PoS(MULTIF2019)082 https://pos.sissa.it/ ∗ [email protected] Speaker. Multi-messenger astrophysics combines multifrequencymain astronomy with in non photonic the information electromagnetic carriers,vide gravitational do- waves, complementary neutrinos, information cosmic rays, about to cosmicdevelopments pro- in sources. the instrumentation The and present thetection first of paper a results reviews binary of the neutron multi-messenger star recent astronomy:Late merger and submission the of of de- high the energy contribution neutrinos at from Frontier Research a in cosmic Astrophysics source. - III (FRAPWS2018) ∗ Copyright owned by the author(s) under the terms of the Creative Commons c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Frontier Research in Astrophysics - III (FRAPWS2018) 28 May - 2 June 2018 Mondello (Palermo), Italy Rosa Poggiani Università di Pisa and Istituto NazionaleE-mail: di Fisica Nucleare, Sezione di Pisa High Energy Astrophysical Techniques PoS(MULTIF2019)082 ]. 94 Rosa Poggiani ]. Multi-messenger as- 110 ] and a binary neutron star system 5 1 The sensitivity of modern instruments is now allowing to investigate not only signals from The following sections will present the rainbow of the different astronomies that compose Multi-messenger astronomy relies on the detectability of the source emission with different The astronomical observations have been performed, for a long time, using the variety of A new age of multi-messenger astrophysics has started after the observation of the gravita- ] and the detection of the first high-energy neutrino from a source [ 11 astrophysical sources, but also backgrounds.background, but only Blazars a small can part explain ofare a neutrino closely background. tied, large Cosmic since fraction rays, the of gamma last rays two gamma and are ray neutrinos produced in the interactions ofmulti-messenger the astronomy. first ones. The variety ofmand information for different carriers instruments and and the differentenergy broad observational observatories techniques, energy routinely that ranges will provide de- be lightwill reviewed. curves be High presented: of GW150914, objects GW170817, and IceCube-170922A. sky maps. Some case studies instruments and on their coordination.physical The source discovery or of the appearance variability of indemanding a a new for known one high requires a observations energy rapid over astro- ation dissemination common of time of interval, the the event event type.facilities, for ranging The the from multi-messenger large follow-up telescopes observations to and involve provide interferometers the down the synergy to characteriza- of meter size large telescopes and [ small [ tronomy allows to investigate extreme environments andneutron compact sources stars, at binary all scales: black black holenation holes, and of different neutron probes star is mergers, thewaves active key. and, galactic In nuclei fact, if the etc. neutron mergersupernovae The of stars produces compact combi- are electromagnetic objects involved, emission produces gravitational electromagnetic andrical, low emission; gravitational energy waves; the neutrinos energetic cosmic stellar and,processes rays core if around produce not collapse compact neutrinos objects axisymmet- in in produce their electromagnetic interactions; radiation. accretion probes provided by the electromagnetic spectrum,rays extending and from gamma rays, the in radio the wavelengthssources context to of emit the multi-wavelength electromagnetic X- astronomy. radiation, The with majority themation of remarkable astrophysical carriers exception of belong black to holes. thelatest Other world infor- addition of to particle the physics:multi-messenger astrophysical astronomy cosmic probes probes rays, is different neutrino, gravitational physical dark radiation.of mechanisms astrophysical matter. contributing Each sources. to The information The the carrier combinationby knowledge of in the the ongoing observations surveys with over differentlogs, the probes containing whole is information electromagnetic completed about spectrum position, andthe fluxes, the variability spectra. building of of targets Time object and domain the cata- astronomytic, appearance investigates with of new supernovae sources. explosions, Cosmic andgamma rays rays with are and Active associated, neutrinos if Galactic are Galac- NucleiBeing produced neutral, if in these extra-galactic. probes the preserve interactions High the of information energy cosmic on the rays direction with of the the environment. originaltional source. wave emission from the mergers of a binary black hole [ High Energy Astrophysical Techniques 1. Introduction PoS(MULTIF2019)082 ], 72 GeV is quite ]. A spectral Rosa Poggiani 13 103 ] and, for ground based , left. High energy protons 78 3 ]. The attenuation length for 188 ], [ 97 . The background at higher energies is the 1 2 . The Cosmic Microwave Background (CMB) has 2 ]. The horizon is shown in Fig. 78 GeV [ 6 , right. eV, the GZK cut-off is expected [ 3 19 The most energetic radiation cannot be detected if it is produced beyond specific horizons. The various spectral regions provide information of different physical processes. The radio All electromagnetic observations face irreducible backgrounds. The measurements of the Ex- The Spectral Energy Distribution (SED) describes the flux/flux density/luminosity of an astro- as examples. steepening at about 10 protons is shown in Fig. High energy astrophysical photons interactExtragalactic with Background the Light Cosmic (EBL) Microwave Background (ultraviolet, (CMB), optical, the infrared) [ whose main results are summarized in Fig. target of the present X-ray andunresolved gamma active ray galactic nuclei. observatories and is believed to be mostly produced by detectors, also with the Earth atmosphere.sion The of soft the photon radiation background via produceson a the strong the pair suppres- source production redshift. process, thatlarge, The in depends photon particular both around absorption on 10 in the the photon energy energy and range from 10 to 10 been measured with high precision.of The the Cosmic zodiacal Optical light Background produced by isparable interplanetary degraded dust. intensity. by The the The Cosmic presence Infrared UV Background backgroundhydrogen, has is as a com- still shown partially by unknown, the due gap to in the the strong SEDs absorption in of Fig. region provides the signature of non thermal processes.of The astrophysical optical information, region, the probes source thermal ofin a processes. high large part energy The astrophysics main are physical non thermal. mechanisms involved tragalactic Background Light (EBL) over 20 decades in wavelength have been presented by [ Figure 1: SpectralBuilder Energy at Distribution https://tools.ssdc.asi.it/ of Crab (left) and TXS 0506+056; data from the SED and nuclei interact via photo-pion production, pair creation and redshift losses [ 1 physical source as a function ofthe energy/frequency/wavelength. combination The of construction of different a instruments SED operatingquires requires in their intercalibration. the The different SED regions of of Crab the and spectrum of and the blazar re- TXS 0506+056 are reported in Fig. High Energy Astrophysical Techniques 2. Astrophysical Messengers PoS(MULTIF2019)082 ]) 103 Rosa Poggiani ) as a function of 1 − sr 2 − (nW m ν I ν ] 3 72 eV, several orders of magnitude above the typical LHC ener- 20 ]). Right: proton attenuation length vs. energy (data from [ 78 , extends up to 10 4 =0.37 (data from [ 1 − The high energy electromagnetic radiation and cosmic rays can be detected with space based Cosmic rays are charged particles with an astrophysical origin. The spectrum of cosmic rays, the radiation wavelength in meters; data from [ gies. Cosmic rays incident on the Earth atmosphere include electron, protons and nuclei. Among Figure 3: Left: distance inbility Mpc of at e which the optical depth corresponds to a photon survival