J/ApJ/858/68 Swift obs. of Mrk 421 in selected epochs. II. (Kapanadze+, 2018)
Swift observations of Mrk 421 in selected epochs.
II. An extreme spectral flux variability in 2009-2012.
Kapanadze B., Vercellone S., Romano P., Hughes P., Aller M., Aller H.,
Kharshiladze O., Tabagari L.
<Astrophys. J., 858, 68-68 (2018)>
=2018ApJ...858...68K 2018ApJ...858...68K (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects; Photometry, ultraviolet; X-ray sources
Keywords: BL Lacertae objects: individual: Mrk 421
Abstract:
We present the results from a detailed spectral and timing study of
Mrk 421 based on the rich archival Swift data obtained during
2009-2012. Best fits of the 0.3-10keV spectra were mostly obtained
using the log-parabolic model showing the relatively low spectral
curvature that is expected in the case of efficient stochastic
acceleration of particles. The position of the synchrotron spectral
energy density peak Ep of 173 spectra is found at energies higher
than 2keV. The photon index at 1 keV exhibited a very broad range of
values a=1.51-3.02, and very hard spectra with a<1.7 were observed
during the strong X-ray flares, hinting at a possible hadronic jet
component. The spectral parameters varied on diverse timescales and
showed a correlation in some periods, which is expected in the case of
first- and second-order Fermi acceleration. The 0.3-10keV flux showed
strong X-ray flaring activity by a factor of 3-17 on timescales of a
few days-weeks between the lowest historical state and that
corresponding to a rate higher than 100ct/s. Moreover, 113 instances
of intraday variability were revealed, exhibiting shortest
flux-doubling/halving times of about 1.2hr, as well as brightenings by
7%-24% in 180-720 s and declines by 68%-22% in 180-900s. The X-ray and
very high-energy fluxes generally showed a correlated variability,
although one incidence of a more complicated variability was also
detected, indicating that the multifrequency emission of Mrk 421 could
not be generated in a single zone.
Description:
The source was observed 370 times by the Swift XRT between 2009
January 12 and 2012 December 30 with a total exposure of 403.6ks. The
information about each pointing and the corresponding count rates is
provided in Table 1, which also contains the results from the
simultaneous UVOT observations in the ultraviolet bands UVW1, UVM2,
and UVW2.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
11 04 27.31 +38 12 31.8 Mrk 421 = SWIFT J1104.5+3813
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 133 370 Summary of the XRT and UVOT observations
in 2009 January - 2012 December
table2.dat 134 850 Results of the spectral analysis with
the log-parabolic model
table5.dat 105 61 The results of the XRT spectral analysis with
a simple power-law model
table7.dat 171 129 Summary of the 0.3-10keV intraday-variabilities
(IDVs) in 2009 February - 2012 April
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See also:
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/ApJ/854/66 : Swift observations of Mrk 421. I. 2005-2008 (Kapanadze+, 2018)
J/ApJ/848/103 : ∼1.5yr Swift observations of Mrk 421 (Kapanadze+, 2017)
J/ApJS/232/7 : 8yr R-band photopolarimetric data of Mrk 421 (Fraija+, 2017)
J/ApJS/222/6 : 4.5yr obs. of Mrk421 with ARGO-YBJ + Fermi (Bartoli+, 2016)
J/ApJ/831/102 : Swift and NuSTAR obs. of the BL Lac Mrk 421 (Kapanadze+, 2016)
J/A+A/593/A91 : Mrk 421 multi-wavelength variability, 2007-2009 (Ahnen+, 2016)
