2021A&A...645A..62B

Query : 2021A&A...645A..62B

2021A&A...645A..62B - Astronomy and Astrophysics, volume 645A, 62-62 (2021/1-1)

Ornstein-Uhlenbeck parameter extraction from light curves of Fermi-LAT observed blazars.

BURD P.R., KOHLHEPP L., WAGNER S.M., MANNHEIM K., BUSON S. and SCARGLE J.D.

Abstract (from CDS):


Context. Monthly binned γ-ray light curves of 236 bright γ-ray sources, particularly blazars, selected from a sample of 2278 high-galactic latitude objects observed with Fermi-LAT show flux variability characterized by power spectral densities consisting of a single power-law component, ranging from Brownian to white noise.
Aims. The main goal here is to assess the Ornstein-Uhlenbeck (OU) model by studying the range of its three parameters that reproduces these statistical properties.
Methods. We develop procedures for extracting values of the three OU model parameters (mean flux, correlation length, and random amplitude) from time series data and apply them to compare numerical integrations of the OU process with the Fermi-LAT data.
Results. The OU process fully describes the statistical properties of the flux variations of the 236 blazars. The distributions of the extracted OU parameters are narrowly peaked around well-defined values (σ, µ, θ) = (0.2, -8.4, 0.5) with variances (0.004, 0.07, 0.13). The distributions of rise and the decay time scales of flares in the numerical simulations, meaning major flux variations fulfilling pre-defined criteria, are in agreement with the observed ones. The power spectral densities of the synthetic light curves are statistically indistinguishable from those of the measured light curves.
Conclusions. The long-term γ-ray flux variability of blazars on monthly time scales is well described by a stochastic model that involves only three parameters. The methods described here are powerful tools for studying randomness in light curves and thereby for constraining the physical mechanisms responsible for the observed flux variations.

Abstract Copyright: © ESO 2021

Journal keyword(s): galaxies: active - gamma rays: general - time - methods: statistical - methods: numerical

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 QSO B2155-304 BLL 21 58 52.0652249880 -30 13 32.118447792   13.36 13.09 12.62   ~ 1733 1

Query : 2021A&A...645A..62B

Basic data :
QSO B2155-304 -- BL Lac
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		Rad (2020A&A,CRATES,...), gam (2AGL,3EG,...), X (2009A&A,2A,...), BLL (2010ApJ,SHBL,...), Bla (2012ApJ,[DGT2001],...), QSO (2011MNRAS,QSO,...), Bz? (2019A&A,3HSP,...), AGN (2011ApJ,CGRaBS), UV (2EUVE,EUVE,...), V* (2018AJ,AAVSO), smm (JCMTSE,JCMTSF), MIR (WISEA,WISE), BL? (2021MNRAS), G (2012A&A), * (Gaia), cm (AT20G), NIR (2MASS), Opt (ATO)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		21 58 52.0652249880 -30 13 32.118447792 (Optical) [ 0.0171 0.0137 90 ] A 2020yCat.1350....0G
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		21 55 58.3502869567 -30 27 54.543262924 [ 0.0171 0.0137 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		017.7304978472482 -52.2458531252353 [ 0.0171 0.0137 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		-0.083 0.012 [0.022 0.018 90] A 2020yCat.1350....0G
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, ∼=unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) 32771 [600] / z(emission) 0.116 [0.002] / cz 34776 [600]
   D 2013MNRAS.435.1233G
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		0.0158 [0.0191] A 2020yCat.1350....0G
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (7) :
B 13.36 [~] D 2010A&A...518A..10V
V 13.09 [~] D 2010A&A...518A..10V
R 12.62 [~] D 2008ApJS..175...97H
G 13.704623 [0.017850] C 2020yCat.1350....0G
J 11.398 [0.027] C 2003yCat.2246....0C
H 10.46 [0.01] B 2012AJ....144..112F
K 10.134 [0.023] C 2003yCat.2246....0C
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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within arcsec The VizieR photometry tool allows for easy visualization of photometry points extracted around the Simbad position from photometry-enabled catalogues in VizieR.
The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!). sed-help-icon
Some important notes on this object about identifications and objects associations.
notes:

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (86) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

QSO B2155-304 3FHL J2158.8-3013 RBS 1807 2XMM J215852.0-301332
2A 2151-316 GLEAM J215852-301318 2RE J2158-301 XSS J21583-3004
3A 2156-306 1H 2156-304 2RE J215852-301327 9Y-MST J2158-3013
2AGL J2157-3015 HESS J2158-302 RE J215852-301324 [BDW2002] q2155-3027
AT20G J215852-301332 H 2155-304 RE J2158-301 [DGT2001] B2155-304
ATO J329.7169-30.2256 H 2154-304 RFC J2158-3013 [FS2003] 1142
CGRaBS J2158-3013 H 2154-30 RORF 2155-304 [HB93] 2155-304
CRATES J215852-301328 3HSP J215852.0-301332 RX J2158.8-3013 [LBD96] J2155-304
2E 4544 ICRF J215852.0-301332 1RXS J215852.2-301338 [MGL2009] BZB J2158-3013
2E 2155.9-3027 IERS B2155-304 SHBL J215852.0-301331 [MML2015] 5BZB J2158-3013
3EG J2158-3023 INTREF 1064 SPASS J215851-301340 [QC93] 2155-304
EGR J2200-3015 IVS B2155-304 SUMSS J215852-301326 [VV2000b] J215852.0-301332
1ES 2155-30.4 JCMTSE J215852.2-301332 TeV J2158-302 [VV2003b] J215852.0-301332
2EUVE J2158-30.2 JCMTSF J215852.2-301332 TGSSADR J215852.0-301324 [VV2006b] J215852.0-301332
EUVE J2158-30.2 2MASS J21585206-3013321 TIC 229013191 [VV2010b] J215852.0-301332
0FGL J2158.8-3014 NVSS J215852-301330 TXS 2155-304 [VV98b] J215852.0-301332
1FGL J2158.8-3013 PKS 2155-304 VLSSr J215852.6-301328 AAVSO 2153-30
2FGL J2158.8-3013 PKS J2158-3013 VLSS J2158.8-3013 Gaia DR3 6616660280724162688
3FGL J2158.8-3013 PKS 2155-30 2WHSP J215852.0-301332 Gaia DR1 6616660280724162688
4FGL J2158.8-3013 PMN J2158-3013 WISEA J215852.06-301332.0 Gaia DR2 6616660280724162688
1FHL J2158.8-3013 QSO J2158-3013 WISE J215852.05-301332.0
2FHL J2158.8-3013 QSO B2155-3027 WISE J215852.06-301332.0

References (1733 between 1850 and 2024) (Total 1733)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 7    V* : 2    PLX : 1    PM : 3   

   

Observing logs


ISO : 42    IUE : 368    XMM : 13   

   

External archives :

Archive data at HEASARC - High-Energy Astrophysics Science Archive Research Center

Data at NED - NASA/IPAC Extragalactic Database : QSO B2155-304

Link by name to the catalogue in VizieR :

2E 4544 3EG J2158-3023 EUVE J2158-30.2 IERS B2155-304 2MASS J21585206-3013321
NVSS J215852-301330 PKS 2155-304 PKS J2158-3013 PKS 2155-30 PMN J2158-3013
2RE J2158-301 2RE J215852-301327 1RXS J215852.2-301338 SUMSS J215852-301326 WISEA J215852.06-301332.0
WISE J215852.05-301332.0 WISE J215852.06-301332.0 Gaia DR3 6616660280724162688 Gaia DR1 6616660280724162688 Gaia DR2 6616660280724162688

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