prospectsfor deteconofgravitaonalwavetransients)...

Prospects for Detec,on of Gravita,onal-‐Wave Transients with Advanced LIGO and Advanced Virgo

Patrick J. SuDon Cardiff University

for the LIGO Scien0fic Collabora0on and the Virgo Collabora0on

LIGO-‐G1500134-‐v1

Outline

•  Possible sources of GW transients •  Advanced GW detector 0melines •  Es0mated detec0on rates (neutron star binaries) •  Sky localisa0on capabili0es for EM followups •  Alert procedure & plans

13 Feb 2015 SuOon: RAS Transients Mtg (London) 2

Gravita0onal Waves

•  Tidal distor0ons in space

produced by 0me-‐varying quadrupole moments

•  Ideal source: rota0ng dumbells.


Credit: John Rowe Anima0on

Neutron Star & Black Hole Binaries

•  Coalescing NS-‐NS, NS-‐BH, BH-‐BH binaries emit GWs in 10-‐1000 Hz range in the last few minutes before merger. –  NS-‐NS rates: 10-‐8 y-‐1 Mpc-‐3 to

10-‐5 y-‐1 Mpc-‐3 –  O(1)/yr within 100 Mpc –  Most promising source for

LIGO / Virgo. –  Short GRB associa0on; e.g.

Tanvir et al. 2013, Berger et al. 2013


Credit: John Rowe Anima0on

J0737-‐3039 binary: John Rowe Anima0on

Galac0c core-‐collapse supernovae

•  Rate: 1/century •  GW emission uncertain

–  Core bounce: 1046 erg (kpc range), robust [eg OO CQG26 063001]

–  E.g. acous0c mechanism: 1050 erg (Mpc range), specula0ve [Burrows et al. ApJ640 878]


Sof Gama Repeaters

•  Rate: 1/decade •  EM emission: 1046 erg •  Energy available for GW emission:

–  Crust-‐cracking < 1047 – 1050 erg –  Magne0c rearrangement < 1045 – 1048 erg –  Ioka, MNRAS 327, 639, Corsi & Owen,

1102.3421


Long GRBs

•  Rate: 1/day/universe •  Collapsars / magnetar forma0on. •  GW emission specula0ve, possibly

strong –  Davies et al. 2002; Fryer et al. 2002;

Shibata et al. 2003; Kobayashi & Meszaros 2003; Piro & Pfahl 2007; Corsi & Meszaros 2009; Romero et al. 2010.


LIGO/Virgo conduct dedicated searches for these & other GW transients (both with & without EM counterparts).


Advanced LIGO Schema0c Harry, CQG 27 084006 (2010) larger,

beOer mirrors

extra op0cal cavity


LIGO-‐Livingston (USA)

Virgo (Italy) KAGRA (Japan)

LIGO-‐Hanford (USA)



KAGRA: first observing 2018

Virgo (Italy) KAGRA (Japan)

LIGO-‐Hanford (USA)

LIGO-‐India: proposal to install LIGO detector in India seeking approval from Indian cabinet. First observing c.2022+

Virgo: installa,on completes late 2015, first observing 2016

LIGO: installa,on complete! First observing late this year (Sept?)

Advanced LIGO Evolu0on


Aasi et al. 1304.0670

NS-‐NS average range

maximum range: x2

BH-‐NS binary: x2

Advanced Virgo Evolu0on


Aasi et al. 1304.0670

Plausible LIGO-‐Virgo Observing Schedule

Assumes NS-‐NS rate between 10-‐8 Mpc-‐3 y-‐1 and 10-‐5 Mpc-‐3y-‐1. Ranges double for 1.4 M¤ – 10 M¤ NS-‐BH binary.


Figure 5: Network sensitivity and localization accuracy for face-on BNS systems with advanceddetector networks. The ellipses show 90% confidence localization areas, and the red crosses showregions of the sky where the signal would not be confidently detected. The top two plots show thelocalization expected for a BNS system at 80 Mpc by the HLV network in the 2016–17 run (left)and 2017–18 run (right). The bottom two plots show the localization expected for a BNS systemat 160 Mpc by the HLV network in the 2019+ run (left) and by the HILV network in 2022+ withall detectors at final design sensitivity (right). The inclusion of a fourth site in India provides goodlocalization over the whole sky.

Estimated Number % BNS LocalizedRun BNS Range (Mpc) of BNS within

Epoch Duration LIGO Virgo Detections 5 deg2 20 deg2

2015 3 months 40 – 80 – 0.0004 – 3 – –2016–17 6 months 80 – 120 20 – 60 0.006 – 20 2 5 – 122017–18 9 months 120 – 170 60 – 85 0.04 – 100 1 – 2 10 – 122019+ (per year) 200 65 – 130 0.2 – 200 3 – 8 8 – 28

2022+ (India) (per year) 200 130 0.4 – 400 17 48

16

Aasi et al. 1304.0670

*

Sky localiza0on


network baselines

Fairhurst, CQG 28 105021 (2011)

detector bandwidth

�⇥ & 1�✓

100 Hz�f

◆ ✓10 ms

d

◆

•  Rough es0mate: 0me-‐of-‐arrival triangula0on between detectors.