proba- instruments (direct detection) or groundthey based are instruments (indirect detected detection). throughgamma In the rays the produce, products latter via of case, pair production theiring and interactions high bremsstrahlung, an energy with electromagnetic photons, the showerhadronic contain- electrons atmosphere. interactions, and charged positrons. High and neutral energy Highcay pions, into energy nuclear muons protons fragments and and neutrinos, and while so nucleicontains neutral electromagnetic on; produce, pions sub-showers. charged decay via The pions into ground de- gamma basedgamma rays, detection thus rays of the and the hadron cosmic products shower of raysparticles high or uses energy fluorescence the radiation direct in detection the atmosphere. or on the Cherenkov radiation of3. charged Astrophysics with Cosmic Rays reported in Fig. Figure 2: Intensity of the extragalactic background reported as High Energy Astrophysical Techniques PoS(MULTIF2019)082 (3.1) ] 147 ]. Nearly Rosa Poggiani 147 eV [ 18 20 10 19 10 Ankle 18 10 2nd Knee 17 qBR the size of the acceleration region; the Larmour 10 [eV] R 4 E = 16 max 10 E Knee and the lateral distribution of the shower particles, using 15 10 µ 14 HEGRA Fly’s Eye Kascade Kascade Grande IceTop•73 HiRes 1 HiRes 2 Telescope Array Auger Grigorov JACEE MGU Tien•Shan Tibet07 Akeno CASA•MIA of an accelerated particle is defined by the Hillas criterion: 10 the magnetic field, max E B ]. The more energetic cosmic rays are believed to have an extragalactic 13 4 3 2 1 10

10

10 10 10

] sr s m [GeV F(E) E

•1 •2 •1 176 1.6 2.6 eV, and a steeper index up to the ankle energy, about 10 16 , the muon number N e is the charge, q The acceleration of Galactic cosmic rays, with energies up to the knee energy, is believed to The maximum energy With the exception of the low energy region where modulation by solar wind occurs, the where The Ultra High Energy Cosmic Rays are detected with ground based instruments that measure Figure 4: The all particle flux as a function of the energy per nucleon; adapted from [ occur via the Fermi acceleration mechanismgoverned at by the diffusion sites [ of supernova remnants. The propagation is 74% of the primary nucleons are protons, with about 70% of the rest are helium nuclei. origin, with a probable association with active galactic nuclei. energy spectrum of cosmic raysenergy, follows about a 10 power law with a spectral index of 2.7 up to the knee the products of theirflux interaction of the with more air energetic cosmic molecules,The rays showers the requires are the hadron reconstructed realization shower. using ofshower instruments three covering size The main large N techniques. rapid areas. drop The Air in Shower the Arrays measure the radius must not exceed the size of the accelerator. High Energy Astrophysical Techniques them, electrons, protons and some nucleierated (He, at C, O, the Fe) original are sources, consideredconsidered while primary secondary cosmic other cosmic rays nuclei rays. accel- (Li, Positrons Be, andincoming antiprotons B) cosmic are not rays also produced considered are by secondaries. affectedproducing nucleosynthesis The by an are the anticorrelation solar with wind, theaffected solar that by activity. deviated the the geomagnetic The field. lower less energy energetic cosmic component, rays are also more PoS(MULTIF2019)082 Rosa Poggiani ] shows the ankle feature 87 eV, as expected for a transition from a 3 . to detect cosmic rays in the energy region 18 2 ]. 105 to 10 5 2 ) is located in Argentina and consists of an array . 5 17 (Fig. ]. The results are in agreement with the results of the TA 1 151 ], [ 96 ], [ 2 depends on the mass of the primary nucleus, being larger for proton induced max Figure 5: The Auger Observatory; Credits: http://auger.org) X ]. The Surface Detector measures photons and charged particles at ground level, ]. 1 0.8 EeV and a flux suppression at higher energies. The chemical composition of ± 119 eV [ 17 0.06 ± https://www.auger.org/ Space based detectors target the composition of the less energetic cosmic rays and search for The cosmic ray spectrum measured by the Auger Observatory [ The Pierre Auger Observatory 1 antimatter in space. Thedetectors common that denominator are of routinely space found basedand at instruments a collider is magnetic experiments: the spectrometer a for combination calorimeterexperiments particle of for on tracking energy size and reconstruction and charge separation. massof of The the the constraints magnet payload of size. force space Transition the Radiation reduction Detectors of (TRDs) the are calorimeter used thickness to measure and the Lorentz factor Galactic heavy composition to anincreases extragalactic light with composition. energy The [ averageexperiment mass [ of primaries at 5.08 while the fluorescence detector monitors thehas longitudinal been evolution recently of completed air with shower. the Thethe addition observatory detection of of the radio emission Auger from Engineering air Radio showers Array [ (AERA) for cosmic rays is lighter in the range from 10 of 1660 water Cherenkov(Fluorescence telescopes Detector, (Surface FD), Detector, deployed over SD)above 3000 and 10 km 27 air fluorescence telescopes High Energy Astrophysical Techniques an array of detectorsinvolved deployed in over the large interaction areas. ofdetect shower The the particles other Cherenkov with radiation two the emitted techniquesthe atmosphere. by rely fluorescence the detectors The on high measure Cherenkov the energy the instruments charged radiation particles. fluorescence particles of of The nitrogen the molecules Cherenkov shower, excited radiation while isotropically, by is allowing the highly the charged collimated, lateral whileradio-frequency observation fluorescence emission of radiation showers. of is shower emitted shower A particle maximum recent via addition geosynchrotron is emission. the detection The of position of the showers than for nuclei induced showers. PoS(MULTIF2019)082 Rosa Poggiani 6 , center) instrument contains a magnetic spectrometer with a NdFeB 6 , left) is operating on the International Space Station (ISS). It hosts a large factor for protons and electrons of a given energy, improving the discrimina- , right) consists of a plastic scintillator strip detector (PSD) as anti-coincidence (Fig. 6 6 Γ 3 (Fig. (Fig. 2 4 https://ams.nasa.gov/ https://pamela-web.web.roma2.infn.it/ http://dpnc.unige.ch/dampe/ DAMPE AMS-02 The PAMELA 2 3 4 Figure 6: Direct cosmic ray detection in(credits: space: https://pamela-web.web.roma2.infn.it/), AMS-02 DAMPE (credits: (credits: https://ams.nasa.gov/), http://dpnc.unige.ch/dampe/) PAMELA detector, followed by asided Si-W silicon tracker-converter (STK), strip with detectors. sixconversion. Tungsten tracking The plates double STK are layers is mountedtion of followed in lengths, by single front made an of of imaging tracking BGO calorimetercalorimeter bars layers and with arranged STK for a tracker as photon thickness is an about of 33 hodoscope. about radiation lengths, The 31 the thickness radia- largest of for a the space combined based BGO calorimeter. magnet equipped with planes of doubleof sided microstrip the silicon incident trackers to particles, measure anshower the tails. trajectories electromagnetic The sampling ToF Si/W system consists calorimeter of and three a groups scintillator of segmented for scintillator the planes. High Energy Astrophysical Techniques of the particle, aseparation proxy of different of species. its energy. The combination of thepermanent above magnet measurements for allows the the more central than Tracker two that thousands double measures sidedon the microstrip scintillator curvature detectors. paddles of A aligned Time charged Of alongcles particles Flight orthogonal and (ToF) with directions system triggers based measures the the othermeasurement transit of detectors, time the allowing of antimatter the parti- discrimination. The TRD provides the tion of positrons against protons. Thelead Electromagnetic and scintillating CALorimeter fiber (ECAL), layers made (total oftion thickness alternating of of 16 the radiation shower lengths) shape, provides areconstruction allowing 3D of the reconstruc- the separation direction of of positron the and incoming proton particle induced with a showers precision and of the a few degrees. PoS(MULTIF2019)082 , right). 