TY - JOUR
T1 - Improved Constraints on H $_0$ from a Combined Analysis of Gravitational-wave and Electromagnetic Emission from GW170817
AU - Guidorzi, C.
AU - Margutti, R.
AU - Brout, D.
AU - Scolnic, D.
AU - Fong, W.
AU - Alexander, K.~D.
AU - Cowperthwaite, P.~S.
AU - Annis, J.
AU - Berger, E.
AU - Blanchard, P.~K.
AU - Chornock, R.
AU - Coppejans, D.~L.
AU - Eftekhari, T.
AU - Frieman, J.~A.
AU - Huterer, D.
AU - Nicholl, M.
AU - Soares-Santos, M.
AU - Terreran, G.
AU - Villar, V.~A.
AU - Williams, P.~K.~G.
PY - 2017/12/1
Y1 - 2017/12/1
N2 - 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 Ek ∼ 1048 −3 × 1050 erg propagating into an environment with density n ∼ 10−2–10−4 cm−3, with preference for wider jets (opening angle θj = 15°). For these jets, our modeling indicates an off-axis angle θobs ∼ 25°–50°. We combine our constraints on θobs 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 ${H}_{0}=74.0\pm \tfrac{11.5}{7.5}$ km s−1 Mpc−1, which is higher than the value of ${H}_{0}=70.0\pm \tfrac{12.0}{8.0}$ 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 ${H}_{0}=75.5\pm \tfrac{11.6}{9.6}$ km s−1 Mpc−1 for H0 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.
AB - 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 Ek ∼ 1048 −3 × 1050 erg propagating into an environment with density n ∼ 10−2–10−4 cm−3, with preference for wider jets (opening angle θj = 15°). For these jets, our modeling indicates an off-axis angle θobs ∼ 25°–50°. We combine our constraints on θobs 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 ${H}_{0}=74.0\pm \tfrac{11.5}{7.5}$ km s−1 Mpc−1, which is higher than the value of ${H}_{0}=70.0\pm \tfrac{12.0}{8.0}$ 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 ${H}_{0}=75.5\pm \tfrac{11.6}{9.6}$ km s−1 Mpc−1 for H0 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.
KW - gamma-ray burst: general
KW - gravitational waves
KW - Astrophysics - Cosmology and Nongalactic Astrophysics
U2 - 10.3847/2041-8213/aaa009
DO - 10.3847/2041-8213/aaa009
M3 - Article
VL - 851
SP - L36
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
IS - 2
ER -