
G. H. Gillanders
S. Griffin
S. T. Griffiths
J. Grube
G. Gyuk
M. Hütten
Nils Hakansson
J. Holder
G. Hughes
T. B. Humensky
C. A. Johnson
P. Kaaret
P. Kar
N. Kelley-Hoskins
M. Kertzman
Y. Khassen
D. Kieda
M. Krause
H. Krawczynski
F. Krennrich
M. J. Lang
A. S. Madhavan
G. Maier
S. McArthur
A. McCann
K. Meagher
J. Millis
P. Moriarty
R. Mukherjee
D. Nieto
R. A. Ong
M. Orr
A. N. Otte
D. Pandel
N. Park
V. Pelassa
J. S. Perkins
A. Pichel
Martin Pohl
A. Popkow
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
J. Rousselle
A. C. Rovero
D. B. Saxon
G. H. Sembroski
K. Shahinyan
F. Sheidaei
C. Skole
A. W. Smith
D. Staszak
Igor O. Telezhinsky
M. Theiling
N. W. Todd
J. V. Tucci
J. Tyler
A. Varlotta
V. V. Vassiliev
S. Vincent
S. P. Wakely
O. M. Weiner
A. Weinstein
R. Welsing
Alina Wilhelm
D. A. Williams
B. Zitzer
M. G. Baring
J. Becerra Gonzalez
A. N. Cillis
D. Horan
D. Paneque
eng
uncontrolled
BL Lacertae objects: individual: Mrk 501
eng
uncontrolled
gamma rays: galaxies
Institut für Physik und Astronomie
Referiert
Import
36605
2011
2011
eng
5
2
738
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Veritas observations of unusual extragalactic transient swift J164449.3+573451
We report on very high energy (>100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the Swift Observatory and later detected by multiple radio, optical, and X-ray observatories. A total exposure of 28 hr was obtained on Swift J164449.3+573451 with the Very Energetic Radiation Imaging Telescope Array System ( VERITAS) during 2011 March 28-April 15. We do not detect the source and place a differential upper limit on the emission at 500 GeV during these observations of 1.4 x 10(-12) erg cm(-2) s(-1) (99% confidence level). We also present time-resolved upper limits and use a flux limit averaged over the X-ray flaring period to constrain various emission scenarios that can accommodate both the radio-through-X-ray emission detected from the source and the lack of detection by VERITAS.
The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
10.1088/2041-8205/738/2/L30
2041-8205
wos:2011-2013
L30
WOS:000294760700014
Aliu, E (reprint author), Columbia Univ Barnard Coll, Dept Phys & Astron, New York, NY 10027 USA., apbouvie@ucsc.edu; boettchm@ohio.edu; daniel-d-gall@uiowa.edu
U.S. Department of Energy; U.S. National Science Foundation; Smithsonian
Institution; NSERC in Canada; Science Foundation Ireland (SFI)
[10/RFP/AST2748]; STFC in the UK
E. Aliu
T. Arlen
T. Aune
M. Beilicke
W. Benbow
Markus Boettcher
A. Bouvier
S. M. Bradbury
J. H. Buckley
V. Bugaev
A. Cannon
A. Cesarini
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
R. Dickherber
M. Errando
A. Falcone
J. P. Finley
L. Fortson
A. Furniss
N. Galante
D. Gall
G. H. Gillanders
S. Godambe
S. Griffin
J. Grube
G. Gyuk
D. Hanna
J. Holder
H. Huan
G. Hughes
C. M. Hui
T. B. Humensky
P. Kaaret
N. Karlsson
M. Kertzman
D. Kieda
H. Krawczynski
F. Krennrich
A. S. Madhavan
G. Maier
P. Majumdar
S. McArthur
A. McCann
P. Moriarty
R. Mukherjee
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
A. Pichel
Martin Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
D. B. Saxon
M. Schroedter
G. H. Sembroski
C. Skole
A. W. Smith
D. Staszak
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
J. Tyler
A. Varlotta
S. Vincent
M. Vivier
S. P. Wakely
J. E. Ward
A. Weinstein
T. Weisgarber
D. A. Williams
eng
uncontrolled
accretion, accretion disks
eng
uncontrolled
galaxies: active
eng
uncontrolled
gamma rays: galaxies
eng
uncontrolled
radiation mechanisms: non-thermal
Institut für Physik und Astronomie
Referiert
36660
2011
2011
eng
8
1
738
article
IOP Publ. Ltd.
