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 (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), 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 64 6 *VERITAS northern blazars table2.dat 44 171 Blazar observations
Note on table1.dat: Blazar properties via TeVCat (Wakely & Horan 2008ICRC....3.1341W; http://tevcat.uchicago.edu/).
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
Bytes Format Units Label Explanations
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;
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) and Inoue+ (2013ApJ...768..197I).
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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)
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.
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Apr-2017
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