Multi-Messenger Astronomy: New Perspectives in the Gravitational Wave and ElectromagneticSky. M.Branchesi

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1 Multi-Messenger Astronomy: New Perspectives in the Gravitational Wave and ElectromagneticSky M.Branchesi FIRB2012)RBFR12PM1F (Università di Urbino/INFN Sezione di Firenze)

2 Ground-based Gravitational Wave Detectors LIGO-Hanford (4 km) GEO (600 m) KAGRA Virgo (3 km) LIGO-India (2022+) LIGO-Livingston (4 km) LIGO and Virgo detectors are currently being upgraded and will observe the sky ( Hz) as a single network aiming at the first direct detection of GWs 2

3 Why the discovery of the EM counterpart signal NASA of a GW candidate event will be a key ingredient for maximizing the science return of GW observations? To consider the GW signal in its astrophysical context To give a precise (arcsecond) localization, identify host galaxy For a complete multi-messenger knowledge of the most energetic events in the Universe GW and EM provide insight into the physics of the progenitors (mass, spin, distance..) and their environment (temperature, density, redshift..) To fix location, distance, system orientation and gain sensitivity on intrinsic parameters like spin and mass estimates To constrain the NS equation of state (Maselli et al. 2014, Pannarale et al. 2014) To start the multi-messenger (GW and photon) astronomy NASA NASA LIGO

4 Expected transient GW sources detectable by LIGO/Virgo TransientGWsignal :signalwithduragoninthedetectorsensigveband significantlyshorterthantheobservagongmeandthatcannotberetobserved Coalescence of Compact Objects Core-collapse of Massive Stars Neutron-Stars and/or Black-Holes Inspiral Merger Ringdown BinarycontainingaNS: Inspiraldominantphase GWemissionenters sensigveband(>50hz) <20sbeforemerger EnergyemiEedinGW: ~10 42 M o c 2 O',C.2009,CQG,26 Energyemi'ed ingwuncertain: M o c 2 Ini%alLIGO/Virgo BinarycontainingaNS detectableto~50mpc likelyrate0.02yr 41 LIGO Ini%alLIGO/Virgo Detectablewithin afracgonofthe MilkyWay(10 kpc) O'etal.2013,ApJ,768 4

5 Electromagnetic emission Merger of NS-NS / NS-BH Core collapse of massive star Short Hard GRB Progenitorindica%ons: lackofobservedsn associagonwitholder stellarpopulagon largerdistancefromthehost galaxycenter(~5t10kpc) Gamma-Ray Burst 2sec Long Soft GRB Progenitorstrong evidence:observed TypeIcSNspectrum Kilonovae (Optical/IR, radio remnant) Supernovae Type II, Ib/c 5

6 LIGO-H Advanced Era GW-detectors (ADE) LIGO-L LIGO and Virgo detectors are currently being upgraded Virgo boost of sensitivity by a factor of ten (of 10 3 in number of detectable sources) Advanced era Detection rates of compact binary coalescences SourceLowRealHighMax yr 41 yr 41 yr 41 yr 41 (Abadieetal.2010,CQG27) Mass:NS=1.4Mo BH=10Mo Advancedera Skyloca%onandorienta%on averagedrange 197MpcforNSTNS 410MpcforNSTBH 968MpcforBHTBH Core-Collapse Supernovae GWTsignaldetectable<MilkyWay(OEetal.2012,Phy.R.D.) 244yr 41 EMTobservedwithin20Mpc fewmpc(fryeretal.2002,apj,565) RateofGWTdetectableeventsunknown LONGTGRBcoreTcollapse104100Mpc(Piro&Pfahl2007) (Fryer&New2011)

7 Abadieetal.2012,Phys.Rev.D,85 Upperlimitsontherateoflowmass compactbinarycoalescence totalmass2425mo MergerratesofBH4BH,NS4BH,NS4NS Ziosietal.2014,MNRAS,441

8 EM emission from transient GW sources

9 GRBs emission - Fireball Model Cataclysmic event Central engine NS-NS NS-BH merger Core Collapse Black Hole + accretion disk Magnetar millisecond magnetized (B> T) Neutron Star Rela%vis%c Ouelow Internalshocks Surrounding medium ExternalShocks Prompt emission ϒ-ray - within seconds Afterglow emission Optical, X-ray, radio - hours, days, months 9

10 Op%calaferglowsforasourceat200Mpc Off4axisGRB On4axisGRB hep://cosmo.nyu.edu/aferglowlibrary/index.html ByvanEerten&MacFadyen