Bristol
1
--
--
--
VERITAS OBSERVATIONS OF THE TeV BINARY LS I+61 degrees 303 DURING 2008-2010
We present the results of observations of the TeV binary LS I + 61 degrees 303 with the VERITAS telescope array between 2008 and 2010, at energies above 300 GeV. In the past, both ground-based gamma-ray telescopes VERITAS and MAGIC have reported detections of TeV emission near the apastron phases of the binary orbit. The observations presented here show no strong evidence for TeV emission during these orbital phases; however, during observations taken in late 2010, significant emission was detected from the source close to the phase of superior conjunction (much closer to periastron passage) at a 5.6 standard deviation (5.6 sigma) post-trials significance. In total, between 2008 October and 2010 December a total exposure of 64.5 hr was accumulated with VERITAS on LS I + 61 degrees 303, resulting in an excess at the 3.3 sigma significance level for constant emission over the entire integrated data set. The flux upper limits derived for emission during the previously reliably active TeV phases (i.e., close to apastron) are less than 5% of the Crab Nebula flux in the same energy range. This result stands in apparent contrast to previous observations by both MAGIC and VERITAS which detected the source during these phases at 10% of the Crab Nebula flux. During the two year span of observations, a large amount of X-ray data were also accrued on LS I + 61 degrees 303 by the Swift X-ray Telescope and the Rossi X-ray Timing Explorer Proportional Counter Array. We find no evidence for a correlation between emission in the X-ray and TeV regimes during 20 directly overlapping observations. We also comment on data obtained contemporaneously by the Fermi Large Area Telescope.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/738/1/3
0004-637X
wos:2011-2013
3
WOS:000294015500003
Holder, J (reprint author), Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA., jholder@physics.udel.edu; awsmith@hep.anl.gov
U.S. Department of Energy; U.S. National Science Foundation; Smithsonian
Institution; NSERC in Canada; Science Foundation Ireland (SFI)
[10/RFP/AST2748]; STFC in the U.K; Argonne, a U.S. Department of Energy
Office of Science laboratory [DE-AC02-06CH11357]; NASA [NNX09AR91G]
V. A. Acciari
E. Aliu
T. Arlen
T. Aune
M. Beilicke
W. Benbow
S. M. Bradbury
J. H. Buckley
V. Bugaev
K. Byrum
A. Cannon
A. Cesarini
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
R. Dickherber
C. Duke
M. Errando
A. Falcone
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
G. H. Gillanders
S. Godambe
S. Griffin
J. Grube
R. Guenette
G. Gyuk
D. Hanna
J. Holder
G. Hughes
C. M. Hui
T. B. Humensky
P. Kaaret
N. Karlsson
M. Kertzman
D. Kieda
H. Krawczynski
F. Krennrich
M. J. Lang
S. LeBohec
G. Maier
P. Majumdar
S. McArthur
A. McCann
P. Moriarty
R. Mukherjee
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
Martin Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
D. B. Saxon
M. Schroedter
G. H. Sembroski
G. D. Senturk
A. W. Smith
D. Staszak
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
A. Varlotta
V. V. Vassiliev
S. Vincent
M. Vivier
S. P. Wakely
J. E. Ward
T. C. Weekes
A. Weinstein
T. Weisgarber
D. A. Williams
B. Zitzer
eng
uncontrolled
binaries: general
eng
uncontrolled
gamma rays: general
eng
uncontrolled
X-rays: binaries
Institut für Physik und Astronomie
Referiert
35761
2012
2012
eng
7
1
754
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Veritas observations of the nova in V407 CYGNI
We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 x 10(-12) erg cm(-2) s(-1) (at the 95% confidence level). When considered jointly with data from Fermi-LAT, this result places limits on the acceleration of very high energy particles in the nova.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/754/1/77
0004-637X
wos:2011-2013
77
WOS:000306111800077
Aliu, E (reprint author), Columbia Univ, Dept Phys & Astron, Barnard Coll, New York, NY 10027 USA., daniel-d-gall@uiowa.edu; kazuma-tsurusaki@uiowa.edu
U.S. Department of Energy Office of Science; U.S. National Science
