J/ApJ/951/94 Swift-XRT & XMM obs. of 1ES 1959+65.0 over 2.5yrs (Wani+, 2023)
X-ray studies of blazar 1ES 1959+650 using Swift and XMM-Newton satellite.
Wani K., Gaur H., Patil M.K.
<Astrophys. J., 951, 94 (2023)>
=2023ApJ...951...94W 2023ApJ...951...94W
ADC_Keywords: BL Lac objects; X-ray sources
Keywords: Active galactic nuclei ; Blazars ; BL Lacertae objects ;
Relativistic jets
Abstract:
High synchrotron energy peaked blazar 1ES 1959+650 was studied with
the Swift and XMM-Newton satellites in a total of 127 observations
during the period 2018 June-2020 December. We extensively studied its
flux and spectral variability on intraday and long-term timescales.
Discrete correlation function analysis between soft and hard X-ray
bands indicates soft as well as hard lags. The results were used to
constrain the magnetic field of the emitting region, which was found
to be 0.64±0.05G. On long-term timescales, the distribution of
fluxes shows lognormal behavior, which could be attributed to the
minijets-in-a-jet model or might be due to the propagation of
relativistic shocks down the jet. The spectral energy distribution
around the synchrotron peak is well described by the log-parabola
model. Spectral parameters like the peak energy Ep, curvature β,
and peak luminosity Lp were derived from spectral analysis. Their
correlations were studied to constrain the acceleration processes of
the emitting particles. Ep shows strong correlation with Lp during the
high state of the source, which indicates spectral changes might be
caused by the variations of the average electron energy. Low values of
the curvature parameter β and a weak correlation between Ep and
β indicate the coexistence of stochastic/statistical acceleration
of electrons in the emitting region. Implications of other results are
also discussed.
Description:
In the present work, we analyzed Swift observations of 1ES 1959+650
during the period 2018 June--2020 December on 125 nights. We retrieved
the Swift-XRT data from the publicly available HEASARC data archive.
Blazar 1ES 1959+650 was observed on 2019 July 05 and 2020 July 16 by
the XMM-Newton satellite. We used the European Photon Imaging Camera
(EPIC)-pn instrument data. We restricted our analysis to the 0.3-10keV
energy range.
Objects:
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RA (ICRS) DE Designation(s) (z)
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19 59 59.85 +65 08 54.6 1ES 1959+650 = 1ES 1959+65.0 (z=0.048)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 142 Observation log of XMM-Newton and Swift-XRT data
for blazar 1ES 1959+650
table2.dat 169 142 Best spectral fit parameters for the Power Law and
Log Parabolic Model of blazar 1ES 1959+650 of
XMM-Newton and Swift-XRT observations from
June 2018 to December 2020
table4.dat 44 142 Results of χ^2 test for Hardness Ratio analysis
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See also:
B/swift : Swift Master Catalog (HEASARC, 2004-)
B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012-)
J/ApJS/97/1 : HST Quasar Absorption Line Key Project. X. (Lockman+ 1995)
J/ApJ/617/262 : X-ray sources in NGC 1600 (Sivakoff+, 2004)
J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)
J/MNRAS/421/1861 : OJ287 polarization and VLBI jet direction (Valtonen+, 2012)
J/ApJ/848/103 : ∼1.5yr Swift observations of Mrk 421 (Kapanadze+, 2017)
