GW170817: observation of gravitational waves from a binary neutron star inspiral
TL;DR: The association of GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts.
Abstract: On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4} years. We infer the component masses of the binary to be between 0.86 and 2.26 M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60 M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28 deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8} Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.
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TL;DR: The kilonova emission observed following the binary neutron star merger event GW170817 provided the first direct evidence for the synthesis of heavy nuclei through the rapid neutron capture process as discussed by the authors.
Abstract: The kilonova emission observed following the binary neutron star merger event GW170817 provided the first direct evidence for the synthesis of heavy nuclei through the rapid neutron capture process ($r$ process) The late-time transition in the spectral energy distribution to near-infrared wavelengths was interpreted as indicating the production of lanthanide nuclei, with atomic mass number $A\ensuremath{\gtrsim}140$ However, compelling evidence for the presence of even heavier third-peak ($A\ensuremath{\approx}195$) $r$-process elements (eg, gold, platinum) or translead nuclei remains elusive At early times ($\ensuremath{\sim}\mathrm{days}$) most of the $r$-process heating arises from a large statistical ensemble of $\ensuremath{\beta}$ decays, which thermalize efficiently while the ejecta is still dense, generating a heating rate that is reasonably approximated by a single power law However, at later times of weeks to months, the decay energy input can also possibly be dominated by a discrete number of $\ensuremath{\alpha}$ decays, $^{223}\mathrm{Ra}$ (half-life ${t}_{1/2}=1143\text{ }\text{ }\mathrm{d}$), $^{225}\mathrm{Ac}$ (${t}_{1/2}=100\text{ }\text{ }\mathrm{d}$, following the $\ensuremath{\beta}$ decay of $^{225}\mathrm{Ra}$ with ${t}_{1/2}=149\text{ }\text{ }\mathrm{d}$), and the fissioning isotope $^{254}\mathrm{Cf}$ (${t}_{1/2}=605\text{ }\text{ }\mathrm{d}$), which liberate more energy per decay and thermalize with greater efficiency than $\ensuremath{\beta}$-decay products Late-time nebular observations of kilonovae which constrain the radioactive power provide the potential to identify signatures of these individual isotopes, thus confirming the production of heavy nuclei In order to constrain the bolometric light to the required accuracy, multiepoch and wideband observations are required with sensitive instruments like the James Webb Space Telescope In addition, by comparing the nuclear heating rate obtained with an abundance distribution that follows the solar $r$ abundance pattern, to the bolometric lightcurve of AT2017gfo, we find that the yet-uncertain $r$ abundance of $^{72}\mathrm{Ge}$ plays a decisive role in powering the lightcurve, if one assumes that GW170817 has produced a full range of the solar $r$ abundances down to mass number $A\ensuremath{\sim}70$
99 citations
Swinburne University of Technology1, Stanford University2, University of Wisconsin–Milwaukee3, Albert Einstein Institution4, Leibniz University of Hanover5, Massachusetts Institute of Technology6, Fisk University7, Vanderbilt University8, Tata Institute of Fundamental Research9, University of Tokyo10, Max Planck Society11, University of Manchester12, California Institute of Technology13, Perimeter Institute for Theoretical Physics14, Australian National University15, West Virginia University16, Inter-University Centre for Astronomy and Astrophysics17, University of Florida18, Sapienza University of Rome19, University of Glasgow20, KEK21, Cardiff University22, Pennsylvania State University23, University of Milan24, Osaka Institute of Technology25, Oregon State University26, Goddard Space Flight Center27, VU University Amsterdam28, University of Trento29
TL;DR: The field of gravitational-wave astronomy is just starting, and this Roadmap of future developments surveys the potential for growth in bandwidth and sensitivity of future gravitationalwave detectors, and discusses the science results anticipated to come from upcoming instruments as discussed by the authors.
Abstract: The 100 years since the publication of Albert Einstein’s theory of general relativity saw significant development of the understanding of the theory, the identification of potential astrophysical sources of sufficiently strong gravitational waves and development of key technologies for gravitational-wave detectors. In 2015, the first gravitational-wave signals were detected by the two US Advanced LIGO instruments. In 2017, Advanced LIGO and the European Advanced Virgo detectors pinpointed a binary neutron star coalescence that was also seen across the electromagnetic spectrum. The field of gravitational-wave astronomy is just starting, and this Roadmap of future developments surveys the potential for growth in bandwidth and sensitivity of future gravitational-wave detectors, and discusses the science results anticipated to come from upcoming instruments.