Foundation; Smithsonian Institution; NSERC in Canada; Science Foundation
Ireland [SFI 10/RFP/AST2748]; STFC in the UK
E. Aliu
S. Archambault
T. Arlen
T. Aune
M. Beilicke
W. Benbow
A. Bouvier
S. M. Bradbury
J. H. Buckley
V. Bugaev
K. Byrum
A. Cannon
A. Cesarini
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
G. Decerprit
R. Dickherber
C. Duke
J. Dumm
Vikram V. Dwarkadas
M. Errando
A. Falcone
Q. Feng
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
S. Godambe
S. Griffin
J. Grube
G. Gyuk
D. Hanna
J. Holder
H. Huan
G. Hughes
T. B. Humensky
P. Kaaret
N. Karlsson
M. Kertzman
Y. Khassen
D. Kieda
H. Krawczynski
F. Krennrich
M. J. Lang
K. Lee
G. Maier
P. Majumdar
S. McArthur
A. McCann
J. Millis
P. Moriarty
R. Mukherjee
P. D. Nunez
R. A. Ong
M. Orr
A. N. Otte
D. Pandel
N. Park
J. S. Perkins
M. Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
D. B. Saxon
M. Schroedter
G. H. Sembroski
C. Skole
A. W. Smith
D. Staszak
Igor O. Telezhinsky
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
J. Tyler
A. Varlotta
S. Vincent
M. Vivier
S. P. Wakely
J. E. Ward
T. C. Weekes
A. Weinstein
T. Weisgarber
R. Welsing
D. A. Williams
B. Zitzer
eng
uncontrolled
gamma rays: general
eng
uncontrolled
novae, cataclysmic variables
eng
uncontrolled
white dwarfs
Institut für Physik und Astronomie
Referiert
39244
2015
2015
eng
9
1
799
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Veritas observations of the BL LAC OBJECT PG 1553+113
We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560 GeV, is well described by a power law with a spectral index of 4.33 +/- 0.09. The time-averaged integral flux above 200 GeV measured for this period was (1.69 +/- 0.06) x 10(-11) photons cm(-2) s(-1), corresponding to 6.9% of the Crab Nebula flux. We also present the combined gamma-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100 MeV to 560 GeV. The data are well fit by a power law with an exponential cutoff at 101.9 +/- 3.2 GeV. The origin of the cutoff could be intrinsic to PG 1553+113 or be due to the gamma-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of z > 0.395 based on optical/UV observations of PG 1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of z <= 0.62. A strongly elevated mean flux of (2.50 +/- 0.14) x10(-11) photons cm(-2) s(-1) (10.3% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as (4.44 +/- 0.71) x10(-11) photons cm(-2) s(-1) (18.3% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a chi(2) probability for a steady flux of 0.03%.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/799/1/7
0004-637X
1538-4357
wos:2015
7
WOS:000348214500007
Aliu, E (reprint author), Columbia Univ Barnard Coll, Dept Phys & Astron, New York, NY 10027 USA.
U.S. Department of Energy Office of Science; U.S. National Science
Foundation; Smithsonian Institution; NSERC in Canada; Science Foundation
Ireland [SFI 10/RFP/AST2748]; STFC in the U.K.
E. Aliu
A. Archer
T. Aune
Anna Barnacka
B. Behera
M. Beilicke
W. Benbow
K. Berger
R. Bird
J. H. Buckley
V. Bugaev
K. Byrum
J. V. Cardenzana
M. Cerruti
Xuhui Chen
L. Ciupik
M. P. Connolly
Wei Cui
H. J. Dickinson
J. Dumm
J. D. Eisch
M. Errando
A. Falcone
Simone Federici
Q. Feng
J. P. Finley
P. Fortin
L. Fortson
A. Furniss
N. Galante
G. H. Gillanders
S. Griffin
S. T. Griffiths
J. Grube
G. Gyuk
Nils Hakansson
D. Hanna
J. Holder
G. Hughes
T. B. Humensky
C. A. Johnson
P. Kaaret
P. Kar
M. Kertzman
Y. Khassen
D. Kieda
H. Krawczynski
F. Krennrich
S. Kumar
M. J. Lang
A. Madhavan
S. McArthur
A. McCann
K. Meagher
J. Millis
P. Moriarty
Daniel Nieto
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
Martin Pohl
A. Popkow
H. Prokoph
Elisa Pueschel
J. Quinn
K. Ragan
J. Rajotte
L. C. Reyes
P. T. Reynolds
G. T. Richards
E. Roache
G. H. Sembroski
K. Shahinyan
D. Staszak
Igor O. Telezhinsky
J. V. Tucci
J. Tyler
A. Varlotta
V. V. Vassiliev
S. P. Wakely
A. Weinstein
R. Welsing
Alina Wilhelm
D. A. Williams
B. Zitzer
eng
uncontrolled
BL Lacertae objects: general
Institut für Physik und Astronomie
Referiert
35522
2012
2012
eng
13
2
759
article
IOP Publ. Ltd.
