J/ApJS/268/20 XRT/UVOT obs. of the TeV-detected blazar Mrk501 (Kapanadze+, 2023)
Long-term X-ray outburst in the TeV-detected blazar Mrk 501 in 2021-2022:
further clues for the emission and unstable processes.
Kapanadze B., Gurchumelia A., Aller M.
<Astrophys. J. Suppl. Ser., 268, 20 (2023)>
=2023ApJS..268...20K 2023ApJS..268...20K
ADC_Keywords: BL Lac objects; X-ray sources; Photometry, UBV; Ultraviolet;
Gamma rays
Keywords: BL Lacertae objects
Abstract:
This paper presents the results of a detailed X-ray timing and
spectral analysis of Mrk 501, which are based mainly on the Swift data
obtained during 2021 February-2022 December. The source showed
strongly enhanced X-ray activity, characterized by a long-term
increase in the baseline 0.3-10keV flux level superimposed by
shorter-term flares on timescales of a few weeks to about 2 months.
During some time intervals, Mrk 501 was the brightest blazar in the
X-ray sky and, moreover, showed an intense intraday variability, which
was sometimes detected within the exposures lasting a few hundred
seconds. These instances were characterized by fractional variability
amplitudes of 4%-18% and were mostly observed during short-term X-ray
flares. The source exhibited extreme spectral properties with
dominance of the spectral curvature, frequent occurrence of hard
photon indices in the 0.3-10keV and 0.3-300GeV bands, and the peak of
a synchrotron spectral energy distribution in the hard X-ray range.
These properties demonstrate the importance of relativistic magnetic
reconnection, first-order Fermi mechanism within the magnetic field of
different confinement efficiencies, stochastic acceleration, and
hadronic processes. The X-ray and γ-ray fluxes showed a
log-normal distribution, which hints at the imprint of accretion disk
instabilities on the blazar jet, as well as the possible presence of
hadronic cascades and random fluctuations in the particle acceleration
rate. The optical-UV and γ-ray variabilities showed a weak or
absent correlation with the X-ray flaring activity, which is not
consistent with simple leptonic models and requires more complex
particle acceleration, emission, and variability scenarios.
Description:
The Swift XRT observational log of Mrk 501 is presented in Table 2.
We retrieved the raw observational data obtained during
2021-February--2022-December from the publicly available archive
maintained by HEASARC.
In the course of each XRT exposure, the target was observed with UVOT
in six optical-UV bands V, B, U, UVW1, UVM2, and UVW2. We retrieved
the sky-corrected images from HEASARC (see Table 3).
Mrk 501 is monitored by the First G-APD Cherenkov Telescope (FACT;
Observatorio del Roque de los Muchachos, La Palma, Spain) in the TeV
energy range since 2011-October. The FACT collaboration publishes the
results of a quick-look analysis on a website. The details of this
analysis are provided in Dorner+ (2015arXiv150202582D 2015arXiv150202582D).
See Section 2.3.
Objects:
--------------------------------------------------------
RA (ICRS) DE Designation(s)
--------------------------------------------------------
16 53 52.21 +39 45 36.6 Mrk 501 = 4FGL J1653.8+3945
--------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 90 190 XRT observations of Mrk 501
table3.dat 50 792 Results from the UVOT observations
table6.dat 173 76 0.3-10keV intraday variabilities (IDVs) detected
