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. =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 E_p_ 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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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 {chi}^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 -------------------------------------------------------------------------------- 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 {chi}^2^ 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 -------------------------------------------------------------------------------- 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 {chi}^2^ 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 -------------------------------------------------------------------------------- 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). -------------------------------------------------------------------------------- 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. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Mar-2019