Bristol
VERITAS Collaboration
1
--
--
--
Veritas observations of six bright, hard-spectrum fermi-lat blazars
We report on VERITAS very high energy (VHE; E >= 100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey spectroscopic data. No VHE emission is detected during the observations of the six sources described here. Corresponding TeV upper limits are presented, along with contemporaneous Fermi observations and non-concurrent Swift UVOT and X-Ray Telescope data. The blazar broadband spectral energy distributions (SEDs) are assembled and modeled with a single-zone synchrotron self-Compton model. The SED built for each of the six blazars shows a synchrotron peak bordering between the intermediate-and high-spectrum-peak classifications, with four of the six resulting in particle-dominated emission regions.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/759/2/102
0004-637X
wos:2011-2013
102
WOS:000310911300025
Furniss, A (reprint author), Univ Calif Santa Cruz, Santa Cruz Inst Particle Phys, Santa Cruz, CA 95064 USA., afurniss@ucsc.edu; pafortin@cfa.harvard.edu; deirdre@llr.in2p3.fr
U.S. Department of Energy Office of Science; U.S. National Science
Foundation; Smithsonian Institution; NSERC in Canada; Science Foundation
Ireland [SFI 10/RFP/AST2748]; STFC in the U.K; NSF [AST-0548180]; Alfred
P. Sloan Foundation; U.S. Department of Energy; National Aeronautics and
Space Administration; Japanese Monbukagakusho; Max Planck Society;
Higher Education Funding Council for England; Istituto Nazionale di
Astrofisica in Italy; Centre National d'Etudes Spatiales in France
E. Aliu
S. Archambault
T. Arlen
T. Aune
M. Beilicke
W. Benbow
Markus Boettcher
A. Bouvier
J. H. Buckley
V. Bugaev
A. Cesarini
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
R. Dickherber
C. Duke
J. Dumm
M. Errando
A. Falcone
Simone Federici
Q. Feng
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
S. Godambe
S. Griffin
J. Grube
G. Gyuk
D. Hanna
J. Holder
H. Huan
P. Kaaret
N. Karlsson
Y. Khassen
D. Kieda
H. Krawczynski
F. Krennrich
K. Lee
A. S. Madhavan
G. Maier
P. Majumdar
S. McArthur
A. McCann
P. Moriarty
R. Mukherjee
T. Nelson
A. O'Faolain de Bhroithe
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
A. Pichel
Martin Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
D. B. Saxon
G. H. Sembroski
D. Staszak
Igor O. Telezhinsky
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
A. Varlotta
V. V. Vassiliev
S. Vincent
M. Vivier
S. P. Wakely
T. C. Weekes
A. Weinstein
R. Welsing
D. A. Williams
B. Zitzer
P. Fortin
D. Horan
M. Fumagalli
K. Kaplan
J. X. Prochaska
eng
uncontrolled
BL Lacertae objects: general
eng
uncontrolled
gamma rays: galaxies
Institut für Physik und Astronomie
Referiert
36437
2011
2011
eng
10
1
743
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Veritas observations of gamma-ray bursts detected by swift
We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t(-1.5) time profile. This temporal model is characteristic of GRB afterglows with high-energy, long-lived emission that have been detected by the Large Area Telescope on board the Fermi satellite. No significant very high energy (VHE) gamma-ray emission was detected and upper limits above the VERITAS threshold energy are calculated. The VERITAS upper limits are corrected for gamma-ray extinction by the extragalactic background light and interpreted in the context of the keV emission detected by Swift. For some bursts the VHE emission must have less power than the keV emission, placing constraints on inverse Compton models of VHE emission.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/743/1/62
0004-637X
wos:2011-2013
62
WOS:000297408300062
Aune, T (reprint author), Univ Calif Santa Cruz, Santa Cruz Inst Particle Phys, Santa Cruz, CA 95064 USA.
