J/ApJ/816/53 Multiwavelength obs. of BL Lac in 2012-2013 (Wehrle+, 2016)
Erratic flaring of BL Lac in 2012-2013: multiwavelength observations.
Wehrle A.E., Grupe D., Jorstad S.G., Marscher A.P., Gurwell M.,
Balokovic M., Hovatta T., Madejski G.M., Harrison F.H., Stern D.
<Astrophys. J., 816, 53 (2016)>
=2016ApJ...816...53W 2016ApJ...816...53W (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Photometry, millimetric/submm ;
Photometry, UBV ; Photometry, ultraviolet ; X-ray sources ;
Energy distributions ; BL Lac objects
Keywords: BL Lacertae objects: individual: BL Lacertae; galaxies: active;
galaxies: individual: BL Lacertae; galaxies: jets
Abstract:
BL Lac, the eponymous blazar, flared to historically high levels at
millimeter, infrared, X-ray, and gamma-ray wavelengths in 2012. We
present observations made with Herschel, Swift, NuSTAR, Fermi, the
Submillimeter Array, CARMA, and the VLBA in 2012-2013, including three
months with nearly daily sampling at several wavebands. We have also
conducted an intensive campaign of 30 hr with every-orbit observations
by Swift and NuSTAR, accompanied by Herschel, and Fermi observations.
The source was highly variable at all bands. Time lags, correlations
between bands, and the changing shapes of the spectral energy
distributions can be explained by synchrotron radiation and inverse
Compton emission from nonthermal seed photons originating from within
the jet. The passage of four new superluminal very long baseline
interferometry knots through the core and two stationary knots about 4
pc downstream accompanied the high flaring in 2012-2013. The seed
photons for inverse Compton scattering may arise from the stationary
knots and from a Mach disk near the core where relatively slow-moving
plasma generates intense nonthermal radiation. The 95 spectral energy
distributions obtained on consecutive days form the most densely
sampled, broad wavelength coverage for any blazar. The observed
spectral energy distributions and multi-waveband light curves are
similar to simulated spectral energy distributions and light curves
generated with a model in which turbulent plasma crosses a conical
shock with a Mach disk.
Description:
Our Herschel target of opportunity observations began on 2012 October
29 (MJD 56229) and continued for the three-month visibility window. We
arranged for daily Swift pointings starting on 2012 October 27 through
2013 February 1. We also arranged for two intense periods of
every-orbit Swift monitoring on 2012 December 11-12 and 2013 January
11-12. We obtained target of opportunity observations with NuSTAR on
2012 December 11-12. Observations of BL Lac every two to four days
were carried out at the SMA on Mauna Kea, HI during the Herschel
observation window, and intermittently thereafter. Monitoring
observations with CARMA at 3mm were already underway. VLBA monitoring
continued throughout the time range reported here as part of the
ongoing Boston University (BU) γ-ray blazar monitoring program.
Observations at other wavebands were already underway by other
collaborations, e.g., the Whole Earth Blazar Telescope. In addition,
roughly weekly Swift observations have been carried out for several
years by A. Falcone and M. Stroh (Stroh & Falcone 2013ApJS..207...28S 2013ApJS..207...28S).
Herschel SPIRE and PACS FIR observations of BL Lac are presented in
table 1 and sections 2.2 and 2.5. SMA millimeter and submillimeter
observations are presented in tables 1, 2 and 3 and sections 2.3 and
2.5. Millimeter observations with CARMA are presented in table 4 and
sections 2.4 and 2.5. Swift optical, UV and X-ray observations are
presented in tables 5 and 6 and section 2.6. Hard X-ray observations
with NuSTAR are presented in section 2.7. γ-ray observations
with Fermi are presented in section 2.8. The 7mm band observations are
presented in section 2.9. The BU group obtained 2.4-10keV X-ray fluxes
with the RXTE PCA three times per week from 2005 March 3 to 2011
December 31; see table 10 and Appendix.
