Electromagnetic Counterparts I M. Benacquista ICE Summer School: - - PowerPoint PPT Presentation

ICE Summer School: Gravitational Wave Astronomy July 3, 2018

Electromagnetic Counterparts I

• M. Benacquista

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What is an electromagnetic counterpart?

• Source of gravitational waves
• Source of electromagnetic waves
• Coincident in time (Events)
• Mergers
• Supernovae
• Coincident in space (Continuous)
• Compact Binaries
• Pulsars
• Statistically correlated (Long Delay)
• Binary SMBH
• Tidal Disruptions

Today Thursday

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Electromagnetic Counterparts of Supernovae

・ ✓ “ hree generic phases” ✓ × ✓ The horizon of LIGO is limited to nearby events. ・ ✓ especially when convection dominates over SASI.

Anisotropic instabilities can generate time varying quadrupole moments

hij ∼ ϵ Rs R ( v c)

2

Rs ∼ 3 km ( M M⊙ ) v c ∼ 0.1

degree of anisotropy ϵ ∼ 10−4 − 10−12 Kei Kotake: LVC Workshop on CCSN: wiki.ligo.org/LSC/2017SupernovaeWorkshop

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• Unmodeled

signal detection

• Coherent

analysis over network of detectors

• Typical best

distance is a few 100 pc

• How many are

there?

Mukherjee et al. PRD 96 104033 (2017)

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Core Collapse Supernovae

• Neutrino burst coincident with gravitational wave burst
• EM burst due to shock break out ~ hours/days later
• Signal detection limits to only nearby events ~ 200 pc
• Very rare events at this distance (1 per 1000yrs)
• Unlikely to have to search for EM counterparts
• Probably a good thing

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Electromagnetic Counterparts of Mergers

Needs:

• Matter to couple to photons
• Neutron star
• Ejection of matter
• Energy source to generate those photons
• Accretion
• Disk shocking
• Radioactive decay (r-process)
• Prompt emission
• Jet breakout — γ-ray burst
• Sustained afterglow
• Radioactive decay
• Disk opacities
• Jet expansion

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Rosswog+Ramirez-Ruiz(2002)

Munbound ∼ 5 × 10−3 − 5 × 10−2 M⊙ vunbound ∼ 0.1 − 0.3 c

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• Neutron rich material and heavy nuclei
• Nucleus can absorb a neutron
• Probability (time-scale) depends on the density of neutrons
• Nucleus can decay through β-decay
• Probability (time-scale) depends on the nucleus
• r-process:
• s-process

τabsorb τdecay

τabsorb < τdecay τabsorb > τdecay

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–2.5 –2.0 –1.5 –1.0 –0.5 0.0 0.5 1.0 8 1

–2

1

–1

1 1

1

1 1 2 140 160 1 8 M a s s n u m b e r ( A ) r

• p

r

• c

e s s a b u n d a n c e 2

Neutron number (N) 00 20 40 60 80 100 120

log(T s–1)

140 160 20 40 60 80 100 120

Nr, (Si = 106)

Proton number (Z)

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r-process network: neutron captures, photo-dissociations, alpha- and beta-decays, fission reactions

Lattimer+Schramm1976, Freiberghaus+99, Goriely+2011, Metzgert+2010, Roberts+2011, Korobkin+2012

Nuclear Evolution of the Debris

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Lightcurves

Change in internal energy of the debris dU dt = − U t − U τd + Lheat

1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10

39

10

40

10

41

Time (days) Luminosity (erg s

1)

∼ 1 day rise (vunbound ∼ 0.1c, Munbound ∼ 102M, κ ∼ 0.1 cm2 g1)

adiabatic radiation

τd = ( 3κ 4πc)

1/2

( Munbound vunbound )

1/2

diffusion timescale nuclear decay

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Spectral Lines

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Finding the counterpart

~ 30 square degrees

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DECam Image—9 square degrees

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Catalog of galaxies (GWGC) out to ~100 Mpc

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1M2H team (UCSC+Carnegie)

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radioactivity: Lippuner & Roberts 2015

kilonova SSS17a bolometric light curve

Q(t) of 0.02 Msun

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What was our viewing angle?

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Figure 8. Evolution of the X-ray emission from GW170817 as seen by the CXO.

Margutti et al. 2018

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= » ´ =

• t

r k k »

• µ

q q

• a

Off-axis view of jet breakout into interstellar medium leads to late-time brightening across all wavelengths Margutti et al. 2018

ICE Summer School: Gravitational Wave Astronomy July 3, 2018

Further detections:

• Learn about the r-process and s-process development.
• Learn about the disk opacities of Lanthanides.
• Learn about the jet break-out mechanism
• Learn about the angle of opening of the jet
• Gives us the rate of "invisible" GRBs