US Department of Energy; US National Science Foundation; Smithsonian
Institution; NSERC in Canada; Science Foundation Ireland [SFI
10/RFP/AST2748]; STFC in the UK; NASA [NNX09AR06G]
V. A. Acciari
E. Aliu
T. Arlen
T. Aune
M. Beilicke
W. Benbow
S. M. Bradbury
J. H. Buckley
V. Bugaev
K. Byrum
A. Cannon
A. Cesarini
J. L. Christiansen
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
C. Duke
M. Errando
A. Falcone
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
S. Godambe
S. Griffin
J. Grube
R. Guenette
G. Gyuk
D. Hanna
J. Holder
G. Hughes
C. M. Hui
T. B. Humensky
D. J. Jackson
P. Kaaret
N. Karlsson
M. Kertzman
D. Kieda
H. Krawczynski
F. Krennrich
M. J. Lang
A. S. Madhavan
G. Maier
S. McArthur
A. McCann
P. Moriarty
M. D. Newbold
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
Martin Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
D. B. Saxon
M. Schroedter
G. H. Sembroski
G. D. Sentuerk
A. W. Smith
D. Staszak
S. P. Swordy
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
A. Varlotta
V. V. Vassiliev
S. Vincent
M. Vivier
S. P. Wakely
J. E. Ward
T. C. Weekes
A. Weinstein
T. Weisgarber
D. A. Williams
M. Wood
eng
uncontrolled
astroparticle physics
eng
uncontrolled
gamma-ray burst: general
Institut für Physik und Astronomie
Referiert
36123
2012
2012
eng
7
2
746
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Veritas observations of day-scale flaring of M 87 in 2010 April
VERITAS has been monitoring the very-high-energy (VHE; > 100 GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +/- 0.16) x 10(-11) cm(-2) s(-1) at energies above 350 GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 +/- 0.68) x 10(-11) cm(-2) s(-1) for E > 350 GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90(-0.15)(+0.22) days. The shortest detected exponential rise time is three times as long, at 2.87(+1.65)(-0.99) days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +/- 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/746/2/141
0004-637X
wos:2011-2013
141
WOS:000300406300027
Aliu, E (reprint author), Columbia Univ Barnard Coll, Dept Phys & Astron, New York, NY 10027 USA., cmhui@physics.utah.edu
U.S. Department of Energy Office of Science; U.S. National Science
Foundation; Smithsonian Institution; NSERC in Canada; Science Foundation
Ireland (SFI) [10/RFP/AST2748]; STFC in the UK
E. Aliu
T. Arlen
T. Aune
M. Beilicke
W. Benbow
A. Bouvier
S. M. Bradbury
J. H. Buckley
V. Bugaev
K. Byrum
A. Cannon
A. Cesarini
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
R. Dickherber
C. Duke
M. Errando
A. Falcone
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
S. Godambe
S. Griffin
J. Grube
R. Guenette
G. Gyuk
D. Hanna
J. Holder
H. Huan
G. Hughes
C. M. Hui
T. B. Humensky
A. Imran
P. Kaaret
N. Karlsson
M. Kertzman
D. Kieda
H. Krawczynski
F. Krennrich
M. J. Lang
S. LeBohec
A. S. Madhavan
G. Maier
P. Majumdar
S. McArthur
A. McCann
P. Moriarty
R. Mukherjee
P. D. Nunez
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
A. Pichel
Martin Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
D. B. Saxon
M. Schroedter
G. H. Sembroski
G. D. Sentuerk
C. Skole
D. Staszak
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
J. Tyler
A. Varlotta
V. V. Vassiliev
S. Vincent
M. Vivier
S. P. Wakely
J. E. Ward
T. C. Weekes
A. Weinstein
T. Weisgarber
D. A. Williams
B. Zitzer
eng
uncontrolled
galaxies: individual (M 87, VER J1230+123)
eng
uncontrolled
gamma rays: galaxies
Institut für Physik und Astronomie
Referiert
36045
2012
2012
eng
12
6
85
article
American Physical Society
College Park
1
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--
--
VERITAS deep observations of the dwarf spheroidal galaxy Segue 1
The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No significant gamma-ray emission is detected at the nominal position of Segue 1, and upper limits on the integrated flux are derived. According to recent studies, Segue 1 is the most dark matter-dominated dwarf spheroidal galaxy currently known. We derive stringent bounds on various annihilating and decaying dark matter particle models. The upper limits on the velocity-weighted annihilation cross-section are <sigma upsilon >(95%) (CL) less than or similar to 10(-23) cm(3) s(-1), improving our limits from previous observations of dwarf spheroidal galaxies by at least a factor of 2 for dark matter particle masses m(chi) greater than or similar to 300 GeV. The lower limits on the decay lifetime are at the level of tau(95%) (CL) greater than or similar to 10(24) s. Finally, we address the interpretation of the cosmic ray lepton anomalies measured by ATIC and PAMELA in terms of dark matter annihilation, and show that the VERITAS observations of Segue 1 disfavor such a scenario.
