J/ApJ/891/170 10yr of radio-to-gamma-ray obs. of 1ES 1215+30.3 (Valverde+, 2020)
A decade of multiwavelength observations of the TeV blazar 1ES 1215+303:
extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray
flux increase.
Valverde J., Horan D., Bernard D., Fegan S., Abeysekara A.U., Archer A.,
Benbow W., Bird R., Brill A., Brose R., Buchovecky M., Buckley J.H.,
Christiansen J.L., Cui W., Falcone A., Feng Q., Finley J.P., Fortson L.,
Furniss A., Gent A., Gillanders G.H., Giuri C., Gueta O., Hanna D.,
Hassan T., Hervet O., Holder J., Hughes G., Humensky T.B., Kaaret P.,
Kelley-Hoskins N., Kertzman M., Kieda D., Krause M., Krennrich F.,
Lang M.J., Maier G., Moriarty P., Mukherjee R., Nieto D., Nievas-Rosillo M.,
O'Brien S., Ong R.A., Otte A.N., Park N., Petrashyk A., Pfrang K.,
Pichel A., Pohl M., Prado R.R., Pueschel E., Quinn J., Ragan K.,
Reynolds P.T., Ribeiro D., Richards G.T., Roache E., Sadeh I., Santander M.,
Scott S.S., Sembroski G.H., Shahinyan K., Shang R., Sushch I.,
Vassiliev V.V., Weinstein A., Wells R.M., Wilcox P., Wilhelm A.,
Williams D.A., Williamson T.J., Noto G., Edwards P.G., Piner B.G.,
Fallah Ramazani V., Hovatta T., Jormanainen J., Lindfors E., Nilsson K.,
Takalo L., Kovalev Y.Y., Lister M.L., Pushkarev A.B., Savolainen T.,
Kiehlmann S., Max-Moerbeck W., Readhead A.C.S., Lahteenmaki A.,
Tornikoski M.
<Astrophys. J., 891, 170 (2020)>
=2020ApJ...891..170V 2020ApJ...891..170V
ADC_Keywords: BL Lac objects; Gamma rays; X-ray sources; Photometry;
Ultraviolet; Optical; Radio sources
Keywords: Active galaxies ; Jets ; Gamma-rays ; Blazars ; BL Lacertae objects
Abstract:
Blazars are known for their variability on a wide range of timescales
at all wavelengths. Most studies of TeV gamma-ray blazars focus on
short timescales, especially during flares. With a decade of
observations from the Fermi-LAT and VERITAS, we present an extensive
study of the long-term multiwavelength radio-to-gamma-ray flux-density
variability, with the addition of a couple of short-time
radio-structure and optical polarization observations of the blazar
1ES 1215+303 (z=0.130), with a focus on its gamma-ray emission from
100MeV to 30TeV. Multiple strong GeV gamma-ray flares, a long-term
increase in the gamma-ray and optical flux baseline, and a linear
correlation between these two bands are observed over the ten-year
period. Typical HBL behaviors are identified in the radio morphology
and broadband spectrum of the source. Three stationary features in the
innermost jet are resolved by Very Long Baseline Array at 43.1, 22.2,
and 15.3GHz. We employ a two-component synchrotron self-Compton model
to describe different flux states of the source, including the epoch
during which an extreme shift in energy of the synchrotron peak
frequency from infrared to soft X-rays is observed.
Description:
In this paper, we present an analysis of the observations of the
high-synchrotron-peaked BL Lac (HBL) 1ES 1215+303 between 2008 and
2017 from radio to VHE gamma-ray energies.
The VHE gamma-ray data come from VERITAS. VERITAS is sensitive to
gamma-rays in the energy range between ∼85GeV and >30TeV. It has a
field of view (FoV) of ∼3.5°. See Section 2.1.
For the energy range from ∼20MeV to more than 500GeV, we analyzed the
Fermi-LAT data from 2008 August 4 (MJD 54682.7), the start of the
all-sky survey, up until 2017 September 4 (MJD 58001.0). See Section 2.2.
The X-Ray Telescope (XRT) on the Neil Gehrels Swift Observatory is
sensitive to photons with energies between 0.2 and 10keV. There were
25 pointed Swift-XRT observations within a 10' radius of 1ES 1215+303.
See Section 2.3.
232 images containing 1ES 1215+303 in the field of view were available
from the Ultraviolet/Optical telescope (UVOT) on the Neil Gehrels
Swift Observatory. See Section 2.4.
Source 1ES 1215+303 was monitored in the R-band at the Tuorla
Observatory over the past 15yr as part of the Tuorla blazar
monitoring program (e.g. Nilsson+ 2018, J/A+A/620/A185).
The source was also monitored with the Nordic Optical Telescope
(NOT)/ALFOSC in R-band from 2014 to 2017.
See Section 2.5.
