J/MNRAS/520/1311 Parkes pulsar flux variabilities and modulations (Wang+, 2023)
Study of pulsar flux density and its variability with Parkes data archive.
Wang Z., Wang J., Wang N., Dai S., Xie J.
<Mon. Not. R. Astron. Soc. 520, 1311-1323 (2023)>
=2023MNRAS.520.1311W 2023MNRAS.520.1311W (SIMBAD/NED BibCode)
ADC_Keywords: Pulsars ; Photometry ; Radio sources ; Velocity dispersion ;
Stars, distances ; Stars, variable
Keywords: methods: observational - stars: neutron - pulsars: general -
ISM: general
Abstract:
We present average flux density measurements of 151 radio pulsars at
1.4 GHz with the Parkes 'Murriyang' radio telescope. We recommend our
results be included in the next version of the Australia Telescope
National Facility Pulsar Catalogue. The large sample of pulsars
together with their wide dispersion measure (DM) range makes this data
set useful for studying variability of flux density, pulsar spectra,
and interstellar medium (ISM). We derive the modulation indices and
structure-function from the flux density time series for 95 and 54
pulsars, respectively. We suggest the modulation index also be
included in the next version of the pulsar catalogue to manifest the
variability of pulsar flux density. The modulation index of flow
density and DM are negatively correlated. The refractive scintillation
(RISS) time-scales or its lower bound for a set of 15 pulsars are
derived. They are very different from theoretical expectations,
implying the complicated properties of the ISM along different lines
of sight. The structure-function for other pulsars is flat. The RISS
parameters for some of these pulsars possibly could be derived with
different observing strategies in the future.
Description:
This work presents flux density measurements of 151 pulsars around
1.4 GHz with the Parkes Murriyang radio telescope. We take our data in
CSIRO pulsar data archive which includes most of the pulsar
observations made with the Parkes. The central frequency of all the
selected observations is close to 1400 MHz. We include data taken with
the H-OH receiver and the multibeam receiver. The majority of data
were recorded with the Parkes Digital Filter Bank system with 256 MHz
bandwidth centred at 1369 MHz and 1024 frequency channels for the
multibeam receiver and the H-OH receiver. These pulsars have not been
well studied for long-term flux density variability. We obtained flux
density and uncertainty for these pulsars. Our sample includes young
pulsars, millisecond pulsars, binary pulsars, and pulsars in globular
clusters. Data processing procedure follows Xie et al.
(2019RAA....19..103X 2019RAA....19..103X), using the psrchive software package which
includes pazi, paas, psrflux, and other tools.
The data set of 151 pulsars represents a large sample to study pulsar
flux density variabilities. It includes pulsars with a wide range of
periods, DM, and distance. The data span for a certain pulsar can be
as short as a few days or as long as 14 yr. About half of these
pulsars were observed for more than two yr. About one-third of pulsars
were observed more than 30 times. 23 pulsars were observed more than
50 times. We present in tablea1.dat, the pulsar name, rotation period
(P), DM, distance (Dist), the span of the observations (T), and the
number of observations (Nobs). More, we provide modulation indeces and
structure function classes for 95 and 54 pulsars as fully described in
section 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 93 151 Pulsation, variability, modulation and structure
properties of our observed pulsar sample
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See also:
J/MNRAS/474/4629 : Polarimetry of 600 pulsars from 1.4GHz obs. (Johnston+,2018)
J/MNRAS/473/4436 : Spectral properties of 441 radio pulsars (Jankowski+, 2018)
J/MNRAS/450/2922 : HTRU survey new pulsars (Ng+, 2015)
J/MNRAS/372/777 : Parkes Multibeam Pulsar Survey. VI. (Lorimer+, 2006)
J/A+A/569/A125 : Spiral structure of the Milky Way (Hou+, 2014)
J/ApJ/874/64 : 5GHz TMRT observations of 71 pulsars (Zhao+, 2019)
J/ApJ/810/85 : Observation of first Fermi-LAT sources at Parkes
(Camilo+, 2015)
J/ApJ/804/23 : 327MHz observations of 124 pulsars (Krishnakumar+, 2015)
B/psr : ATNF Pulsar Catalogue (Manchester+, 2005)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- PSR Pulsar name designation as JHHMM+DDMM (Name)
13- 17 F5.3 s P0 Fundamental period of rotation (P0)
19- 23 F5.1 pc/cm3 DM Pulsar dispersion measure (DM)
25- 28 F4.1 kpc Dist Pulsar distance (Dist)
30- 33 I4 d T The time span of the observations data set (T)
35- 37 I3 --- o_S The total number of flux density measurements
39- 43 F5.2 mJy S The weighted mean flux density based on each
observation's flux densities and uncertainties
as fully explicited in section 3.1 (Sbar)
45- 50 F6.3 mJy e_S Uncertainty of S calculated with equation 3 as
fully explicited in section 3.1 (sigma)
52- 55 F4.2 --- m ? The modulation index to characterize the
variability as σS/S as fully explained
in section 3.2 (m)
57- 60 F4.2 --- mn ? The radiometer noise estimated as ebart/S
as fully explained in section 3.2 (mn)
62- 65 F4.2 --- mj ? Jitter noise from pulse-to-pulse variations
contribute to modulation index as
sqrt[1/Npulse] = sqrt[P/tobs] as
in section 3.2 (mj)
67- 70 F4.2 --- mcorr ? The modulation index after correcting for
jitter and measurement noise
as sqrt[m2 - mn2 - mj2] as fully
explained in section 3.2 (mcorr)
72- 76 F5.2 --- md ? The diffraction scintillation modulation
index estimated with its expression in section
3.1 (md)
78- 81 F4.2 --- mr ? The expected RISS modulation index as
expressed in section 3.1 (mr)
83- 88 F6.1 d Tr The estimated refractive scintillation RISS
time scale (Tr)
90- 93 A4 --- Class Defined with structure functions in the study
of pulsar scintillation as explained in section
3.3 (Class) (1)
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Note (1): For 48 pulsars classes are categorized as follows:
F-R = RISS but our shortest lag is longer than the refraction time,
20 occurences in our sample
S = Structure functions showing all three regimes or a rising
slope with saturation, 10 occurences in our sample
I = Structure functions that show the continuous increase,
5 occurences in our sample
X = Class with significantly abnormal modulation index for
pulsars, 4 occurences in our sample
F-N = The weak pulsars and/or measurement noise, 3 occurences in
our sample
F-DR = The combination of diffractive and refractive scintillation,
3 occurences in our sample
F-D = The diffractive scintillation, 2 occurences in our sample
F-J = The jitter noise, 1 occurence in our sample
As explained in section 3.3, we calculated the structure functions
for pulsars observed more than 30 times and classified them according
to the scheme of Kumamoto et al. (2021MNRAS.501.4490K 2021MNRAS.501.4490K). Structure
functions showing all three regimes or a rising slope with saturation
are classified as 'S'. Structure functions that show the continuous
increase are classified as 'I' and imply that the maximum lag is
shorter than the refractive time-scale. Pulsars with a flat structure
function are classified as 'F', and these pulsars account for the
majority. These flat structure functions could result from different
reasons, including the intrinsic intensity variability, the
radiometer noise, and the diffractive and refractive effects.
We categorized them by the factors that dominate the modulation
index as explained above for classes "F-R", "F-N", "F-DR", "F-D",
"F-J".
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History:
From electronic version of the journal
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Luc Trabelsi [CDS] 09-Mar-2026