Image provided by the Max Planck Institute for Gravitational Physics/Zuse Institute Berlin Eric Howell

Joint gravitational wave - gamma-ray burst detection rates

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

EM observations of GRB170817A sGRB detection rates

sGRB/GW detection rates

GW170817/GRB170817A

GRB 170817A Luminosity

Swift data

• Distance: 42.5 Mpc (2nd closest GRB – GRB980425)

• Peak Flux: 3.6 +/- 1.1 ph s-1cm-2 [median 7.3 ph s-1cm-2 ]

• Luminosity: 1.4x1047 erg/s [average 1052 erg s-1]

Structured jet

Top hat: constant emission and lorentz factor across jet

Structured jet: luminosity per solid angle decreases smoothly outside a narrow ultra-relativistic core

A structured jet is a by product of a successful jet penetrating a cocoon (Lazzati et al 2017, Gottlieb 2017, Alexander 2018)

2 popular profiles - Power law or Gaussian

Structured jet profiles from EM observations

Take parameters from late time EM observations and convert to prompt phase

Fermi prompt observed Eiso

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

VLBI observations (HAS, VLBA, VLA, GBT)

Mooley et al, Nature 2018 constrained the evolution in size, shape, position of GW170817 and identified superluminal motion with milli-arcsec resolution

Observations (> 150 days) supported successful jet breakout

EM observations of GRB170817A sGRB detection rates

sGRB/GW detection rates

Infer structured jet profile Assume a Gaussian jet profile with observationally motivated priors

θCORE – Uniform prior

LCORE – Can take a Lognormal distribution around the average sGRB Luminosity as a prior

θVIEW – Gaussian prior based on Mooley et al (15-25 deg) Likelihood function - a lognormal distribution based on the observed luminosity of GRB170817

θCORE – 4.7 deg LCORE – 1 X 1052 erg s-1 θVIEW – 21 deg

Fold this angular dependence into the Fermi detection efficiency

Inferred GRB170817A structured jet profile

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

The GRB efficiency function assuming a structured jet

Solid line – structured jet Dashed line – top-hat model

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

Viewing angle – distance relation for a GRB170817A-like structured jet profile

The Fermi detection rate

Fold GRB efficiency function with BNS rate evolution Predicts around 40/yr detections in line with Fermi observations

BNS intrinsic rate Fermi sGRB detection rate

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

EM observations of GRB170817 sGRB detection rates

sGRB/GW detection rates

BNS rate evolution model

GW BNS detection rate - fold a GW detection efficiency model into a BNS source rate evolution model

Detection efficiency model based on the projection parameter of Finn & Chernoff 1993

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

Future BNS detection rates

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

O3a BNS candidates

0

5

10

15

20

25

BNS NSBH BBH

2 Probability >90%

CANDIDATE PROBABILITY DISTANCE/NETWORK

SKYMAP

190910h BNS (61%), Terrestrial (39%)

230 ± 80 L1

190901ap BNS (86%), Terrestrial (14%)

241 ± 79 L1, V1

190718y Terrestrial (98%), BNS (2%)

227 ± 165 H1,L1,V1

S190510g Terrestrial (58%), BNS (42%)

227 ± 92 H1,L1,V1

S190426c BNS (49%), MassGap (24%), Terrestrial (14%), NSBH (13%)

377 ± 100 H1,L1,V1

190424z BNS (>99%) 157 ± 41 L1, V1

Future joint sGRB-BNS rates

O3 Observation run 2019-20 Detection range = 120 Mpc Rate = 0.2-1.8(0.6) yr-1

A+ Observation run 2023-26 Detection range = 325Mpc (z=0.07) Rate = 0.7-9.1 (3.2) yr-1

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

Projected joint GW/sGRB event rates

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

Bottom row – percentage of BNS with a sGRB counterpart

As GW range increases – events viewed at wider opening angles more difficult to detect – GRB detector sensitivity critical

A higher percentage BNS with sGRB counterparts will be face-on as GW sensitivity increases

Conclusions

Inferred a structured jet profile for GRB170817A

Calculated sGRB efficiency curve for Fermi that agrees with observations

Provided Fermi and Joint GW/sGRB detection rates for O3 and beyond

The percentage of BNS with sGRBs counterparts decrease with GW detector sensitivity

Sensitivity of future GRB satellites will be critical

See Future Survey Missions on Tuesday [15:35-17:35]

BNS rate evolution model

Star formation rate – Madau & Dickinson (2014)

Delay time distribution – P(td) ∝ 1/td ;20 Myr min

Flat Λ cosmology: Ω𝑀=0.31, ΩΛ =0.69, H0=67.8 km s-1Mpc-1 (Planck Collab et al. 2015)