Physical review : D, Particles, fields, gravitation, and cosmology
10.1103/PhysRevD.85.062001
1550-7998
wos:2011-2013
062001
WOS:000301117000003
Vivier, M (reprint author), Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA., mvivier@bartol.udel.edu
US Department of Energy Office of Science; US National Science
Foundation; Smithsonian Institution; NSERC in Canada; Science Foundation
Ireland [SFI 10/RFP/AST2748]; STFC in the United Kingdom
E. Aliu
S. Archambault
T. Arlen
T. Aune
M. Beilicke
W. Benbow
A. Bouvier
S. M. Bradbury
J. H. Buckley
V. Bugaev
K. Byrum
A. Cannon
A. Cesarini
J. L. Christiansen
L. Ciupik
E. Collins-Hughes
M. P. Connolly
W. Cui
G. Decerprit
R. Dickherber
J. Dumm
M. Errando
A. Falcone
Q. Feng
F. Ferrer
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
S. Godambe
S. Griffin
J. Grube
G. Gyuk
D. Hanna
J. Holder
H. Huan
G. Hughes
T. B. Humensky
P. Kaaret
N. Karlsson
M. Kertzman
Y. Khassen
D. Kieda
H. Krawczynski
F. Krennrich
K. Lee
A. S. Madhavan
G. Maier
P. Majumdar
S. McArthur
A. McCann
P. Moriarty
R. Mukherjee
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
Martin Pohl
H. Prokoph
J. Quinn
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
D. B. Saxon
M. Schroedter
G. H. Sembroski
G. D. Sentuerk
C. Skole
A. W. Smith
D. Staszak
Igor O. Telezhinsky
G. Tesic
M. Theiling
S. Thibadeau
K. Tsurusaki
A. Varlotta
V. V. Vassiliev
S. Vincent
M. Vivier
R. G. Wagner
S. P. Wakely
J. E. Ward
T. C. Weekes
A. Weinstein
T. Weisgarber
D. A. Williams
B. Zitzer
Institut für Physik und Astronomie
Referiert
36122
2012
2012
eng
18
2
746
article
IOP Publ. Ltd.
Bristol
HESS Collaboration, MAGIC Collaboration, VERITAS Collaboration
1
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--
--
The 2010 very high energy gamma-ray flare and 10 years ofmulti-wavelength oservations of M 87
The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3-6) x 10(9) M-circle dot) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz Very Long Baseline Array, VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times of tau(rise)(d) = (1.69 +/- 0.30) days and tau(decay)(d) = (0.611 +/- 0.080) days, respectively. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (similar to day), peak fluxes (Phi(>0.35 TeV) similar or equal to (1-3) x 10(-11) photons cm(-2) s(-1)), and VHE spectra. VLBA radio observations of 43 GHz of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken similar to 3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core (flux increased by factor similar to 2; variability timescale <2 days). The long-term (2001-2010) multi-wavelength (MWL) light curve of M 87, spanning from radio to VHE and including data from Hubble Space Telescope, Liverpool Telescope, Very Large Array, and European VLBI Network, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified. In the outer kiloparsec jet region, in particular in HST-1, no enhanced MWL activity was detected in 2008 and 2010, disfavoring it as the origin of the VHE flares during these years. Shortly after two of the three flares (2008 and 2010), the X-ray core was observed to be at a higher flux level than its characteristic range (determined from more than 60 monitoring observations: 2002-2009). In 2005, the strong flux dominance of HST-1 could have suppressed the detection of such a feature. Published models for VHE gamma-ray emission from M 87 are reviewed in the light of the new data.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/746/2/151
0004-637X
wos:2011-2013
151
WOS:000300406300037
Abramowski, A (reprint author), Univ Hamburg, Inst Expt Phys, Luruper Chaussee 149, D-22761 Hamburg, Germany., martin.raue@desy.de; stawarz@astro.isas.jaxa.jp; colin@mppmu.mpg.de; mazin@ifae.es; beilicke@physics.wustl.edu; cmhui@physics.utah.edu
Namibian authorities; German Ministry for Education and Research (BMBF);
Max Planck Society; French Ministry for Research; CNRS-IN2P3; CNRS; U.K.
