Universidade de São Paulo
ASTRI Mini-Array @Teide: observing the gamma-ray sky up to 100 TeV Giovanni Pareschi – INAF on behalf of ASTRI Team ASTRI: Outline of the presentation
• ASTRI Project background
• ASTRI Prototype
• ASTRI mini array ASTRI: What’s in a name? ASTRI - Astrofisica con Specchi a Tecnologia Replicante Italiana Astrophysics with Mirrors via Italian Replication Technology
Name given by Nanni Bignami ASTRI was born as a “flagship project” funded by the Italian Ministry of University and Scientific Research with the l aim to design, realize and deploy:
a) an innovative end-to-end prototype of the 4 meters class wide-field telescopes to be tested in an astronomical site (INAF – Catania on Etna Volcano); b) a mini-array of telescopes based on the new technology, aiming also to early science in the 1-100 TeV energy window.
ASTRI will also pave the way to INAF participation in CTA He’s not fat, he’s just big boned! Mechanical Structure Dimensions & Mass Height of the Telescope (pointing 7.5 m & 8.6 m horizontally & vertically) Radius of free area for Az. 5.3 m Movements Total Mass of the prototype 19000 kg Tracking & Pointing Driver Encoder Precision 2 arcsec
A&A proofs: manuscript no. aa_paper_optical_quality_ver1Tracking Precision <0.1° Pointing Precision After Calibration 5 arcsec has been carried out using Polaris as a target and included two Polynomial design developed by P. Conconi phases:
- Alignment of the OS components - PSF characterization over the entire FoV
3.1. Alignment of the OS components Active mirror control system (AMC) (Gardiol et al. 2014) of AS- TRI SST-2M consists of tip-tilt correction alignment mechanism installed on each individual M1 segment and tip-tilt combined with translation alignment mechanism installed on monolithic M2.105 Each kg M1 x 172 segment cm has three points mounting with one point fixed on a ball joint and two others attached to the actuators al- lowing tip-tilt adjustment in the range of 1.5 with the resolution Fig. 3. Comparison of D80 as a function of field angle (o↵-axis) be- of a few arcseconds. Three actuators control the position of M2 tween its ideal (solid curve) and measured at ASTRI SST-2M (dashed permitting 15mm motion along optical axis with the resolution curve) values. SiPM pixel size (dashed horizontal line) and CTA design of 0.1 mm and maximum range of tip-tilt correction of 0.25 .To requirement (solid horizontal line) are also shown for reference. The align the OS a large size CCD (37 mm 37 mm, corresponding pixel size of the CCD camera used for these measurements has dimen- 3 ⇥ to 1 1 in the sky, ) was placed at the nominal position of sion of about 2 arcsec on the focal plane, which is negligible for the the telescope⇥ focal plane pointing the Polaris star. The structure interpretation of these curves. of Polaris image was then analyzed to deduce alignment correc- tions for M2 and each individual M1 segment. As described in section ??, the on-axis image of a point source for the ideal re- alization of ASTRI SST-2M OS has non-zero PSF and, hence, has extended image whose structure depends on the alignment of the OS components. Figure 2 shows the on-axis simulated structure of such an ideal image in which di↵erent colors denote the contributions from the three types of M1 segments illustrated in Figure 1. The alignment procedure consists of moving all the OS elements to reproduce the structure of the ideal PSF. As a first step in the alignment process the distance between M2 and the focal surface were adjusted to match the dimension of the images of M1 segments of ideal on-axis PSF. Once this distance is fixed, the tip-tilt corrections were applied to each individual M1 segment to reproduce its contribution to the ideal PSF. Non- idealities of the fabrication of figures of individual M1 segments and M2 as well as M1–to–M2 distance misalignment residual were not taken into account at this stage. A detailed description Fig. 4. EE parameter measured as function of radial distance for di↵er- of all alignment procedures undertaken is currently in prepara- ent angular positions on the focal plane. The vertical lines represent the tion (?). SiPM pixel size (thin) and the CTA design requirement (thick). As a second step a smaller size CCD (27 mm 18 mm i.e. 4 ⇥ 0.5 0.7 in the sky) has been mounted on a custom jig de- signed⇥ to allow the positioning of the camera at 7 field angles on the