at the 99.997% and 99.5% confidence levels
table7.dat 97 236 Results of the Swift-XRT spectral analysis
with the log-parabolic model
table11.dat 77 204 Results of the Swift-XRT spectral analysis
with a simple power-law model
--------------------------------------------------------------------------------
See also:
B/swift : Swift Master Catalog (HEASARC, 2004-)
J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)
J/ApJ/700/597 : FERMI LAT detected blazars (Abdo+, 2009)
J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)
J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)
J/ApJ/831/102 : Swift and NuSTAR obs. of Mrk 421 (Kapanadze+, 2016)
J/MNRAS/468/4992 : MOJAVE XIV. AGN jet shapes & angles (Pushkarev+, 2017)
J/ApJS/235/39 : Jet properties of γ-ray-loud 3FGL AGNs (Chen, 2018)
J/ApJS/238/13 : Spectral & timing results of 1ES 1959+650 (Kapanadze+, 2018)
J/ApJS/247/33 : Fermi LAT fourth source catalog (4FGL) (Abdollahi+, 2020)
J/ApJS/247/27 : Swift obs. of Mrk 421. III. (Kapanadze+, 2020)
J/A+A/668/A75 : Long-term MWL variability of 1ES 0033+595 (Kapanadze+, 2022)
J/ApJS/266/37 : Time evolution of Mrk501 emission during 4yrs (Abe+, 2023)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- ObsID XRT Observation identifier
10- 19 A10 "Y/M/D" St.date Start Date, YYYY-MM-DD (UTC)
21- 28 A8 "h:m:s" St.time Start Time, HH:MM:SS.ss (UTC)
30- 39 A10 "Y/M/D" End.date Start Date, YYYY-MM-DD (UTC)
41- 48 A8 "h:m:s" End.time Start Time, HH:MM:SS.ss (UTC)
50- 53 I4 s ExpTime [240/1584] Total Exposure time
55- 63 F9.3 d MJD [59257.5/59945.8] Modified Julian Date,
observation start (JD-2400000.5)
65- 69 F5.2 ct/s CR [2.5/15.6] Mean 0.3-1.0keV count rate
71- 74 F4.2 ct/s e_CR [0.05/0.3] Error in CR
76- 80 F5.2 --- chi2r [0.28/37.2] Reduced χ2
82- 83 I2 --- dof [1/19] Degrees of freedom of fit
85- 87 A3 s Bin Time bin ("120", "60" or "Or"=Orbit)
89- 90 A2 --- Var Brightness variability? (1)
--------------------------------------------------------------------------------
Note (1): Brightness variability code as follows:
V = Variability detection (40 occurrences);
PV = Possibly variable (17 occurrences);
NV = non-variable (133 occurrences).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- ObsID [11184079/96558009] XRT Observation identifier
10- 13 A4 --- Filt Filter (U, B, V, UVM2, UVW1 or UVW2)
15- 20 F6.3 mag omag [13/14]? Observed magnitude in Filt
22- 25 F4.2 mag e_omag [0.02/0.14]? Uncertainty in omag
27- 31 F5.2 mJy Flux [2/14.4]? Observed Flux in Filt
33- 36 F4.2 mJy e_Flux [0.04/0.7]? Uncertainty in Flux
38- 44 F7.3 [-] lognuFnu [-10.52/-10.1]? Snu Flux density in Filt
46- 50 F5.3 [-] e_lognuFnu [0.007/0.06]? Uncertainty in lognuFnu
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- Set [1/2] IDV subset (1)
3- 14 A12 --- ObsID1 XRT Observation identifier, 1st observation (2)
17- 24 I8 --- ObsID2 ? XRT second observation ID if needed
26- 35 A10 "Y/M/D" Date1 Date of ObsID1
37- 46 A10 "Y/M/D" Date2 Date of ObsID2, if needed
48- 53 I6 d MJD1 [49576/59919] Modified Julian date, ObsID1
55- 59 I5 d MJD2 [56787/59780]? Modified Julian date, ObsID2
61- 65 F5.2 s ExpTime [0.07/23.82] Total length of the particular
observation (1)
67- 72 F6.3 --- chi2r [2.42/37.2] Reduced χ2
74- 75 I2 --- dof [3/25] Degrees of freedom of fit
77- 79 I3 s Bin [60/120]? Time bin
81- 85 F5.2 % Fvar [3.8/19.2] Fractional variability amplitude
