1 e-ASTROGAM and the future of gamma-ray space astronomy

Vincent Tascheff (CSNSM Orsay)

Probing Quantum Spaceme with Astrophysical Sources: the CTA era and beyond LPNHE, Paris, France 29 - 30 November 2017 Mul-wavelength/messenger context 2 UHE Cosmic-rays LHAASO Auger Auger Prime Neutrinos KM3Net IceCube IceCube-Gen2 IndiGO Gravitational waves KAGRA Advanced Virgo Advanced LIGO LHAASO HESS CTA South MAGIC CTA North DAMPE γ-rays Fermi AGILE ? INTEGRAL Swift SVOM NuSTAR X-rays Spektr-RG XMM-Newton Athena Chandra Ultraviolet, visible HST E-ELT & near infrared TMT LSST VLT Infrared Euclid JWST ALMA SKA Radio waves VLA LOFAR 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 3 The MeV/sub-GeV domain -8 3

) 10

-1 SPI

s IBIS-PICsIT

-2 -9 10 COMPTEL

-10 10 EGRET

-11 10 HAWC CTA North Fermi-LAT -12 IBIS-ISGRI HESS 10 Sensitivity (erg cm JEM-X HiSCORE -13 MAGIC 10 CTA South

-14 LHAASO 10 -2 -1 2 3 4 5 6 7 8 9 10 10 10 1 10 10 10 10 10 10 10 10 10 10 Energy (MeV) • Worst covered part of the electromagnec spectrum (only a few tens of steady sources detected so far between 0.2 and 30 MeV) • Many objects have their peak emissivity in this range (GRBs, blazars, pulsars...)

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Observaonal challenges 4 ☺ The MeV range is the domain of nuclear γ-ray lines (radioacvity, nuclear collision, positron annihilaon, neutron capture) ☹ Strong instrumental background from acvaon of space- irradiated materials ) -1 g 2 10 Mass attenuation for Si

☹ Photon interacon probability 1 reaches a minimum at ∼ 10 MeV -1 ☹ Three compeng processes of 10

Mass attenuation (cm -2 Compton interacon, Compton scaering 10 Pair being dominant around 1 MeV Photoel. -3 10 ⇒ complicated event reconstrucon -2 -1 2 3 4 10 10 1 10 10 10 10 Photon energy (MeV)

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Scienfic requirements 5 1. Excellent sensivity in the 1-30 MeV energy range (beer than CGRO/COMPTEL by a factor of 50 - 100) 2. Gamma-ray polarizaon for both transient and steady sources 3. Unprecedented angular resoluon (e.g., ∼ 10’ at 1 GeV) 4. Large field of view (∼ 2.5 sr) ⇒ efficient monitoring of the γ-ray sky 5. Sub-millisecond trigger and alert capability for transients -8

) 10

-1 SPI

s IBIS-PICsIT

-2 -9 10 COMPTEL

-10 10 EGRET

-11 10 HAWC CTA North Fermi-LAT -12 IBIS-ISGRI HESS 10 Sensitivity (erg cm JEM-X e-ASTROGAM HiSCORE -13 MAGIC 10 CTA South

-14 LHAASO 10 -2 -1 2 3 4 5 6 7 8 9 10 10 10 1 10 10 10 10 10 10 10 10 10 10 Energy (MeV) V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Angular resoluon 6 • Angular resoluon needs to be 10 improved close to the physical limits COMPTEL Fermi/LAT (Doppler broadening, nuclear recoil) 1 Compton Pair e-ASTROGAM Cygnus region in the 1 - 3 MeV energy band -1 with the e-ASTROGAM PSF (extrapolation 10

of the 3FGL source spectra to low energies) Angular resolution (degree) -1 2 3 4 10 1 10 10 10 10 Gamma-ray energy (MeV)

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Gamma-ray polarizaon 7 INTEGRAL/IBIS - GRB 140206A (z = 2.74) • γ-ray polarizaon in objects eming jets (GRBs, Blazars, X-ray binaries) or with strong magnec field (pulsars, magnetars) ⇒ magnezaon and content (hadrons, leptons, Poynng flux) of the oulows + radiaon processes Π > 48% (68% c. l.) • γ-ray polarizaon from cosmological (2014) al. et Götz Geometry corrected polarization signature sources (GRBs, Blazars) ⇒ fundamental quesons of physics related to Lorentz 100 GRB 140206A with e-ASTROGAM