9 Rosa Poggiani , XMM-Newton K (white dwarfs, 5 7 (Fig. 10 to 10 6 will use silicon pore optics for photon 8 , left) and Swift-BAT 9 7 (Fig. 9 . 7 ). The future instrument ATHENA 8 (Fig. 7 ), an array of concentric paraboloid mirrors where X-ray photons undergo reflection with a 8 The most common detectors in the focal plane of X-ray telescopes are CCDs, that detect The telescopes for hard X-rays, about 100 keV, cannot rely on photon focusing and use coded http://chandra.harvard.edu http://sci.esa.int/xmm-newton/ http://www.russianspaceweb.com/spektr-rg-erosita.html https://www.the-athena-x-ray-observatory.eu/ https://www.cosmos.esa.int/web/integral https://swift.gsfc.nasa.gov/ The X-ray Universe includes thermal sources with temperatures of 10 The sensitivities of different X-ray and gamma ray instruments that will be described in the 5 6 7 8 9 10 , eROSITA individual X-ray photons, recording their arrivalintrinsic time, energy position and resolution energy. capability CCDsfound for for in X-rays spectroscopy. have optical spectrographs are GratingNewton. used ATHENA configurations will for use similar achieving X-ray to Integral high Field resolution, those Units. as in Chandraaperture and masks, XMM- where radiationand enters transparent the sections producing instrument a shadow: throughThe sources a are solution extracted mask has with been with deconvolution adopted techniques. a in INTEGRAL pattern of opaque 6 focusing. very small angle with respect to thethe surface, radiation followed onto by an a array focal of plane. hyperboloid mirrors The that focus solution has been adopted in the Chandra Figure 7: Pointhttp://eastrogam.iaps.inaf.it/) source continuum sensitivity of X-ray and gamma rayneutron stars, instruments supernova remnants, (credits: stellar coronae,sars, galaxy supernovae, clusters) active and galactic non nuclei). thermalquires sources operation The (pul- in detection space, of sincecused X-rays the from with atmosphere astrophysical refractive is sources elements, opaque re- (Fig. to the X-rays. soft X-rays Since X-rays are cannot detected be using fo- grazing incidence telescopes following is shown in Fig. High Energy Astrophysical Techniques 4. X-ray and gamma ray astronomy PoS(MULTIF2019)082 . 10 Rosa Poggiani ]. Polarimetric 55 . 12 , eXTP 11 8 ]. Future missions include IXPE 55 X-ray polarimetry can provide information about strong gravity sources [ https://ixpe.msfc.nasa.gov/ https://www.isdc.unige.ch/extp/ X-ray observatories routinely provide all sky maps and long term light curves of objects. As The energy region from 1 MeV to about 30 MeV is still relatively unexplored, despite its 12 11 Figure 8:XMM-Newton Grazing incidencehttp://www.russianspaceweb.com/spektr-rg-erosita.html) (credits: telescopes: Chandra (credits: http://chandra.harvard.edu); http://sci.esa.int/xmm-newton/); eROSITA (credits: an example, the map produced by Swift-BAT in the 105 months sky survey is show in Fig. Figure 9: Coded mask telescopes:and INTEGRAL Swift-BAT (credits: (credits: https://www.cosmos.esa.int/web/integral) https://swift.gsfc.nasa.gov/) relevance for nuclear processes, thekeV physics line of from Gamma positron annihilation. Raythat rely Bursts on The and the MeV Compton the scattering region to signatureA is estimate of Compton the investigated energy telescope the using and consists the 511 Compton direction of telescopes, ofwhile two the detector incoming the photon. arrays. bottom The one toptop is one detector is made made and with with are an aCompton absorbed low high interaction Z in is Z material, measured the material. by the bottomscattered first Gamma one. photon detector, is often rays measured a The undergo in plastic the energy scintillator. scatteringmeasured bottom The transferred in energies detector, energy a allow to of the scintillating to the the crystal estimate or electron the a in Compton semiconductor. The scattering the angle. The COMPTEL telescope on High Energy Astrophysical Techniques instruments are based on Compton scattering, Bragghard scattering and or soft photoelectric X-ray effect, regions covering [ the PoS(MULTIF2019)082 Rosa Poggiani . The energy interval from the 11 9 . 13 http://eastrogam.iaps.inaf.it/ Gamma ray astrophysics is particularly suitable to probe the mechanisms of particle acceler- 13 ation. Astrophysical gamma raystechniques needed, span the a range broad is split energyHigh into Energy range. (HE, different the energy GeV bands: Due region) and Low toMeV, Very Energy High pair the (LE, (VHE, production TeV 0.1-100 different and becomes MeV), above). instrumental the For energies dominantconversion above telescopes. mechanism some for The photon direction detection, andby leading the combining to energy the the tracking of pair of the the incident direction gamma of ray motion are of reconstructed the pair and the energy measurement with Figurehttps://https://www.sron.nl/missions-astrophysics/past/cgro-comptel) 11: Schematics of the Compton telescope COMPTEL (credits: Figurehttps://swift.gsfc.nasa.gov/results/bs105mon/) 10:board of the Compton Gamma Ray Observatory is Swift-BAT shown in Fig. 105 months all-sky survey (credits: High Energy Astrophysical Techniques region covered by COMPTEL to theObservatory low energy side is the target of the proposed e-ASTROGAM PoS(MULTIF2019)082 Rosa Poggiani , right) includes twelve 12 (Fig. ], whose extragalactic counterpart 15 25 10 , left) uses a tracker made of layers of an absorbing 12 ). 13 (Fig. 14 ] (Fig. 27 https://glast.sites.stanford.edu/ https://fermi.gsfc.nasa.gov/science/instruments/gbm.html The low rates of gamma ray fluxes above one hundred GeV preclude the use of space based in- An an example of gamma ray astronomy, Fermi-LAT has measured the diffuse gamma ray 15 14 can be explained by blazars [ Figure 13:https://fermi.gsfc.nasa.gov/science/eteu/diffuse/) Diffuse gammastruments, whose effective areas ray are relativelyobserving small. the The electromagnetic emission most cascades energetic gamma producedrection rays in of are the the observed detected incident interaction gamma with ray is the estimated atmosphere. from by the The direction di- of the shower, while Fermi-LAT the energy of (credits: background in the region between 100 MeV and 820 GeV [ Figure 12: Fermi-LAT (left, credits:https://fermi.gsfc.nasa.gov/science/instruments/gbm.html) https://glast.sites.stanford.edu/); Fermi-GBM (right, credits: sodium iodide (NaI) scintillators andregions two from bismuth germanate a (BGO) few scintillators, keVtors sensitive provide to burst in triggers 1 the and MeV localization,those and while the of from BGO NaI 150 detectors at have low keV a energies sensitivity to and overlapping of 30 the MeV, Fermi-LAT respectively. at high The energies. NaI detec- material with high atomic number andreconstruct silicon the strips x,y arranged coordinates along of twois orthogonal the measured directions electron/positron by that in a each cesium layer. iodide The calorimeter. energy The of Fermi-GBM the particles High Energy Astrophysical Techniques a calorimeter. The Fermi-LAT PoS(MULTIF2019)082 . 16 Rosa Poggiani ). 15 . 