Science and Technology Facilities Council (STFC); IPNP of the Charles
University; Polish Ministry of Science and Higher Education; South
African Department of Science and Technology; National Research
Foundation; University of Namibia; German BMBF; German MPG; Italian
INFN; Swiss National Fund SNF; Spanish MICINN; Bulgarian NSF
[CSD2007-00042, CSD2009-00064, DO02-353]; Academy of Finland [127740];
YIP of the Helmholtz Gemeinschaft; DFG Cluster of Excellence "Origin and
Structure of the Universe,"; DFG Collaborative Research Centers
[SFB823/C4, SFB876/C3]; Polish MNiSzW [745/N-HESS-MAGIC/2010/0]; US
Department of Energy Office of Science; US National Science Foundation;
Smithsonian Institution; NSERC in Canada; Science Foundation Ireland
(SFI) [10/RFP/AST2748]; STFC in the UK; Istituto Nazionale di
Astrofisica in Italy; Centre National d'Etudes Spatiales in France; NASA
[GO0-11120X]; Associated Universities, Inc.; European Community [227290]
Attila Abramowski
F. Acero
Felix A. Aharonian
A. G. Akhperjanian
Gisela Anton
Arnim Balzer
Anna Barnacka
U. Barres de Almeida
Yvonne Becherini
J. Becker
B. Behera
K. Bernlöhr
E. Birsin
Jonathan Biteau
A. Bochow
Catherine Boisson
J. Bolmont
Pol Bordas
J. Brucker
Francois Brun
Pierre Brun
Tomasz Bulik
I. Buesching
Svenja Carrigan
Sabrina Casanova
M. Cerruti
Paula M. Chadwick
A. Charbonnier
Ryan C. G. Chaves
A. Cheesebrough
A. C. Clapson
G. Coignet
Gabriele Cologna
Jan Conrad
M. Dalton
M. K. Daniel
I. D. Davids
B. Degrange
C. Deil
H. J. Dickinson
A. Djannati-Ataï
W. Domainko
L. O'C. Drury
G. Dubus
K. Dutson
J. Dyks
M. Dyrda
Kathrin Egberts
P. Eger
P. Espigat
L. Fallon
C. Farnier
S. Fegan
F. Feinstein
M. V. Fernandes
A. Fiasson
G. Fontaine
A. Foerster
M. Fuessling
Y. A. Gallant
H. Gast
L. Gerard
D. Gerbig
B. Giebels
J. F. Glicenstein
B. Glueck
P. Goret
D. Goering
S. Haeffner
J. D. Hague
D. Hampf
M. Hauser
S. Heinz
G. Heinzelmann
G. Henri
G. Hermann
James Anthony Hinton
A. Hoffmann
W. Hofmann
P. Hofverberg
M. Holler
D. Horns
A. Jacholkowska
O. C. de Jager
C. Jahn
M. Jamrozy
I. Jung
M. A. Kastendieck
K. Katarzynski
U. Katz
S. Kaufmann
D. Keogh
D. Khangulyan
B. Khelifi
D. Klochkov
W. Kluzniak
T. Kneiske
Nu. Komin
K. Kosack
R. Kossakowski
H. Laffon
G. Lamanna
D. Lennarz
T. Lohse
A. Lopatin
C. -C. Lu
V. Marandon
A. Marcowith
J. Masbou
D. Maurin
N. Maxted
M. Mayer
T. J. L. McComb
M. C. Medina
J. Mehault
R. Moderski
E. Moulin
C. L. Naumann
M. Naumann-Godo
M. de Naurois
D. Nedbal
D. Nekrassov
N. Nguyen
B. Nicholas
J. Niemiec
S. J. Nolan
S. Ohm
E. de Ona Wilhelmi
B. Opitz
M. Ostrowski
I. Oya
M. Panter
M. Paz Arribas
G. Pedaletti
G. Pelletier
P. -O. Petrucci
S. Pita
G. Puehlhofer
M. Punch
A. Quirrenbach
M. Raue
S. M. Rayner
A. Reimer
O. Reimer
M. Renaud
R. de los Reyes
F. Rieger
J. Ripken
L. Rob
S. Rosier-Lees
G. Rowell
B. Rudak
C. B. Rulten
J. Ruppel
V. Sahakian
David M. Sanchez
A. Santangelo
R. Schlickeiser
F. M. Schoeck
A. Schulz
U. Schwanke
S. Schwarzburg
S. Schwemmer
F. Sheidaei
J. L. Skilton
H. Sol
G. Spengler
L. Stawarz
R. Steenkamp
Christian Stegmann
F. Stinzing
K. Stycz
Iurii Sushch
A. Szostek
J. -P. Tavernet
R. Terrier
M. Tluczykont
K. Valerius
C. van Eldik
G. Vasileiadis
C. Venter
J. P. Vialle
A. Viana
P. Vincent
H. J. Voelk
F. Volpe
S. Vorobiov
