J/ApJ/916/100 Galactic pulsar with proper motions (Ronchi+, 2021)
Analyzing the Galactic pulsar distribution with machine learning.
Ronchi M., Graber V., Garcia-Garcia A., Rea N., Pons J.A.
<Astrophys. J., 916, 100 (2021)>
=2021ApJ...916..100R 2021ApJ...916..100R
ADC_Keywords: Pulsars; Proper motions; Stars, distances; Stars, neutron;
Parallaxes, trigonometric
Keywords: Neutron stars ; Pulsars ; Convolutional neural networks ;
Proper motions ; Neural networks
Abstract:
We explore the possibility of inferring the properties of the Galactic
population of neutron stars through machine learning. In particular,
in this paper we focus on their dynamical characteristics and show
that an artificial neural network is able to estimate with high
accuracy the parameters that control the current positions of a mock
population of pulsars. For this purpose, we implement a simplified
population-synthesis framework (where selection biases are neglected
at this stage) and concentrate on the natal kick-velocity distribution
and the distribution of birth distances from the Galactic plane. By
varying these and evolving the pulsar trajectories in time, we
generate a series of simulations that are used to train and validate a
suitably structured convolutional neural network. We demonstrate that
our network is able to recover the parameters governing the
distribution of kick velocity and Galactic height with a mean relative
error of about 10-2. We discuss the limitations of our idealized
approach and study a toy problem to introduce selection effects in a
phenomenological way by incorporating the observed proper motions of
216 isolated pulsars. Our analysis highlights that by increasing the
sample of pulsars with accurate proper-motion measurements by a factor
of ∼10, one of the future breakthroughs of the Square Kilometre Array,
we might succeed in constraining the birth spatial and kick-velocity
distribution of the neutron stars in the Milky Way with high precision
through machine learning.
Description:
With the aim of obtaining a rough idea of how selection effects and
biases could potentially influence a future comparison with
observation, we perform the following experiment.
We first collect those neutron stars that have measured proper
motions. As the main resource we use the pulsar catalog of the
Australia Telescope National Facility (ATNF)
(Manchester+ 2005, B/psr), but in some cases we provide proper-motion
results from more recent analyses (see Appendix C for details). We
find a total of 417 neutron stars whose angular positions, proper
motions in ICRS coordinates, spin periods, spin-period derivatives, DM
values, and distance estimates are reported in Table 5. See Section 5.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 239 417 Up-to-date list of 417 neutron stars with
measured proper motions in RA and DEC
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See also:
B/psr : ATNF Pulsar Catalogue (Manchester+, 2005)
J/MNRAS/328/17 : Parkes Multi-Beam Pulsar Survey (Manchester+, 2001)
J/MNRAS/353/1311 : Long-term timing obs. of 374 pulsars (Hobbs+, 2004)
J/MNRAS/360/974 : Proper motionsof pulsars (Hobbs+, 2005)
J/MNRAS/372/777 : Parkes Multibeam Pulsar Survey. VI. (Lorimer+, 2006)
J/ApJ/885/131 : ∼200 high-mass SFR plx & PM with VLBI (Reid+, 2019)
J/other/Sci/365.478 : Milky Way classical Cepheids sample (Skowron+, 2019)
http://www.atnf.csiro.au/research/pulsar/psrcat/ : Online ATNF catalog
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- JName Object name based on J2000 coordinates
14- 15 I2 h RAh Hour of Right Ascension (J2000)
17- 18 I2 min RAm Minute of Right Ascension (J2000)
20- 29 F10.7 s RAs Second of Right Ascension (J2000)
31- 39 F9.7 s e_RAs [1e-7/0.8] Uncertainty in RAs
41- 41 A1 --- DE- Sign of the Declination (J2000)
42- 43 I2 deg DEd Degree of Declination (J2000)
45- 46 I2 arcmin DEm Arcminute of Declination (J2000)
48- 56 F9.6 arcsec DEs Arcsecond of Declination (J2000)
58- 66 F9.6 arcsec e_DEs [7e-6/83] Uncertainty in DEs
68- 75 F8.3 mas/yr pmRA [-207/326.6] Proper motion, right ascension
77- 82 F6.3 mas/yr e_pmRA [0/72] Uncertainty in pmRA
84- 91 F8.3 mas/yr pmDE [-262/367] Proper motion, declination
93- 99 F7.3 mas/yr e_pmDE [0/220] Uncertainty in pmDE
101-106 F6.3 mas Plx [-1/6.42]? Parallax
108-113 F6.4 mas e_Plx [0.01/3]? Uncertainty in Plx
115-124 F10.4 d Epoch [40706/58137]? Position epoch (MJD)
126-143 F18.15 s P0 [0.0015/10.32]? Spin period
145-151 A7 s e_P0 Uncertainty in P0
153-166 A14 --- P1 Spin-period derivative, s/s
168-174 A7 --- e_P1 Uncertainty in P1, s/s
176-186 F11.6 pc/cm3 DM [2.38/1778.0]? Dispersion measure
188-196 F9.6 pc/cm3 e_DM [0.0/50.0]? Uncertainty in DM
198-203 F6.3 kpc Dist [0.09/58.73]? Heliocentric distance, from DM (1)
205-205 A1 --- f_Dist Flag on Dist (2)
207-222 A16 --- Class Class/Association (3)
224-239 A16 --- Ref Reference (4)
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Note (1): The heliocentric distance derived from the DM using the YMW16
(Yao+ 2017ApJ...835...29Y 2017ApJ...835...29Y) free-electron density model; for some
objects the DM exceeds the maximum Galactic DM allowed by the YMW16
model, which assigns a default value of 25kpc. When available, we
quote other distance estimates.
Note (2): Flag as follows:
d = a distance derived from other techniques especially for X-rays
and gamma-ray sources, which have no measured DM.
Note (3): The classification of the object, as follows:
PSR = radio pulsar (348+32 occurrences)
Binary∼PSR = binary pulsar (20+1 occurrences)
Gamma-/X-ray∼PSR = gamma-/X-ray pulsar (5 occurrences)
MAG = magnetar (7 occurrences)
XDINS = X-ray dim isolated neutron star (4 occurrences)
If the object is associated with a globular cluster (GC) or the Small
Magellanic Cloud (SMC) this is reported in brackets.
Note (4): References for proper motion measurements if different from the
one reported in the ATNF catalog as follows:
Danilenko+2020 = Danilenko et al. (2020MNRAS.493.1874D 2020MNRAS.493.1874D);
Eisenbeiss+ 2010 = Eisenbeiss et al. (2010AN....331..243E 2010AN....331..243E);
Jennings+ 2018 = Jennings et al. (2018ApJ...864...26J 2018ApJ...864...26J);
Motch+ 2009 = Motch et al. (2009A&A...497..423M 2009A&A...497..423M);
Perera+ 2019 = Perera et al. (2019MNRAS.490.4666P 2019MNRAS.490.4666P);
S.J.Dang+ 2020 = Dang et al. (2020ApJ...896..140D 2020ApJ...896..140D);
Stovall+ 2014 = Stovall et al. (2014ApJ...791...67S 2014ApJ...791...67S);
Walter+ 2010 = Walter et al. (2010ApJ...724..669W 2010ApJ...724..669W).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Dec-2022