The luminosity distance measurement of GW170817 derived from gravitational-wave analysis in Abbott et al. (2017a, hereafter A17:H0) is highly correlated with the measured inclination of the NS-NS system. To improve the precision of the distance measurement, we attempt to constrain the inclination by modeling the broadband X-ray-to-radio emission from GW170817, which is dominated by the interaction of the jet with the environment. We update our previous analysis and we consider the radio and X-ray data obtained at t < 40 days since merger. We find that the afterglow emission from GW170817 is consistent with an off-axis relativistic jet with energy E k ∼ 1048 -3 1050 erg propagating into an environment with density n ∼ 10-2-10-4 cm-3, with preference for wider jets (opening angle θ j = 15°). For these jets, our modeling indicates an off-axis angle θ obs ∼ 25°-50°. We combine our constraints on θ obs with the joint distance-inclination constraint from LIGO. Using the same ∼170 km s-1 peculiar velocity uncertainty assumed in A17:H0 but with an inclination constraint from the afterglow data, we get a value of km s-1 Mpc-1, which is higher than the value of km s-1 Mpc-1 found in A17:H0. Further, using a more realistic peculiar velocity uncertainty of 250 km s-1 derived from previous work, we find km s-1 Mpc-1 for H 0 from this system. This is in modestly better agreement with the local distance ladder than the Planck cosmic microwave background, though such a significant discrimination will require ∼50 such events. Measurements at t > 100 days of the X-ray and radio emission will lead to tighter constraints.

Improved constraints on H0 from a combined analysis of gravitational-wave and electromagnetic emission from GW170817

GUIDORZI, Cristiano
;
2017

Abstract

The luminosity distance measurement of GW170817 derived from gravitational-wave analysis in Abbott et al. (2017a, hereafter A17:H0) is highly correlated with the measured inclination of the NS-NS system. To improve the precision of the distance measurement, we attempt to constrain the inclination by modeling the broadband X-ray-to-radio emission from GW170817, which is dominated by the interaction of the jet with the environment. We update our previous analysis and we consider the radio and X-ray data obtained at t < 40 days since merger. We find that the afterglow emission from GW170817 is consistent with an off-axis relativistic jet with energy E k ∼ 1048 -3 1050 erg propagating into an environment with density n ∼ 10-2-10-4 cm-3, with preference for wider jets (opening angle θ j = 15°). For these jets, our modeling indicates an off-axis angle θ obs ∼ 25°-50°. We combine our constraints on θ obs with the joint distance-inclination constraint from LIGO. Using the same ∼170 km s-1 peculiar velocity uncertainty assumed in A17:H0 but with an inclination constraint from the afterglow data, we get a value of km s-1 Mpc-1, which is higher than the value of km s-1 Mpc-1 found in A17:H0. Further, using a more realistic peculiar velocity uncertainty of 250 km s-1 derived from previous work, we find km s-1 Mpc-1 for H 0 from this system. This is in modestly better agreement with the local distance ladder than the Planck cosmic microwave background, though such a significant discrimination will require ∼50 such events. Measurements at t > 100 days of the X-ray and radio emission will lead to tighter constraints.
2017
Guidorzi, Cristiano; Margutti, R.; Brout, D.; Scolnic, D.; Fong, W.; Alexander, K. D.; Cowperthwaite, P. S.; Annis, J.; Berger, E.; Blanchard, P. K.; ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2379972
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