19 11 are examples of Cherenkov telescope arrays operating in the energy 17 and MAGIC 16 will cover an energy range from 20 GeV to 300 TeV, with 40 medium size telescopes (100 18 https://www.mpi-hd.mpg.de/hfm/HESS/ https://magic.mpp.mpg.de/ https://www.cta-observatory.org https://www.hawc-observatory.org/ The second approach is the use of detectors distributed over large areas, to probe the number of The TeV sky presently contains more than two hundred sources (Fig. The spectrum of neutrinos encompasses aAstrophysical broad neutrinos range from of the energies, Sun as or shown supernovae in are Fig. in the MeV energy range and are pro- 17 18 19 16 Figure 14:https://www.eso.org/public/teles-instr/paranal-observatory/cta/ MAGIC (left, credits:particles reaching https://magic.mpp.mpg.de/); ground, proportional to the energydetector of CTA is the incident the gamma water (right, ray. Cherenkov, The whereproduce most particles common Cherenkov with radiation. credits: a An speed example larger is then the the HAWC experiment Cherenkov threshold duced in nuclear reactions. The detection of neutrinos from the Sun by the Homestake experiment 5. Neutrino Astrophysics High Energy Astrophysical Techniques the gamma ray is proportional tomeasured the with two number different of techniques. particles The insion first the produced approach shower. is by The the the shower detection electrons properties of andTelescopes the are positrons Cherenkov (IACT) in emis- are the reflectors shower. The equippedsignal Imaging is with Atmospheric highly Cherenkov photon collimated, detectors with anglesof at of the their the order order focii. of of a oneused The degree, few to Cherenkov and ns. discriminate very the short, The signal with from shortis a the duration proportional duration sky and background. to the The the high intensity numberray. of collimation of HESS the of particles Cherenkov the radiation and Cherenkov is flashband a from are proxy 30 GeV of to thetory 10 energy TeV, with of reflector the diameters progenitor upGeV-10 gamma to TeV) over 30 two meters. sites, The 810 future large TeV). CTA telescopes observa- The (below observatory 100 will GeV)in and be the 70 split, Southern small one. with telescopes 19 Theshowers (above produced main instruments by background in cosmic in the rays, ground Northernfrom that based hemisphere protons include gamma electromagnetic and and ray subshowers. nuclei 99 detectors contain The isThe hadron given pions electromagnetic showers by and and the hadron heavy showers particles,hadron are in showers discriminate addition have on a to the larger electron basis angular and spread of compared their positrons. to morphology, the since electromagnetic showers. PoS(MULTIF2019)082 ], Baikal 36 and KM3Net Rosa Poggiani 20 ]) 175 ]. ANTARES 24 ], [ 102 ]. The detection of energetic neutrinos 40 ] experiments. ], [ 45 102 12 ], [ 118 ]. Neutrinos from the supernova SN 1987A were observed ] and Baksan [ 77 100 ], IMB [ 104 Figure 16: The neutrino energy spectrum (data from [ Figure 15: The TeV sky (credits: http://tevcat.uchicago.edu/) ], the South Pole based detector IceCube [ 30 High energy neutrinos with energies in the GeV range or above are produced in the interac- http://antares.in2p3.fr/ ], KM3Net [ 20 57 tions of protons orsources ions of with cosmic rays, matter. since they Energetic aretrino not neutrinos astrophysics deflected have are by been magnetic a presented field. suitable by Reviews of probe [ high to energy neu- reconstruct the triggered the solar neutrino problem [ [ by the Kamiokande II [ requires large volume detectors, typicallythe water charged or particles ice, (usually muons) for produced measuringis in the given the by Cherenkov neutrino the interactions. radiation showers of Theoccurs main produced background inside by the cosmic detector rays or andvolume is from detector reduced the is by Earth at requiring direction. aatmospheric that great In neutrinos, the depth addition, that interaction in the are ice not sensitive orcidence part shielded in with of by water. muons. the the Cosmic Currently large Earth ray operating and showers and can contain future be neutrinos, instruments rejected the include by ANTARES looking [ at coin- High Energy Astrophysical Techniques PoS(MULTIF2019)082 Rosa Poggiani . 18 ] is shown in Fig. 4 13 consists of about one cubic kilometer of ice at depths ranging 22 ) 17 Figure 18: The IceCube sky (credits: https://icecube.wisc.edu/) Figure 17: The IceCube detector (credits: https://icecube.wisc.edu/) ]. IceCube is able to detect all neutrino flavors, that exhibit different signatures. Muon 24 ], whose spectrum can be described by a broken power law with a break at around 200 108 The detection of neutrinos from the blazar TXS 0506+056 is discussedhttps://www.km3net.org/ in detail inhttps://icecube.wisc.edu/ Section IceCube has observed a diffuse flux of neutrinos in the energy interval from 100 TeV to 1 PeV . 22 21 rely on the Cherenkov effect of charged particles produced in neutrino interactions in deep water. ], [ 3 10.3 TeV. The all sky map built using 10 years of data [ [ neutrinos interacting via the chargedflavors current produce reaction showers. produce The a arrival Cherenkovtracks direction track, and can abut while be ten the degrees reconstructed other or at more the for level showers. of one degree for The IceCube detector (Fig. High Energy Astrophysical Techniques 21 from 1.4 to 2.4 km at86 strings the [ South Pole, equipped with 5160 optical photomultipliers arranged along PoS(MULTIF2019)082 3 1 ], 24 − − 9 y 3 ], [ − 8 ] and was ], [ 7 11 Rosa Poggiani ), that so far has 19 and Advanced Virgo 23 , left) with distances rang- ]. During the first run (O1) ]. The detected binary black 20 ]. An extensive search with , right), while black holes in 21 21 21 20 (Fig.

M 6 9 . . 15 10 + − for binary black holes and below 610 Gpc 14 1 ]. The estimated merger rates are 110-3840 Gpc − and 85.1 y 21

3 − M 7 1 . ]. The majority of the detected black holes have low spins . . 0 3 Mpc [ − + 21 10.2 1350 1320 + − ] was followed by the detection of the similar events GW151226 [ 5 Mpc to 2750 120 110 + − Figure 19: The gravitational wave spectrum (credits: http://gwplotter.com/) The first binary neutron star merger, GW170817, occurred on 2017 August 17 [ https://www.ligo.org/ http://www.virgo-gw.eu/ The third LIGO-Virgo observing run (O3) started on April 1, 2019 and several candidate merg- The discovery of gravitational waves from the binary black hole merger GW150914 announced The gravitational wave spectrum extends over a broad frequency band (Fig. for binary neutron stars, 9.7-101 Gpc ] and GW170729, GW170809, GW170818 and GW170823 [ 24 23 1 − 10 interferometers, a network of three groundfew based Hz detectors to operating some in kHz. the frequency range from a [ three different algorithms for coalescing compactmass binaries with in component the masses above O1 one andproduced solar the O2 first observing Gravitational runs Wave Transient ofthree Catalog, binary the GWTC-1 black advanced hole [ mergers gravitational were wave detected.tron detector star During merger the network and second has seven observing binary run black (O2) hole a mergers binary were neu- detected [ ing from 320 y X-ray binaries can have very large spins. followed by the short Gamma Ray Bursttion GRB triggered 170817A a after multi-messenger 1.7 campaign seconds. overThe The the multi-messenger gravitational electromagnetic detec- observations spectrum of and GW170817 withtrophysics and neutrinos. are the discussed impact in on Section fundamental physics and as- or misaligned spins with respect to the orbital momentum (Fig. ers have been detected. The LIGO-Virgo alerts and event maps in O3 are public. The gravitational been explored only in the high frequency region by the Advanced LIGO by LIGO in 2016 [ holes have total masses between 18.6 High Energy Astrophysical Techniques 6. Gravitational Astrophysics for neutron star-black hole systems [ PoS(MULTIF2019)082 ] 46 and 25 ]. The 158 Rosa Poggiani ]. ]. There are sev- 168 has completed con- 147 [ 27 will have 10 km arms, ]. The Cosmic Explorer 3 − 28 169 . 