Objects:
--------------------------------------------------
RA (ICRS) DE Designation(s)
--------------------------------------------------
22 02 43.29 +42 16 40.0 BL Lac = NAME BL Lac
--------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 94 112 SMA and Herschel data
table2.dat 54 348 SMA 225GHz data
table3.dat 54 82 SMA 345GHz data
table4.dat 37 71 CARMA data
table5.dat 106 154 Swift observation log of BL Lac (ObsID 30720
and 35028)
table6.dat 134 154 Observed 0.3-10keV fluxes, X-ray energy indices
αX and UVOT flux densities of BL Lac
table10.dat 55 2072 Observed RXTE 2.4-10keV fluxes and X-ray spectral
slopes αX and count rates of BL Lac
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See also:
J/MNRAS/441/1899 : Fermi bright blazars (Fuhrmann+, 2014)
J/AJ/146/120 : MOJAVE. X. Parsec-scale kinematics of AGNs (Lister+, 2013)
J/A+A/551/A142 : 7 yr Swift-XRT point source catalog (1SWXRT) (D'Elia+, 2013)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJ/761/125 : X and γ spectral indexes of Fermi blazars (Fan+, 2012)
J/ApJ/732/116 : IR spectra of γ-ray bright blazars (Malmrose+, 2011)
J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)
J/AJ/138/1874 : MOJAVE VI. Kinematic analysis of blazar jets (Lister+, 2009)
J/AJ/134/799 : Multiwaveband polarimetry of 15 AGN (Jorstad+, 2007)
J/A+A/450/39 : BVRI photometry of 8 red blazars (Gu+, 2006)
J/MNRAS/373/209 : BATC eim photometry of BL Lac (Hu+, 2006)
J/AJ/130/1418 : AGN jet kinematics (Jorstad+, 2005)
J/PAZh/30/243 : BVRIJHK phot. of BL Lac in 1999-2001 (Hagen-Thorn+, 2004)
J/A+A/385/55 : Long-Term Polarization of BL Lac (Hagen-Thorn+ 2002)
J/A+A/369/758 : VRI photometry of BL Lac (1997-1999) (Fan+, 2001)
J/ApJ/522/846 : Optical monitoring of GeV loud blazars (Xie+, 1999)
J/A+AS/136/455 : BVRI photometry of 3 BL Lac objects (Bai+, 1999)
J/A+AS/132/83 : BVRI photometry of 7 BL Lac objects (Bai+ 1998)
J/AZh/71/717 : Polarimetric Observations of BL Lac (Gagen-Torn+ 1994)
http://www.swift.psu.edu/monitoring/ : Swift obs. of LAT monitored sources
http://www.astro.caltech.edu/marmot/ : The MARMOT project
http://www.bu.edu/blazars/VLBAproject.html : Research by BU blazar group
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "Y/M/D" Date Date of the observation
13- 17 I5 d MJD Modified Julian Date of the observation
19- 24 F6.2 Jy F1.3 [8.2/14.7]?=-99.99 SMA 1.3mm flux density
26- 31 F6.2 Jy e_F1.3 [0.4/0.8]?=-99.99 Error in F1.3
33- 38 F6.2 Jy F0.87 [5.5/14]?=-99.99 SMA 0.87mm flux density
40- 45 F6.2 Jy e_F0.87 [0.4/1.6]?=-99.99 Error in F0.87
47- 52 F6.2 Jy F500 [5.7/9]?=-99.99 Herschel 500um flux density (2)
54- 59 F6.2 Jy F350 [4.7/7.3]?=-99.99 Herschel 350um flux density (2)
61- 66 F6.2 Jy F250 [3.7/6.4]?=-99.99 Herschel 250um flux density (2)
68- 73 F6.2 Jy F160a [1.3/4.7]?=-99.99 First Herschel 160um
flux density (3)
75- 80 F6.2 Jy F100 [0.8/3.6]?=-99.99 Herschel 100um flux density (3)
82- 87 F6.2 Jy F160b [1.2/4.8]?=-99.99 Second Herschel 160um
flux density (3)
89- 94 F6.2 Jy F70 [0.6/2.8]?=-99.99 Herschel 70um flux density (3)
--------------------------------------------------------------------------------
Note (2): The errors are 5% at 500, 350 and 250 microns.
Note (3): The errors are 4.15% at 160, 2.75% at 100 microns, and 2.64% at
70 microns. Data were taken at 160 and 100 microns simultaneously,
followed a few minutes later by data taken at 160 and 70 microns
simultaneously.
