J/ApJ/864/84 Swift follow-up obs. of the TXS 0506+056 blazar (Keivani+, 2018)
A multimessenger picture of the flaring blazar TXS 0506+056: implications for
high-energy neutrino emission and cosmic-ray acceleration.
Keivani A., Murase K., Petropoulou M., Fox D.B., Cenko S.B., Chaty S.,
Coleiro A., DeLaunay J.J., Dimitrakoudis S., Evans P.A., Kennea J.A.,
Marshall F.E., Mastichiadis A., Osborne J.P., Santander M., Tohuvavohu A.,
Turley C.F.
<Astrophys. J., 864, 84 (2018)>
=2018ApJ...864...84K 2018ApJ...864...84K
ADC_Keywords: BL Lac objects; X-ray sources; Photometry, UBV; Ultraviolet
Keywords: BL Lacertae objects: general ; radiation mechanisms: non-thermal ;
BL Lacertae objects: individual (TXS 0506+056) ;
galaxies: active ; gamma rays: galaxies ; neutrinos ;
Abstract:
Detection of the IceCube-170922A neutrino coincident with the flaring
blazar TXS 0506+056, the first and only ∼3σ high-energy neutrino
source association to date, offers a potential breakthrough in our
understanding of high-energy cosmic particles and blazar physics. We
present a comprehensive analysis of TXS 0506+056 during its flaring
state, using newly collected Swift, NuSTAR, and X-shooter data with
Fermi observations and numerical models to constrain the blazar's
particle acceleration processes and multimessenger (electromagnetic
(EM) and high-energy neutrino) emissions. Accounting properly for EM
cascades in the emission region, we find a physically consistent
picture only within a hybrid leptonic scenario, with γ-rays
produced by external inverse-Compton processes and high-energy
neutrinos via a radiatively subdominant hadronic component. We derive
robust constraints on the blazar's neutrino and cosmic-ray emissions
and demonstrate that, because of cascade effects, the 0.1-100keV
emissions of TXS 0506+056 serve as a better probe of its hadronic
acceleration and high-energy neutrino production processes than its
GeV-TeV emissions. If the IceCube neutrino association holds, physical
conditions in the TXS 0506+056 jet must be close to optimal for
high-energy neutrino production, and are not favorable for
ultrahigh-energy cosmic-ray acceleration. Alternatively, the
challenges we identify in generating a significant rate of IceCube
neutrino detections from TXS 0506+056 may disfavor single-zone models,
in which γ-rays and high-energy neutrinos are produced in a
single emission region. In concert with continued operations of the
high-energy neutrino observatories, we advocate regular X-ray
monitoring of TXS 0506+056 and other blazars in order to test
single-zone blazar emission models, clarify the nature and extent of
their hadronic acceleration processes, and carry out the most
sensitive possible search for additional multimessenger sources.
Description:
IceCube-170922A was an EHE neutrino event (GCN/AMON NOTICE 2016)
identified and distributed by the IceCube Observatory via AMON and GCN
within δt∼43s of its detection at 20:54:30 UT on 2017 September
22 (GCN/AMON NOTICE IceCube-170922A 2017ApJ...843..109G 2017ApJ...843..109G). A refined
localization was reported four hours later (Kopper & Blaufuss
2017GCN.21916....1K 2017GCN.21916....1K): RAJ2000=77.43-0.8+1.3°,
DEJ2000=+5.72-0.4+0.7° (90% containment ellipse).
IceCube-170922A triggered the Neil Gehrels Swift Observatory in
automated fashion via AMON cyberinfrastructure, resulting in
rapid-response mosaic-type follow-up observations, covering a roughly
circular region of sky centered on the prompt localization in a
19-point tiling that began 3.25hr after the neutrino detection. This
initial epoch of Swift observations spanned 22.5hr and accumulated
∼800s exposure per pointing. The mosaic tiling yielded coverage of a
region with radius ∼0.8° centered on RAJ2000=05:09:08.784,
DEJ2000=+05:45:13.32, amounting to a sky area of 2.1deg2.