11 X-RAY and Radio bands X-RAY: Short GRB at distance of 200 Mpc Swif4XRTFoV=0.16sq.degree Radio Short GRB : radio opgcal XTray Observed On4AxissGRB Synthe%c off4axisgrb Kanner et al. 2013, ApJ, 759 Shock breakout in SN Short (up to a few thousands seconds) and long (several days) X-ray flashes Fox et al. 2005, Nature 437 Radio emission from the 1) ultrarelativistic jet and 2) mild relativistic ejecta time scale for the peak weeks to months Radio precursor at low radio frequencies (Pshirkov & Postnov 2010)

12 Kilonovae Significant mass ( m o ) is dynamically ejected during NS-NS NS-BH mergers at sub-relativistic velocity ( c) (Piranetal.2013,MNRAS,430;Rosswogetal.2013,MNRAS,430) EM signature similar to Supernovae Macronova Kilonova shortlivedir4uvsignal(days)powered bytheradioacgvedecayofheavy elementssynthesizedintheejected ouelow Kulkarni2005,astro4ph ; Li&Paczynski1998,ApJL,507 Metzgeretal.2010,MNRAS,406; Piranetal.2013,MNRAS,430 RADIOREMNANT longlas%ngradiosignals(years) producedbyinteracgonofejected subtrelagvisgcouelowwith surroundingma'er Piranetal.2013,MNRAS,430 12

13 Source at distance of 200 Mpc Kilonovae Light Curves Red magnitude NS4BHPiranetal. NS4NSPiranetal. BlackbodyMetzger.etal. Fe4OpacityMetzgeretal Days NewsimulaGonsincluding lanthanidesopaci%esshow: broaderlightcurve suppressionofuv/oemission andshiftoinfraredbands Luminosity(ergs/s) Kilonovamodelaferglowpeaksabout adayaferthemerger/gwevent Major uncertainty OPACITY of heavy r-process elements M/Mo=10 42 Fe4Kilonova,β=0.1 r4process,β= Days Days Barnes&Kasen2013,ApJ,775 Magnitude Opaci%es: Fer4process 45 13

14 Possible HST kilonova detection for short GRB B after 9.4 days Tanviretal.2013,Nature,500 HST two epochs (9d, 30d) observations F606W/optical NIR/F160W Aferglowandhostgalaxyz= TimesinceGRB130603B(days) OrangecurveskilonovaNIRmodel ejectedmassesof10 42 Moand10 41 Mo Solidredcurvesaferglow+kilonova Cyancurvekilonovaop%calmodel AB4magnitude X4rayFlux(ergs 41 cm 42 )

15 Radio Flare Light Curves Fv[mJy]Fv[mJy] Source at distance of 300 Externalambientdensityn=1cm t(year) Dominatedbymildlyrela%vis%c ouelowv>0.3cnotincluded inthesimulagon expectedbrighteremission 150MHz 1.4GHz 150MHz Fpeak 0.241mJy tpeak 245years 1.4GHz Fpeak mJy tpeak 1.545years Piranetal.2013,MNRAS,430 External ambient density critical parameter n=0.1 cm -3 an order of magnitude fainter signals

16 EM signals from NS-NS/NS-BH merger and massive star core-collapse UltraTrelaGvisGc Γ>100ouelow On4axissGRB Off4axis GRB # Promptϒ4rayemission(beamed): GRBGWsearch GRBTriggeredanalysis # GRBaferglowemission,kilonovae: GWtriggerEMsearch Low4latencyEMfollow4up dynamicejecta v 0.1c Kilonovae Credit:Rosswog # Radioflares: GWtriggerradiosearch High4latencyfollow4up BlindradiosearchGWsearch Triggeredoff4lineanalysis

17 GW detection rate based on short GRB observations R GRB (<z)yr GW/on-axis short GRB detection rate All)skygamma)raymonitor 0.3shortGRBsperyear(NSTNSrange) 3shortGRBsperyear(NSTBHrange) Metzger&Berger2012,ApJ Redshifz1 aligo and Virgo NS-NS detection rate ShortGRBobserva%onsNS4NSmergerrate R NS4NS =R GRB /(14cos(θ)) R NS4NS Gpc T3 yr 1 (Cowardetal.2012) Gpc T3 yr T1 (Siellezetal.2013) TheoreGcalpredicGon Gpc T3 yr T1 (Abadieetal.2010) ALIGO/VirgoNS4NS detec%onrate(yr 41 ) GWdetec%onrate(0.2 40)yr 1 Cowardetal.2012,MNRAS, sgrbbeamingangle(degree)