29 ] 15 . The number of gravitational wave 26 15 ]) 21 ] and suggests the presence of a dark halo. The estimated local Dark 163 ], that will be sensitive to resolved binaries, massive binary black hole mergers, 112 The very low frequency region will be explored by the space based interferometers LISA [ The evidence for Dark Matter was initially suggested by astrophysical observations of the https://gracedb.ligo.org https://gcn.gsfc.nasa.gov/ https://gwcenter.icrr.u-tokyo.ac.jp/en/ http://www.et-gw.eu/ https://cosmicexplorer.org/ https://www.elisascience.org/ The third generation ground based interferometers are expected to be operative after 2030, 26 27 28 29 30 25 and TianQin [ galactic rotation curves, wheredecreasing the with rotation radius velocity [ becomes approximately constant instead of cryogenic LIGO Voyager will operate in the same(CE) LIGO will infrastructure have [ 40 km arms and one cryogenic silicon detector30 [ 7. Dark Matter Matter density in the Eartheral neighborhood candidates is for of Dark the Matter, order that of must have 0.4 weak GeV interactions cm with electromagnetic radiation, but also to the finalground stages based of interferometers the in merger multifrequency gravitational of wave stellar astronomy black [ holes, that could trigger the operation of improving the sensitivity by oneof order suspensions) of to magnitude, reduce relying the to cryogenics thermal (test noise. masses and The part Einstein Telescope distributed by the Gamma-Ray Coordinateobservatories is Network steadily GCN increasing. Thestruction and Japanese is KAGRA expected interferometer to joinfor LIGO the and beginning Virgo during of the next O3 decade. run. India has planned LIGO India will be operated underground to reduce seismic noise and with cryogenic suspensions [ Figure 20: Masses (left) ans spinsO2 (right) of observing the runs binary (adapted mergers from detected [ by LIGO/Virgo during O1, event candidates are stored in the Gravitational Wave Candidate Event Database GraceDb High Energy Astrophysical Techniques PoS(MULTIF2019)082 , ]. ]. 33 61 149 ], [ ]. If the ]. Sterile 83 148 122 Rosa Poggiani ], [ eV [ µ 89 ]. Baryonic matter ], that has not been ], [ 66 , using radio pure NaI 65 62 32 , detectors must be massive. 1 − kg ], whose presence can be detected 1 − 143 ] the strongest candidate so far. The WIMPs ]. Primordial black holes, formed before Big ]. ] and could be detected through the mixing with 113 16 182 164 124 ], [ 39 (440 g Ge). The DAMA/LIBRA Collaboration 31 ] and that the GW150914 event could be pointing to this class of dark matter [ 67 ]. It has been suggested that primordial black holes could give a relevant contribution to 43 https://cogent.pnnl.gov/ http://people.roma2.infn.it/ dama/web/home.html https://www.science.purdue.edu/xenon1t The WIMPs are particles with a mass in the range 10 GeV to some TeV, with the lightest The axion particles have been proposed to solve the strong CP problem in QCD [ Different detector strategies have been adopted. Semiconductor detectors have been used in ]. Liquid noble gas detectors usually rely on the detection of two physical effects, the scin- 32 33 31 60 tillation and the ionizationof in XENON the detectors liquid at to Gran separate Sasso of has nuclear evolved from and 10kg, electron 100 recoils. kg to The one family ton, in XENON1t supersymmetric particle (LSP), the neutralino [ They can be detected through theexcluded axion the to range photon of conversion axion-photon process. couplings in Theneutrinos the ADMX mass are experiment range expected has from 2.66 to to have 2.81 keV masses [ confirmed by other X-rayBang observatories Nucleosynthesis, [ are strongly constrained as Dark Matter candidates [ through the microlensing, butsurvey strong [ limits have been set, see e. g.Stellar mass the black results holes of alonegravitational the are wave MACHO event not GW150914 able was toexpected produced reproduce merger by all rate the dark exceeds merger matter theblack of [ holes rate primordial are estimated black a by small holes, fraction gravitational the of observations, dark unless matter primordial [ are expected to be gravitationally trappedwhose inside average galaxies value with at a the MaxwellianThe Sun velocity position main distribution, is physical of process thenuclei. order used Since of predictions for a for the few the WIMP hundredsa direct masses kilometers recoil range detection per energy from second. of 10 from GeV WIMPs 1is to is to 10 exponential, TeV, with the 100 the nuclei a keV, elastic will demanding larger have WIMPs mean for scattering is for low on more spin threshold massive independent detectors. WIMPs. orthe spin The nuclear The cross spin dependent, recoil factor, section scaling spectrum respectively, for thus as onfor high the mass relativistic detectors. square nuclei Since of such the as the Xenon expected nucleus are rates mass the are and chosen below on materials 1 event day dark matter [ standard neutrinos, that leadsthat to is a one radiative half decaythe of with X-ray the monochromatic stacked neutrino photons spectra mass. with of an galaxy There energy clusters is secured an with XMM-Newton astrophysical [ evidence for a 3.5 keV line in the CoGent experiment High Energy Astrophysical Techniques among them axions, sterile neutrinos, primordialticles black (WIMPs). holes and Weakly Interacting Massive Par- could exist as MAssive Compact Halo Objects (MACHOs) [ The background is reduced using radioare pure expected materials and show placing a detectors dailydetected underground. forward/backward recoils. WIMPs recoil asymmetry and an annual modulation of the scintillators, has claimed a signal[ in a 13 year observation, with the predicted annual modulation PoS(MULTIF2019)082 ]. 38 Rosa Poggiani detector relies on . On the other hand, 36 38 , 21 ]. Other detector operating with 47 and EDELWEISS 37 ], is shown in Fig. (500 kg). The DarkSide 35 166 17 ], among them the TeV source HESS J1745-290 [ 28 relies on scintillation to discriminate against background. 39 (370 kg) and PandaX 34 ]. The Fermi-LAT observations have constrained the annihilation of WIMPs in dwarf ]. ]) 26 106 166 Since the interaction rate depends on the interaction cross section and on the WIMP mass, the http://luxdarkmatter.org/ https://pandax.sjtu.edu.cn/ http://darkside.lngs.infn.it/ https://supercdms.slac.stanford.edu/ http://edelweiss.in2p3.fr/ https://www.cresst.de/ In addition to direct WIMP searches, there are several approaches for indirect searches. WIMPs 35 36 37 38 39 34 galaxies [ limits on dark matter areThe usually experimental presented status as of the contours art, in according the to cross [ section vs. WIMP mass plot. the cryogenic detector CRESST An excess of GeV gammahilation rays [ around the Galactic center have been explained with WIMP anni- can annihilate producing Standardneutrinos. Model particles, WIMPs could such be as deceleratedability gamma and of rays, annihilation trapped and antiprotons, in producing the positrons, muonand Earth neutrinos, or IceCube. potentially the detectable Other Sun, by indirect increasing SuperKamiokande astrophysical the searches sources: prob- for the halo, dark the matter Galacticcess are center, is dwarf searching made galaxies. difficult for The by search gamma the presence for rayscenter of gamma hosts astrophysical produced rays backgrounds. ex- several in The gamma region ray around sources the Galactic [ Figure 21: The parameterdashed line space is for the spinfrom irreducible independent [ neutrino WIMP-nucleon floor cross from section, coherent where neutrino-nucleus the scattering (adapted liquid Xenon are LUX the principle of a twoand phase the liquid ionization argon produced Timeatures by Projection using recoiling Chamber, the nuclei. that simultaneous detects measurement Otherbetween the of nuclear detectors scintillation ionization and operate electron and recoils, at phonons, like milliKelvin to SuperCDMS temper- provide discrimination High Energy Astrophysical Techniques which set the best constraints on the interaction cross section [ PoS(MULTIF2019)082 41 are ) − e (LSST) + 43 + e ] show a rise Rosa Poggiani ( / 34 + e ], [ 33 . Sky surveys, differently 40 is producing the most accurate ] are consistent with the standard 42 35 ] and AMS02 [ ], [ 32 and the positron ratio p 31 / p 18 ]. The Data Release DR2 has provided the position, 90 (left and right). The data of PAMELA [ 22 https://www.eso.org/public/teles-instr/paranal-observatory/vlt/ https://www.sdss.org/ http://sci.esa.int/gaia/ https://www.lsst.org/ New instruments are about to enter operation. The Large Synoptic Space Telescope Optical astronomy plays a relevant role in high energy astrophysics: the detections of new tran- While the elemental composition of cosmic rays is dominated by protons and nuclei, there is ]. 