focal surface: 0 , 1.5 , 3 , 4.5 . A fine tuning of the tip-tilt corrections of M1± segments± was± performed at the o↵-axis detected energy flux. To calculate D80 parameter a background position where the PSF dimension is minimized by design. As image was acquired on the nearby sky patch without bright stars shown in 5 this condition corresponds to 3 o↵-axis. in the CCD field and it was directly subtracted from the corre- sponding PSF image. The D80 values for each o↵-axis position wer calculated using the total photon flux contained in the sub- 3.2. PSF characterization over the entire FoV tracted PSF image of the entire CCD field and then plotted in To characterize PSF over the entire FoV we maintained the same Figure 3. The obtained values (filled circles on dashed curve) fol- configuration described for the fine-tuning. A typical PSF image low a pattern similar to the ideal PSF design (continuous curve) is covering an area with a diameter of about 600 CCD pixels re- with an additional aberration due to contributions from manufac- solving reliably details of the substructures in it. For each of the turing errors of M1 and M2 figures and residual misalignment seven field angles, four frames were acquired with 2.5 seconds of the OS. These contributions are consistent with the estimates exposure on October 16th, 2016. These images are shown in Fig. foreseen during ASTRI SST-2M design for uncorrelated compo- 5. A square, representing the dimension of the SiPM pixel, is nents and are of about 0.1 . over–plotted on each PSF for reference. The energy flux in the In summary, the measured D80 values are contained within the small substructures of the PSF image visible outside the SiPM SiPM pixel size (dashed horizontal line) across the entire FoV pixel area doesn’t exceed a few parts over hundred of the total and they are well below the CTA requirement (horizontal solid line). Figure 4 shows the EE values derived from the subtracted 3 CCD KAF-09000 is mounted in a Pro Line Fingerlake camera PSF images for each o↵-axis position. The SiPM pixel size 4 CCD KAI-16050-A is assembled in a SVS-VISTEK GigE camera (thick line) is displayed on this figure for reference.
Article number, page 4 of 5 Vladimir Vassiliev recovered the configuration for Cherenkov telescopes. Thanks! Generalized Schwarzschild theorem: 4For any geometry with reasonable separations between the optical elements, it is possible to
Karl Schwarzschild - Wikipedia, the free encyclopedia correct n primary 23/02/15 09:27 aberrations with n Karl Schwarzschild From Wikipedia, the free encyclopedia powered elements.<
Karl Schwarzschild ([ˈkaʁl ˈʃvaʁtsʃɪlt]) (October 9, 1873(1905) – May 11, 1916) was a German physicist and astronomer. Karl Schwarzschild He is also the father of astrophysicist Martin Schwarzschild.
He provided the first exact solution to the Einstein field equations of general relativity, for the limited case of a single spherical non-rotating mass, which he accomplished in 1915, the same year that Einstein first introduced general relativity. The Schwarzschild solution, which makes use of Schwarzschild coordinates and the Schwarzschild metric, leads to a derivation of the Schwarzschild radius, which is the size of the event Karl Schwarzschild (1873–1916) horizon of a non-rotating black hole. Born October 9, 1873 Schwarzschild accomplished this triumph while serving in Frankfurt am Main the German army during World War I. He died the Died May 11, 1916 (aged 42) following year from the autoimmune disease pemphigus, Potsdam which he developed while at the Russian front. Nationality German Physics Asteroid 837 Schwarzschilda is named in his honor. Fields Astronomy Alma mater Ludwig Maximilian University of Munich Contents Doctoral Hugo von Seeliger advisor 1 Life Influenced Martin Schwarzschild 2 Work 2.1 Physics of photography 2.2 Electrodynamics 2.3 Relativity 3 See also 4 Works 5 References 6 External links
Life
http://en.wikipedia.org/wiki/Karl_Schwarzschild Pagina 1 di 8 Addio al premio Nobel per la fisica Riccardo Giacconi - Wired 30/05/19 11:27
(https://www.wired.it/scienza/spazio/2019/05/15/artemide- HOME (HTTPS://WWW.WIRED.IT/) SCIENZA (HTTPS://WWW.WIRED.IT/SCIENZA/) SPAZIO (HTTPS://WWW.WIRED.IT/SCIENZA/SPAZIO/)
nasa-