18 Triggered analysis EM observations GW analysis 18

19 GRB prompt emission TRIGGERED GW SEARCH Known GRB event time and sky position: reduction in search parameter space gain in search sensitivity GW transient searches Unmodeled GW burst (< 1 sec duration) Arbitrary waveform Excess power Offsource Onsource Offsource Compact Binary Coalescence Known waveform Matched filter Background es%mate GRB trigger Background es%mate Analyzed 154 GRBs detected by gamma-ray satellites during while 2 or 3 LIGO/Virgo detectors were taken good data No evidence for gravitational-wave counterparts Abadieetal.2012,ApJ,760 19

20 GRB prompt emission - TRIGGERED SEARCH Non GW-detection result: lower bounds on the progenitor distance NumberofGRBs Unmodeled GW burst (150 GRBs) with 10-2 Moc 2 energy in GW (optimistic) burst150hz burst300hz Exclusiondistance(Mpc) NumberofGRBs Abadieetal.2012,ApJ,760 Binary system coalescence (26 short GRBs) NS4NS NS4BH Exclusiondistance(Mpc) Median distances: 7 17 Mpc Median distances: Mpc

21 Cumula%vedistribu%on Population exclusion on cumulative redshift distribution GRB prompt emission - TRIGGERED SEARCH Results & prospects for Advanced LIGO/Virgo Unmodeled GW burst (150 GRBs) x5grbs ~40Mpc~400Mpc x10sensi%vity ObservedSwifGRBs (Jakobssonetal.2012) redshif M o c 2 exclusion M o c 2 extrapola%on M o c 2 extrapola%on ~40Mpc~400Mpc x10sensi%vity ObservedSwif shortgrbs (Dietz2011) Detection is quite possible in the advanced detector era No detection will place relevant constraints on GRB population models Cumula%vedistribu%on x5grbs Abadieetal.2012,ApJ,760 Binary system coalescence (26 GRBs) NS4NSexclusion NS4BHexclusion NS4NSextrapola%on NS4BHextrapola%on redshif SeealsoAasietal.2014,PhRvL,113 21

22 Astrophysical non-detection results for single events Short GRB / GRB $ gamma-ray emission: GRB sky position overlaps with M31 (Andromeda, 770 kpc) GRB sky position overlaps with M81 (3.6 Mpc) $ Non detction of GWs from binary coalescence compact binary progenitor in M31excluded at 99% c.l. comapct binary progenitor in M81excluded at 98% c.l. $ Non detection of GW burst sets limits on emitted energy compatible with: soft gamma-ray repeater giant flare coalescence in galaxy more distant than M31/M81 IPNskyposi%on GRB Abbott et al 2008, ApJ, 681; Abadie et al. 2012, ApJ, 755 IPNskyposi%on GRB051103

23 Other EM Triggered GW Searches Soft Gamma Ray Repeaters & Anomalous X-ray Pulsars MagnetarswhichemithardX4ray/gamma repe%%ve0.1secflares(10 42 erg/s) &giantflares(10 47 erg/s) MaximumenergyavailableforGWs: CrustTcracking Moc 2 MagneGcrearrangement Moc 2 AbboNetal.2008,PRL,21110 AbboNetal.2009,ApJ,701 Abadieetal.2011,ApJ,734 Core-Collapse Supernovae EnergyinGW Moc 2 2T4yr T1 EMTobservedwithin20Mpc ChallengesinEM:nightly/weekly op%cal/x4raysurveyofnearbygalaxies LowTenergyneutrinos Pulsar glitches: suddenincreaseinthens rotagonalphase,frequencyor frequencyderivagvesobservableinradioand Vela gamma4raypulsars ExpectedenergyinGW: Moc 2 Abadieetal.2011PhRvD,83

24 Continuous GW signal Single Neutron Star GWcon4nuoussourcesemit quasi9periodicwaveswhosefrequency changesslowly GWamplitudeupperlimits from195knownpulsars Crablimitat1%oftotalenergyloss Velalimitat10%oftotalenergyloss Aasietal.2014,ApJ, alig/adv StrainSensi%vity Gravita%onalWaveFrequency(Hz)

25 Electromagnetic follow-up GW prompt EM observations

26 first Electromagnetic follow-up of candidate GW events Low-latency GW data analysis pipelines 26 GW transient searches Unmodeled GW burst (< 1 sec duration) Arbitrary waveform Excess power Compact Binary Coalescence Known waveform Matched filter enabled us to: 1) identify GW candidates in real time 2) obtain prompt EM observations Abadieetal.2012,A&A539 Abadieetal.2012,A&A541

