gw170817/grb 170817a - an astronomy/astrophysics...
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Premise GW-GRB association GW Inference EMGW Inference Follow-up
GW170817/GRB 170817AAn Astronomy/Astrophysics Viewpoint
Deep Chatterjee12
on behalf of the LIGO-Virgo Collaboration
1University of Wisconsin – Milwaukee
2LIGO–Virgo Collaboration
Rencontres de Moriond, La ThuileMarch 26, 2019
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Lights, Camera, Follow-up...
GW170817[Abbott et al., 2017c]GRB 170817A[Goldstein et al., 2017,Abbott et al., 2017b]
SSS17aEM170817...AT 2017gfo[Abbott et al., 2017d]
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Notice TimelineUnprecedented Follow-up Operations
10−4 10−3 10−2 10−1 100 101
t− tmerger (days)
GWDetection
InitialCircular
InitialSkymap
FinalSkymapGWs
γ Rays
X rays/UV
Optical/IR/UV
Radio
Radio, X-ray follow-up operations ∼ 1yr.
Speed of gravity = c ?
On August 17, it was established correctup to 15 decimal places!
Premise GW-GRB association GW Inference EMGW Inference Follow-up
The Story it Told...In this talk
The astrophysics:
• Independent measurement of H0
• Tidal deformability & neutron star equation of state (EoS)
• Physics of “kilonova”
• Progenitor model
• Post-merger remnant
• Stochastic background & merger rates
Multi-messenger astronomy:
• Follow-up operations
• Looking ahead at the third observing run (O3)
Premise GW-GRB association GW Inference EMGW Inference Follow-up
GW-GRB Association
• GW170817 - GRB 170817A unambiguous association
• Chance spatio-temporal coincidence, p = 5× 10−8 ⇒ 5.3σsignificance. [Abbott et al., 2017b]
BNS system are progenitors of, at least, some short GRBs
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Parameter EstimatesGW170817 Masses and Spins
1.4 1.5 1.6 1.7 1.8m1 (M)
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
m2
(M
)
TaylorF2
SEOBNRv4NRT
IMRPhenomPv2NRT
SEOBNRv4T
TEOBResumS
0
30
60
90
120
150
180
0.0
0.2
0.4
0.6
0.8
0
30
60
90
120
150
180
0.0
0.2
0.4
0.6
0.8
0
30
60 90
120
150
180
0
30
60 90
120
150
180
GW170817
cS1/(Gm21) cS2/(Gm
22)
Credits [Abbott et al., 2018b]
Mc↑
Chirp mass
= 1.186M; ∆Ω↑
Sky loc.
= 16deg2; dL↑
Lumin. dist.
= 40Mpc; SNR↑
Signal to noise
= 33
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Parameter EstimatesTidal Deformability
Tidal Deformability
↓Λ︸︷︷︸
in signal
= (2/3)
EoS dependent︷ ︸︸ ︷k2
(Gm
c2R
)−5
Effective tidal parameters enter waveform @ 5 PNCredits [Abbott et al., 2018a]
8 10 12 14
R (km)
0.5
1.0
1.5
2.0
2.5
3.0
m(M
)
WF
F1
AP
R4
SL
yM
PA
1
H4
BHlim
it
Buchd
ahl lim
it0
1
0 10 250 500 750 1000 1250
Λ1
0
500
1000
1500
2000
Λ2
WFF1
APR4
SLy
MPA1
H4
MS1b
MS1
More Compact
Less Compact
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Neutron Star Equation of State
0 200 400 600 800 1000 1200 1400 1600
Λ
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.0035
PD
F
WF
F1
AP
R4
SL
y
MP
A1
H4
MS
1b
MS
1
IMRPhenomPv2NRT
SEOBNRv4NRT
SEOBNRv4T
TEOBResumS
TaylorF2
Prior
Low Spin Prior
0 200 400 600 800 1000 1200 1400 1600
Λ
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.0035
PD
F
WF
F1
AP
R4
SL
y
MP
A1
H4
MS
1b
MS
1
IMRPhenomPv2NRT
SEOBNRv4NRT
SEOBNRv4T
TEOBResumS
TaylorF2
Prior
High Spin Prior
Low Support for stiff EoS
MS1 like EoS ruled out with ≥ 90% confidence
• Compact NS favored
• For GW170817, R1 = 11.9+1.4−1.4km; R2 = 11.9+1.4
−1.4km[Abbott et al., 2018a]
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Dynamical EjectaGW parameters → Mej
Mej = Mej(m, mb↑
Baryon mass
, R↑
Radius
)
m,Λ︸︷︷︸from GW
EoS−−→ mb,R
NR fitting [Dietrich and Ujevic, 2017]
4 3 2 1 0 1
log10(Mej/M¯)
0.0
0.2
0.4
0.6
0.8
1.0
H4 (low spin)
SLy (low spin)
MPA1 (low spin)
APR4 (low spin)
H4 (high spin)
SLy (high spin)
MPA1 (high spin)
APR4 (high spin)
100 101
tpeak (hr)
15
16
17
18
19
20
Pea
ki-
ban
dA
pp
aren
tM
agn
itu
de
−4.0
−3.6
−3.2
−2.8
−2.4
−2.0
−1.6
−1.2
log 1
0(M
ej/M
)
Credits [Abbott et al., 2017a]
Premise GW-GRB association GW Inference EMGW Inference Follow-up
r -process Abundance
ρrp = frp︸︷︷︸fraction converted
×Mej ×merger rate︷︸︸︷R ×
Total time considering SFR
↓〈Tmergers〉
Xrp︸︷︷︸r -process fraction
= ρrp/ ρ∗︸︷︷︸Star form.
