J/MNRAS/453/2599 Fermi-LAT pulsar spectral data (Vigano+, 2015)
A systematic synchro-curvature modelling of pulsar γ-ray spectra unveils
hidden trends.
Vigano D., Torres D.F., Martin J.
<Mon. Not. R. Astron. Soc., 453, 2599-2621 (2015)>
=2015MNRAS.453.2599V 2015MNRAS.453.2599V (SIMBAD/NED BibCode)
ADC_Keywords: Pulsars ; Gamma rays ; Models
Keywords: radiation mechanisms: non-thermal - stars: neutron - gamma-rays: stars
Abstract:
γ-ray radiation from pulsars is usually thought to be mostly
produced by the synchro-curvature (SC) losses of accelerated particles.
Here, we present a systematic study of all currently reported, good-quality
Fermi-LAT pulsar spectral data. We do so by applying a model which follows
the particle dynamics and consistently computes the emission of SC
radiation. By fitting observational data on a case by case basis, we are
able to obtain constraints about the parallel electric field, the typical
length-scale over which particles emit the bulk of the detected radiation,
and the number of involved particles. The model copes well with data of
several dozens of millisecond (MSPs) and young pulsars (YPs). By
correlating the inferred model parameters with the observed timing
properties, some trends are discovered. First, a non-negligible part of
the radiation comes from the loss of perpendicular momentum soon after pair
creation. Second, the electric field strongly correlates with both the
inverse of the emission length-scale and the magnetic field at light
cylinder, thus ruling out models with high-energy photon production close
to the surface. These correlations unify young and millisecond pulsars
under the same physical scenario, and predict that magnetars are
intrinsically γ-ray quiet via synchro-curvature processes, since
magnetospheric particles are not accelerated enough to emit a detectable
γ-ray flux.
Description:
We consider the publicly available, Fermi-LAT processed data for the
phase-averaged pulsar spectra contained in the second Fermi-LAT pulsar
catalogue (2PC hereafter; Abdo et al. 2013, J/ApJS/208/17). As a
good-quality criterion, and not to consider less constraining data, we
select those sources having measured flux (not upper limits) in at least
five consecutive energy bins. Such selection criterion somewhat favours
the YPs, since they are brighter in γ-rays. Among the 81 sources
of our sample (out of the 117 of the 2PC), 59 are YPs (Table 2) and 22
are MSPs (Table 3).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 129 59 Timing parameters, timing-inferred properties,
0.1-100 GeV luminosity, and best-fitting
parameters to the phase-averaged spectra for
the 59 YPs of our sample
table3.dat 129 22 Timing parameters, timing-inferred properties,
0.1-100 GeV luminosity, and best-fitting
parameters to the phase-averaged spectra for
the 22 MSPs of our sample
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See also:
J/A+A/492/923 : Pulsar Timing for Fermi Gamma-ray Space Telescope
(Smith+, 2008)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/MNRAS/424/2832 : Pulsars in γ-ray sources (Lee+, 2012)
J/ApJ/769/108 : Optical photometry of 4 millisecond pulsars (Breton+, 2013)
J/ApJS/208/17 : 2nd Fermi LAT cat. of gamma-ray pulsars (2PC) (Abdo+, 2013)
J/ApJ/814/128 : Timing noise + astrometry of Fermi-LAT pulsars (Kerr+, 2015)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- PSR Pulsar identifier (JHHMM+DDMM)
12- 16 F5.1 ms P [1.7/444.1] Spin period
18- 23 F6.2 [-] log(dP/dt) [-20.7/-11.39] Log spin period derivative
25- 29 F5.2 [10-7W] log(dE/dt) [33.49/38.64] Log spin-down energy loss
(in erg/s)
31- 35 F5.2 [yr] logtau [3.1/10.18] Log spin-down age logτ
37- 41 F5.2 [gauss] logBs [7.95/13.61] Log inferred value of the
magnetic field at the polar surface
43- 46 F4.2 [gauss] logBlc [2.41/5.96] Log magnetic field at light
cylinder
48 A1 --- l_logL [<] Limit flag on logL (only in Table 2)
49- 53 F5.2 [10-7W] logL [31.69/37.45] Log 0.1-100 GeV luminosity
(in erg/s)
55 A1 --- l_logEl [>] Limit flag on logEl
56- 59 F4.2 [V/m] logEl [6.42/9.84] Log parallel electric field
in the gap
61- 64 F4.2 [V/m] E_logEl [0.01/0.42]? Upper limit uncertainty
in logEl
66- 69 F4.2 [V/m] e_logEl [0.01/0.6]? Lower limit uncertainty
in logEl
71 A1 --- l_logx0 [<] Limit flag on logx0
72- 75 F4.2 [cm] logx0 [4.47/8.06] Log weighting parameter
77- 80 F4.2 [cm] E_logx0 [0.01/2.6]? Upper limit uncertainty
in logx0
82- 85 F4.2 [cm] e_logx0 [0.01/0.73]? Lower limit uncertainty
in logx0
87 A1 --- l_log(x0/Rlc) [<] Limit flag on log(x0/Rlc)
88- 92 F5.2 [-] log(x0/Rlc) [-3.6/-0.8] Log length-scale of the bulk
γ-ray emission
94- 97 F4.2 [-] E_log(x0/Rlc) [0.01/2.6]? Upper limit uncertainty
in log(x0/Rlc)
99-102 F4.2 [-] e_log(x0/Rlc) [0.01/0.73]? Lower limit uncertainty
in log(x0/Rlc)
104-108 F5.2 [-] logN0 [27.51/34.08] Log effective number of
particles
110-113 F4.2 [-] E_logN0 [0.01/0.92]? Upper limit uncertainty
in logN0
115-118 F4.2 [-] e_logN0 [0.01/0.7]? Lower limit uncertainty
in logN0
120-126 F7.2 --- chi2min [0.8/1418] Value of χ2 for
the best-fitting model
128-129 I2 --- Nbins [5/11] Number of considered data points
(the number of degrees of freedom (dof)
is Nbin-3)
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 09-Dec-2019