luna- Addio al premio Nobel per la fisica (https://www.wired.it/author/gdotti/) di Gianluca Dotti Riccardo Giacconi 2024-(https://www.wired.it/author/gdotti/) Giornalista donna/)scientifico (https://www.wired.it/author/gdotti/) Aveva.IT 87 anni. Insignito del Nobel per la fisica nel 10 DEC, 2018 (https://www.wired.it) 2002, Giacconi è da tutti riconosciuto come padre e VEDI TUTTI SezionifondatoreX-ray telescopes dell'astronomiaGallery : a Polynomial raggiWired NextX. A (https://next.wired.it) lui si deve la
HOT TOPIC (HTTPS://WWW.WIRED.IT/TOPICS/)scoperta di ScorpiusWIRED X-1, NEXT FESTma 2019 anche (HTTPS://WWW.WIRED.IT/TOPIC/WIRED-NEXT-FEST-2019/) il lancio del GAME VIDEOOF THRONES satellite Uhuru della Nasa 2010: Conconi et al. applied polynomial solution to design an X-ray38 telescope with a resolution of 5’’ on a field of 1° () () Polynomial design of SC grazing() incidence() optics elaborated by P. Conconi (2010), after first Riccardo’s suggestion (1991) …and many interaction with him Study for WFXT
(foto: Roberto Serra/Iguana Press/Getty Images)
Dopo aver mostrato al mondo il cuore violento dell’Universo, è scomparso a San Diego, a 87 anni e due mesi di età, l’astrofisico Riccardo Giacconi, di origini italiane e naturalizzato statunitense. La notizia è stata confermata, per primo, dall’Istituto nazionale di astrofisica (l’Inaf). Giacconi è noto soprattutto per aver vinto nel 2002, insieme a Raymond Davis Jr e Masatoshi Koshiba, il premio Nobel per la fisica, grazie ai suoi contributi pionieristici nel campo dell’astronomia basata sui raggi X
https://www.wired.it/scienza/spazio/2018/12/10/morto-riccardo-giacconi-nobel/?refresh_ce= Pagina 1 di 7
Conconi et al. 2013, arXiv:0912.5331
6 ASTRI SST-2M prototype end-to-end
• Test of new technologies
• Test of the dual mirror approach for Cherenkov astronomy
• Development of a new camera (entarily developed in INAF!) with low data rate and consumption
• Debug of the entire system! è increase of reliability for array
7 Mirror replication technology
2. Design and Prototyping 2.1 Design
Figure 2.22 –Mainstepsofthepanelmanufacturingprocess.Fromtop-left, clockwise: mould realization; front glass is made to adhere by vacuum suction to the mould; the epoxy resin structural adhesive is spread on the glass; the Aluminium honeycomb is positioned and the back glass foil is added on thetop.Theresinismadetopolymerizewiththepropercuring cycle and the sandwich is finally released and coated.
few samples. For the ASTRI-SST-2M prototype both solutions have been produced in order to better evaluate the two technologies during operation in Serra La Nave.
Even though the dielectric based coating appears to cut off sharply at wavelengths shorter than 350nm, somewhat longer than the specification value of 300 nm, we nevertheless decided to install it in the prototype telescope for its value as a demonstrator of the technology.
Figure 2.23 –Leftside:simulated(dottedbluecurve)andmeasured(black curve) of dielectric based coating. Right side: Simulated curves (dotted curves) and measured one (Black curve) for metallic coating.
The cut-off at 350 nm will be mostly compensated by the higher efficiency of the Silicon photomultipliers at theshorter wavelengths, so that we expect only minor reductions in sensitivity. We have designed a shipping crate in order to ship M1 mirrors safely. Two crates, that can fit on a standard wooden pallet, are large enough for the shipping of acompletesetofM1mirrors.
CTA Construction Project Page 29 of 134 SST-TDR/140530 | v.1.3 | 16 May 2015 SST-2M ASTRI TDR Segmented reflecting surface
Credits: NASA
JWST, reflecting suface cost: è ASTRI, reflecting surface cost: 2 M$/m2 è 0.002 M$/m2
Tenerife, 13 Nov 2019 9 ASTRI - HORN: Inauguration
24th September 2014 Inauguration of the prototype @ INAF-Catania mountain station in Serra La Nave placed at 1725 meters on the Etna volcano ASTRI dedication to Horn d’Arturo, the father of the segmented mirrors ASTRI - HORN: Dedication to Horn D’Arturo
10th of November 2018 Dedication of ASTRI prototype telescope to Guido Horn D’Arturo inventor of the segmented astronomical mirrors CITIROC ASIC
The ASTRI Camera Weeroc + INAF PDM: CITIROC ASIC
The first batch of CITIROC ASICs is ready
INAF has the Intellectual Property of the design
CITIROC is available as: • LQFP160 case • Naked die 4.1 x 4.1 mm2
M. Fiorini SST Meeting, Amsterdam 4-5 June 2014 10 12 ASTRI Prototype: PSF across the field of view
FoV D80 position (mm) (deg) 4.5 6.72 3.0 6.32 1.5 7.28 0.0 6.86 -1.5 6.32 -3.0 5.50 -4.5 6.90 SiPM pixel linear dimension: 7 mm ® 11.2 arcmin