41 42 43 40 63 from targeted astronomical observations ofabout one a or large a number few oficated objects, sources observations. provide or systematic Surveys some provide information class catalogsare of of in objects, the any that sky case could and necessaryphysical become discover to properties unexpected the begin of transients, subject any sources and of other detected ded- abundances, investigation. in radial imaging velocities Spectroscopic or surveys, surveys redshift providing investigate for their(SDSS) the extragalactic characterization, has sources. produced The with multiband Sloan imaging Digital of Skythree one Survey million third astronomical of objects. the The sky astrometry andthree mission secured dimensional Gaia spectra map for of more the than Milky Way [ 8. Optical and Radio Astronomy sients are cross-checked against existing catalogsto and search archives for for an possible accurate progenitors. skytures localization Present as and optical large astronomy as involves ten large meters, telescopes such with as aper- the Very Large Telescope (VLT) Figure 22:https://tools.ssdc.asi.it/CosmicRays/ The antiproton to proton and the positron ratios; data from proper motion, multi-band photometry, radial[ velocities and parallaxes for nearly 1.7 billion stars reported in Fig. of the positron fraction above 10models GeV. The for observations production [ and propagation of cosmic rays. also a fraction of antiparticles,of positrons dark and matter particles. antiprotons, The that antiproton could to be proton related ratio to ¯ the annihilation High Energy Astrophysical Techniques PoS(MULTIF2019)082 ] 56 (ZTF) [ Rosa Poggiani 47 is the aperture ] scheduled for D 91 , where D / λ ∼ aims to produce a fast sky survey will be a folded Ritchey-Chretien 49 46 ] presently consists of a network of 24 157 [ 48 ]. The detection of transients relevant for high 93 19 is the distance between the interferometer elements. The Very Large B ]. The instrument will be a fully steerable five mirror system, providing 92 , where (E-ELT) is a future 40 m class instrument that will become the largest optical/IR B 45 / will observe sky patches of about 400 square degrees every month, surveying each observatory in Chile includes fifty four 12 meter diameter antennas whose distance λ 44 51 ∼ (VLA) has a Y-like configuration, with nine 35 m parabolic dishes on each arm whose 50 Present radio astronomy is strongly focused on interferometry, combining several individual http://sci.esa.int/euclid/ https://www.eso.org/public/teles-instr/elt/ https://www.tmt.org/ https://www.ztf.caltech.edu/ http://www.astronomy.ohio-state.edu/ assassin/index.shtml http://observ.pereplet.ru/ https://science.nrao.edu/facilities/vla https://www.almaobservatory.org/en/home/ The James Webb Space Telescope (JWST) is a space based telescope [ Smaller telescopes will still play a role, since they are able to provide long term monitoring of Planned instruments will have apertures in the range 30 to 40 meters. The European Extremely ]. 44 45 46 47 48 49 50 51 128 energy or gravitational astrophysics is performed by timenetwork domain of facilities telescopes that with rely on relatively telescopes small or started apertures. operation The Zwicky in Transient 2017 Facility afterThe the ZTF uses successful a operation camera of48 with the inch a Palomar Schmidt field Transient telescope of Factory andhour view (PTF). at of has the 47 the level square of ability 20.5 degrees of mag. installed scanning The at ASAS-SN more the facility than Samuel 3750 Oschin square degrees in an diameter, to Array separation ranges from 1 to 36The km. ALMA The array provides observations from about 1 m to a few mm. systems to improve the angular resolution, from the diffraction limit systems. Since the angular resolutionadaptive of optics ground will based be telescope an is integral limited part by of atmospheric the instruments seeing, to achieve diffraction limited operation. telescopes with apertures of the orderof of the 14 whole cm, visible distributed around sky thewith every world, night. the providing observation The the of MASTER survey the network [ whole sky over a single night down to a limiting magnitude of 19-20 diffraction limited operation. The Thirty Meter Telescope sources and prompt response to new transients [ High Energy Astrophysical Techniques will survey the Southern sky everyan few aperture days. of The 8.4m, LSST equipped telescopeLSST with is camera active a is optics, three-mirror with the telescope with a largestthe wide digital near field camera ultraviolet of ever to view built, and near withObservatory fast infrared, a slewing. with size The a of 1.65m 3.5 by degrees 3m, field sensitive of from view. The space based EUCLID launch in 2021. TheInfrared telescope Instrument has (MIRI), the an Near-Infrared aperture Spectrograph(NIRCam), of (NIRSpec), the the 6.5 Fine Near-Infrared m Camera Guidance and Sensor/ hosts NearNIRISS). InfraRed several Imager instruments: and the the Mid- Slitless Spectrograph (FGS- hemisphere every six months. Large Telescope telescope in history [ PoS(MULTIF2019)082 ] photome- Rosa Poggiani 51 ]. The science 107 ], [ 98 (EHT) Collaboration has ] and Iqueye [ 52 ] achieving a time resolution 114 79 ], Transition Edge Sensors (TES) 184 (SKA) will include some hundreds stations ]). The time scale of optical microvariability ]. 53 ] and the Doppler factor of blazars. The time 185 154 20 ], [ 186 159 ], [ 134 ]. Some classes of cryogenic detectors have sub-microsecond 70 ]. Several systems show variability at subsecond scales: accret- 98 ], [ 81 ]. Eclipsing binaries, Cepheids and RR Lyrae variables have periods smaller 81 ], with the observation of a variability up to 600 seconds and distinct bursts on 37 km. Using this technique, the Event Horizon Telescope 4 ]. The forthcoming Square Kilometer Array ]. 86 Different instruments in operation are performing high time cadence optical observations at https://eventhorizontelescope.org/ https://www.skatelescope.org/ An example of interest for high energy astrophysics is the gamma ray flare of PKS 2155-304 The high time cadence of modern surveys allows to identify a large number of transients and Time variability in sources involves time scales spanning several orders of magnitude, from 187 ] and Visible Light Photon Counters (VLPC) [ ]. The efforts of time domain astrophysics are focused on achieving high temporal cadence over 53 52 54 98 medium and large telescopes. UltraCam and UltraSpec use CCDs [ drivers for time domainstants, astronomy, the that frequency include of the compactby measure binary [ of mergers, fundamental the physics cosmological of con- supernovae, have been discussed can constrain the size ofscales the of emission microvariability in region the [ they have optical a and common gamma origin or ray not. domains allows to discriminate whether of a few milliseconds. The Single photontime Avalanche resolution Photo-Diodes in (SPADs), that the allow nanosecond to region, achieve are a used in the OPTIMA [ in July 2006 [ time resolutions: Superconducting Tunnel Junctions (STJs) [ or of the order of days.Blazars and Dwarfs quasars novae show show flares periodic at outbursts[ intervals with of periods years or from decades, months as to the years. outbursts of recurrent novae to send alerts for follow-up andThe the classification foreseen of frequency transient of type alerts withper with spectroscopic night, observations. the demanding Large a Synoptic redefinition Telescope on is the of follow-up the strategies. order of 10 millions the whole electromagnetic spectrum andinvestigate to both digitize superfast the processes plate and archives processes back varying to over one decades century [ ago, to timescales of about 200 seconds.blazars by Optical different microvariability authors at (see e.g. minutes [ scales has been observed in ters and in the GASP polarimeter [ [ ing systems containing a compact object, pulsarsor emitting optical white radiation, oscillating dwarfs neutron [ stars milliseconds to centuries [ High Energy Astrophysical Techniques can be varied from 0.15 toallows 16 km observations and from four additional about 12(VLBI) 10 m technique, and mm twelve the to 7 meter single some antennas.up antennas cm. The to are array In distributed 10 the overproduced the Very the Long whole first Baseline Earth, image Interferometry achieving of theM87 baselines [ shadow of a black hole,with the baselines up supermassive black to hundreds hole kilometers. at the core of 9. Time domain astrophysics PoS(MULTIF2019)082 ], 140 ]. 