Invariance Violaon (vacuum 80 birefringence) 60 corrected counts/degree

! e-ASTROGAM will measure the γ-ray 40

polarizaon of ∼ 100 GRBs per year Θoff-axis = 30° ΔE = 0.2 - 1 MeV 20 (promising candidates for highly γ-ray Π = (75.0 ± 7.2)%

0 polarized sources) -180 -135 -90 -45 0 45 90 135 180 [degree]

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Core science movaon 8 1. Jet & oulow astrophysics (acve galacc nuclei, gamma-ray bursts, compact binaries) and the link to new messenger astronomies (gravitaonal waves, neutrinos, ultra-high energy cosmic rays)

2. Origin & impact of high-energy parcles on Galaxy evoluon, from cosmic rays to anmaer

3. Supernovae, nucleosynthesis & cosmic evoluon of maer

+ ... tests of Lorentz Invariance Violaon (polarizaon, me tagging of 1 µs, spectral range covering 4 orders of magnitude)

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Core science topic #1 9

• Why did the most luminous jeed AGN PKS 2149-306 (z = 2.345) 9 with mass > 10 M⊙ formed earlier than non-jeed AGN? • Launch of ultra-relavisc jets in GRBs? Ejecta composion, energy dissipaon site, radiaon processes? • Are BL Lac blazars AGN sources of high- energy neutrinos and UHECRs? • Are some short GRBs associated with gravitaonal waves from neutron star/ black hole mergers? ! e-ASTROGAM: wide field of view, unprecedented sensivity, polarimetry ⇒ access to a variety of extreme transient phenomena - More than 1000 AGN detecons up to z > 6 - (1.2 - 18) NS-NS mergers per year with gravitaonal waves V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Core science topic #2 10

Fermi LAT • What are the energy distribuons and fluxes of 40 - 150 MeV CRs produced in supernova remnants and propagang in the interstellar medium? • What is the role of CRs in the self regulaon of the Galacc ecosystem (star formaon, galacc winds, magnec field growth...)? • What are the origins of the Fermi Bubbles and the 511 keV emission from the Galaxy’s bulge? e-ASTROGAM 40 - 150 MeV Are these linked to a past acvity of the central supermassive black hole?

! e-ASTROGAM: detailed spectro-imaging, thanks to the significantly improved sensivity and angular resoluon in the MeV - GeV range

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Core science topic #3 11

• Progenitor system(s) & explosion mechanism(s) of thermonuclear SNe? Standard candles for precision cosmology? • Diversity of core-collapse events? Formaon of black holes & neutron stars? • How are cosmic isotopes created in stars and supernovae, distributed in the ISM and recycled into new stars? 7 ]

1 W7 (Chandrasekhar−Deflagration) − He−Detonation s

2 Merger Detonation

− 6 ! e-ASTROGAM: excellent sensivity SN 2014J Pulsating Delayed Detonation Superluminous He−Detonation (adapted from SPI Data for detecon of key γ-ray lines ⇒ 5 SPI Exposure

ph cm Diehl et al. 2015) 4 − - Mass and evoluon of ejected 4 56Ni/56Co in a dozen of SN Ia e-ASTROGAM 3 - 44Ti radioacvity from all young Galacc SNRs & SN 1987A 2 847 26 60 1 - Deep survey of the Al, Fe and Co 1238 keV line flux [10 56 0 positron annihilaon radiaons 0 50 100 150 200 Time past explosion [days]

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 e-ASTROGAM observatory in context Athena E-ELT/LSST 12 CTA e-ASTROGAM JWST ALMA SKA

High-redshiB blazars, high-accre=on AGN Cosmic rays & the interstellar Supernova remnants medium (tracing gas & & PeVatrons Supernovae, cosmic-ray feedback) (kilo)novae, nucleosynthesis GRBs, merger events Pulsars, magnetars & other transients Fundamental X- & -ray binaries, γ (polariza=on) (polariza=on) physics microquasars

LIGO/Virgo, KAGRA, INDIGO, European Pulsar Timing Array, IceCube/KM3NeT Einstein Telescope, Cosmic Explorer, LISA

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 10 CHAPTER 1. NEW MISSION IN MEDIUM-ENERGY GAMMA-RAY ASTRONOMY Measurement principle Pair event 13 γ Compton event γ γ θ

