Gravitational and multimessenger astronomy after the observation of a neutron star merger
Tito Dal Canton
XXXVIII International Symposium on Physics in Collision Bogotá, 2018 Contents
● Theory, instruments and methods
● Current results
● Near and long-term future
2 Multimessenger astronomy
Radio Infrared Optical Ultraviolet X-rays γ-rays
Matter, composition, chemistry, temperature
Supernova SN1987A Neutrinos Cosmic rays
Nuclear reactions, decays
Gravitational waves
Motion/geometry, regardless of composition 3 Gravitational waves
1 8 G π Radiation from Rμ ν− R gμ ν= 4 T μ ν 2 c accelerated motion: G Q¨ T μ ν=0 h ∼ ij c4 r gμ ν=ημ ν+hμ ν
|ημ ν|≪1
Black hole & neutron star binaries
Collapse of stellar cores
Rotating neutron stars
Decay of Hulse-Taylor binary
4 The instruments of GW astronomy
LIGO
Observable quantity: strain h = ΔL/L
Astrophysical signals h < 10-21
5 Virgo The instruments of GW astronomy
Amplitude spectral density of detector noise (Aug 2017)
Less sensitive
More sensitive
PRL 119, 141101 (2017)
6 Analysis of GW data
Transient signals (< ~1 min) Continuous signals (> ~1 day)
Robust analytic/numerical Deterministic waveform model (e.g. rotating neutron stars) (e.g. black hole mergers)
Stochastic No waveform model - yet (e.g. superposition (e.g. stellar core collapse) of incoherent signals)
Time-frequency decompositions, excess power above noise Correlation (coincident or coherent)
Matched filtering Bayesian inference for parameter estimation (coincident or coherent) 7 Detecting compact binary mergers
Compact binary merger template waveform Template bank
Matched filtering
Instrumental transient
8 Organizing multimessenger observations
Fermi/GBM INTEGRAL Low-latency detection (e.g. GW) LIGO/Virgo Overlap in time / sky location Gamma-ray coordinates network / Low-latency detection (e.g. GRB) Transient astronomy network Low-latency detection (e.g. GRB) MASTER Swift-BAT IceCube Targeted followup (e.g. optical)
TITLE: GCN CIRCULAR NUMBER: 23153 SUBJECT: GRB 180818B: Fermi GBM observations DATE: 18/08/18 23:14:07 GMT FROM: Peter Veres at UAH
"At 12:28:57.24 UT on 18 August 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180818B (trigger 556288142 / 180818520). Overlap in time / sky location which was also detected by the Swift/BAT (Marshall et al., GCN 23149). The GBM on-ground location is consistent with the Swift position. 9 […] Blind deep search (e.g. GRB) Contents
● Theory, instruments and methods
● Current results
● Short- and long-term future
10 Performance of advanced GW detectors
S/N ~ d-1 & S/N > ~8 to have a detection → Maximum d (range)
Virgo
Number of detected sources 3 ∼d T obs
losc.ligo.org 11 A zoo of binary black hole mergers Actual data on losc.ligo.org GW151226 GW150914
GW170104 GW170608
SXS collaboration
GW170814
12 Are they really black holes?
● Perfectly match theoretical waveforms
● Waveform shape → Quasi-circular orbit
● df / dt → Limits on masses
● Maximum frequency → Min separation
● Black holes are the only known objects
that can weigh ~10 MSun and orbit at ~100 Hz
● ~1 MSun radiated in GWs and no clear evidence of multimessenger counterparts
13 How heavy are these black holes?
14 Do these black holes spin?
15 Do LIGO/Virgo black holes match x-ray candidates?
Nielsen 2016
Hynes 2010 ??? LIGO/Virgo black holes
16 What created these binary black holes?
Binary stellar evolution Dynamical BH capture with common envelope in dense clusters
?