J/MNRAS/458/56 : TeV blazar X-ray spectral studies (Wierzcholska+, 2016)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/A+A/578/A22 : Mrk421 in March 2010 (Aleksic+, 2015)
J/A+A/576/A126 : The 2009 multiwavelength campaign on Mrk421 (Aleksic+, 2015)
J/A+A/559/A75 : 43GHz observation of the blazar Mrk 421 (Blasi+, 2013)
J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)
J/A+A/545/A117 : Monitoring of Mrk 421 at 15 and 24 GHz (Lico+, 2012)
J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- obsID Observation identifier
10- 19 A10 "Y/M/D" start.date UTC date of observation start, YYYY-MM-DD
21- 28 A8 "h:m:s" start.time UTC time of observation start, HH:MM:SS
30- 39 A10 "Y/M/D" end.date UTC date of observation end, YYYY-MM-DD
41- 48 A8 "h:m:s" end.time UTC time of observation end, HH:MM:SS
50- 53 I4 s Exp [35/4363] Exposure time
55- 61 F7.3 ct/s XRT [1.8/115]? Observation-binned 0.3-10keV
count rate
63- 66 F4.2 ct/s e_XRT [0.04/1.3]? Uncertainty in XRT
68- 72 F5.2 mag uvw1mag [10.6/12.5]? De-reddened Swift/UVOT
uvw1 band magnitude
74- 77 F4.2 mag e_uvw1mag [0.02/0.06]? Uncertainty in uvw1mag
79- 83 F5.2 mJy Fuvw1 [9/47.4]? De-reddened Swift/UVOT uvw1 band
flux density
85- 88 F4.2 mJy e_Fuvw1 [0.07/1.5]? Uncertainty in Fuvw1
90- 94 F5.2 mag uvm2mag [11/13]? De-reddened Swift/UVOT uvm2 band
magnitude
96- 99 F4.2 mag e_uvm2mag [0.03/0.05]? Uncertainty in uvm2mag
101-105 F5.2 mJy Fuvm2 [5/29.4]? De-reddened Swift/UVOT uvm2 band
flux density
107-111 F5.3 mJy e_Fuvm2 [0.01/0.7]? Uncertainty in Fuvm2
113-117 F5.2 mag uvw2mag [10.6/12.5]? De-reddened Swift/UVOT uvw2
band magnitude
119-122 F4.2 mag e_uvw2mag [0.03/0.06]? Uncertainty in uvw2mag
124-128 F5.2 mJy Fuvw2 [6.2/40.2]? De-reddened Swift/UVOT uvw2 band
flux density
130-133 F4.2 mJy e_Fuvw2 [0.1/1]? Uncertainty in Fuvw2
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- obsID Observation identifier
11- 25 A15 --- ORS Orbit/Segment code for model fit (G1)
27- 30 F4.2 --- a [1.5/3.1] Model parameter, photon index
at the energy E1
32- 35 F4.2 --- e_a [0.01/0.1] Uncertainty in a
37- 40 F4.2 --- b [0.08/0.7] Model parameter, curvature parameter
42- 45 F4.2 --- e_b [0.03/0.2] Uncertainty in b
47- 52 F6.3 keV Ep [0.002/15.2] Model parameter, position of
the SED peak
54- 58 F5.3 keV e_Ep [0.001/1.6] Uncertainty in Ep
60- 64 F5.3 --- 10K [0.01/9.2] Model parameter, normalization
factor, x10
66- 70 F5.3 --- e_10K [0.001/0.02] Uncertainty in K
72- 76 F5.3 --- chi2 [0.8/2.3] Reduced χ^2 parameter
78- 80 I3 --- DOF [14/332] Fit degrees of freedom
82- 88 F7.3 [mW/m2] logFS [-10.4/-8.6] Log unabsorbed 0.3-2 keV Flux
90- 94 F5.3 [mW/m2] e_logFS [0.003/0.02] Uncertainty in logFS
96-102 F7.3 [mW/m2] logFH [-11.3/-8.5] Log unabsorbed 2-10 keV Flux
104-108 F5.3 [mW/m2] e_logFH [0.007/0.2] Uncertainty in logFH
110-116 F7.3 [mW/m2] logFT [-10.4/-8.3] Log unabsorbed 0.3-10 keV Flux
118-122 F5.3 [mW/m2] e_logFT [0.004/0.03] Uncertainty in logFH
124-128 F5.3 --- HR [0.04/1.5] Hardness ratio (G2)
130-134 F5.3 --- e_HR [0.003/0.07] Uncertainty in HR
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- obsID Observation identifier
10- 19 A10 --- ORS Orbit/Segment code for model fit (G1)
21- 24 F4.2 --- Gamma [1.7/3] Photon index in PL model
26- 29 F4.2 --- e_Gamma [0.01/0.05] Uncertainty in Gamma
31- 35 F5.3 --- K [0.01/0.6] Normalization
37- 41 F5.3 --- e_K [0.001/0.007] Uncertainty in K
43- 47 F5.3 --- chi2 [0.8/1.2] Reduced χ2 parameter
49- 51 I3 --- DOF [40/335] Fit degrees of freedom
53- 59 F7.3 [mW/m2] logFS [-10.4/-8.8] Log unabsorbed 0.3-2keV Flux
