The double neutron star PSR J1946+2052 - I. Masses and tests of general relativity

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Volume 704 (December 2025)

A&A, 704 (2025) A153

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Table 1.

Fitted and derived parameters for PSR J1946+2052.

Data and data reduction parameters
Solar System ephemeris	DE440
Time Units	TDB
Clock	TT(BIPM2023)
Epoch (MJD)	57982.080242
Span of Timing Data (MJD)	57953–60460
Number of ToAs	9625
Binary model	DDFWHE	DDGR
RMS Residual (μs)	18.221	18.221
χ²	9589.61	9589.64
Reduced χ²	0.999	0.997

Measured parameters

Right ascension, α (J2000.0)	19:46:14.13475(4)
Declination, δ (J2000.0)	+20:52:24.829(1)
Proper Motion in R.A., μ_α (mas yr⁻¹)	−1.5(1)
Proper Motion in Dec., μ_δ (mas yr⁻¹)	−4.0(2)
Pulse frequency, ν (s⁻¹)	58.961654637293(4)
First derivative of pulse frequency, $\dot{ν}$ $\dot \nu$ (s⁻²)	−3.87147(3)×10⁻¹⁵
Dispersion measure, DM (pc cm⁻³)	93.9281(9)
Number of DM derivatives	10
Orbital period, P_b (days)	0.07848805554(2)	0.078488055530(8)
Projected semi-major axis, x (s)	1.154474(2)	1.1544738(3)
Orbital eccentricity, e	0.0638363(8)	0.0638365(4)
Epoch of periastron, T₀ (MJD)	57953.2123884(5)	57953.2123886(2)
Longitude of periastron, ω (deg)	130.357(2)	130.3584(8)
Rate of periastron advance, $\dot{ω}$ $\dot \omega$ (deg yr⁻¹)	25.79205(40)	[25.7918222]
Observed change in orbital period, Ṗ_b,obs (10⁻¹² s s⁻¹)	−1.8296(15)	[−1.8286549]
Ṗ_b,obs minus GR prediction (XPBDOT), ΔṖ_b (10⁻¹² s s⁻¹)	–	−0.0009(14)
Gravitational Redshift and Time Dilation, γ (ms)	0.2591(6)	[0.259029]
Total System Mass, M (M_⊙)	–	2.531837(24)
Companion Mass, m_c (M_⊙)	–	1.2476(20)
Orthometric ratio of Shapiro delay, ς	0.760(36)	–
Orthometric amplitude of Shapiro delay, h₃ (μs)	2.58(14)	–

Derived parameters

Galactic longitude, l (deg)	57.66
Galactic latitude, b (deg)	−1.98
DM-derived distance (NE2001), d_DM (kpc)	4.2
DM-derived distance (YMW16), d_DM (kpc)	3.5
Galactic height (NE2001), z_DM (kpc)	0.16
Galactic height (YMW16), z_DM (kpc)	0.12
Magnitude of proper motion, μ (mas yr⁻¹)	4.5(2)
Position angle of proper motion, Θ_μ (deg, J2000)	200(2)
Position angle of proper motion, Θ_μ (deg, Galactic)	260(2)
Heliocentric transverse velocity, v_hel (km s⁻¹)	70(3)a
Spin period, P (s)	0.016960175323294(1)
Spin period derivative, Ṗ	1.113620(9)×10⁻¹⁸
Inferred characteristic age, τ_c = P/2Ṗ (Myr)	241
Inferred surface magnetic field, $B_{S} = 3 \times 10^{19} \sqrt{P \dot{P}}$ $B_{\mathrm{S}} = 3 \times 10^{19}\sqrt{ P \dot P}$ (10⁹ G)	4.4
Inferred light cylinder magnetic field, $B_{LC} ≃ 9.2 P^{- 5 / 2} {\dot{P}}^{1 / 2}$ $B_{\mathrm{LC}}\simeq9.2 \, P^{-5/2}\dot{P}^{1/2}$ (G)	8.2 × 10³
Inferred spin-down luminosity, $\dot{E} ≃ 0.395 \dot{P} P^{- 3}$ $\dot{E}\simeq0.395\,\dot{P}P^{-3}$ (10³³ erg s⁻¹)	9^b
Mass function, f_mass (M_⊙)	0.268181(1)	0.2681809(2)
Total System Mass, M (M_⊙)	2.531858(60) ^c	–
Companion Mass, m_c (M_⊙)	1.2480(21) ^d	–
Pulsar mass, m_p (M_⊙)	1.2838(21)	1.2842(21)
Sine of orbital inclination, sin(i)	0.9599(16) ^e	–

Notes.

The numbers in parentheses represent 1-σ uncertainties from TEMPO, scaled for reduced χ² = 1. Numbers in square parentheses are derived from the DDGR model by assuming GR is correct.

Used the DM derived distance from the YMW16 model.

The expression used to calculate this assumes the moment of inertia is $I = 1 \times 10^{45} g {cm}^{2}$ $I = 1\times 10^{45}\, \rm g\, cm^2$ .

Derived from ${\dot{ω}}^{1 PN}$ $\dot{\omega}^{\mathrm{1PN}}$ .

Derived from ${\dot{ω}}^{1 PN}$ $\dot{\omega}^{\mathrm{1PN}}$ and γ.

Derived from ${\dot{ω}}^{1 PN}$ $\dot{\omega}^{\mathrm{1PN}}$ , γ and f_mass.

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