J/ApJ/908/L46 Light curve & radial velocities for PSRJ1810+1744 (Romani+, 2021)
PSR J1810+1744: Companion Darkening and a Precise High Neutron Star Mass.
Romani R.W., Kandel D., Filippenko A.V., Brink T.G., Zheng W.
<Astrophys. J., 908, L46 (2021)>
=2021ApJ...908L..46R 2021ApJ...908L..46R
ADC_Keywords: Stars, double and multiple; Spectra, optical; Photometry, ugriz;
Radial velocities
Keywords: Binary stars
Abstract:
Keck-telescope spectrophotometry of the companion of PSR-J1810+1744
shows a flat, but asymmetric light-curve maximum and a deep, narrow
minimum. The maximum indicates strong gravity darkening (GD) near the
L1 point, along with a heated pole and surface winds. The minimum
indicates a low underlying temperature and substantial limb darkening.
The GD is a consequence of extreme pulsar heating and the near-filling
of the Roche lobe. Light-curve modeling gives a binary inclination
i=65.7±0.4. With the Keck-measured radial-velocity amplitude
Kc=462.3±2.2km/s, this gives an accurate neutron star mass
MNS=2.13±0.04M☉, with important implications for the
dense-matter equation of state. A classic direct-heating model,
ignoring the L1 gravitational darkening, would predict an unphysical
MNS>3M☉. A few other "spider" pulsar binaries have similar large
heating and fill factor; thus, they should be checked for such
effects.
Description:
We collected J1810 spectra with the Keck I 10m telescope and the Low
Resolution Imaging Spectrometer (LRIS) for 23x600s on UT August 26,
2017 (MJD 57991.285-57991.452), covering 1.1 binary orbits. We used
the 5600Å dichroic, the 600l/4000Å blue grism, and the
400l/8500Å red grating, covering ∼3300-10500Å with dispersions
of 0.63Å/pixel (blue side) and 1.2Å/pixel (red side).
Thus, we also used LRIS for direct dual-band photometry, collecting a
sequence of g/I images on UT 2020 August 21 (MJD 59083.38-59083.46) as
well as g/R, U/R, and g/I images on UT 2020 September 17 (MJD
59100.21-59100.38).
Objects:
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RA (2000) DE Designation(s)
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18 10 37.27 +17 44 37.4 PSR J1810+1744 = 1FGL J1810.3+1741
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 47 185 Calibrated ugriz light curves
fig2.dat 23 23 Radial-velocity measurements for J1810
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See also:
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/ApJS/208/17 : 2nd Fermi LAT cat. of gamma-ray pulsars (2PC) (Abdo+, 2013)
J/ApJ/769/108 : Optical photometry of 4 millisecond pulsars (Breton+, 2013)
J/A+A/564/A125 : AGN Torus model comparison of AGN in the CDFS (Buchner+, 2014)
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Inst Instrument identifier (1)
8- 11 A4 --- Band Photometric band; ugriz (2)
13- 14 I2 "month" Obs.M ? Observation date (3)
16- 17 I2 d Obs.D ? Observation date (3)
19- 20 I2 yr Obs.Y [10/20] Observation date (3)
22- 27 F6.4 --- Phase [0.0002/1] Binary phase
29- 34 F6.4 --- HWidth [0/0.03] Half-Width of Phase range
36- 41 F6.3 mag mag [19.8/25.2] Apparent magnitude in Band
43- 47 F5.3 mag e_mag [0.009/0.2] Uncertainty in mag
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Note (1): Instruments as follows:
LRIS = Keck LRIS spectroscopy (2017) or photometry (2020).
GMOS-N = Gemini GMOS-N photometry (2010).
Note (2): The sb prefix on the photometic bands indicates an extracted value
from the LRIS spectrum using the sbands script in IRAF and calibrated
with the catalog magnitudes. See text for full details.
Note (3): The year for GMOS-N or MM/DD/YYYY for the LRIS data.
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Byte-by-byte Description of file: fig2.dat
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ytes Format Units Label Explanations
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1- 6 F6.4 --- Phase [0.02/0.98] Binary phase
8- 13 F6.1 km/s RVel [-882/460] Radial velocity (1)
15- 18 F4.1 km/s e_RVel [5/66.4] Uncertainty in RVel
20- 23 F4.1 --- R [1.6/34.9] Correlation Significance (1)
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Note (1): RVel measured against an A2 template; not used in fit if R<10.
RVel with larger R plotted only in the second cycle.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 27-Feb-2024