J/other/NatAs/7.967 Variability of extragalactic X-ray jets (Meyer+, 2023)
Variability of extragalactic X-ray jets on kiloparsec scales.
Meyer E.T., Shaik A., Tang Y., Reid N., Reddy K., Breiding P.,
Georganopoulos M., Chiaberge M., Perlman E., Clautice D., Sparks W.,
Denigris N., Trevor M.
<Nature Astronomy, 7, 967-967 (2023)>
=2023NatAs...7..967M 2023NatAs...7..967M (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; X-ray sources ; Redshifts
Abstract:
Unexpectedly strong X-ray emission from extragalactic radio jets on
kiloparsec scales has been one of the major discoveries of Chandra,
the only X-ray observatory capable of sub-arcsecond-scale imaging. The
origin of this X-ray emission, which appears as a second spectral
component from that of the radio emission, has been debated for over
two decades. The most commonly assumed mechanism is inverse-Compton
upscattering of the cosmic microwave background by very low-energy
electrons in a still highly relativistic jet. Under this mechanism, no
variability in the X-ray emission is expected. Here we report the
detection of X-ray variability in the large-scale jet population,
using a novel statistical analysis of 53 jets with multiple Chandra
observations. Taken as a population, we find that the distribution of
P values from a Poisson model is strongly inconsistent with steady
emission, with a global P value of 1.96x10-4 under a
Kolmogorov-Smirnov test against the expected uniform (0, 1)
distribution. These results strongly imply that the dominant mechanism
of X-ray production in kiloparsec-scale jets is synchrotron emission
by a second population of electrons reaching multi-teraelectronvolt
energies. X-ray variability on the timescale of months to a few years
implies extremely small emitting volumes much smaller than the
cross-section of the jet.
Description:
Complete table of the radio observations.
Four supplemental tables giving the full sample description and all
measurements required for repeating the analysis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables1.dat 65 54 Radio observations
tables2.dat 109 55 Characteristics of our sample of 55 jets
tables3.dat 44 183 Characteristics of each Chandra observation
tables4.dat 128 200 Characteristics of all 155 analysis regions, as
well as the 'total jet' regions for jets with
more than one knot
tables5.dat 76 556 Details specific to a particular knot and
epoch of observation
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
http://www.vla.nrao.edu/astro/nvas : NRAO VLA Archive Survey Images Page
Byte-by-byte Description of file: tables1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- JName Source
12- 21 A10 "date" Date Obsservation date
23- 29 A7 --- Tel Telescope
31- 45 A15 --- Projet Project Code
46- 51 F6.2 GHz Freq Observed frequency
53 A1 --- Image [abcd] Image (1)
55- 59 F5.2 arcsec Major Beam major axis
61- 65 F5.2 arcsec Minor Beam minor axis
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Note (1): Image ocde as follows:
a = data reduced for this paper
b = taken from XJET database
c = taken from NVAS cutout archive
d = taken from NED
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Byte-by-byte Description of file: tables2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- JName IAU Name (J2000), JHHMM+DDMM
12- 22 A11 --- Name Common name
24- 30 A7 --- Class Jet classification
32- 33 I2 h RAh Right ascension (J2000)
35- 36 I2 min RAm Right ascension (J2000)
38- 39 I2 s RAs Right ascension (J2000)
41 A1 --- DE- Declination sign (J2000)
42- 43 I2 deg DEd Declination (J2000)
45- 46 I2 arcmin DEm Declination (J2000)
48- 52 F5.2 arcsec DEs Declination (J2000)
55- 61 F7.5 --- z Redshift
63- 67 F5.2 deg JetAngle Estimated jet angle
69 I1 --- NReg Number of distinct jet features analysed
71- 72 I2 --- NObs Number of distinct Chandra observations
(epochs)
74- 83 A10 --- Baseline Maximum and minimum time separation
between observations
85- 89 F5.3 kpc/arcsec Scale Cosmology-corrected angular size scale
91- 97 F7.5 10+22cm-2 NH Galactic Hydrogen column density value used
98-102 F5.1 arcsec JetLength Total observed jet length in arcseconds
104-109 F6.2 kpc JetLength2 Total observed jet length in kiloparsecs
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Byte-by-byte Description of file: tables3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- JName IAU name of the target source
12- 16 I5 --- EpochID Chandra observation ID number
18- 26 F9.4 yr Date Decimal Date of the observation
28- 30 A3 --- RStreak Flag column for readout streak correction
32- 37 F6.2 ks ExpTot Initial total exposure time
39- 44 F6.2 ks ExpFilt Total observing time after removing
background flares
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Byte-by-byte Description of file: tables4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- JName IAU name of the source
12- 23 A12 --- KnotID region name
25- 27 A3 --- BGType type of background region used,
annulus (ANN) or generic (GEN)
29- 33 I5 ct CTtot Total counts in the region over all
observations
35- 42 A8 --- BGModel Background model or treatment used for the
spectral fit
44- 50 F7.2 pix KnotArea Knot area in ACIS pixels
52- 59 F8.3 arcsec+2 KnotArea2 Knot area in arcseconds squared
61- 69 E9.4 nJy F1keV ?=- Flux normalisation of the region
SHERPA fit
71- 79 E9.4 nJy e_F1keV ? Flux normalisation of the region
SHERPA fit error
81- 85 F5.3 --- Gamma ?=- Spectral index from the region
SHERPA fit
87- 91 F5.3 --- e_Gamma ? Spectral index from the region
SHERPA fit error
93-100 E8.3 --- pvalue ?=- Single-region p-value from the
Poisson model
102-109 E8.3 ct/s/cm2 MLErate ?=- Estimated mean source rate
111-119 E9.3 --- STmin ?=- Upper sensitivity threshold
121-128 E8.3 --- STmax ?=- Lower sensitivity threshold
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Byte-by-byte Description of file: tables5.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- JName IAU name of the source
12- 22 A11 --- Knot Region name
24- 28 A5 --- EpochID Chandra observation ID number
30- 38 E9.4 ks ExpSource Source region exposure
40- 48 E9.4 ks ExpBkg Exposure background exposure
50- 53 I4 ct Source Counts source region counts
55- 60 I6 ct Background Counts background region counts
62- 67 F6.4 --- ECF Encircled counts fraction
69- 76 E8.3 ct/s/cm2 Flux Estimated source flux
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 03-May-2024