13 ASTRI - HORN: ASTRI camera first Cherenkov Light
25th of May 2017 First Cherenkov light with the ASTRI camera
1500 A dedication to Nanni!
0 ASTRI – Horn: Crab Nebula Detection Observations between 5th and 11th december 2018
ASTRI SST-2M prototype, December 2018 250 ON-CRAB (12.4 hours) Data Analysis with astripipe Counts OFF-CRAB (12.0 hours) 200 First detection of a NON = 360, NOFF = 233, NEXC = 127, NORMON/OFF=0.9 sLi&Ma = 5.4 Gamma Ray Source 150 with a IACT dual- mirror telescope!!! 100
50 Energy threshold ~ 3.5 TeV
0 0 10 20 30 40 50 60 70 80 90 |Alpha| [deg] 15 1 5 ASTRI mini-array: The next step of the program
Credits: M. Leone
The ASTRI mini-array will be a new pathfinder of the arrays of Cherenkov telescopes
• INAF commitment with the Italian government and international partners (University of Sao Paulo/FPESP - Brazil, North-West University - South Africa) • Dedicated funding • It will composed by 9 ASTRI telescopes, evolution of the ASTRI-Horn prototype successfully implemented and tested • It will deployed at the Teide Observatory (Canary Islands) in collaboration with IAC
16 Cherenkov light and pool versu energy
Radial profile of Cherenkov light originated from an electromag-netic shower initiated by a gamma ray:
~103
~100 ASTRI: a new pathfinder of the arrays of Cherenkov telescopes — English 13/11/19 08:00
INAF
Istituto italiano di astrofisica - national institute for astrophisics
You are here: Home › INAF News › ASTRI: a new pathfinder of the arrays of Cherenkov telescopes
ASTRI: a new ASTRI:pathfinder a new pathfinder of the arrays of Cherenkov telescopes of — Englishthe arrays of 13/11/19 08:00 Cherenkov telescopesINAF Istituto italiano di astrofisica - national institute for astrophisics On June 12nd 2019, in LaYou areLaguna here: Home (Tenerife, › INAF News ›Spain) ASTRI: a new Prof. pathfinder Nichi of theD’Amico, arrays of President of Cherenkov telescopes The ASTRI mini-array @Tenerife the Italian National Institute for Astrophysics (INAF), and Prof. Rafael Rebolo Lopez, Director of the Instituto ASTRI:de Astrofisica a new pathfinderde Canaries, of signedthe arrays a Record of of Understanding to enter Cherenkova detailed negotiation telescopes on a technical and programmatic
basis aimed to install andOn Juneoperate 12nd 2019, the in LaASTRI Laguna (Tenerife, Mini-Array Spain) Prof. at Nichithe D’Amico, Observatorio President of del Teide the Italian National Institute for Astrophysics (INAF), and Prof. Rafael Rebolo Lopez, Director of the Instituto de Astrofisica de Canaries, signed a Record of Understanding to enter a detailed negotiation on a technical and programmatic basis aimed to installASTRI: and aoperate new pathfinder the of ASTRI the arrays Mini-Array of Cherenkov telescopesat the Observatorio — English del 13/11/19 08:00 Teide
Prof. Nichi D’Amico, President of the Italian National Institute for Astrophysics (INAF), and Prof. Rafael Rebolo Lopez, Director of the Instituto de Astrofisica de Canaries
On June 12nd 2019, in La Laguna (Tenerife, Spain) Prof. Nichi D’Amico, President of Prof. Nichi D’Amico, Presidentthe Italian ofNational the Institute Italian for AstrophysicsNational (INAF), Institute and Prof. forRafael Astrophysics Rebolo Lopez, (INAF), and Prof. RafaelDirector Rebolo of the Lopez, Instituto deDirector Astrofisica de of Canaries, the Instituto signed a Record de of Astrofisica de Understanding to enter a detailed negotiation on a technical and programmatic Canaries basis aimed to install and operate the ASTRI Mini-Array at the Observatorio del Teide. INAF and IAC Representatives on the Teide Observatory site 18 On June 12nd 2019, in LaThis Lagunais an important (Tenerife, stepASTRI forward (Astrofisica forSpain) the ASTRI con Prof. Collaboration Specchi Nichi a amongTecnologia D’Amico, INAF, Replicantethe President Italiana), of was born in 2011 Universidade de Sao Paulo in Brazil and the North-Western University in South the Italian National InstituteAfrica, including for Astrophysics now theas prestigiousa Flag-ship (INAF),Spanish Project institution. ofand the ItalianProf. MinistryRafael for Rebolo Education Lopez, and Research (MIUR) in order to establish a new and innovative end-to-end technology dedicated to the Director of the Instituto de Astrofisicaimplementation de Canaries, of Cherenkov signed aimaging Record telescopes of for high energy astrophysics. The Understanding to enter a detailed negotiationproject was againon a funded technical in 2015 and in order programmatic to finalize a collection of up to nine basis aimed to install and operate thetelescopes ASTRI toMini-Array be operated asat anthe array. Observatorio This option, already del foreseen in the original Project, and denominated “ASTRI Mini-Array”, is now prone to be implemented on Teide. http://www.inaf.it/en/inaf-news/astri-a-new-pathfinder-of-the-arrays-of-cherenkov-telescopesan adequate observing site, and launched towardsPagina 1 dian 4 authoritative “early science” by using the technique of Cherenkov telescopes arrays. This is an important step forward for the ASTRI Collaboration among INAF, the Universidade de Sao Paulo in Brazil and the North-Western University in South Africa, including now the prestigious Spanish institution.
