A Measurement of the Galactic Plane Mass Density from Binary Pulsar Accelerations
A Measurement of the Galactic Plane Mass Density from Binary Pulsar Accelerations
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DOI：
10.3847/2041-8213/abd635
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发表时间：
2021-01
期刊：
影响因子：
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通讯作者：
S. Chakrabarti;P. Chang;M. Lam;S. Vigeland;A. Quillen
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作者：
S. Chakrabarti;P. Chang;M. Lam;S. Vigeland;A. Quillen
我们使用编译的高精度脉冲星定时测量，直接测量银河系相对于太阳系质心的加速度。给定垂直加速度，我们使用泊松方程推导奥尔特极限，即，银河系中平面的总体积质量密度。我们的最佳拟合模型给出的奥尔特极限为0.08 - 0.020.05M/cm 3，这接近于最近Jeans分析的估计。考虑到麦基等人对重子预算的计算，我们得到的局部暗物质密度为−0.004−0.020.05M <$pc−3，略低于其他现代估计值，但与我们方法当前的不确定性一致。目前的误差线大约是运动学估计值的五倍，但对于这种新的动力学方法来说，未来应该会有所改善。我们还限制了潜在的扁率，发现它与预期的磁盘和不一致的潜在的主导球形晕，是适当的，我们的样本是在太阳的10 kpc。我们发现，目前测量的脉冲双星加速度导致旋转曲线的斜率有很大的不确定性。我们给出垂直加速度a z的拟合函数：a z = − α 1 z; log 10（α1/Gyr−2）=3.69−0.120.19。通过分析银河系的相互作用模拟，我们发现，大的不对称变化的da z /dz作为垂直高度的函数可能是一个签名的子结构。最后，我们讨论了结合脉冲星定时和高精度径向速度测量对视线附近的脉冲星的约束，以测试引力理论和约束暗物质子结构的力量。
We use compiled high-precision pulsar timing measurements to directly measure the Galactic acceleration of binary pulsars relative to the solar system barycenter. Given the vertical accelerations, we use the Poisson equation to derive the Oort limit, i.e., the total volume mass density in the Galactic mid-plane. Our best-fitting model gives an Oort limit of 0.08−0.020.05M⊙pc−3 , which is close to estimates from recent Jeans analyses. Given the accounting of the baryon budget from McKee et al., we obtain a local dark matter density of −0.004−0.020.05M⊙pc−3 , which is slightly below other modern estimates but consistent within the current uncertainties of our method. The error bars are currently about five times larger than kinematical estimates, but should improve in the future for this novel dynamical method. We also constrain the oblateness of the potential, finding it consistent with that expected from the disk and inconsistent with a potential dominated by a spherical halo, as is appropriate for our sample that is within a ∼kpc of the Sun. We find that current measurements of binary pulsar accelerations lead to large uncertainties in the slope of the rotation curve. We give a fitting function for the vertical acceleration a z : a z = − α 1 z; log10(α1/Gyr−2)=3.69−0.120.19 . By analyzing interacting simulations of the Milky Way, we find that large asymmetric variations in da z /dz as a function of vertical height may be a signature of sub-structure. We end by discussing the power of combining constraints from pulsar timing and high-precision radial velocity measurements toward lines-of-sight near pulsars, to test theories of gravity and constrain dark matter sub-structure.