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
log10(ρrp/frp [M Mpc−3])
0.0
0.2
0.4
0.6
0.8
1.0
PD
F
H4
MPA1
SLy
APR4
−8 −7 −6 −5log10(Xrp/frp)
Credits [Abbott et al., 2017a]
frp ≥ 10%accounts forMW abundance[Abbott et al., 2017a]
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Post-Merger RemnantGW Signatures
• Possible scenarios:• Prompt collapse into BH; quasi-normal modes• Hypermassive NS; collapse to BH . 1s• Supramassive NS; collapse to BH ∼ 10− 104s• Stable NS
• Absence of template waveform
• Generic search for excess power in spectrogram
• Whatever the scenario, optimistic GW emission @SNR ∼ 1− 2 in LIGO-Virgo band.
No GW signature found
Signal, if present, is too weak for current sensitivity/searches[Abbott et al., 2017f, Abbott et al., 2019]
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Progenitor of GW170817Occurrence ∼ 2kpc from center of NGC 4993, constrains:
• Delay time, Tdelay
• Distance of second CC-SNe, RSN
• Natal kick, vkick
Credits [Abbott et al., 2017e]
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Progenitor of GW170817
Progenitor properties robust if stellar properties of NGC 4993 isolder that ∼ 1Gyr [Abbott et al., 2017e]
v90%kick ' 300+250
−200kms−1; R90%SN ' 2.0+4.0
−1.5kpc
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Hubble Constant Measurement
50 60 70 80 90 100 110 120 130 140H0 (km s 1 Mpc 1)
0.00
0.01
0.02
0.03
0.04p(
H0)
(km
1sM
pc)
p(H0 GW170817)Planck17
SHoES18
Credits [The LIGO Scientific Collaboration et al., 2017]
General agreement with H0 from SNIa’s and CMBMore detections will sharpen posterior
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Looking ahead in O3Implication of Rates
Detector BNS range (Mpc)LIGO ∼ 120–140
Virgo ∼ 50
Kagra . 25
• Expected Rates 1:• Total BNS count ∼ 1–10.• BBH candidates are expected once a week.• NSBH rates uncertain at this stage.
• Skymaps:• BNS systems will have median 90% sky areas between
120− 180 deg2.• 12− 21% such systems expected to be localized ≤ 20 deg2.
1https://dcc.ligo.org/LIGO-G1800370/public
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Follow-up campaign
• GW170817:
• First success story ofelectromagnetic &gravitational-wave (EMGW)astronomy.
• Follow-up operations wereunprecedented.
O2 partners
• Need for a rapid, robust alert infrastructure:• Semi-automated with low false alarm.• Data products from GW side to aid EM follow-up.• Crucial to capture the transient at early times.
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Public AlertsFor the first time, LIGO-Virgo Alerts will be public!
PreliminaryAlert Sent
Rapid Localization Classification
Automated Vetting Set Preferred Event
Original Detection
Initial Alert orRetraction Sent
Classification Human Vetting
Parameter Estimation
10 second 1 minute 1 hour 1 day 1 week
UpdateAlert Sent Classification
Parameter Estimation
• All alerts are sent over Gamma-ray Coordinate Network (GCN)
• Retractions might happen at the Initial stage
• Circulars are sent during Initial alert
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Low-latency Data ProductsSkymaps Chances of EM-counterpart
100 101 102
m1[M ]
100
101
m2[
M]
BNS NSBH
BBH
Mrem =0
Pastro by source category
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Combined SkymapsWill be sent for Fermi and IceCube
(a) GW170817 (HL) (b) Fermi GBM
(c) Combined
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Userguide for alerts in O3
https://emfollow.docs.ligo.org/userguide/
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Abbott, B. P. et al. (2017a).
Estimating the contribution of dynamical ejecta in the kilonova associated with GW170817.The Astrophysical Journal, 850(2):L39.
Abbott, B. P. et al. (2017b).
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A.The Astrophysical Journal Letters, 848:L13.
Abbott, B. P. et al. (2017c).
GW170817: Observation of gravitational waves from a binary neutron star inspiral.Phys. Rev. Lett., 119:161101.
Abbott, B. P. et al. (2017d).
Multi-messenger Observations of a Binary Neutron Star Merger.ApJ Lett., 848:L12.
Abbott, B. P. et al. (2017e).
On the progenitor of binary neutron star merger GW170817.The Astrophysical Journal, 850(2):L40.
Abbott, B. P. et al. (2017f).
Search for Post-merger Gravitational Waves from the Remnant of the Binary Neutron Star MergerGW170817.ApJ Lett., 851:L16.
Abbott, B. P. et al. (2018a).
GW170817: Measurements of Neutron Star Radii and Equation of State.Phys. Rev. Lett., 121:161101.
Abbott, B. P. et al. (2018b).
GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO andVirgo during the First and Second Observing Runs.arXiv e-prints, page arXiv:1811.12907.
Abbott, B. P. et al. (2019).
Premise GW-GRB association GW Inference EMGW Inference Follow-up
Properties of the Binary Neutron Star Merger GW170817.Physical Review X, 9:011001.
Dietrich, T. and Ujevic, M. (2017).
Modeling dynamical ejecta from binary neutron star mergers and implications for electromagneticcounterparts.Classical and Quantum Gravity, 34:105014.
Goldstein, A. et al. (2017).
An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB170817A.ApJL, 848:L14.
The LIGO Scientific Collaboration, The Virgo Collaboration, The 1M2H Collaboration, The Dark Energy
Camera GW-EM Collaboration, The DES Collaboration, The DLT40 Collaboration, The Las CumbresObservatory Collaboration, The VINROUGE Collaboration, and The MASTER Collaboration (2017).A gravitational-wave standard siren measurement of the Hubble constant.Nature, 551(7678):85–88.