M. Vorster
S. J. Wagner
M. Ward
R. White
A. Wierzcholska
M. Zacharias
A. Zajczyk
A. A. Zdziarski
Alraune Zech
H. -S. Zechlin
J. Aleksic
L. A. Antonelli
P. Antoranz
Michael Backes
J. A. Barrio
D. Bastieri
J. Becerra Gonzalez
W. Bednarek
A. Berdyugin
K. Berger
E. Bernardini
A. Biland
O. Blanch Bigas
R. K. Bock
A. Boller
G. Bonnoli
D. Borla Tridon
I. Braun
T. Bretz
A. Canellas
E. Carmona
A. Carosi
P. Colin
E. Colombo
J. L. Contreras
J. Cortina
L. Cossio
S. Covino
F. Dazzi
A. De Angelis
E. De Cea del Pozo
B. De Lotto
C. Delgado Mendez
A. Diago Ortega
M. Doert
A. Dominguez
Dijana Dominis Prester
D. Dorner
M. Doro
D. Elsaesser
D. Ferenc
M. V. Fonseca
L. Font
C. Fruck
R. J. Garcia Lopez
M. Garczarczyk
D. Garrido
G. Giavitto
N. Godinovic
D. Hadasch
D. Haefner
A. Herrero
D. Hildebrand
D. Hoehne-Moench
J. Hose
D. Hrupec
B. Huber
T. Jogler
S. Klepser
T. Kraehenbuehl
J. Krause
A. La Barbera
D. Lelas
E. Leonardo
E. Lindfors
S. Lombardi
M. Lopez
E. Lorenz
M. Makariev
G. Maneva
N. Mankuzhiyil
K. Mannheim
L. Maraschi
M. Mariotti
M. Martinez
D. Mazin
M. Meucci
J. M. Miranda
R. Mirzoyan
H. Miyamoto
J. Moldon
A. Moralejo
P. Munar
D. Nieto
K. Nilsson
R. Orito
I. Oya
D. Paneque
R. Paoletti
S. Pardo
J. M. Paredes
S. Partini
M. Pasanen
F. Pauss
M. A. Perez-Torres
M. Persic
L. Peruzzo
M. Pilia
J. Pochon
F. Prada
P. G. Prada Moroni
E. Prandini
I. Puljak
I. Reichardt
R. Reinthal
W. Rhode
M. Ribo
J. Rico
S. Ruegamer
A. Saggion
K. Saito
T. Y. Saito
M. Salvati
K. Satalecka
V. Scalzotto
V. Scapin
C. Schultz
T. Schweizer
M. Shayduk
S. N. Shore
A. Sillanpaa
J. Sitarek
D. Sobczynska
F. Spanier
S. Spiro
A. Stamerra
B. Steinke
J. Storz
N. Strah
T. Suric
L. Takalo
H. Takami
F. Tavecchio
P. Temnikov
T. Terzic
D. Tescaro
M. Teshima
M. Thom
O. Tibolla
D. F. Torres
A. Treves
H. Vankov
P. Vogler
R. M. Wagner
Q. Weitzel
V. Zabalza
F. Zandanel
R. Zanin
T. Arlen
T. Aune
M. Beilicke
W. Benbow
A. Bouvier
S. M. Bradbury
J. H. Buckley
V. Bugaev
K. Byrum
A. Cannon
A. Cesarini
L. Ciupik
M. P. Connolly
W. Cui
R. Dickherber
C. Duke
M. Errando
A. Falcone
J. P. Finley
G. Finnegan
L. Fortson
A. Furniss
N. Galante
D. Gall
S. Godambe
S. Griffin
J. Grube
G. Gyuk
D. Hanna
J. Holder
H. Huan
C. M. Hui
P. Kaaret
N. Karlsson
M. Kertzman
Y. Khassen
D. Kieda
H. Krawczynski
F. Krennrich
M. J. Lang
S. LeBohec
G. Maier
S. McArthur
A. McCann
P. Moriarty
R. Mukherjee
P. D. Nunez
R. A. Ong
M. Orr
A. N. Otte
N. Park
J. S. Perkins
A. Pichel
Martin Pohl
H. Prokoph
K. Ragan
L. C. Reyes
P. T. Reynolds
E. Roache
H. J. Rose
J. Ruppel
M. Schroedter
G. H. Sembroski
G. D. Sentuerk
Igor O. Telezhinsky
G. Tesic
M. Theiling
S. Thibadeau
A. Varlotta
V. V. Vassiliev
M. Vivier
S. P. Wakely
T. C. Weekes
D. A. Williams
B. Zitzer
U. Barres de Almeida
M. Cara
C. Casadio
C. C. Cheung
W. McConville
F. Davies
A. Doi
G. Giovannini
M. Giroletti
K. Hada
P. Hardee
D. E. Harris
W. Junor
M. Kino
N. P. Lee
C. Ly
J. Madrid
F. Massaro
C. G. Mundell
H. Nagai
E. S. Perlman
I. A. Steele
R. C. Walker
D. L. Wood
eng
uncontrolled
galaxies: active
eng
uncontrolled
galaxies: individual (M 87)
eng
uncontrolled
galaxies: jets
eng
uncontrolled
galaxies: nuclei
eng
uncontrolled
gamma rays: galaxies
eng
uncontrolled
radiation mechanisms: non-thermal
Institut für Physik und Astronomie
Referiert