Systematic uncertainty of standard sirens from the viewing angle of binary neutron star inspirals. (arXiv:2006.02779v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chen_H/0/1/0/all/0/1">Hsin-Yu Chen</a>
The independent measurement of Hubble constant with gravitational-wave
standard sirens will potentially shed light on the tension between the local
distance ladders and Planck’s experiments. Therefore, thorough understanding of
the sources of systematic uncertainty for the standard siren method is crucial.
In this paper, we focus on two scenarios that will potentially dominate the
systematic uncertainty of standard sirens. First, simulations of
electromagnetic counterparts of binary neutron star mergers suggest aspherical
emissions, so the binaries available for the standard siren method can be
selected by their viewing angles. This selection effect can lead to $gtrsim
2%$ bias in Hubble constant measurement even with mild selection, making the
standard siren method difficult to resolve the tension in Hubble constant.
Second, if the binary viewing angles are constrained by the electromagnetic
counterpart observations but the bias of the constraints is not controlled
under $sim 10^{circ}$, the resulting systematic uncertainty in Hubble
constant will be $>3%$. In addition, we find that both of the systematics
cannot be fully disclosed by the viewing angle measurement from
gravitational-wave observations. Comparing to the known dominant systematic
uncertainty for standard sirens, the gravitational-wave calibration
uncertainty, the effects from viewing angle can be more prominent.
The independent measurement of Hubble constant with gravitational-wave
standard sirens will potentially shed light on the tension between the local
distance ladders and Planck’s experiments. Therefore, thorough understanding of
the sources of systematic uncertainty for the standard siren method is crucial.
In this paper, we focus on two scenarios that will potentially dominate the
systematic uncertainty of standard sirens. First, simulations of
electromagnetic counterparts of binary neutron star mergers suggest aspherical
emissions, so the binaries available for the standard siren method can be
selected by their viewing angles. This selection effect can lead to $gtrsim
2%$ bias in Hubble constant measurement even with mild selection, making the
standard siren method difficult to resolve the tension in Hubble constant.
Second, if the binary viewing angles are constrained by the electromagnetic
counterpart observations but the bias of the constraints is not controlled
under $sim 10^{circ}$, the resulting systematic uncertainty in Hubble
constant will be $>3%$. In addition, we find that both of the systematics
cannot be fully disclosed by the viewing angle measurement from
gravitational-wave observations. Comparing to the known dominant systematic
uncertainty for standard sirens, the gravitational-wave calibration
uncertainty, the effects from viewing angle can be more prominent.
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