12 Rosa Poggiani ], [ ], at a distance 13 171 ], [ 11 ]. The presence of material at ]. The gravitational signal was ]. SN 1987A is the first astro- ]. Fermi-GBM detected an un- ]. 6 53 11 146 150 Mpc [ ], [ ]. The event was recorded by the IMB 8 14 + − 115 104 21 , left). The gravitational source was localized within a ]. The transient was explained as a faint sGRB at a large 24 71 ] (Fig. 11 ). Despite the electromagnetic emission is expected to be absent or ] 23 5 ] detectors, with 8 and 5 neutrinos, respectively, within a few seconds. The and at a luminosity distance of 40 2 45 ] (Fig. 5 ]. Since there is no accretion material coming from tidal disruption, the binary black hole 71 The joint detection of the gravitational radiation from the binary neutron star merger GW170817 On August 17, 2017 at 12:41:04 UTC the Advanced LIGO and Advanced Virgo instruments The detection of the GW15014 black hole merger provided the first direct detection of grav- Before the label multi-messenger achieved popularity, an astronomical event was observed ], or be embedded in the disk of an active galactic nucleus [ ] and Baksan [ 130 100 sky region of 28 deg and from the shortphysics Gamma using Ray gravitational waves Burst and the GRB whole 170817A electromagnetic spectrum is [ an exampledetected the of event multi-messenger GW170817 [ astro- [ 10.2 GW170817 Figure 23: Spectrograms ofdetectors; adapted the from GW150914 [ signal in the LIGO-Hanford and LIGO-Livingston weak, follow-up searches have been performed for GW150914 [ expected weak transient above 50 keV,was 0.4 not s observed after by the other GW150914 instrumentangle event [ [ and lasting about 1systems s, that should have occurred in a site with existing materialthe left time from of merger its could previous lead history to [ the production of jets [ neutrino detection occurred before the familiar brightening of the optical light curve. 10.1 GW150914 itational waves [ over the electromagnetic spectrum and1978 with February neutrinos. 24.23 as Supernova a SN 5 1987A magnitude was object discovered in on the Large Magellanic Cloud [ High Energy Astrophysical Techniques 10. Case Studies of about 50 kpc. Aphysical review source of that the produced event particles hasKamiokande detected been II instrument presented on on by Earth. February [ 23, Aevents 07:35:35 in neutrino UT, during the burst an energy was interval band observed ofthe from 13 by Large seconds, 7.5 the Magellanic with to 11 Cloud 36 within MeV;[ about the 15 first degrees two [ events pointed towards the direction PoS(MULTIF2019)082 ], ]. 48 153 ]. The ], [ ], [ 183 174 ]. 135 Rosa Poggiani 13 ], [ ], [ ], in agreement c [ 64 129 69 ]. The light curves 16 ], [ − ]) 12 ], [ ], [ 10 13 170 179 × 179 ], [ ], [ 183 and +7 126 ] with respect to the merger. The 15 13 ], [ , right. The difference between the − 24 10 180 × ], [ 0.054 s [ 82 ± ] and constrained the equation of state and the ], [ 18 22 173 ], [ 11 ], [ 74 ]. 19 ], [ ]). Right: joint gravitational and electromagnetic detection of ], [ 49 11 18 ], [ ] with a delay of 1.734 ], [ 120 13 16 ], [ ], [ 165 116 ], [ ], [ 95 117 ], [ ] and was promptly confirmed by other observatories [ 142 172 A worldwide observing campaign across the whole electromagnetic spectrum discovered an The Fermi-GBM and INTEGRAL SPI-ACS instruments detected the short Gamma Ray Burst ], [ ], [ , left. The optical and infrared spectra showed the signatures of a kilonova, that evolved from a 132 73 [ optical transient (SSS17a/AT 2017gfo) inconsistent with the the elliptical gravitational luminosity galaxy distance.the NGC The event first 4993, by detection the located occurred One-Meter, 10.87 Two-Hemisphere at (1M2H) hours[ Collaboration a after with distance the 1m Swope telescope featureless blue continuum to the appearance of broad lanthanide features [ The source was not present in archival images secured a few weeks before the merger [ 25 GW170817 and GRB 170817A. From top10-50 to keV; bottom: the Fermi-GBM same lighttime-frequency as curve map for above, of GRB GW170817 50-300 170817A, gravitational keV; waveform (adapted INTEGRAL from SPI-ACS [ light curve above 100 keV; Figure 24: Left: spectrogramsand of Virgo detectors the (adapted GW170817 from [ signal in the LIGO-Hanford, LIGO-Livingston properties of neutron stars [ gravitational and gamma ray waveformsmerger are time shown and in the Fig. gammaof ray light emission and constrained the the speed fractional of difference gravity in between the the interval speed between -3 transient AT 2017gfo was associated with theof gravitational GW170817/GRB event GW170817 170817A/AT 2017gfo [ during the first weeks after the merger are shown in Fig. GRB 170817A [ High Energy Astrophysical Techniques associated to a binary neutron star merger [ PoS(MULTIF2019)082 ] ], ], ], ], 22 125 123 121 160 ], [ ], [ ], [ ], [ 180 133 127 138 Rosa Poggiani ], [ ], [ 76 181 ], [ ], [ 162 ]. The initial brightness 133 138 ], [ ] show that the event was pro- ], [ 12 132 101 ], [ ], [ 13 76 ], [ ], the Baksan Underground Scintillation 11 50 , right. 23 25 ]. The radio afterglow was detected with the VLA on 2017 99 ]. ], the Super-Kamiokande Observatory (3.5 MeV to 100 PeV) [ ], [ 41 152 85 ], but not with a uniform jet. ], [ 181 180 500 s window around the merger epoch nor in the 14 days after the merger. ± ], [ ]. The afterglow evolution was consistent with an off-axis structured jet [ 138 44 ], [ 80 The multi-messenger observations of GW170817 [ No associated low energy or high energy neutrinos were observed in association to GW170817 The first X-ray and radio detections of the transient occurred at 9 and 16 days after the merger, ], [ ] was followed by a turnover at about 149-170 days after the merger [ ]. A selection of spectra is shown in Fig. 139 162 136 duced by the merger ofand two by neutron a stars, kilonova followed whose by emission the was short powered gamma by ray the burst radioactive GRB decay 170817A of r-process nuclei syn- [ rise observed in the X-rays,[ optical and radio observations [ [ or a cocoon [ Upper limits have been set byand The IceCube, MeV ANTARES and energy Pierre ranges) Auger [ the observatories (GeV-EeV Baikal-GVD telescope (from TeV to 100 PeV) [ neither within a respectively. The X-raya afterglow was rising discovered emission on [ September 2017 2 Aug and showed 26 a with rising Chandra flux in and the showed following weeks [ Telescope (above 1 GeV) [ Figure 25: Left: lightthe curve merger of (data GW170817 from in https://kilonova.space/kne/GW170817/); different right:first photometric spectra days bands of after GW170817 in the in the merger the (image first credit: month ESO/E. after Pian et al./S. Smartt & ePESSTO) High Energy Astrophysical Techniques with the predictions of r-process nucleosynthesis in the ejecta and radioactive decay [ PoS(MULTIF2019)082 ]. ], ], ]. ]. 