http://www.inaf.it/en/inaf-news/astri-a-new-pathfinder-of-the-arrays-of-cherenkov-telescopes Pagina 1 di 4
ASTRI-Horn prototype telescope, which is installed since a few years at the astronomical INAF site on the slopes of the Etna Mount in Sicily
The first ASTRI prototype was installed at INAF Serra La Nave Observatory in Sicily, and was inaugurated in 2014. Subsequently dedicated to Guido Horn d’Arturo, the
http://www.inaf.it/en/inaf-news/astri-a-new-pathfinder-of-the-arrays-of-cherenkov-telescopes Pagina 2 di 4 ASTRI Pre-production activities: Design Consolidation
M2 bus Mast modified structure with only three legs Prototype Pre-production
AMC radially mounted for an easier mirrors Scheduled production of the first telescope integration for the end of the year 19 ASTRI mini-array: Site design
Site ready to host the first telescope in one year
ASTRI-1
ASTRI-3 ASTRI-2
ASTRI-4
ASTRI-6 ASTRI-5 ASTRI-7
ASTRI-9 ASTRI-8
20 ASTRI mini-array: The physical layout
CTRL room @ IAC
Remote CTRL rooms Array @ OT 10 Gbit 10 Gbit
On-Site ICT @ OT CTRL room @ OT
Data Analysis & Archive
• It will be developed in order to be operated, after the commissioning phase, remotely. • Data analysis will be performed off-site (3 TeraBytes/night)
21 Science Operations 1/2
• During the first years of operations the ASTRI mini array will be run as an experiment and not as an observatory
• The ASTRI Science team will develop a strategy to concentrate the ASTRI observational time on a limited number of programs with clearly identified objectives. This will produce an observation schedule that will span several months at a time.
• No real time analysis of the data is foreseen but only a data quality check. Data analysis policy adopted will then be next day processing. Science Operations 2/2
• No array trigger (stereo trigger) will be implemented at the site. Any search for Cherenkov events detected in coincidence by more than one telescope will be performed via software off-line at the Rome Data Center.
• No subarray operation is foreseen for the ASTRI mini array.
• Night Science operation is controlled from a control room located in La Laguna @ IAC (possibly also from TNG and Italy, TBC), so no people are required to be present at the mini array site during the night. A control room will be also available at the mini array site at the Themis Observatory (TBC) and will be mainly used during commissioning and science verification or in case of other special activities.
23 ASTRI mini-array: mini but not small… Science at very high gamma ray energy in the northern hemisphere!
Expected performance: • Sensitivity: better than current IACTs (E > 10 TeV): • Possibility to extend the spectra of already detected sources and/or measure cut- offs • Possibility to characterize the morphology of extended sources at the highest VHE • Energy/Angular resolution: < ~10% / < ~ 0.1° (E > ~ 10 TeV) • Wide FoV (3 ° diameter in gamma rays 5% sens), with homogeneous off-axis acceptance • Optimal for multi-target fields, surveys, and extended sources • Enhanced chance for serendipity discoveries
24 ASTRI Mini-Array Core Science rays in each estimated-energy bin (21 logarithmic bins be- 0.3 tween 10*1.9Ù 0.01 TeV and 102.3Ù 200 TeV) and in each ASTRI Mini-Array on-axis (50h) o -axis bin (10 linear bins between 0° and 5°). The defini- 0.25 tion of the energy bins are compliant with the usual prescrip- 0.2 tion adopted in the CTA Consortium (Acharyya et al., 2019).