BNS rates – Abbott et al, 2017

1680 Gpc-3 yr -1

Assume that all BNSs can produce a sGRB

+3050 -1310

Howell, Ackley et al 2018 in prep

Projected joint event rates – events close to jet axis

Howell, Ackley, Rowlinson et al 2018 in prep

Future BNS detection ranges

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

The GRB efficiency function

Selection function for a top hat jet

Selection function for a structured jet

θCORE – 4.7 deg LCORE – 1 X 1052 erg s-1 θVIEW – 21 deg

Fold this angular dependence into the Fermi detection efficiency

Inferred GRB170817A structured jet profile

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

ETD – Theseus Joint GW/sGRB rate

THESEUS mission (2026 – 2029) selected with 2 other missions for "phase A" and is under evaluation by ESA. Unique combinations of instruments: Soft X-ray imager SXI – 0.3 – 6 keV 1sr FoV and 1-2 arcsec localisation IR Telescope IRT – 0.7m class 10x10 arcmin FoV (imaging + spectroscopic capabilities) X/Gamma Ray XGIS– instruments covering range 2 – 20 MeV, FoV 2pi sr > 150 keV

Projected joint event rates

At increased GW detection ranges, GRB emissions from wider opening angles will be more difficult to detect

Howell, Ackley, Rowlinson & Coward, 2019, MNRAS, 485, 1435

EXTRA SLIDES

Future BNS detection rates

O3 Observation run 2019-20 Detection range = 120 Mpc Rate = 1-16 (6) yr-1

A+ Observation run 2023-26 Detection range = 325 (z=0.07) Rate = 31-394 (140) yr-1

Howell et al, 2018 astro-ph: 1811.09168

GW detections looking ahead

ETD – Theseus Joint GW/sGRB rate

Theseus sGRB rate : 146.15 ^{+265.33}_{-113.96} Theseus + ETD rate : 47.15 ^{+85.60}_{-36.77} Theseus + CE rate : 67.78 ^{+123.05}_{-52.85}

THESEUS mission (2026 – 2029) selected with 2 other missions for "phase A" and is under evaluation by ESA.

Swift early Follow-up Swift FoV was occulted by earth at time of Fermi-GBM trigger After 1h XRT imaged 90% of GW skymap – no bright sources 12h Swope reported NGC 4993 – no XRT detection

Delayed onset of X-ray (9 days) and Radio (15 days) strongly we were viewing from a wide angle (not an on-axis jet)

VLA ruled out a slightly off-axis jet

𝝋(𝑳) 𝝋(𝑳)

𝑳 𝑳 𝑳min 𝑳min

The GRB efficiency function Given a flux limit FL there is a limiting accessible luminosity as a function of redshift Lmin(FL, z) Integrate over the luminosity function to determine the detectable fraction of sources – the efficiency (selection) function

Increasing redshift, z

This model works for a top hat jet

𝝋(𝑳) 𝝋(𝑳)

𝑳 𝑳 𝑳min 𝑳min

The GRB efficiency function

Increasing redshift, z

For a structured jet profile there is also an angular dependence with redshift Lmin(FL, z, 𝜽)

low z : emissions from wider angles are more likely higher z: only see emissions from nearer the core

We need L(𝜽) angular dependence on luminosity

GRB X-ray Plateaus and GWs

X-ray plateaus (60% SGRBs)

Rowlinson 2010, 2013

Long lived GW emission? Corsi & Meszaros 2009

Projected joint event rates Epoch Detection range/

Horizon BNS Detection rate (yr-1)

BNS+sGRB/ yr On-axes / yr

O3 (2019-20)

117 Mpc 270 Mpc

1-16 (6) 0.2-1.8(0.6) 0.05-0.6 (0.2)

Design (2021-)

173 Mpc 413 Mpc; z~0.1

4-55 (20) 0.3-3.7 (1.3) 0.1-1.3 (0.5)

A+ (2023-2026)

325 Mpc 843 Mpc; z~0.17

31-394 (140) 0.7-9.1 (3.2) 0.3-3.6 (1.3)

Voyager (2.5G) 2027-2030

736 Mpc; z~0.15 2.4Gpc; z~0.4

438-5598(1988) 1.7-22.0(7.8) 0.8-10.5 (3.7)

Structured jet profiles increase number over top hat The BNS/GW detection fraction limited by Fermi as GW

ranges increase Kilonova and late EM searches for most BNS Fermi will be running sub-threshold pipelines

<- Top hat

Gamma-ray bursts (GRBs))

10keV-GeV photons

1051-1054 ergs in few seconds

γ-rays - ultra-relativistic energy flow converted to radiation

lon

g-so

ft L

GR

B

sh

ort

-har

d S

GR

B

>2s

< 2

s

1. Off-axes cocoon model

Matter ejected into circum-merger medium (UVOIR evidence)

Jet drills through ejector it converts fraction of its energy to matter enveloping the jet.