Source 1ES 1215+303 was observed with the Long Baseline Observatory's
VLBA at 22.2 and 43.1GHz on 2014 November 11 (observation code S7017E3).
Source 1ES 1215+303 was also observed at 15.3GHz with the MOJAVE
program for 10 epochs between 2009 and 2016. See Section 2.6.
We show the radio flux density measured by the Owens Valley Radio
Observatory (OVRO) at 15GHz over the past decade (2008-2017) in
Figure 1, where a total of 475 data points are presented. See Section 2.7.
We also show the radio flux density measured by Metsahovi Radio
Observatory (MRO) at 37GHz in Figure 1. See Section 2.8.
Objects:
------------------------------------------------------------
RA (ICRS) DE Designation(s)
------------------------------------------------------------
12 17 52.08 +30 07 00.6 1ES 1215+30.3 = QSO J1217+3007
------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
veritas.dat 36 113 VERITAS >200GeV flux time series
lat.dat 35 1045 Fermi-LAT 0.1-500GeV flux time series
xrt_pc.dat 132 20 Swift XRT PC 0.3-10keV flux time series
xrt_wt.dat 132 5 Swift XRT WT 0.3-10keV flux time series
uvot.dat 135 232 Swift UVOT magnitude and flux time series
tuorla.dat 35 424 Tuorla Observatory optical R band flux density
time series
not.dat 45 49 Nordic Optical Telescope R band flux density and
polarization time series
ovro.dat 33 475 OVRO 15GHz flux density time series
met.dat 59 53 Metsahovi Radio Observatory 37GHz flux density
time series
--------------------------------------------------------------------------------
See also:
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/A+AS/132/305 : Extragal. radio sources at 22, 37 and 87GHz (Terasranta+ 1998)
J/ApJS/148/275 : ASCA AGN optical identifications (Akiyama+, 2003)
J/A+A/445/441 : SED of BL Lacertae objects (Nieppola+, 2006)
J/ApJ/690/163 : The first Swift UV-Opt GRB afterglow catalog (Roming+, 2009)
J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)
J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)
J/AJ/142/89 : Precise astrometry with VLBA (VIPS) (Petrov+, 2011)
J/A+A/545/A117 : Monitoring of Mrk 421 at 15 and 24 GHz (Lico+, 2012)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/ApJ/810/14 : Third catalog of LAT-detected AGNs (3LAC) (Ackermann+, 2015)
J/ApJ/814/35 : Flare events in M dwarf of M37 (Chang+, 2015)
J/A+A/590/A10 : 3C 279 optical photometry and polarimetry (Kiehlmann+, 2016)
J/A+A/594/A26 : 2nd Planck Catalog of Compact Sources (PCCS2) (Planck+, 2016)
J/A+A/596/A78 : R-band polarization curves of 48 BL Lacs (Hovatta+, 2016)
J/MNRAS/467/4565 : Bimodal radio variability in OVRO blazars (Liodakis+, 2017)
J/MNRAS/468/4992 : MOJAVE XIV. AGN jet shapes (Pushkarev+, 2017)
J/ApJ/853/68 : Multi-epoch VLBA imaging of 20 Tev blazars (Piner+, 2018)
J/ApJS/234/12 : MOJAVE XV. 15GHz obs. of AGN jets 1996-2016 (Lister+, 2018)
J/A+A/620/A185 : Long-term optical monitoring of TeV Blazars (Nilsson+, 2018)
J/ApJ/874/43 : MOJAVE. XVII. pc-scale jet kinematics of AGNs (Lister+, 2019)
J/ApJS/247/33 : The Fermi LAT fourth source catalog (4FGL) (Abdollahi+, 2020)
Byte-by-byte Description of file: veritas.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 d MJD [54834.5/57902.5] Modified Julian Date
(JD-2400000.5)
12 A1 --- l_Flux 95% upper limit flags
13- 24 E12.7 ph/cm2/s Flux [-6.8e-12/5e-10] Flux, VERITAS >200GeV
26- 36 E11.6 ph/cm2/s e_Flux [1.4e-12/1.7e-11]? Uncertainty in Flux
--------------------------------------------------------------------------------
Byte-by-byte Description of file: lat.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.5 d MJD [54684.15/57999.2] Modified Julian Date
(JD-2400000.5)
13- 23 E11.5 ph/cm2/s Flux [1.8e-10/5.7e-7] Flux, Fermi-LAT 0.1-500GeV
25- 35 E11.5 ph/cm2/s e_Flux [5.2e-9/1.4e-7] Uncertainty in Flux
--------------------------------------------------------------------------------
Byte-by-byte Description of file: xrt_pc.dat xrt_wt.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.12 d MJD [55168.67/57866.6] Modified Julian Date,
observation midpoint