However, it should be noted that the response function of Angular Resolution [deg] 0.15 the ASTRI Mini-Array are meaningful above Ì0.5 TeV, be- cause of the energy threshold of the system. The final IRFs 0.1 include e ective collection area, angular resolution, energy dispersion, and residual background rate1, as a function of 0.05 the energy and o -axis angle. 0 −1 −0.5 0 0.5 1 1.5 2 2.5 log (E [TeV]) 2.3. The ASTRI Mini-Array Performance 10 2.4. On-axis performance Figure 3: On-axis angular resolution of the ASTRI Mini-Array In order to obtain the on-axis performance the MC point- as a function of the energy between Ù 0.1 TeV and Ù 300 TeV. like gamma and di use background samples (see Tab. 1) were used. In Fig. 2, 3, and 4, the main on-axis perfor- mance quantities are displayed, in the energy range between , 10*1Ù 0.1 TeV and 102.5Ù 300 TeV, considering five loga-
rithmic energy bins per decade. Above a few TeV, the en- ] -1 s ergy resolution is of the order of 10%, while the angular res- -2 olution is better than Ì4 arcmin, reaching a minimum value ASTRI Mini-Array on-axis (50h) of 3 arcmin (0.05°) at Ì10 TeV. The di erential sensitiv- ity in 50 hours of observations surpasses the ones achieved 10−11 by the present IACTs (H.E.S.S., MAGIC, and VERITAS) Flux Sensitivity [erg cm
for energies above a few TeV (Acharyya et al., 2019). In ×
2 Fig. 5, the integral sensitivity (expressed in Crab Nebula E Units, C.U. (Aharonian et al., 2004)) for sources with a Crab 10−12 Nebula-like spectrum above a given energy threshold (5 per ASTRI Mini-Array Core Science decade) for 50 hours of observations is depicted. The inte- ASTRI mini-array: energy resolution 1 0.5 0 0.5 1 1.5 2 2.5 gral sensitivity of the system is Ì1.5% and Ì15% of the Crab − −0.35 log (E [TeV]) ASTRI Mini-Array 0.5 deg off-axis10 (50h) Ì Ì ASTRI Mini-Array 1.5 deg off-axis (50h) Nebula flux above an energy) [C.U.] thresholdASTRI of Mini-Array2 TeV, on-axis (50h) 30 TeV,
th 0.3 ASTRI Mini-Array 2.5 deg off-axis (50h) ASTRI Mini-Array 3.5 deg off-axis (50h) respectively. 1 ASTRI Mini-Array 4.5 deg off-axis (50h) Figure 4: On-axis0.25 differential sensitivity (multiplied by energy
, squared) of theEnergy Resolution ASTRI Mini-Array for 50 hours of observations as a function of the0.2 energy between Ù 0.1 TeV and Ù 300 TeV. 0.35 0.15 10−1 0.1 0.3 Integral Flux Sensitivity (E>E , 0.05 0.25 10−2 0 Energy Resolution −1 −0.5 0 0.5 1 1.5 22.5.2.5 O -axis performance−1 −0.5 0 0.5 1 1.5 2 2.5 log (E [TeV]) log (E [TeV]) 0.2 10 th The o -axis performance quantities were derived10 con- Figure 5: On-axis integral sensitivity of the ASTRI Mini-Arraysidering the MC2 di use gamma sample, along with the dif- 0.15 ASTRI Mini-Array 0.5 deg off-axis (50h) Ratio for sources with a Crab Nebula-like spectrum for 50 hours of 1.8 ASTRI Mini-Array 1.5 deg off-axis (50h) fuse background samples (see Tab. 1). AllASTRI samples Mini-Array 2.5 deg off-axis were (50h) di- observations as a function of the energy threshold in the range 1.6 0.1 ASTRI Mini-Array 3.5 deg off-axis (50h) vided in 5 source o -axis bins between 0° andASTRI Mini-Array 5°. 4.5 In deg off-axis Fig. (50h) 6, 7, between Ù 0.1 TeV and Ù 300 TeV. 1.4 0.05 and 8, the main1.2 o -axis performance quantities are display for each o -axis bins1 (left plots), in the energy range between 0 , *1 2.5 −1 −0.5 0 0.5 1 1.5 2 2.5 10 Ù 0.1 TeV0.8 and 10 Ù 300 TeV, considering five loga- , log (E [TeV]) 0.6 10 rithmic energy bins per decade. In the same figures (right 0.4 2.6. Impact of the di erent ASTRI Mini-Arrayplots), the ratio between the o -axis performance quantities Figure 2: On-axis energy resolution of the ASTRI Mini-Array 0.2 layout at the Teide observatory with respect the one achieved in the first considered o -axis as a function of the energy between Ù 0.1 TeV and Ù 300 TeV. 0 As already discussed, the ASTRI Mini-Array will be de- −1 −0.5 0 0.5 1 1.5 2 2.5 bin are also shown. Remarkably, the o -axis performancelog (E [TeV]) ployed at the Teide Observatory, in the Canary Island of 10 worsen down to Ì50% of the on-axis performance at 5°, al- Tenerife. While the main single-telescope components will Figure 6: Top:Off-axis energy resolution of the ASTRI Mini- , be basically the same as the ones considered in thislowing work, theArray system as a to function reach of an the unprecedented energy between 10* performance1Ù 0.1 TeV and the overall array layout (henceforth, Teide layout)over will adif- wide10 field2.5Ù 300 of TeV view for of 5 source several off-axis squared bins between degrees. 