88 68 1.66 109 110 167 ± ]. The 23 ], [ ]: difference Rosa Poggiani 20 110 ], [ ]. The ANTARES 13 111 ]. IceCube-170922A 137 ], [ ]. Binary neutron star systems 177 178 1 day around the event time [ ± ], [ 52 ]. The precision on the Hubble constant ]. An analysis of data prior to the event ] up to 400 GeV. No source above 1 TeV ], [ 14 75 110 110 ], [ 59 24 ]. The combination of gamma ray and X-ray obser- ], [ ]. The X-ray follow-up included Swift-XRT, NuSTAR, 110 141 110 ], [ 144 ]. The object had been previously observed by Fermi-LAT and ], [ 2.8 TeV in IceCube [ 110 ], is in tension with the value estimated with Cepheids, 73.48 ± 143 29 [ ]. The observations with Swift showed an increased emission correlated ], [ 1 − 84 110 ]. The value of the Hubble constant estimated with the GW170817 event, ]. The track pointed to the position of a known blazar, TXS 0506+056 [ , has been determined by the combination of the gravitational distance with 1 Mpc − 161 1 [ 110 − 1 neutrino excess in the direction of TXS 0506+056 before 2017 [ − σ ]. Mpc 17 km s Mpc 1 0.9 km s − The IceCube neutrino telescope detected a muon track from a neutrino interaction on 2017 The follow-up of the IceCube-170922A event involved gamma rays, X-rays, optical and radio The first observation of a gravitational event with an electromagnetic counterpart has produced The observation of GW170817 has allowed to probe the strong field dynamics of compact ]. The observations of TXS 0506+056 at very high energy with the Cherenkov instruments ± 12 8 ]. + − 131 42 MAXI, INTEGRAL [ September 22, triggering an alert withinof one instruments minute [ and an extensive follow-up with a wide range HESS, VERITAS, MAGIC showed no gamma ray emission during the first days [ 10.3 IceCube-170922A whose gamma ray emission increased around the same epoch [ neutrino telescope did not find any[ neutrino candidate within had shown a brightening instrument the in GeV a band 13 days since[ window 2017 around April. the event The were observations consistent of with the the AGILE Fermi-LAT observations in- with the increase of gamma ray emission [ the recession velocity of the host galaxy NGC 4993 [ showed a 3 observatories. On September 28 thetrino Fermi-LAT was instrument consistent reported with that the the positionan direction of of the increased blazar the GeV TXS neu- emission 0506+056, that [ at that epoch was showing was detected by the HAWC instrument [ 70 The value of the67.8 Hubble constant measured withkm the s value measured using CMB observations, An alternative method to measurewithout the electromagnetic Hubble counterpart, constant considering is the basedand galaxies combining on within the a the redshift event statistical of localization the analysis region contained of galaxies events with the gravitational estimated distance [ deposited an energy of 23.7 source was detected on September 28 by MAGIC [ an estimation of the Hubbletions, since constant GW170817 completely is a independent standard siren, on the the gravitational equivalent electromagnetic of the determina- standard candle [ achievable with additional GW170817 like events is 2% in five years and of 1% in ten years [ binaries and to test and set constraints on several aspects of General Relativity [ High Energy Astrophysical Techniques thesized in the ejecta [ are the progenitors of short GRBs (or part of them). between the speed of gravity andNewtonian the dynamics speed during of light, the deviations inspiral;of from the anomalous General Local Relativity dispersion Lorentz in of Invariance; the number gravitational Post states. of waves; large violation The extra spatial detection dimensions; ofwaves alternative [ GW170817 polarization has set limits on the stochastic background of gravitational PoS(MULTIF2019)082 Rosa Poggiani ]. The observations with the 110 ). The archival observations with 27 25 0.0010, was measured in an investigation triggered by the ± ]. The gamma ray observations by Fermi-LAT and MAGIC are presented ]. 145 110 ] after the neutrino event, showing a variable radio flux [ . 26 110 High energy astronomy encompasses experimental physics and observational astrophysics. The multi-messenger behavior of TXS 0506+056 in the months before the flare was recon- ]. The blazar has been monitored by the Very Large Array in different bands from 2 to 20 110 ASAS-SN survey showed that TXS[ 0506+056 had achieved the highest flux in theOVRO telescope recent at 15 years GHz show athe progressive neutrino increase event of [ the radio flux during the months before 11. Preparing Future Multi-Messenger Astronomers Figure 27: The multi-messenger light curvesies of 7 TXS (2019) 0506+056; 40 adapted from R. Reimann, Galax- GHz [ in Fig. Figure 26:arXiv:1807.08816 Fermi-LAT and MAGIC observationsstructed of with the interplay TXS of observations and 0506+056; archives (Fig. adapted from High Energy Astrophysical Techniques vations showed a soft power spectrumNuSTAR in hard the X-ray Swift soft band X-ray and band,redshift a an of hard power TXS power law spectrum 0506+0506, spectrum inneutrino with 0.3365 the observation index [ 2 in the Fermi-LAT band. The PoS(MULTIF2019)082 Rosa Poggiani ], both as lab- 156 ], [ 155 26 (2016) 288. (2013) 021103. (2016) 061102. (2016) 241103. (2017) 221101. (2016) 13. (2017) L35. 762 111 (2015) 172. 116 116 118 851 826 798 PRL PRL ApJ PRL PRL ApJ NIM A Phys. Lett. B https://www.gw-openscience.org/about/ The detection of gravitational waves and the observation of neutrinos from a blazar mark the 54 [1] A. Aab et al., [2] A. Aab et al., [3] M. G. Aartsen et al., [4] M. G. Aartsen et al., arXiv:1910.08488.[5] L194. B. P. Abbott et al., [6] B. P. Abbott et al., [7] B. P. Abbott et al., [8] B. P. Abbott et al., [9] B. P. Abbott et al., , accompanied by the study of the public electromagnetic observations of the second event. 12. Conclusions beginning of multi-messenger astronomy, with electromagneticwaves spectrum, and neutrinos, cosmic gravitational rays providingcombined use complementary of information all about information carrierover astrophysical a is sources. broad accompanied interval of by The time the scales. explorationrole High of in energy multi-messenger astrophysical astrophysical techniques astronomy. events are playing an increasing References oratory courses (Astrophysical Techniques) and asdata lecture (Experimental Methodologies course for with Astroparticle Physics). in class Theray lab sessions detection experiments with include: with open plastic cosmic scintillators, gammawith ray PMT detection and and SiPMs); spectroscopy (crystal studysuspensions); scintillators of optical vibration observations at modes the with telescope;characterization; accelerometers measurement measurement (as of of the in atmospheric night tests transparency sky with of brightness;strumentation photometers; Virgo/LIGO CCD and radio astronomy sun in- transit observation atsolar different flare radio frequencies detection with at commercial VLF receivers; frequencies.tical X-ray, The gamma data ray, analysis gravitational sessionspulsars, observatories are supernova for based remnants, on a gravitational open events). wide data Examples varietythe of of of analysis op- multi-messenger of sources investigation the are (blazars, time54 GRBs, series of the GW150914 and GW170817 events, provided by LIGO LOSC High Energy Astrophysical Techniques Physicists contribute to the building ofastronomers. the The high preparation energy of instruments the andteaching use next of them generation the as of techniques observational multi-messenger of astronomersastronomies, the requires due whole to the the multi-messenger different science, instruments and that observationalof techniques involves view of involved. a high From large energy the astrophysics, number point optical of andenergy radio and astronomy gravitational are events related and to to the the follow-upauthor search of for has high possible designed progenitors. and During the taught last courses years, on the multi-messenger astronomy [ PoS(MULTIF2019)082 Rosa Poggiani 27 (2016) 084001. 43 (2018) 73. 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