J/ApJS/238/13 : Spectral & timing results of 1ES 1959+650 (Kapanadze+, 2018)
J/ApJS/247/27 : Swift obs. of Mrk 421. III. ∼3yr obs. (Kapanadze+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Tel Satellite ("Swift-XRT" or "XMM-Newton")
12- 22 I011 --- obsID Observation identifier
24- 27 A4 --- Orbit Orbit number
29- 32 I4 yr Obs.Y [2018/2020] Observation year
34- 35 I2 "month" Obs.M Observation Month
37- 38 I2 d Obs.D Observation day
40- 47 F8.2 s ExpTime [114.5/42140] Exposure time
49- 52 F4.2 % Fvar [0.3/7.4]? Fractional rms variability amplitude
54- 58 F5.2 % e_Fvar [0.07/11]? Uncertainty in fvar
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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 I1 --- Sat [1/2] Satellite (G1)
4- 14 I011 --- obsID Observation identifier
16- 19 F4.2 --- alpha-PL [1.78/2.4] Power-law spectral fit slope,
α
21- 26 F6.3 --- E_alpha-PL [0.002/0.07] Upper Uncertainty on
alpha-PL
28- 33 F6.3 --- e_alpha-PL [-0.07/-0.002] Lower Uncertainty on
alpha-PL
35- 39 F5.2 [mW/m2] logFlux-PL [-9.6/-8.8] Log, Integrated Flux,
power-law spectral fit
41- 46 F6.3 [mW/m2] E_logFlux-PL [0.001/0.03] Upper Uncertainty on
logFlux-PL
48- 53 F6.3 [mW/m2] e_logFlux-PL [-0.03/-0.001] Lower Uncertainty on
logFlux-PL
55- 59 F5.2 --- chi2red-PL [0.89/41.5] Reduced χ2, power-law
model fit
61- 63 I3 --- DoF-PL [56/434] Degrees of freedom, power-law
model fit
65- 68 F4.2 --- alpha-LP [1.3/2.3] Log Parabolic spectral fit
parameter, α
70- 75 F6.3 --- E_alpha-LP [0.002/0.12] Upper Uncertainty on
alpha-LP
77- 82 F6.3 --- e_alpha-LP [-0.13/-0.002] Lower Uncertainty on
alpha-LP
84- 87 F4.2 --- beta-LP [0.2/1] Log Parabolic spectral fit
parameter, β
89- 94 F6.3 --- E_beta-LP [0.005/0.3] Upper Uncertainty on beta-LP
96- 101 F6.3 --- e_beta-LP [-0.3/-0.005] Lower Uncertainty on
beta-LP
103- 107 F5.2 [mW/m2] logFlux-LP [-9.6/-8.8] Log, Integrated Flux, Log
Parabolic spectral fit
109- 114 F6.3 [mW/m2] E_logFlux-LP [0.001/0.03] Upper Uncertainty on
logFlux-LP
116- 121 F6.3 [mW/m2] e_logFlux-LP [-0.03/-0.001] Lower Uncertainty on
logFlux-LP
123- 126 F4.2 --- chi2red-LP [0.7/5.6] Reduced χ^2, Log Parabolic
model fit
128- 130 I3 --- DoF-LP [55/433] Degrees of freedom, Log
Parabolic model fit
132- 138 F7.2 --- Ftest [9.6/1688] Statistical F-test
140- 147 E8.2 --- pvalue [2.2e-39/0.0023]? Statistical p-value
149 A1 --- f_pvalue l: values < 1e-40 have been set to NULL
by CDS
151- 154 F4.2 keV Ep [0.46/2.9] Synchrotron Peak Energy
156- 159 F4.2 keV e_Ep [0.01/0.6] Uncertainty in Ep
161- 164 F4.2 10+38W Lp [0.5/2.5] Peak Luminosity, 10+45erg/s
166- 169 F4.2 10+38W e_Lp [0/0.07] Uncertainty in Lp
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 1 I1 --- Sat [1/2] Satellite (G1)
3- 13 I011 --- obsID Observation identifier
15- 18 A4 --- Orbit Orbit number
20- 23 I4 yr Obs.Y [2018/2020] Observation year
25- 26 I2 "month" Obs.M Observation Month
28- 29 I2 d Obs.D Observation day
31- 32 I2 --- DoF [3/81] Degrees of Freedom,
Hardness Ratio analysis
34- 38 F5.2 --- chi2 [0.8/54] χ2 fit statistic,
Hardness Ratio analysis
40- 44 F5.2 --- chi20.90 [6.2/98] χ2 0.90 fit statistic,
Hardness Ratio analysis
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Global notes:
Note (G1): Satellite as follows:
1 = XMM-Newton (2 occurrences)
2 = Swift-XRT (140 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Aug-2025