0° and This 5°. 1For the computation of the residual background rate, the background fer, to some extent, from the one shown in Fig. performance1 (hence- Bottom represents: Energy a resolution key feature ratios of with the respect system, to the which energy is events were reweighed in orderforth, to match Paranal the layout). experimental In order fluxes to get as a preliminarymea- estimate resolution achieved in the first considered off-axis bin (from 0° sured by the BESS Collaborationof the (Sanuki possible et al. impact, 2000 on) for the protons performance, and by a dedicatedparticularly MC to important 1°). The ratio for is observations calculated so that of higher extended values correspond sources, to better performance. The dashed, thin red line represents the the Fermi-LAT (Ackermann etproduction al., 2010) of and only H.E.S.S. point-like (Aharonian gamma-ray et al. events, large was pro- sky-surveys, and possible serendipity discoveries. 50% performance drop. 25 2008a) Collaborations for electrons,duced, respectively. considering the same shower parameters as shown, in Tab. 1 and a realistic, although preliminary, Teide lay- S. Vercellone et al.: Preprintout. submitted Then, some to comparisons Elsevier of basic quantities at trigger Page 5 of 61 level between the two layouts were performed. The main approximation, almost invariably at the higher analysis level, outcomes of such comparisons were: one can estimate that the performance of the ASTRI Mini- Array at the Teide observatory (for low zenith angles and • The trigger energy threshold of the Teide layout is energies above Ì1 TeV) should not di er more than Ì20% Ì40% lower than the one achieved by the Paranal lay- from the one presented in Sec. 2.4 and 2.5. The actual dif- out. ference in performance will be fully characterized once the complete MC production of the ASTRI Mini-Array at the • For energies above Ì1 TeV (up to the highest ener- Teide Observatory will be accomplished. gies), the e ective collection area of the Teide layout is Ì80% of the Paranal layout one. For energies below Ì1 TeV, instead, the former quantity becomes signif- 3. ASTRI Mini-Array Core Science icantly higher than the latter. The ASTRI Mini-Array will start deploying the first tele- • In the entire energy range, the average multiplicity (i.e. scopes on-site starting from late 2021 (??). Commissioning the average number of telescopes that give trigger for and preliminary observations will begin in 2022 (??). We a given event) of the Teide layout is always higher (up plan to devote the first two or three years on specific science to Ì30%, depending on the energy) than the one of the topic, with the aim to provide robust answers to a few well- determined open questions. In particular, we will take ad- Paranal layout. ˝ vantage of the wide field of view (Ì 10 ) to simultaneously All the above mentioned results are likely due to the some- investigate more than one source during the same pointing what more compact configuration of the Teide layout with and to study complex Galactic regions, such as the Cygnus respect the Paranal layout. Assuming that the di erences be- region or the Galactic center, where the di use emission and tween the two layouts at the trigger level propagate, on a first the high number of sources need careful data analysis. We
S. Vercellone et al.: Preprint submitted to Elsevier Page 6 of 61 ASTRI Vs. other Gamma ray telescopes
ASTRI Mini-Array Core Science
Table 6 Summary of the performance of the current main imaging atmospheric Cherenkov telescope arrays and water Cherenkov detectors. References. ASTRI Mini-array: this work. MAGIC: Aleksić et al. (2016). VERITAS: Holder et al. (2006)and https://veritas.sao.arizona.edu.H.E.S.S.:Aharonian et al. (2006a). HAWC: Abeysekara et al. (2017c,b). LHAASO: Cao ( ) ( ) ( ) ( ) (2010). Notes. a : as a function of the event size. b : w.r.t. on axis at 3°. c : w.r.t. on axis at 2°. d : for ZA g 35 °.