Primordial BHs decoupling from the background (e.g. arXiv:1801.10327)
Need more events! 17 Testing general relativity with LIGO/Virgo’s black holes
Deviations in post-Newtonian coefficients - arXiv:1606.04856
GW150914, GW151226, GW170104:
−23 Mg ≤ 7.7 × 10 eV from limits on waveform phase deviations Phys. Rev. Lett. 118, 221101 (2017) Pre- and post-merger parameter consistency 18 GW170817: a neutron star merger
Most precisely localized
Loudest
Closest
PRL 119, 161101 (2017) 19 Longest GW170817’s components
Two objects with masses …and no sign of significant spins similar to neutron stars…
20 arXiv:1805.11579 GW170817’s components
Disfavored equations of state Tidal deformability parameter
Two black holes 21 arXiv:1805.11579 170817’s γ-ray burst arXiv:1710.05834
???
● “Ordinary” short GRB on its own
● But knowledge of distance implies it is incredibly dim 22 ● Hard spike + thermal tail 170817’s γ-ray burst
23 arXiv:1710.05834 Fundamental physics with GW170817 and its γ-rays
Two reference events spatially coincident and temporally closer than 10 s:
● End of GW waveform ● Start of γ-ray emission
Propagate over ~1024 m…
Speed of GWs vs photons Lorentz invariance Equivalence principle
GWs and photons “fall” in the same way
24 arXiv:1710.05834 170817: UV - optical - IR
NGC 4993
25 arXiv:1710.05833 170817: UV - optical - IR
26 arXiv:1710.05833 Kilonova and nucleosynthesis from GW170817
arXiv:1710.05841
a
r
X
i
v
:
1
1
0
8
.
6
0
5
6
Post-merger ejecta expanding at ~0.2 c
Blue → red evolution, rapid cooling
Late spectral features 27 of heavy elements GW170817 as a standard siren for cosmology
GW Luminosity distance
Sky location
H0
Host galaxy Redshift NGC 4993 arXiv:1710.05835
Need more events! 28 170817: radio and x-ray afterglow
arXiv:1805.04093 arXiv:1801.06164
● X-ray flux increases, starts fading at ~150 days ● Radio flux follows similar evolution
✗ Off-axis “top-hat” jet arXiv:1803.06853 ✓ Off-axis jet with angular structure 29 ✓ Isotropic outflow model 170817’s non-detections
Neutrinos Post-merger GWs
● IceCube
● ANTARES arXiv:1805.11579
● Pierre Auger Observatory Consistent with off-axis jet
Current sensitivity insufficient for setting constraints
30 A ~300 TeV ν from an active blazar?
● Atmospheric origin not fully excluded ● Chance association rejected at 3σ ● Consistent with long-expected blazar origin of neutrinos
31 arXiv:1807.08816 Theoretical & modeling efforts GW waveforms MM counterparts
Credit: S. Noble
arXiv:1701.08738
arXiv:1806.05697 32 Contents
● Theory, instruments and methods
● Current results
● Short- and long-term future
33 GW astronomy in the near future arXiv:1304.0670v6
34 GW astronomy in the near future
O2 O3 - Feb 2019, ~1 year ● Open public alerts ● End-of-run results papers ● Many more BH-BH mergers ● Binary merger population ● Few to O(10) NS-NS mergers ● Up to a few/year with sGRBs ● Improve tests of GR ● BH-NS mergers? ● Additional ● New sources? multimessenger followup studies ● Supernovæ ● Continuous waves
● Stochastic background
35 Multimessenger astronomy in the near future
Fermi Swift Chandra INTEGRAL XMM-Newton NuStar ZTF TAROT
IceCube CHIME LSST
SVOM ISS-TAO BurstCube arXiv:1708.09292 JWST
36 GW astronomy in the far future
3rd generation ground-based interferometers
Cosmic Explorer (US) Einstein Telescope (EU) ● L-shaped ● Underground ● 40 km arms ● 10 km arms ● Cryogenic? ● Cryogenic
arXiv:1607.08697
● Higher binary merger rates ● SNR > 20 at cosmological redshifts ● Early alert for binary mergers
37 GW astronomy in the far future
Space interferometers – LISA mission
arXiv:1702.00786
38 Phys. Rev. Lett. 120, 061101 Multimessenger astronomy in the far future
ATHENA
TAP
WFIRST
LUVOIR SKA 39 Gracias!
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