99 citations
TL;DR: In this article, the authors 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.
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 100 days of the X-ray and radio emission will lead to tighter constraints.
99 citations
Cites methods from "GW170817: observation of gravitatio..."
...We acknowledge members of the LIGO Scientific Collaboration and the Virgo Collaboration for contributions in formulating some of the ideas in this work, in particular through our collaborative efforts on Abbott et al. (2017a)....
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...The first BNS event discovered by LIGO–Virgo allows for the first independent measurement of the Hubble constant using GWs (Abbott et al. 2017a, hereafter A17:H0)....
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...The first gravitational-wave (GW) detection of a binary neutron star (BNS) merger was made on 2017 August 17 at 12:41:02 UT by the Advanced LIGO/Virgo detectors (Abbott et al. 2017b; LIGO Scientific Collaboration & Virgo Collaboration 2017)....
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TL;DR: In this article, a review of the recent development of relativistic hydrodynamics and its applications to heavy-ion collisions is presented, with emphasis on the so-called attractor solution.
99 citations
TL;DR: In this paper, a noncanonical kinetic term was proposed to enhance the power spectrum at small scales by introducing a non-canonical term with the function of the primordial scalar power spectrum having a peak.
Abstract: The possibility that in the mass range around ${10}^{\ensuremath{-}12}\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ most of dark matter is constituted of primordial black holes (PBHs) is a very interesting topic. To produce PBHs with this mass, the primordial scalar power spectrum needs to be enhanced to the order of 0.01 at the scale $k\ensuremath{\sim}{10}^{12}\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$. The enhanced power spectrum also produces large secondary gravitational waves at the mHz band. A phenomenological delta function power spectrum is usually used to discuss the production of PBHs and secondary gravitational waves. Based on $k$ and $G$ inflations, we propose a new mechanism to enhance the power spectrum at small scales by introducing a noncanonical kinetic term $[1\ensuremath{-}2G(\ensuremath{\phi})]X$ with the function $\ensuremath{-}G(\ensuremath{\phi})$ having a peak. Away from the peak, $G(\ensuremath{\phi})$ is negligible and we recover the usual slow-roll inflation which is constrained by the cosmic microwave background anisotropy observations. Around the peak, the slow-roll inflation transiently turns to ultra slow-roll inflation. The enhancement of the power spectrum can be obtained with generic potentials, and there is no need to fine tune the parameters in $G(\ensuremath{\phi})$ to several significant digits. The energy spectrum ${\mathrm{\ensuremath{\Omega}}}_{\mathrm{GW}}(f)$ of secondary gravitational waves produced by the model have the characteristic power law behavior ${\mathrm{\ensuremath{\Omega}}}_{\mathrm{GW}}(f)\ensuremath{\sim}{f}^{n}$ and is testable by pulsar timing array and space based gravitational wave detectors.
99 citations
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TL;DR: In this article, the authors present a cosmological analysis based on full-mission Planck observations of temperature and polarization anisotropies of the cosmic microwave background (CMB) radiation.
Abstract: This paper presents cosmological results based on full-mission Planck observations of temperature and polarization anisotropies of the cosmic microwave background (CMB) radiation. Our results are in very good agreement with the 2013 analysis of the Planck nominal-mission temperature data, but with increased precision. The temperature and polarization power spectra are consistent with the standard spatially-flat 6-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations (denoted “base ΛCDM” in this paper). From the Planck temperature data combined with Planck lensing, for this cosmology we find a Hubble constant, H0 = (67.8 ± 0.9) km s-1Mpc-1, a matter density parameter Ωm = 0.308 ± 0.012, and a tilted scalar spectral index with ns = 0.968 ± 0.006, consistent with the 2013 analysis. Note that in this abstract we quote 68% confidence limits on measured parameters and 95% upper limits on other parameters. We present the first results of polarization measurements with the Low Frequency Instrument at large angular scales. Combined with the Planck temperature and lensing data, these measurements give a reionization optical depth of τ = 0.066 ± 0.016, corresponding to a reionization redshift of . These results are consistent with those from WMAP polarization measurements cleaned for dust emission using 353-GHz polarization maps from the High Frequency Instrument. We find no evidence for any departure from base ΛCDM in the neutrino sector of the theory; for example, combining Planck observations with other astrophysical data we find Neff = 3.15 ± 0.23 for the effective number of relativistic degrees of freedom, consistent with the value Neff = 3.046 of the Standard Model of particle physics. The sum of neutrino masses is constrained to ∑ mν < 0.23 eV. The spatial curvature of our Universe is found to be very close to zero, with | ΩK | < 0.005. Adding a tensor component as a single-parameter extension to base ΛCDM we find an upper limit on the tensor-to-scalar ratio of r0.002< 0.11, consistent with the Planck 2013 results and consistent with the B-mode polarization constraints from a joint analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP B-mode data to our analysis leads to a tighter constraint of r0.002 < 0.09 and disfavours inflationarymodels with a V(φ) ∝ φ2 potential. The addition of Planck polarization data leads to strong constraints on deviations from a purely adiabatic spectrum of fluctuations. We find no evidence for any contribution from isocurvature perturbations or from cosmic defects. Combining Planck data with other astrophysical data, including Type Ia supernovae, the equation of state of dark energy is constrained to w = −1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints on annihilating dark matter and on possible deviations from the standard recombination history. In neither case do we find no evidence for new physics. The Planck results for base ΛCDM are in good agreement with baryon acoustic oscillation data and with the JLA sample of Type Ia supernovae. However, as in the 2013 analysis, the amplitude of the fluctuation spectrum is found to be higher than inferred from some analyses of rich cluster counts and weak gravitational lensing. We show that these tensions cannot easily be resolved with simple modifications of the base ΛCDM cosmology. Apart from these tensions, the base ΛCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.