27 LIGO-H LIGO-L GW triggers Sky Pointing Position EM facilities ESO Virgo Event validation NASA Search Algorithms to identify the GW-triggers Software to identify GW-trigger for the EM follow-up: select statistically significant triggers wrt background determine telescope pointing Abadieetal.2012,A&A539 Abadieetal.2012,A&A541 Evansetal.2012,ApJS203 Aasietal.2014,ApJS, min. 30 min. ADE latency expected to be improved

28 Sky Localization of GW transients The sky position of a GW source is mainly evaluated by triangulation based on arrival time delay between detector sites Binary coalescence localization in run low SNR signals were localized into regions of tens to hundreds of sq. degrees possibly in several disconnected patches Necessity of wide field of view EM telescopes Network SNR Abadie et al. 2012, A&A 539

29 Ground-based and space EM facilities involved in follow-up program EVLA Optical Telescopes (FOV, limiting magnitude) TAROT SOUTH/NORTH 3.4 deg 2, 17.5 mag Zadko 0.17 deg 2, 20.5 mag ROTSE 3.4 deg 2, 17.5 mag QUEST 9.4 deg 2, 20.5 mag SkyMapper 5.7 deg 2, 21 mag Pi of the Sky 400 deg 2, 11.5 mag Palomar Transient Factory 7.8 deg 2, 20.5 mag Liverpool telescope 21 arcmin 2, 21 mag X-ray and UV/Optical Telescope Swift Satellite XRT-FOV 0.16 deg 2 Flux ergs/cm 2 /s Radio Interferometer LOFAR MHz MHz Maximum 25 deg 2 EVLA 5 GHz - 7 arcmin 2

30 Additional priors to improve the localization accuracy and increase the chance to observe the EM counterpart To determine each telescope pointing position: The probability skymap of each GW trigger was weighted taking into account luminosity and distance of galaxies within the LIGO/Virgo horizon for binary containing a NS 50 Mpc Galaxy targeting strategy

31 Optical telescope 8 GW alerts Aasietal.2014,ApJS,211 Swift Satellite: XRT-UVOT 2 GW alerts Evansetal.2012,ApjS,203 Radio Interferometers LOFAR E-VLA 5 GW alerts 2 GW alerts Lazioetal.,2012IAUS,285 GW/EMtransientdataanalysisresults: $ Off4lineanalysisoftheGWdataaloneGWcandidatesshownoevidence ofanastrophysicalorigin $ EMtransientsdetectedintheimagesconsistentwiththeEMbackground

32 EM counterpart search Time domain astronomy 1 day Main steps: 1) Identification of all Transient Objects in the images 2) Removal of Contaminating Transients Main challenge due to the large sky area to analyze This requires a detailed knowledge of the transient sky for a rapid transient discovery and classification based on light curve/color/shape/..

33 Optical transient sky Exploration of the optical transient sky at faint magnitudes and short timescale has started recently, but it is still unknown.. Kasliwal2011,BASI,39 Optical contaminating transients: foreground - asteroids, M-dwarf flares, CVs, Galactc variable stars background - AGN, Supernovae For rate see Rau et al. 2009, PASP, 121 and for fast transient (0.5 hr 1d) see Berger et al. 2013, arxiv Transient X-ray and radio sky is emptier than the optical one X-ray contaminating transients: tidal disruption events, AGN variability Ultra-luminous X-ray Source variability, background GRBs For rate in the Advanced LIGO/Virgo Horizon see Kanner et al. 2013, ApJ, 774 Radio contaminating transients: Supernovae, AGN variability For rate see Mooley et al. 2013, ApJ,768

34 Advanced detector era observing scenario LSC&VirgoCollabora%ons,arXiv:

35 Advanced Detector Era Observing Scenario LSC&VirgoCollabora%ons,arXiv: Progression of sensitivity and range for Binary Neutron Stars Larger GW-detectable Universe 32

36 Sky Localization of Gravitational-Wave Transients HLV HLV BNSsystemat80Mpc BNSsystemat160Mpc HLV HLIV HLV Position uncertainties with areas of tens to hundreds of sq. degrees 90%confidencelocaliza%onareas X signalnotconfidentlydetected

37 Summary of plausible observing scenario LSC&Virgocollabora%on aligo/virgorange arxiv: Rate Localiza%on 37 AssumingBNSmergerrate of1x10 46 Mpc T3 year T1 37