AC system

Dt Si Tracker Compton e- Calorimeter

Tracked Compton e+ e- • Tracker - Double sided Si strip detectors (DSSDs) for excellent spectral resoluon Figure 1.3: Comparison of the different Compton telescopes: The left figure shows the classical COMPTEL type instrument. It comprisesand fine 3-D posion resoluon two detector planes. The first one is the scatterer (D1) and the second is the absorber (D2). The planes• Calorimeter have a large - High-Z material for an efficient absorpon of the scaered photon distance in order to measure the time-of-flight of the scattered gamma-ray. The central picture⇒ shows CsI( aTl) scinllaon crystals Compton telescope consistingreadout by of severalSi Dri Diodes thick layersfor beer energy resoluon in which the photon undergoes multiple Compton scatterings. The redundant scatter information allows to determine the direction of motion of the photon.• TheAncoincidence detector figure on the right shows to veto charged-parcle induced background an electron tracking Compton telescope like MEGA.⇒ plasc The tracker consists of severalscinllators readout by Si photomulpliers layers, thin enough to track the recoil electron. The scattered photon is stopped in a second detector whichV. Tascheff encloses the tracker.Probing quantum The track ofspaceme the electron: the CTA era and beyond determines the direction LPNHE of motion 29 - of 30 Nov 2017 the photon. The illustrations are not to scale.

1.2.2.1 Compton Telescopes Compton scattering is the dominant interaction process between 200 keV and 10 MeV (de- ∼ ∼ pending on the scatter material). If one measures the position of the initial Compton interac- tion, energy and direction of the recoil electron as well as direction and energy of the scattered gamma-ray, then the origin of the photon can be identified. The final accuracy depends on several factors, which are extensively discussed in Section 2.2. The key objective for a Compton telescope is to determine the direction of motion of the scattered gamma-ray. For this problem three solutions exist which distinguish the three basic types of Compton telescopes (see Figure 1.3). In COMPTEL (Figure 1.3 left) the two detector systems, a low Z scatterer, where the initial Compton interaction takes place, and a high Z absorber, where the scattered gamma ray is stopped, are well separated so that the time-of-flight of the scattered photon between the two detectors can be measured. Thus top-to-bottom events can be distinguished from bottom-to-top events. With COMPTEL it was not possible to measure the direction of the recoil electron, so an ambiguity in the reconstruction of the origin of original photon emerged: the origin could only be reconstructed to a cone. This ambiguity has to be resolved by measuring several photons from the source and by image reconstruction (details see Chapter 5). Several of the instrument concepts currently under consideration for an Advanced Compton Telescope (ACT) (Boggs et al.,2005)willdetectmorethanoneComptoninteractionperphoton (Figure 1.3 center). From the resulting redundant information the ordering of the interactions can be retrieved. A detailed discussion of this approach is given in Chapter 4. Representatives of this group of Compton telescopes are NCT (Boggs et al.,2004),LXeGRIT(Aprile et al., 2000) or the thick Silicon concept described by (Kurfess et al.,2004). In contrast to COMPTEL and most ACT concepts, a third group of detectors is capable of measuring the direction of the recoil electron (Figure 1.3 right). This enables the determination of the direction of motion of the scattered photon and allows to resolve the origin of the photon much more accurately: the Compton cone is reduced to a segment of the cone, whose length depends on the measurement accuracy of the recoil electron. The main representatives of this e-ASTROGAM payload 14 Detail of the detector-ASIC • Tracker: 56 layers of 4 mes 5×5 DSSDs (5 600 bonding in the AGILE Si Tracker in total) of 500 µm thickness and 240 µm pitch • DSSDs bonded strip to strip to form 5×5 ladders • Light and sff mechanical structure • Ultra low-noise front end electronics

Sandwich panel

PICSiT CsI(Tl) pixel Design of the •calorimeter Calorimeter composed: 33 of 856 CsI(Tl) bars coupled at both 1 module of 14x14 modulesends to of 64 crystalslow-noise Silicon Dri Detectors 64 crystals • ACD: segmented plasc scinllators coupled to SiPM by opcal fibers • Heritage: AGILE, Fermi/LAT, AMS-02, INTEGRAL, Fermi/LAT AC system LHC/ALICE…

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 Satellite and mission profile 15 Radiator Payload Solar panel