20- 30 E11.6 mW/m2 Flux [2.7e-12/3.4e-11] Swift XRT/PC Flux, 0.3-10keV
32- 42 E11.6 mW/m2 b_Flux [2.5e-12/3.3e-11] Lower bound on Flux
44- 54 E11.6 mW/m2 B_Flux [2.9e-12/3.4e-11] Upper bound on Flux
56- 68 F13.11 --- Gamma [2.1/3.1] Photon Index
70- 84 F15.13 --- e_Gamma [0.03/0.4] Uncertainty in Gamma
86-103 F18.12 d MJD0 [55168.67/57866.6] Modified Julian Date,
observation start
105-123 A19 "datime" Date Observation start, ISO 8601 date time string
125-132 F8.3 s Exp [907.6/4995.3] XRT exposure time
--------------------------------------------------------------------------------
Byte-by-byte Description of file: uvot.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- File Filename
21- 27 A7 --- Obj Object
29- 32 I4 yr Obs.Y [2009/2017] Observation UTC date, year
33- 34 I2 "month" Obs.M Observation UTC date, numeric month
35- 36 I2 d Obs.D Observation UTC date, day
38- 39 I2 h Obs.h Observation UTC time, hour
41- 42 I2 min Obs.m Observation UTC time, minute
44- 45 I2 s Obs.s Observation UTC time, second
47- 57 F11.5 d MJD [55168.68/57866.8] Modified Julian Date of
observation (JD-2400000.5)
59- 66 F8.3 s Exp [36.19/1963.66] Exposure time
68 I1 --- Filt [1/6] Filter Code (1)
70- 75 F6.3 mag omag [13.5/16.03] Observed magnitude in Filt
77- 81 F5.3 mag e_omag [0.03/0.07] Uncertainty in omag
83- 88 F6.3 mag omag0 [13.43/15.96] Magnitude, corrected
for extinction (2)
90- 98 E9.4 mW/m2 Flux [8.3e-12/4.5e-11] Flux in Filt,
in erg/s/cm2 units
100-108 E9.4 mW/m2 e_Flux [3.4e-13/2.1e-12] Uncertainty in Flux
110-114 F5.3 mJy Flux2 [0.56/7.63] Flux in Filter
116-120 F5.3 mJy e_Flux2 [0.02/0.4] Uncertainty in Flux2
122-127 F6.3 [Hz] log(nu) [14.74/15.17] log10, central frequency of Filt
129-135 F7.3 [-] log(nuf) [-11.1/-10.3] log10, nu*Flux
--------------------------------------------------------------------------------
Note (1): Filter Code as follows:
1 = B (36 occurrences);
2 = UVM2 (37 occurrences);
3 = U (40 occurrences);
4 = V (31 occurrences);
5 = UVW1 (46 occurrences);
6 = UVW2 (42 occurrences).
Note (2): Magnitude corrected for extinction using E(b-v)=0.021000 from NED.
A_lambda(B): 0.085, A_lambda(V): 0.064, yield E(B-V) = 0.021
which corresponds to the follow corrections applied for each filter
A(V):0.065;
A(B):0.086;
A(U):0.104;
A(UVW1):0.140;
A(UVM2):0.198;
A(UVW2):0.173.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tuorla.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d JD Julian Date
15- 24 E10.4 mJy Flux [0.0016/0.0088] Flux density, Tuorla
optical R band
26- 35 E10.4 mJy e_Flux [4.7e-5/0.0002] Uncertainty in Flux
--------------------------------------------------------------------------------
Byte-by-byte Description of file: not.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d JD Julian Date of observation
15- 20 F6.3 % Pol [0/16.4] Polarization fraction
22- 27 F6.3 % b_Pol [0/16.3] Lower bound on Pol, Pol-e_Pol
29- 34 F6.3 % B_Pol [5/67.1] Upper bound on Pol, Pol+e_Pol
36- 40 F5.1 deg PA [134.6/173.7] Positional angle of polarization
42- 45 F4.1 deg e_PA [0.2/63.3] Uncertainty in PA
--------------------------------------------------------------------------------
Byte-by-byte Description of file: ovro.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.7 d MJD [54473.38/57999.04] Modified Julian Date
(JD-2400000.5)
15- 23 F9.7 Jy Flux [0.04/0.53] Flux density, OVRO 15GHz
25- 33 F9.7 Jy e_Flux [0.003/0.3] Uncertainty in Flux
--------------------------------------------------------------------------------
Byte-by-byte Description of file: met.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.6 --- Year [2002.14/2016.21] Observation date,
Fractional year
13- 31 A19 "datime" Date Observation date, ISO 8601 date time string
33- 38 F6.4 Jy Flux [0.08/0.7] Flux density, Metsahovi Radio
Observatory 37GHz
40- 45 F6.4 Jy e_Flux [0.04/0.15] Uncertainty in Flux
47 A1 --- f_Flux Flag on Flux, *= detection S/N>4
49- 59 F11.5 d MJD Modified Julian Date; column added by CDS
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Aug-2021