J/A+A/693/A158 4FGL J1544.2-2554 light curves (Karpova+, 2025)
4FGL J1544.2-2554: A new spider pulsar candidate.
Karpova A.V., Zharikov S.V., Zyuzin D.A., Kirichenko A.Yu., Shibanov Yu.A.,
Marquez I.F.
<Astron. Astrophys. 693, A158 (2025)>
=2025A&A...693A.158K 2025A&A...693A.158K (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays ; Stars, neutron ; Stars, double and multiple ;
Photometry, UBVRI
Keywords: binaries: close - stars: neutron - pulsars: general
Abstract:
Spider pulsars are millisecond pulsars in tight binary systems in
which a low-mass companion star is heated and ablated by the pulsar
wind. Observations of these objects allow one to study stellar
evolution with the formation of millisecond pulsars and the physics of
superdense matter in neutron stars. However, spiders are rare due to
difficulties related to their discovery when using typical radio
search techniques. The Fermi gamma-ray source 4FGL J1544.2-2554 was
recently proposed as a pulsar candidate, and its likely X-ray and
optical counterparts, with the galactic coordinates l≃344.76deg,
b≃22.59deg and the magnitude G≃20.6, were found using the eROSITA
and Gaia surveys.
Our goals are to study whether the source is a new spider pulsar and
to estimate its fundamental parameters.
We performed the first optical time series multi-band photometry of
the object. We used the Lomb-Scargle periodogram to search for its
brightness periodicity and fitted its light curves with a model of
direct heating of the binary companion by the pulsar wind.
The source shows a strong brightness variability with a period of
≃2.724h and an amplitude of >2.5mag, and its light curves have a
single broad peak per period. These features are typical for spider
pulsars. The curves are well fitted by the direct heating model,
resulting in an orbit inclination of the presumed spider system of
≃83deg, a companion mass of ≃0.1M☉, 'day-side' and
'night-side' temperatures of ≃7200K and ≃3000K, a Roche lobe filling
factor of ≃0.65, and a distance of ≃2.1kpc.
Our findings suggest that 4FGL J1544.2-2554 is a spider pulsar. This
result encourages the search for pulsar millisecond pulsations in
radio and gamma-rays to confirm its nature.
Description:
Time series photometry of the likely optical counterpart to the Fermi
source 4FGL J1544.2-2554 obtained in the Johnson-Cousins B, V, and R
bands with the 2.1-m OAN-SPM telescope on June 8-13, 2024.
Objects:
------------------------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------------------------
15 44 12.75 -25 50 01.4 4FGL J1544.2-2554 = FL8Y J1544.2-2554
------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
phot.dat 31 57 Photometric measurements in the B, V, and Rc bands
--------------------------------------------------------------------------------
Byte-by-byte Description of file: phot.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.8 d BJD Barycentric Julian Date of observation
18- 23 F6.3 mag mag Magnitude in Band
25- 29 F5.3 mag e_mag 1-sigma magnitude uncertainty
31 A1 --- Band [BVR] Broadband filter
--------------------------------------------------------------------------------
Acknowledgements:
Anna Karpova, annakarpova1989(at)gmail.com
(End) Patricia Vannier [CDS] 06-Dec-2024