• Plaorm - Thales Alenia Space Background environment in an ELEO

PROTEUS 800 (SWOT CNES/NASA) ) 7 -1 10 Atmospheric photons 10 6 Cosmic photons • Orbit - Equatorial (inclinaon i < 2.5°, Primary protons MeV

-1 Secondary protons eccentricity e < 0.01) low-Earth orbit s 4 Primary electrons

-2 10 Secondary electrons (altude in the range 550 - 600 km) Secondary positrons 2 - 10 Albedo neutrons • Launcher Ariane 6.2 Flux (m • Observaon modes - (i) zenith-poinng 1 -2 sky-scanning mode, (ii) nearly ineral 10

poinng, and (iii) fast repoinng to -4 avoid the Earth in the field of view 10 -6 10 • In-orbit operaon - 3 years duraon + -2 -1 2 3 4 5 10 10 1 10 10 10 10 10 provisions for a 2+ year extension Energy (MeV)

V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 e-ASTROGAM Collaboraon 16

Lead proposer: A. De Angelis (INFN, It.) Co-lead proposer: V.T. (CNRS, Fr.) >400 collaborators from instuons in 24 countries; Science White Book just published (224 authors; 194 pages) 16 V. Tascheff Probing quantum spaceme: the CTA era and beyond LPNHE 29 - 30 Nov 2017 All-sky Medium Energy Gamma-ray Observatory NASA/GSFC, G. Wash. Univ., Clemson Univ., NRL, UC Berkeley, Wash. Univ., UNH, NASA/MSFC, UAH, USRA, OSU, UIUC, UNLV, UDel, UCSC, SLAC, Stanford, UNF, Yale, RICE, INFN, Pisa Univ., Padova Univ., Stockholm Univ., INAF, LIP, Udine Univ., Rome Univ., CSNSM Instrument Concept Square 80 cm side

Si Tracker An;coincidence DSSD in 60 layers Detector with 1 cm PlasWc scinWllator spacing. Strip shell for charged pitch 0.5 mm. parWcle rejecWon.

CZT Calorimeter CsI Calorimeter DriV configuraWon with single Hodoscopic arrangement of Mission and layer array of 0.6 cm x 0.6 cm 1.5 cm x 1.5 cm CsI bars in 6 spacecraV x 2 cm bars surrounding layers with SiPM sensors. design can build lower tracker layers. on development for ComPair Designed for a NASA Probe mission • THESEUS is a submitted project to ESA for the M5 slot. The expected selection for phase A will be announced early 2018, for an expected launch date as early as 2029.

• THESEUS Core Science is based on two pillars: o probe the physical properties of the early Universe, by discovering and exploiting the population of high redshift GRBs. o provide an unprecedented deep monitoring of the soft X- ray transient Universe, providing a fundamental contribution to multi-messenger and time domain astrophysics in the early 2030s (synergy with aLIGO/aVirgo, eLISA, ET, Km3NET and EM facilities e.g., LSST, E-ELT, SKA, CTA, ATHENA). THESEUS Payload

So X-ray Imager: a set of four « Lobster Eye » telescope with an overall field of view of 1 sr,

X-Gamma ray Imaging Spectrometer : three coded mask telescopes with a focal plane composed by a combinaon of • Autonomous plaorm, Si and CsI detectors (possibility of polarizaon with rapid repoinng measurements). Sensive in the 2 keV to 20 MeV, with an capabilies (up to) 4 sr field of view, a source locaon accuracy of 5 arc • Low Earth Orbit (~600 min. Provided by a consorum led by Italy. km), low inclinaon (<5°) Near Infra-Red Telescope for rapid on-board follow-up with • Fast ground a 0.7 m primary mirror, sensive in the 0.7-1.8 μm range, communicaon for with a 10x10 arc min field of view and moderate alert disseminaon spectroscopic capabilies (goal of 500). Provided by a consorum lead by France. hp://www.isdc.unige.ch/theseus/ M5 proposal down-selected by ESA’s Technical Office to 13 best candidates ⇒ 3 to be selected for a phase A early 2018 Expected launch date: 2029

Instrument paper: hps://arxiv.org/abs/1611.02232 Exp. Astronomy 2017, 44, 25

Science White Book: hps://arxiv.org/abs/1711.01265

hp://eastrogam.iaps.inaf.it