J/ApJ/833/117 VERITAS gamma-ray TeV LCs of 6 blazars (Turley+, 2016)
Search for blazar flux-correlated TeV neutrinos in IceCube 40-string data.
Turley C.F., Fox D.B., Murase K., Falcone A., Barnaba M., Coutu S.,
Cowen D.F., Filippatos G., Hanna C., Keivani A., Messick C., Meszaros P.,
Mostafa M., Oikonomou F., Shoemaker I., Toomey M., Tesic G.,
(for The Astrophysical Multimessenger Observatory Network)
<Astrophys. J., 833, 117-117 (2016)>
=2016ApJ...833..117T 2016ApJ...833..117T (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Gamma rays ; Redshifts
Keywords: BL Lacertae objects: general;
BL Lacertae objects: individual: (Markarian 421, Markarian 501);
cosmic rays; gamma-rays: general; neutrinos
Abstract:
We present a targeted search for blazar flux-correlated high-energy
(εν≳1TeV) neutrinos from six bright northern blazars,
using the public database of northern hemisphere neutrinos detected
during "IC40" 40-string operations of the IceCube neutrino observatory
(2008 April to 2009 May). Our six targeted blazars are subjects of
long-term monitoring campaigns by the VERITAS TeV γ-ray
observatory. We use the publicly available VERITAS light curves to
identify periods of excess and flaring emission. These predefined
intervals serve as our "active temporal windows" in a search for an
excess of neutrinos, relative to Poisson fluctuations of the
near-isotropic atmospheric neutrino background, which dominates at
these energies. After defining the parameters of an optimized search,
we confirm the expected Poisson behavior with Monte Carlo simulations
prior to testing for excess neutrinos in the actual data. We make two
searches: one for excess neutrinos associated with the bright flares
of Mrk 421 that occurred during the IC40 run, and one for excess
neutrinos associated with the brightest emission periods of five other
blazars (Mrk 501, 1ES 0806+524, 1ES 1218+304, 3C 66A, and W Comae),
all significantly fainter than the Mrk 421 flares. We find no
significant excess of neutrinos from the preselected blazar directions
during the selected temporal windows. We derive 90% confidence upper
limits on the number of expected flux-associated neutrinos from each
search. These limits are consistent with previous point-source
searches and Fermi GeV flux-correlated searches. Our upper limits are
sufficiently close to the physically interesting regime that we
anticipate that future analyses using already-collected data will
either constrain models or yield discovery of the first
blazar-associated high-energy neutrinos.
Description:
The IceCube 40-string data set (hereafter IC40) was collected between
2008 April and 2009 May, a total live time of 375.5 days (Abbasi+
2011ApJ...732...18A 2011ApJ...732...18A), during which the detector had 40 of the final 86
planned strings deployed.
Publicly available blazar data (presented in Table 2) were collected
by the four-telescope Very Energetic Radiation Imaging Telescope Array
System (VERITAS) and (for Mrk 421 historical data only) its
predecessor, the Whipple Telescope. Both facilities consist of
atmospheric Cerenkov telescopes located at the Fred Lawrence Whipple
Observatory in Arizona, yielding similar effective energy ranges of
0.1TeV≲εγ≲30TeV.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 6 *VERITAS northern blazars
table2.dat 44 171 Blazar observations
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Note on table1.dat: Blazar properties via TeVCat
(Wakely & Horan 2008ICRC....3.1341W 2008ICRC....3.1341W; http://tevcat.uchicago.edu/).
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See also:
J/ApJS/222/6 : 4.5yr obs. of Mrk421 with ARGO-YBJ + Fermi (Bartoli+, 2016)
J/A+A/573/A50 : Multiwavelength obs. of Mrk 501 in 2008 (Aleksic+, 2015)
J/A+A/576/A126 : The 2009 multiwavelength campaign on Mrk421 (Aleksic+, 2015)
J/A+A/578/A22 : Mrk421 in March 2010 (Aleksic+, 2015)
J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)
J/A+A/559/A9 : Neutrinos from GRBs with ANTARES (Adrian-Martinez+ 2013)
http://veritas.sao.arizona.edu/veritas-science/veritas-blazar-spectra : VERITAS
blazar spectral information & light curves
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Blazar name
14 A1 --- f_Name Flag on Name (1)
16- 17 I2 h RAh Hour of right ascension (J2000)
19- 20 I2 min RAm Minute of right ascension (J2000)
22- 25 F4.1 s RAs Second of right ascension (J2000)
27 A1 --- DE- Sign of declination (J2000)
28- 29 I2 deg DEd Degree of declination (J2000)
31- 32 I2 arcmin DEm Arcminute of declination (J2000)
34- 35 I2 arcsec DEs Arcsecond of declination (J2000)
37- 41 F5.3 --- z [0.03/0.5] Redshift
43- 45 F3.1 10+37W LTeV [0.1/5.8] TeV luminosity; in 1044erg/s (2)
47- 49 F3.1 --- FTeV [0.2/4.6] TeV flux; in 10-11cm-2/s (2)
51- 53 F3.1 TeV Eth [0.2/0.4] Threshold energy for VERITAS
observations (εth)
55- 57 F3.1 --- Gamobs [2.2/4.1] Measured γ-ray spectral index
(Γobs)
59- 61 F3.1 --- Gamsrc [2/3] Spectral index corrected for
extragalactic background light absorption
(Γsrc) (3)
63- 64 I2 --- Nobs [4/93] Number of observations during
the IC40 observing run;
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Note (1): Flag on Name as follows:
a = Power-law photon indices for Mrk 421 and Mrk 501 are known to be variable.
b = The redshift of 3C 66A is uncertain, but bounded between 0.33 and 0.44.
Note (2): Typical luminosities LTeV and fluxes FTeV are over
0.2TeV<εγ<30TeV.
Note (3): The spectral index corrected for extragalactic background light
absorption using the models of Finke+ (2010ApJ...712..238F 2010ApJ...712..238F) and
Inoue+ (2013ApJ...768..197I 2013ApJ...768..197I).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 -- Name Name of target blazar
14- 22 F9.3 d MJD Observation mean epoch; JD-2400000.5
24- 28 F5.3 h Exp [0.2/8.1] Total exposure time
30- 34 F5.2 10-11cm-2/s Flux [-4.3/61] Flux, 10e-11photons/cm2/s (1)
36- 39 F4.2 10-11cm-2/s e_Flux [0.3/3.6] Flux uncertainty (1)
41- 44 F4.2 10-11cm-2/s FluxR [0.09/0.9]? Forced-positive revised flux (1)
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Note (1): Fluxes over 0.2TeV < energy < 30TeV reported as observed flux (Flux)
with Gaussian uncertainties (e_Flux), and with forced-positive revised
flux estimates (Flux-Revised) where necessary.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Apr-2017