87- 89 F3.1 % e_Fvar [0.6/3] Uncertainty in fvar
91- 96 F6.2 --- a1 [1.6/2.2]? Logparabolic photon index, or lower
limit of range
98- 101 F4.2 --- e_a1 [0.03/0.07]? Uncertainty in a1
103- 106 F4.2 --- a2 [1.7/2.2]? Logparabolic photon index, upper
limit of range if needed
108- 113 F6.2 --- e_a2 [0.03/0.05]? Uncertainty in a2
115- 118 F4.2 --- Gamma1 [1.7/2.3]? 0.3-10keV photon index, or lower
limit of range
120- 123 F4.2 --- e_Gamma1 [0.03/0.06]? Uncertainty in Gamma1
125- 128 F4.2 --- Gamma2 [1.8/2.3]? 0.3-10keV photon index, upper limit
of range if needed
130- 133 F4.2 --- e_Gamma2 [0.03/0.05]? Uncertainty in Gamma2
135- 138 F4.2 --- b1 [0.1/2.2]? Curvature parameter, or lower limit
of range
140- 143 F4.2 --- e_b1 [0.06/0.2]? Uncertainty in b1
145- 148 F4.2 --- b2 [0.17/0.5]? Curvature parameter, upper limit
of range if needed
150- 153 F4.2 --- e_b2 [0.07/0.2]? Uncertainty in b2
155- 158 F4.2 keV Ep1 [0.26/4.3]? Synchrotron SED peak, or lower
limit of range
160- 163 F4.2 keV e_Ep1 [0.08/0.4]? Uncertainty in Ep1
165- 168 F4.2 keV Ep2 [0.7/6]? Synchrotron SED peak, upper limit of
range if needed
170- 173 F4.2 keV e_Ep2 [0.09/0.6]? Uncertainty in Ep2
--------------------------------------------------------------------------------
Note (1): Subsets of 0.3-10keV IDVs detected at the 99.997% (Set=1)
and 99.5% (Set=2) confidence levels
Note (2): For some ObsID1 entries, the XRT ObsID + orbit (Or#) is given.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ORS XRT Observation ID + orbit (Or#)
or Segment (S#) number
17- 20 F4.2 --- a [1.62/2.19] Photon index
22- 25 F4.2 --- e_a [0.03/0.07] Uncertainty in a
27- 30 F4.2 --- b [0.12/0.62] Curvature parameter
32- 35 F4.2 --- e_b [0.06/0.17] Uncertainty in b
37- 40 F4.2 --- Ep [0.24/5.8] Synchrotron SED peak
42- 45 F4.2 --- e_Ep [0.07/0.52] Uncertainty in Ep
47- 50 F4.2 0.1 K [2.11/8.94] Normalisation factor (10*K)
52- 55 F4.2 0.1 e_K [0.06/0.26] Uncertainty in K
57- 60 F4.2 --- chi2r [0.84/1.17] Reduced χ^2
62- 64 I3 --- dof [52/200] Degrees of freedom of fit
66- 70 F5.2 10-14W/m2 F1 [5.36/33] Unabsorbed 0.3-2keV Flux,
in 10-11erg/s/cm2
72- 75 F4.2 10-14W/m2 e_F1 [0.1/3.5] Uncertainty in F3
77- 81 F5.2 10-14W/m2 F2 [4/27.6] Unabsorbed 2-10keV Flux,
in 10-11erg/s/cm2
83- 86 F4.2 10-14W/m2 e_F2 [0.2/2] Uncertainty in F3
88- 92 F5.2 10-14W/m2 F3 [10.7/53.3] Unabsorbed 0.3-10keV Flux,
in 10-11erg/s/cm2
94- 97 F4.2 10-14W/m2 e_F3 [0.3/2] Uncertainty in F3
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table11.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ORS XRT Observation ID + orbit (Or#)
or Segment (S#) number
17- 20 F4.2 --- Gamma [1.76/2.3] 0.3-10keV photon index
22- 25 F4.2 --- e_Gamma [0.02/0.06] Uncertainty in Gamma
27- 30 F4.2 0.1 K [1.75/9.1] Normalisation factor (10*K)
32- 35 F4.2 0.1 e_K [0.04/0.3] Uncertainty in K
37- 40 F4.2 --- chi2r [0.8/1.2] Reduced χ2
42- 44 I3 --- dof [32/165] Degrees of freedom of fit
46- 50 F5.2 10-14W/m2 F1 [5.3/41.2] Unabsorbed 0.3-2keV Flux
in 10-11erg/s/cm2
52- 55 F4.2 10-14W/m2 e_F1 [0.16/4.1] Uncertainty in F3
57- 61 F5.2 10-14W/m2 F2 [3.7/29.8] Unabsorbed 2-10keV Flux
in 10-11erg/s/cm2
63- 66 F4.2 10-14W/m2 e_F2 [0.2/1.4] Uncertainty in F3
68- 72 F5.2 10-14W/m2 F3 [9.89/54.7] Unabsorbed 0.3-10keV Flux
in 10-11erg/s/cm2
74- 77 F4.2 10-14W/m2 e_F3 [0.05/7] Uncertainty in F3
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Dec-2023