ASTRI Mini-Array MAGIC VERITAS H.E.S.S. HAWC LHAASO
® ®® ® ®® ® ®® ® ®® ® ®® ® ®® Location 28° 18 04 N28° 45 22 N31° 40 30 N23° 16 18 S18° 59 41 N29° 21 31 N 16° 30® 38®® W 17° 53® 30®® W 110° 57® 7.8®® W 16° 30® 00®® E97° 18® 27®® W 100° 08® 15®® E
Altitude [m] 2,390 2,396 1,268 1,800 4,100 4,410 FoV 9.6° Ì 3.5° Ì 3.5° Ì 5° 2sr 2sr ( ) Angular Res. Ì 0.07° (10 TeV) 0.04° (1 TeV) 0.08° (1 TeV) < 0.1° (0.2–1)° a Ì xx° (10 TeV) Energy Res. (10-15)% (10 TeV) 17% (1 TeV) 10% 30% (10 TeV) xx% (10 TeV) Energy Range (0.6-200) TeV (0.85-30) TeV (0.2-30) TeV (0.1-100) TeV (0.1-1,000) TeV ( ) ( ) ( ) ( ) Sensitivity Drop 50% a < 40% b Factor > 5 c Factor > xx d
for extended sources investigating both their VHE emis- • The region near the Galactic Center will be accessible sion at the very edges and the spectral properties in by both the ASTRI Mini-Array and HAWC. Thanks 26 di erent regions of the source. to the wide field of view of the ASTRI Mini-Array ˝ (9.6 in diameter) a large portion of the sky will be • Since we can plan well in advance our observing strat- investigated simultaneously, so that the ASTRI Mini- egy, we can choose a few scientific targets and devote Array can study, by means of deep observations, sky to them very long (>>50 hrs) exposures. “hot-spots” detected by HAWC, similarly to the ones 8.2.3. HAWC and LHAASO identified by the MILAGRO (Atkins et al., 2003) ex- periment. The HAWC array (Abeysekara et al., 2013) has been in- augurated on 2015 March 20 on the flanks of the Sierra Ne- • HAWC is be able to detect intense flares from a large gra volcano near Puebla, Mexico. To record the particles portion of the sky (Abeysekara et al., 2017d), allowing created in cosmic-ray and gamma-ray air showers, the HAWC us to promptly re-point the ASTRI mini-array to any detector will use an array of water Cherenkov detectors (WCDA). observable flaring source. In this technique, the detector is used to sample air-shower particles at ground level by recording the Cherenkov light • The high-energy boundary of both HAWC and the AS- produced when the particles pass through tanks full of puri- TRI Mini-Array will allow us to study the VHE (E>10 TeV) fied water. HAWC is located in the northern hemisphere, its emission from extended source such as SNR and PWN, performance in terms of the highest achievable energy range and to investigate the presence of spectral cut-o s. make it an excellent reference for the ASTRI Mini-Array. The LHAASO array is similar to HAWC, but combines 8.3. ASTRI Mini-Array expected legacy products both Acknowledgments We can summarize the possible ASTRI Mini-Array syn- This work was conducted in the context of the ASTRI Project. ergies with respect to HAWC as follows. This work is supported by the Italian Ministry of Education, • The low energy threshold HAWC (˘200 GeV) and the University, and Research (MIUR) with funds specifically as- wider energy range of the ASTRI mini-array (about or signed to the Italian National Institute of Astrophysics (INAF). beyond 100 TeV) will allow us a direct comparison of We acknowledge support from the Brazilian Funding Agency scientific data (spectra, light-curves, integral fluxes) FAPESP (Grant 2013/10559-5) and from the South African of those sources which could be simultaneously mon- Department of Science and Technology through Funding Agree- itored. ment 0227/2014 for the South African Gamma-Ray Astron- omy Programme. This work has been supported by H2020- • At time of the ASTRI Mini-Array operation, HAWC ASTERICS, a project funded by the European Commission will have performed a few years of operation, accu- Framework Programme Horizon 2020 Research and Innova- mulating a sensitivity that, on selected sources, could tion action under grant agreement n. 653477. IAC is sup- be reached by the ASTRI mini-array in a few months ported by the Spanish Ministry Ministry of Science and In- of pointings. novation (MICIU).
S. Vercellone et al.: Preprint submitted to Elsevier Page 39 of 61 Galactic sources
27 ASTRI mini-array: Science programme
Core science program in the first ~2/3 years (detailed strategy under definition): • Restricted number of targets/deep exposures (>~ 200 h) ® strong scientific cases • Galactic sources: wide FoV ® multi-target fields • Extragalactic sources: survey of a few promising targets at > ~10 TeV scale • Fundamental physics: studies on LIV, EBL, Axion-Like Particles, … • Science beyond VHE astronomy also envisaged ® Stellar Intensity Interferometry
Crab Nebula spectrum up to Synergies with current VHE Northern Arrays: 100 TeV in ~100 h • Observations of HAWC and LHAAZO sources with higher angular/energy resolution • Simultaneous observations with MAGIC and LSTs will be possible
28 ASTRI: Pevatronic sources
ASTRI Mini-Array Core Science
Table 2 List of selected -ray sources relevant for the study of CR origin, observable from the Observatorio del Teide and studied with ASTRI-MA simulations
Name RA Dec Type Zenith Angle1 Visibility2 Flux3(1 TeV) Index Section (deg) (deg) (deg) (hr/yr) (10*13 TeV*1cm*2s*1)
Tycho 6.36 64.13 SNR 35.8 410+340 1.71 2.28 4.1.1 Galactic Center 266.40 -28.94 Diffuse 57.2 0+180 36 2.32 4.1.2 eHWC 1907+063 286.91 6.32 SNR+PWN 22 400+170 0.85(7 TeV) 2.33 4.1.3 SNR G106.3+2.7 337.00 60.88 SNR 32.6 460+300 1.15 (3 TeV) 2.29 4.1.3