•  Near the detec0on threshold:

Sky localiza0on

•  Refined analysis using amplitude phasing between sites: x 4 smaller area.

e.g.: Grover et al., 1310.7454


�⇥ & 1�✓

100 Hz�f

◆ ✓10 ms

d

◆



Two-‐detectors: 2015 run


Example sky posterior for one simulated NS-‐NS merger

Berry et al., 1411.6934

Sky localiza0on c.2016-‐17


Schema0c 90% error box areas for NS-‐NS binaries.

Aasi et al. 1304.0670

null sensi0vity

Sky localiza0on c.2019+ (design)


Aasi et al. 1304.0670

Sample 90% error box areas for NS-‐NS binaries.

Sky localiza0on c.2022+ (LIGO-‐India)


Aasi et al. 1304.0670

LIGO-‐KAGRA network qualita0vely similar. (Fairhurst 2011)

Plausible Observing Schedule


Aasi et al. 1304.0670

Estimated Number % BNS LocalizedRun of BNS within

Epoch Duration Detections 5 deg2 20 deg2

2015 3 months 0.0004 – 3 – –2016–17 6 months 0.006 – 20 2 5 – 122017–18 9 months 0.04 – 100 1 – 2 10 – 122019+ (per year) 0.2 – 200 3 – 8 8 – 28

2022+ (India) (per year) 0.4 – 400 17 48

Estimated Number % BNS LocalizedRun BNS Range (Mpc) of BNS within

Epoch Duration LIGO Virgo Detections 5 deg2 20 deg2

2015 3 months 40 – 80 – 0.0004 – 3 – –2016–17 6 months 80 – 120 20 – 60 0.006 – 20 2 5 – 122017–18 9 months 120 – 170 60 – 85 0.04 – 100 1 – 2 10 – 122019+ (per year) 200 65 – 130 0.2 – 200 3 – 8 8 – 28

2022+ (India) (per year) 200 130 0.4 – 400 17 48

5 ConclusionsWe have presented a possible observing scenario for the Advanced LIGO and Advanced Virgonetwork of gravitational wave detectors, with emphasis on the expected sensitivities and sky local-ization accuracies. This network is expected to begin operations in 2015. Unless the most optimisticastrophysical rates hold, two or more detectors with an average range of at least 100 Mpc and witha run of several months will be required for detection.

Electromagnetic followup of GW candidates may help confirm GW candidates that would notbe confidently identified from GW observations alone. However, such follow-ups would need todeal with large position uncertainties, with areas of many tens to thousands of square degrees.This is likely to remain the situation until late in the decade. Optimizing the EM follow-up andsource identification is an outstanding research topic. Triggering of focused searches in GW databy EM-detected events can also help in recovering otherwise hidden GW signals.

Networks with at least 2 detectors with sensitivities of the order of 200Mpc are expected to yielddetections with a year of observation based purely on GW data even under pessimistic predictionsof signal rates. Sky localization will continue to be poor until a third detector reaches a sensitivitywithin a factor of ⇠ 2 of the others and with a broad frequency bandwidth. With a four-sitedetector network at final design sensitivity, we may expect a significant fraction of GW signals tobe localized to as well as a few square degrees by GW observations alone.

The purpose of this document is to provide information to the astronomy community to facil-itate planning for multi-messenger astronomy with advanced gravitational-wave detectors. Whilethe scenarios described here are our best current projections, they will likely evolve as detectorinstallation and commissioning progresses. We will therefore update this document regularly.

The authors gratefully acknowledge the support of the United States National Science Foun-dation for the construction and operation of the LIGO Laboratory, the Science and TechnologyFacilities Council of the United Kingdom, the Max-Planck-Society, and the State of Niedersach-sen/Germany for support of the construction and operation of the GEO600 detector, and the ItalianIstituto Nazionale di Fisica Nucleare and the French Centre National de la Recherche Scientifique

17

Challenging! But see, e.g., Singer et al., ApJL 776 L34 “Discovery and redshiJ of an opKcal aJerglow in 71 square degrees: iPTF13BXL and GRB 130702A”

(90% confidence region)

GW Alerts

Advanced LIGO first science run: late 2015. •  Data will be analysed for BNS and other transient signals with few-‐

minute latency & prompt GW alerts will be released [Abadie et al. 1109.3498].

Phase 1 (first four detec0ons): •  Private: exchange of GW candidates with EM partners will be

governed by memoranda of understanding (MOUs). –  Currently about 60 partners. –  Next MOU cycle deadline: Feb 15 (Sunday). –  Workshop for MOU partners: April 23, Cascina.

Phase 2 (afer first 4 detec0ons): •  Public release of GW candidates.