38 End to end simulation of GW binary NS search and sky localization in the 2015 and 2016 science runs by Singer et al. arxiv: onlyLIGO Median90%CR about500deg LIGO4Virgo Median90%CR about200deg 2 Fast sky localization code (~minute scale) Parameter estimation code (~hours scale) SeeforBurstSearch Essicketal.arXiv: GRBX4ray/op%calaferglowkilonovaRadioaferglow Detec%onRapidLocaliza%onFullParameteres%ma%on

39 EM-follow up challenges: # Fast faint transient counterparts # Large GW error box difficult to be entirely observed many transient contaminants # Larger Universe observed by LIGO/Virgo EM-follow up key points: # How to set up an optimal observational strategy? to image the whole GW error box or the most propable galaxy hosts? # How to uniquely identify the EM counterpart? TIGHT LINK is required between GW/EM/Theoretical COMMUNITIES 39

40 Hierachical EM-follow up Search Wide-field telescope FOV >1 sq.degree Aasietal.2014,ApJS,211 Fast and smart software to select a sample of candidate counterparts Galaxytarge%ng? ELT VLT Larger telescope to characterize the candidates The EM Counterpart 40

41 Hierachical EM-follow up Search Wide-field telescope FOV > 1 sq.degree ELT VLT Fast and smart software to select a sample of candidate counterparts Larger telescope to characterize the candidates PTFdiscoveryandredshis ofop%calaferglow forthelonggrb over71sq.deg Singeretal.2013,ApJ,776L The EM Counterpart 41

42 LIGO-Virgo EM-follow up plan $ AgreedLVCPolicyforreleasingGWtriggers(dcc.ligo.org/M ,VIR40173A412) Un%lfirstfourGWeventshavebeenpublished,triggerswillbesharedpromptly onlywithastronomypartnerswhohavesignedanmouwithlvc $ OpenedcalltosignMoUfortheidenGficaGonofEMcounterpartsto GWtriggersfoundinthenextsciencerunsofaLIGO/Virgo,whichwillstart in2015deadline16feb,2014 $ AboutsixtyMoU from19countries about150instruments coveringthefullspectrum fromradioto veryhightenergygammatrays 8% 11% 8% 73% UV/OPTICAL/IR RADIO XTRAY GAMMATRAY

43 The multi-messenger photon and GW astronomy Photons+Theory OpGmalobservaGonalstartegies anddataanalysistodetectthe GWsourceanditsEMsignal

44 The multi-messenger photon and GW astronomy Photons+Theory ThemostenergeGc emissionmechanisms GRB/kilonovae PulsarSN SGR/Magnetars OpGmalobservaGonalstartegies anddataanalysistodetectthe GWsourceanditsEMsignal GWs+photons Necessarytoprobe Therates,spaGal distribugon,and demographyof compactobjects Abadieetal.2012

45 The multi-messenger photon and GW astronomy Photons+Theory ThemostenergeGc emissionmechanisms GRB/kilonovae PulsarSN SGR/Magnetars OpGmalobservaGonalstartegies anddataanalysistodetectthe GWsourceanditsEMsignal GWs+photons Necessarytoprobe +theory Necessarytounveil Thenatureand structureof compactobjects Torevealthe unknown exogcsources, newphysics Therates,spaGal distribugon,and demographyof compactobjects Abadieetal.2012 Toconstrain modelsofbirthand evolugonofcos

46 Some (Astro)Physical open questions..that need GWs, photons and theory to be answered: Are NS-NS and/or NS-BH merger progenitors of Short GRBs? What are the beaming angle of the GRB prompt emission, and the details of the energy radiation processes? Are NS mergers/kilonova able to explain the presence of elements heavier than iron in the Universe? How are BHs born and how do they evolve? What are their rates, mass and spatial distributions? What are the details of the mechanism through which SN explode? What is the EoS of matter in the interior of NS? Do gravitational waves travel at the speed of light? Does the graviton have mass?

47 EXTRA SLIDES 47

48 From VIRGO+ to ADVANCED VIRGO (AdV) Goal to realize a competitive detector joining the international network made by the two aligo and AdV SUPERATTENUATORS BEING UPGRADED Status of the AdV project construction well on track FIRST LARGE OPTICS First science data in 2016

49 LIGO recent progress Hugestepforwardtothe advancedligo FirstlockofLIGOLivingston inmay ThesensiGvitysurpassed theinigalligos Firstobservingrun expectedinthesecondhalf of