61- 65 F5.3 [mW/m2] e_logFS [0.004/0.02] Uncertainty in logFS
67- 73 F7.3 [mW/m2] logFH [-11.2/-8.7] Log unabsorbed 2-10keV Flux
75- 79 F5.3 [mW/m2] e_logFH [0.006/0.04] Uncertainty in logFH
81- 87 F7.3 [mW/m2] logFT [-10.3/-8.4] Log unabsorbed 0.3-10keV Flux
89- 93 F5.3 [mW/m2] e_logFT [0.004/0.02] Uncertainty in logFH
95- 99 F5.3 --- HR [0.1/1.4] Hardness ratio (G2)
101-105 F5.3 --- e_HR [0.007/0.07] Uncertainty in HR
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- obsID Observation identifier (1)
9 A1 --- --- [-]
10- 17 I8 --- obsID2 ? Second observation identifier (1)
19- 28 A10 "Y/M/D" UTDate1 UT Date of observation 1, YYYY-MM-DD (2)
30- 39 A10 "Y/M/D" UTDate2 UT Date of observation 2, YYYY-MM-DD (2)
41- 45 F5.2 h Exp [0.07/24] Total length of the particular
observation (2)
47- 54 F8.3 --- chi2 [2.5/7858]? Reduced χ2 parameter
56- 57 I2 --- DOF [1/31]? Fit degrees of freedom
59- 71 A13 --- ORS Orbit segment (G1) (2)
73- 77 F5.2 % Fvar [2/63.4]? Fractional variability amplitude
79- 81 F3.1 % e_Fvar [0.2/2.7]? Uncertainty in Fvar
83- 86 F4.2 --- Param-Min [1.5/2.9]? LP/PL model Param minimum (3)
88- 91 F4.2 --- e_Param-Min [0.01/0.05]? Uncertainty in e_Param-Min (3)
93- 96 F4.2 --- Param-Max [1.6/3]? LP/PL model Param maximum (3)
98-101 F4.2 --- e_Param-Max [0.01/0.05]? Uncertainty in e_Param-Max (3)
103-104 A2 --- Param ? Param designation (3)
106-109 F4.2 --- b-min [0.08/0.6]? Min curvature parameter
in LP model
111-114 F4.2 --- e_b-min [0.03/0.2]? Uncertainty in b-min
116-119 F4.2 --- b-max [0.1/0.7]? Max curvature parameter in LP model
121-124 F4.2 --- e_b-max [0.03/0.2]? Uncertainty in b-max
126-130 F5.3 keV Ep-min [0.002/7]? Minimum position of the SED peak
in LP model
132-136 F5.3 keV e_Ep-min [0.001/0.7]? Uncertainty in Ep-min
138-142 F5.2 keV Ep-max [0.03/15.2]? Max position of the SED peak
in LP model
144-147 F4.2 keV e_Ep-max [0.01/1.6]? Uncertainty in Ep-max
149-153 F5.3 --- HR-min [0.1/1.4]? Minimum hardness ratio
155-159 F5.3 --- e_HR-min [0.004/0.04]? Uncertainty in HR-min
161-165 F5.3 --- HR-max [0.1/1.5]? Maximum hardness ratio
167-171 F5.3 --- e_HR-max [0.009/0.06]? Uncertainty in HR-max
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Note (1): This column includes a range of obsIDs, and specific "orbit" (Or#)
subset(s).
Note (2): The total exposure used for IDV calculations can segment a single
obsID or span multiple obsIDs. The columns that define the exposure for
calculating IDVs are:
obsID = includes the orbit subsets for an obsID used in IDV;
Obs.Y/Obs.M/Obs.D-1/Obs.D-2 = Range of observation UT date from D-1 to D-2;
Exp = Total exposure length in hours, including intervals between obsIDs;
Bin = That segment, in seconds, of the Orbit.
Note (3): The contents of the columns Param designate which parameter is
given in the Param-Min, Param-Max, etc columns. If Param="LP" then the
Param- values are the log-parabolic parameter "a". If Param="PL" then
the Param- values are the power-law parameter Gamma. When only one
spectrum is available for the particular observation, only a single
value is provided for each spectral parameters instead of a range (given
as Param-Max with Param-Min values set to null).
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Global notes:
Note (G1): This column contains the "orbit" (Or#) and "segment" (S#) in seconds
[#s] of that orbit used in the fit.
Note (G2): Hardness ratio is calculated as a ratio of unabsorbed 2-10keV to
0.3-2keV fluxes.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Mar-2019