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Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "Y/M/D" Obs.date UT date of the observation
13- 17 A5 "h:m" Obs.time UT time of the observation
19- 27 F9.3 d MJD Modified Julian Date of the observation
29- 34 F6.2 GHz Freq [203.5/362.7] Frequency
36- 40 F5.2 Jy FDen [1.1/14.7] SMA flux density
42- 45 F4.2 Jy e_FDen [0.06/1.6] Error in FDen
47- 54 A8 --- PI Principal investigator identifier
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "Y/M/D" Obs.date UT date of the observation
13- 17 A5 "h:m" Obs.time UT time of the observation
19- 26 F8.2 d MJD Modified Julian Date of the observation
28- 32 F5.2 Jy FDen [5.1/18.1] CARMA 94.75GHz flux density
34- 37 F4.2 Jy e_FDen [0.5/1.8] Error in FDen
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Swift [30720/35028] Swift target identifier
7- 9 I3 --- Seg [5/143] Swift observation segment
11- 20 A10 "Y/M/D" St.date Date of the observation start
22- 26 A5 "h:m" St.time UT time of the observation start
28- 37 A10 "Y/M/D" End.date Date of the observation end
39- 43 A5 "h:m" End.time UT time of the observation end
45- 56 F12.6 d MJD Modified Julian Date of mid-observation
58- 61 I4 s T-XRT [109/9323] Exposure time with Swift/XRT
63- 68 F6.2 s T-V ?=-99.99 Exposure time with Swift/UVOT V filter
70- 75 F6.2 s T-B ?=-99.99 Exposure time with Swift/UVOT B filter
77- 82 F6.2 s T-U ?=-99.99 Exposure time with Swift/UVOT U filter
84- 90 F7.2 s T-UVW1 ?=-99.99 Exposure time with Swift/UVOT UVW1
filter
92- 98 F7.2 s T-UVM2 ?=-99.99 Exposure time with Swift/UVOT UVM2
filter
100-106 F7.2 s T-UVW2 ?=-99.99 Exposure time with Swift/UVOT UVW2
filter
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Swift [30720/35028] Swift target identifier
7- 9 I3 --- Seg [5/143] Swift observation segment
11- 20 F10.4 d MJD Modified Julian Date of mid-observation
22- 27 F6.2 10-14W/m2 F0.3-10 [1/8.1]?=-99.99 Swift/XRT 0.3-10keV flux (1)
29- 34 F6.2 10-14W/m2 e_F0.3-10 ?=-99.99 Uncertainty in F0.3-10 (1)
36 I1 --- f_F0.3-10 [3]? Flag on F0.3-10 (2)
38- 43 F6.2 --- alphax [0.4/1.6]?=-99.99 X-ray spectral index (3)
45- 50 F6.2 --- e_alphax ?=-99.99 Uncertainty in alphax (3)
52- 57 F6.2 mJy FV [2.9/33.3]?=-99.99 Swift/UVOT V filter
flux density (4)
59- 64 F6.2 mJy e_FV ?=-99.99 Uncertainty in FV
66- 71 F6.2 mJy FB [1.7/26.4]?=-99.99 Swift/UVOT B filter
flux density (4)
73- 78 F6.2 mJy e_FB ?=-99.99 Uncertainty in FB
80- 85 F6.2 mJy FU [1/17.1]?=-99.99 Swift/UVOT U filter
flux density (4)
87- 92 F6.2 mJy e_FU ?=-99.99 Uncertainty in FU
94- 99 F6.2 mJy FUVW1 [0.5/10.7]?=-99.99 Swift/UVOT UVW1 filter
flux density (4)
101-106 F6.2 mJy e_FUVW1 ?=-99.99 Uncertainty in FUVW1
108-113 F6.2 mJy FUVM2 [0.4/8.9]?=-99.99 Swift/UVOT UVM2 filter
flux density (4)
115-120 F6.2 mJy e_FUVM2 ?=-99.99 Uncertainty in FUVM2
122-127 F6.2 mJy FUVW2 [0.3/7.6]?=-99.99 Swift/UVOT UVW2 filter
flux density (4)
129-134 F6.2 mJy e_FUVW2 ?=-99.99 Uncertainty in FUVW2
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Note (1): In units of 1e-11erg/s/cm2, uncorrected for Galactic absorption.
Note (2):
3 = No reliable flux can be given for Swift target identifier 30720,
segment 104 because the source was at the edge of the WT window.
Note (3): Calculated in XSPEC after correction for Galactic absorption
was applied.
Note (4): Reddening-corrected flux densities in units of mJy. Reddening
correction was performed according to the correction factors given
in the text, as taken from Raiteri et al. (2013MNRAS.436.1530R 2013MNRAS.436.1530R).
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d JD Julian Date of the observation
14- 17 I4 s Int [208/3184] Integration time
19- 26 E8.2 mW/m2 F2.4-10 RXTE 2.4-10keV flux; erg/s/cm2
28- 35 E8.2 mW/m2 e_F2.4-10 Error in F2.4-10; erg/s/cm2
37- 40 F4.2 --- alphax [0.4/2.4] RXTE X-ray spectral index
42- 45 F4.2 --- e_alphax [0.05/0.6] Error in alphax
47- 50 F4.2 ct/s CRate [0.4/4.1] RXTE count rate
52- 55 F4.2 ct/s e_CRate [0.04/0.2] Error in CRate
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Mar-2016