10,728 citations
TL;DR: In this paper, the authors present results based on full-mission Planck observations of temperature and polarization anisotropies of the CMB, which are consistent with the six-parameter inflationary LCDM cosmology.
Abstract: We present results based on full-mission Planck observations of temperature and polarization anisotropies of the CMB. These data are consistent with the six-parameter inflationary LCDM cosmology. From the Planck temperature and lensing data, for this cosmology we find a Hubble constant, H0= (67.8 +/- 0.9) km/s/Mpc, a matter density parameter Omega_m = 0.308 +/- 0.012 and a scalar spectral index with n_s = 0.968 +/- 0.006. (We quote 68% errors on measured parameters and 95% limits on other parameters.) Combined with Planck temperature and lensing data, Planck LFI polarization measurements lead to a reionization optical depth of tau = 0.066 +/- 0.016. Combining Planck with other astrophysical data we find N_ eff = 3.15 +/- 0.23 for the effective number of relativistic degrees of freedom and the sum of neutrino masses is constrained to < 0.23 eV. Spatial curvature is found to be |Omega_K| < 0.005. For LCDM we find a limit on the tensor-to-scalar ratio of r <0.11 consistent with the B-mode constraints from an analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP data leads to a tighter constraint of r < 0.09. We find no evidence for isocurvature perturbations or cosmic defects. The equation of state of dark energy is constrained to w = -1.006 +/- 0.045. Standard big bang nucleosynthesis predictions for the Planck LCDM cosmology are in excellent agreement with observations. We investigate annihilating dark matter and deviations from standard recombination, finding no evidence for new physics. The Planck results for base LCDM are in agreement with BAO data and with the JLA SNe sample. However the amplitude of the fluctuations is found to be higher than inferred from rich cluster counts and weak gravitational lensing. Apart from these tensions, the base LCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.
9,745 citations
TL;DR: This is the first direct detection of gravitational waves and the first observation of a binary black hole merger, and these observations demonstrate the existence of binary stellar-mass black hole systems.
Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of $1.0 \times 10^{-21}$. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1 {\sigma}. The source lies at a luminosity distance of $410^{+160}_{-180}$ Mpc corresponding to a redshift $z = 0.09^{+0.03}_{-0.04}$. In the source frame, the initial black hole masses are $36^{+5}_{-4} M_\odot$ and $29^{+4}_{-4} M_\odot$, and the final black hole mass is $62^{+4}_{-4} M_\odot$, with $3.0^{+0.5}_{-0.5} M_\odot c^2$ radiated in gravitational waves. All uncertainties define 90% credible intervals.These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.
9,596 citations
Journal Article•
TL;DR: The first direct detection of gravitational waves and the first observation of a binary black hole merger were reported in this paper, with a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ.
Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160) Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.
4,375 citations
TL;DR: This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.
Abstract: We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5 σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4+0.7−0.9×10−22. The inferred source-frame initial black hole masses are 14.2+8.3−3.7M⊙ and 7.5+2.3−2.3M⊙ and the final black hole mass is 20.8+6.1−1.7M⊙. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440+180−190 Mpc corresponding to a redshift 0.09+0.03−0.04. All uncertainties define a 90 % credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.
3,448 citations