Source 2 from these observations (marked as X2 on Figure 1), located
4.6' from the center of the neutrino localization, was identified
by us as the likely X-ray counterpart to QSO J0509+0541, also known as
TXS 0506+056. This was the first report to connect TXS 0506+056 to
IceCube-170922A (Keivani+ 2017GCN.21930....1K 2017GCN.21930....1K).
Following the Fermi report that TXS 0506+056 was in a rare GeV-flaring
state (Tanaka+ 2017ATel10791....1T 2017ATel10791....1T), we commenced a Swift monitoring
campaign on September 27 (Evans+ 2017ATel10792....1E 2017ATel10792....1E). Swift monitored
TXS 0506+056 for 36 epochs by November 30 with 53.7ks total exposure
time (Table 1).
The Swift-UVOT also participated in the rapid-response follow-up
observations of the IceCube-170922A and the subsequent monitoring of
the flaring blazar TXS 0506+056.
Objects:
---------------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------------
05 09.7 +05 43 IceCube-170922A = IceCube-170922A
05 09 25.96 +05 41 35.3 TXS 0506+056 = QSO J0509+0541
---------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 67 36 Swift-XRT monitoring of TXS 0506+056
table2.dat 38 157 Swift UVOT monitoring of TXS 0506+056
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See also:
B/swift : Swift Master Catalog (HEASARC, 2004-)
VIII/85 : SPECFIND V2.0 Catalog of radio continuum spectra (Vollmer+ 2009)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)
J/ApJ/742/27 : 15GHz and jet properties of MOJAVE blazars (Lister+, 2011)
J/ApJ/748/68 : WISE IR colors of gamma-ray blazars (D'Abrusco+, 2012)
J/AJ/146/120 : MOJAVE. X. Parsec-scale kinematics of AGNs (Lister+, 2013)
J/other/RAA/14.1135 : Doppler factor for a Fermi blazar sample (Fan+, 2014)
J/ApJ/799/86 : Isotropic diffuse gamma emission 0.1-820GeV (Ackermann+, 2015)
J/ApJ/810/14 : Third catalog of LAT-detected AGNs (3LAC) (Ackermann+, 2015)
J/ApJ/833/117 : VERITAS gamma-ray TeV LCs of 6 blazars (Turley+, 2016)
J/AJ/152/12 : MOJAVE. XIII. New 15GHz obs. on 1994-2013 (Lister+, 2016)
J/MNRAS/468/4992 : MOJAVE XIV. AGN jets + opening angles (Pushkarev+, 2017)
J/ApJS/234/12 : MOJAVE XV. 15GHz obs. of AGN jets 1996-2016 (Lister+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 d MJD [58019.4/58087.2] Modified Julian Date
12- 17 F6.4 d e_MJD [0.001/0.7] MJD uncertainty
19- 21 F3.1 ks Exp [0.2/4.9] Exposure time
23- 26 F4.2 --- PInd [1.5/3.5] Photon index
28- 31 F4.2 --- e_PInd [0.1/1] Negative uncertainty on PInd (1)
33- 36 F4.2 --- E_PInd [0.1/1.2] Positive uncertainty on PInd (1)
38- 42 F5.1 10-3ct RX [30/255] Count rate
44- 47 F4.1 10-3ct e_RX [4/25] Negative uncertainty on RX (1)
49- 52 F4.1 10-3ct E_RX [4/30] Positive uncertainty on RX (1)
54- 57 F4.2 10-15W/m2 FX [0.8/6.5] Energy flux
in 10-12erg/cm2/s units
59- 62 F4.2 10-15W/m2 e_FX [0.2/1.1] Negative uncertainty on FX (1)
64- 67 F4.2 10-15W/m2 E_FX [0.3/2.4] Positive uncertainty on FX (1)
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Note (1): Uncertainties are quoted at 90% confidence.
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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- 10 F10.4 d MJD [58019.4/58087.2] Modified Julian Date (1)
12- 17 F6.4 d e_MJD [0.0002/0.51] Uncertainty in MJD
19- 22 I4 s Exp [32/2930] Exposure time
24- 27 A4 --- Filt Filter used observation
29- 33 F5.2 mag mag [14.19/15.67] Apparent magnitude in Filter
35- 38 F4.2 mag e_mag [0.03/0.07] The 1-σ uncertainty in mag
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Note (1): At the middle of the observation.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Aug-2019