Inflates forming a hot mildly relativistic (Γ ~2-3 ) expanding cocoon

Narrow jet (~10o)- drills out leaving a fraction of energy in the cocoon Wide jet (~30o)- - choked and deposits all energy in cocoon Both scenarios predict weak gamma ray emission over wide opening angles.

[Gottlieb et al. 2017a,b, Nakar et al. 2017, Lazzati et al, 2017a,b, Bromberg et al. 2017]

Comparison to other models of GRB170817A structured jet

Comparison to other models of GRB170817A structured jet

Comparison to other models of GRB170817A structured jet

Talk outline

Key EM prompt and follow-up observations

Infer a structured jet profile for GRB170817A

Produce a model for BNS source rate evolution and

Detection rate for future GW IFO upgrades

Calculate sGRB efficiency curve for Fermi and calculate

Fermi sGRB detection rate (cross check)

Fermi and Joint GW/sGRB detection rates – the percentage of BNS with sGRBs counterparts decrease as GW detectors become more sensitive

Look at 3G era

• See also complementary study led by • Nihar Gupte, Imre Bartos on DCC

Joint GW/sGRB detection rate

Assume Fermi GBM

All BNS can have associated sGRBs

BNS source rate evolution O2 BNS rate and standard assumptions

BNS detections - fold in GW BNS efficiency curves

Fermi and Joint GW/sGRB detection rates - fold in a Fermi detection efficiency curve (based on wide angled emissions suggested by EM observations of GRB170817)

• See also complementary study led by • Nihar Gupte, Imre Bartos on DCC

VLBI observations (HAS, VLBA, VLA, GBT)

Mooley et al, Nature 2018 constrained the evolution in size, shape, position of GW170817 and identified superluminal motion with milli-arcsec resolution

Observations (> 150 days) suggest successful jet breakout from a cocoon (consistent with structured jet model)

Choked jet cocoon scenario produces a shallower decay

The angular dependence on maximum detection distance

BNS rate to Fermi sGRB rate (assuming top hat)

Joint on-axis GW-BNS detection rate - fold a GRB detection efficiency model, FoV, DC etc

Howell, Ackley, Rowlinson et al 2018 in prep

Projected joint event rates 3G

Assuming 2G DRB detector (Fermi) – some instrument like Theseus (G. Stratta et al 2018) would be better

ETD - 19.62 ^{+35.62}_-15.30} /yr

CE - 22.39 ^{+40.64}_{-17.46} /yr

Late time radio observations of off-axes emissions

Lazzati et al, 2018

Cocoon (choked jet)/structured jet scenarios can be discriminated by late observations

indistinguishable until the peak time (~ 200-300 days) post-peak slopes are expected to differ – i.e. cocoon will have a shallower decay than jet models

Troja et al. 2018 (astro-ph:1801.06516 )

3 GHz

5keV

Fermi detection distance to SJ model

Less extreme Lazzati 2017 cocoon-jet breakout model (dashed) consistent with low θv edge up to around θv =20

Howell, Ackley et al 2018 in prep

On-axes low-luminosity burst

A dimmer LF lower limit requires a rate increase of 100 For consistency with the O2 BNS rate upper limit

requires an average on-axis beaming angle of > 24 deg sGRB Sample with observed jet breaks [3 – 8]deg

This scenario is disfavoured by the geometry Steep drop-off suggests low-probability Similar scenario exists when considering Epeak

GRB observed slightly off-axis

GBM: keV-30 MeV; 70% sky

LAT: 0.02-300 GeV ; 20% sky; 240 GRBs/yr (40s sGRBs) >10GeV photons detected

BAT: 15-150 KeV; 10% sky

XRT: arc min localisation >1000 GRBs (13% sGRBs) > 200 redshifts

Satellites for GW/GRB coincidence detection

Fermi

(2008-)

Swift

(late 2004-)

INTEGRAL

(2002-)

IBIS (Imager) ; 15keV-10MeV SPI (Spectrometer) SPI-ACS (AntiCoincidence Shield) surrounds SPI

75–2000 keV; all sky > 75 keV; 20 sGRBs/yr

Multimessenger pathways and end products

Chu, Howell, Rowlinson et al., MNRAS, 2015

Multimessenger Pathways associated with NS mergers

Chu, Howell, Rowlinson et al., MNRAS, 2015

GRB170817 with Theseus

SNR scaling

Scale SNR for untriggered against triggered using sky region and observation duration (P B. Patricelli et al 2016)

EM observations of GRB170817 BNS detection Rates sGRB detection rates

sGRB/GW detection rates

EM observations of GRB170817 BNS detection Rates sGRB detection rates

sGRB/GW detection rates