Alert Mechanics

•  SKll under development – collaborator input welcomed! •  Minutes-‐scale latency analysis of data for transients (binaries,

generic bursts). –  Also hours-‐scale dedicated follow-‐ups of GRBs, SNEWS, and other

“external triggers”. •  Candidate GW event released afer basic vesng. Rate: TBD.

–  VOEvent format, distributed via private GCN. –  Updated alerts as refined sky posi0on informa0on or other

informa0on becomes available. –  Observing partners able to annotate GW database with informa0on

about follow-‐up observa0ons and possible counterparts. •  Tools s0ll under development; aim to exercise in next

engineering run (April/May).


Example Tool: “Skymap Viewer”


Summary

•  2015 – 2020 will be the early years of GW astronomy

•  Uncertainty in source rates mean first detec0ons could be early or late in this period.

•  GW source localisa0on depends strongly on the number and rela0ve sensi0vity of detectors, but always > several sq deg. –  Need both wide FOV and deep follow-‐up observa0ons across the EM spectrum: high energy (GRB & X-‐ray satellites), UV/visible/IR, radio.

–  EM alerts also need for triggering deep GW searches (short/long/low-‐luminosity GRBs, supernovae, magnetar flares, etc.)

–  Strong GW – astronomer collabora0ons to tackle needle-‐in-‐a-‐haystack problem.


Supplemental Slides


Sky localiza0on

•  Refined analysis using amplitude phasing between sites: x 4 smaller area.

e.g.: Grover et al., 1310.7454


network baselines

Fairhurst, CQG 28 105021 (2011)

detector bandwidth

HV

HL

LVV

S

S

L

H

LV

HL

HV�⇥ & 1�

✓100 Hz

�f

◆ ✓10 ms

d

◆



GWs as Astrophysical Probes

•  GWs trace the bulk mo0on of their source –  not scaOered / absorbed –  non-‐imaging (wavelength larger than source)

•  GW detectors are all-‐sky, low bandwidth. –  archival searches: easy. –  source localiza0on: hard.

•  Complementary to proper0es of photons.



LIGO-‐ India

LIGO-‐Hanford (USA) Virgo

(Italy) KAGRA (Japan)


The Global Network c. 2022

•  PaOern of chirp tells us chirp mass (≈0.01%)

•  May measure BH spin. •  Constrain beaming angle

from frac0on of GW detec0ons coincident with SGRBs.

What will advanced detectors tell us?

•  A characteris0c “chirp” GW coincident with short GRB:

•  Smoking gun proof for a

binary progenitor!

13 Feb 2015 SuOon: RAS Transients Mtg (London)

e.g., Finn & Chernoff, PRD 47, 2198 (1993)

t

hHtL

J Read / YITP

29

GWs + GRBs = cosmology •  Binaries are “standard

sirens” (candles) –  GW amplitude gives luminosity distance (≈10%) if GRB observed.

•  Side-‐step cosmological distance ladder. –  Measure H0 with to ~5% with 15 GW-‐GRB detec0ons.


Schutz, B. F. 1986, Nature, 323, 310 Nissanke et al., ApJ 725 496–514 (2010)

inclina0on-‐distance degeneracy from Nissanke et al. (2010)

30

Case study: GW 100916, “The Big Dog”


Sky map reconstructed by online processor (>130 sq deg)

Binary signal detected in LIGO-‐Virgo network on 16 Sept 2010

31

The Big Dog: EM Follow-‐up


Partner telescopes collected images from t0 + 44 min to t0 + 30 day.

No significant EM transients seen in preliminary analysis.

March 2011: Big Dog revealed to be a simulated GW added to the data as a test.

hOp://ligo.org/science/GW100916/

nearby galaxies

TAROT, ROTSE

SwiJ SkyMapper

Zadko

Zadko

32

Current EM Partners


GW Bursts: Frequency & Dura0on

05 June 2013 SuOon: GW Bursts (YKIS 2013) 34

C. D. OD, LIGO-‐G1000171

GW Burst Sources & Science Payoff


Core-‐Collapse Supernovae

SGRs/AXPs

NS/NS, NS/BH merger

String Cusps

Pulsar Glitches

Long GRBs

Short GRBs

NS Collapse

Unexpected

nuclear EOS / par0cle physics

NS Structure

Structure/Dynamics of Space0me

GRB Central Engine(s)

Core-‐Collapse Supernova Mechanism(s)

Exo0c Theories

SGR Mechanism

Pulsar Glitch Mechanism

Unknown Unknowns

C. D. OD, LIGO-‐G1000171

Burst Range (SNR≥20)


Reff '

G2⇡2c3

EGWS(f0)f 20 ⇢

2det

!1/2(1)

15 / 20 Sutton network analysis & GWBs

EGW=10-‐8 Mo

EGW = 10-‐2 Mo

PS, 1304.0210

AdV

H1 (2010)

aLIGO

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