PARTICLE ACCELERATION ON COSMOLOGICAL SCALES
@HambObs MARCUS BRÜGGEN
Abell 2744 Optical
1 Mpc
Pearce+ (2017) Abell 2744 X-rays: intracluster mediumOptical (ICM)
1 Mpc
Pearce+ (2017) Abell 2744 Radio: cosmicX-rays: rays intracluster (CR) + magnetic mediumOptical fields(ICM)
1 Mpc
Pearce+ (2017) Abell 2744 Radio: cosmicX-rays: rays intracluster (CR) + magnetic mediumOptical fields(ICM) ~μGauss
1 Mpc
Pearce+ (2017) Abell 2744 Radio: cosmicX-rays: rays intracluster (CR) + magnetic mediumOptical fields(ICM) ~μGauss
radio spectra slope: spectral index (α)
“flat”
“steep”
Diffuse cluster radio emission has a steep 1 Mpc spectrum Pearce+ (2017) DIFFUSE CLUSTER EMISSION JVLA 1-4 GHz latest reviews: Feretti+2012; Brunetti & Jones 2014 Pearce et al. (2017) 1.0 Mpc X-rays: 0.5-2.0 keV RELIC
HALOS HALO • Mpc sizes, centrally located • Unpolarized Tailed radio galaxy • X-ray luminosity radio power correlation foreground AGN • Found in disturbed clusters DIFFUSE CLUSTER EMISSION JVLA 1-4 GHz latest reviews: Feretti+2012; Brunetti & Jones 2014 Pearce et al. (2017) 1.0 Mpc X-rays: 0.5-2.0 keV RELICS RELIC • Mpc sizes, cluster outskits • Elongated, filamentary morphologies • Polarized • Found in disturbed clusters
HALOS HALO • Mpc sizes, centrally located • Unpolarized Tailed radio galaxy • X-ray luminosity radio power correlation foreground AGN • Found in disturbed clusters HOW DO YOU ACCELERATE PARTICLES?
FERMI (1949): SCATTER OFF MOVING CLOUDS. VERY SLOW (V2/C2) BECAUSE CLOUDS BOTH APPROACH AND RECEDE
IN SHOCKS, ACCELERATION IS 1ST ORDER IN V/C BECAUSE FLOWS ARE ALWAYS CONVERGING (BLANDFORD & OSTRIKER 78)
FERMI I: SHOCKS: BOUNCING BETWEEN APPROACHING MAGNETIC MIRRORS FREE ENERGY: CONVERGING FLOWS ! $ N = N0E ! = ⁄%&'
FERMI II: TURBULENCE: BOUNCING OF RANDOM MAGNETIC SCATTERERS Clusters grow through mergers MACSJ0025.4 - 1222
Dark Dark Matter Matter Gas + Gas Galaxies Key Key N Matter Dark Gas Dark Matter + Gas S Galaxies Key N Matter GravitationalAttraction Dark Gas Dark Matter + Gas S Galaxies Key Matter Dark N Gas Dark Matter + Gas S Galaxies Key Matter Dark Gas N Dark Matter S + Gas Galaxies Key Matter Dark Gas N+S Dark Matter + Gas Galaxies Key Momentum Matter Dark Gas S Dark Matter N + Gas Momentum Galaxies Shocks Radio
Key Matter Dark relics S Gas C Dark Matter + Gas N Galaxies PARTICLE ACCELERATION AT SHOCKS
CIZA J2242.8+5301
•2 Mpc radio relic •additional fainter Radio relics X-rays •z = 0.19 •LX = 6 × 1044 erg/s
van Weeren+ (2010, Science) Credit: van Weeren, MB, Chandra press Rajpurohit, Hoeft, van Weeren, MB et al. (2017) TOOTHBRUSHCOMPLICATED IS AND HERE THE SPECTRAL INDEX... Rajpurohit , Hoeft,, van Weeren , MB, et al. (2017)
THE CENTRE OF THE MILKY WAY
MeerKAT Collab. Radio relics Radio halos
Shock (re)acceleration at Turbulent (re)acceleration in merger shocks merging galaxy clusters
Botteon et al. 2020 TESTS OF FERMI I PROBLEM #1: WHY IS THE ACCELERATION SO EFFICIENT?
PROBLEM #2: WHERE DOES THE B-FIELD COME FROM? PROBLEMS WITH SHOCK ACCELERATION
Low Mach number shocks and luminous relics → Macario+(2011); Vazza • & Brüggen (2014); van Unrealistic fraction of shock energy transferred Weeren+(2016) into relativistic electrons
Ogrean+ (2014); •Mismatch between spectral index and Mach Akamatsu+ (2013) number
•No γ-rays from relics: relative acceleration efficiency of electrons and protons different from Vazza+ (2014,2015,2016) DSA RELICS: ORIGIN OF CR ELECTRONS
Shock acceleration •Particles accelerated via diffusive shock acceleration acceleration (DSA / SDA) •Start from the thermal pool
Ensslin+ (1998); Blandford & Eichler (1987); Guo+ (2014); Caprioli & Spitkovsky (2014) van Weeren+ (2017) Re-acceleration •Similar to DSA but start with seed fossil relativistic electron population (DSRA)
•More efficient re-acceleration for Markevitch+ (2005); low-Mach shocks (compared to DSA) Giacintucci+ (2008); Kang+ (2012, 2016); •Additional models proposed Shimwell+ (2015); GMRT 610 MHz (Fermi-II type) Bonafede+ (2014) Chandra Fujita+(2015) Botteon+ (2016)
Vazza, MB + 2021 Rudnick, MB+ 2021 MAGNETIC FIELD? SMALL-SCALE DYNAMO LOFAR Onsala
Birr Irbene
Dutch stations Chilbolton Norderstedt Bałdy Potsdam Borówiec Jülich Efelsberg
Tautenburg Łazy
Nançay Unterweilenbach
Medicina
GOING DEEP A2255 has been chosen as the first LOFAR Cluster Deep Field
Botteon, MB, et al. (2020) MEGAHALOS ABELL 665
Cuciti et al. (in prep) Questions
• How common are Megahalos?
• What is the relation between Megahalos and radio galaxies inside the cluster?
• What is the relation between Megahalos and classical radio halos? BRIDGES Why are radio bridges interesting? The non-thermal cosmic web
Stochastic acceleration • Bridges contain plenty of turbulent power ~ 1045 erg /s • ~ 0.01% is enough to explain radio power • Turbulence is super-Alfvenic (MA ~10) and solenoidal (>50%) • Fermi-II-like acceleration mediated by solenoidal turbulence (Brunetti & Vazza, 2020) • Predictions: • Low-frequency emission is smooth • High-frequency emission is clumpy • Bright phase is < 0.5 Gyr long
2 Mpc 2 Mpc 2 Mpc
0.000000 0.000004 0.000014 0.000035 0.000079 0.000174 0.000381 0.000827 0.001789 0.003842 Continuum emission from bridges between clusters
LOFAR 140 MHz LOFAR + Planck
Weak shocks or volume-filling turbulence?
Only detected by LOFAR no spectrum. Govoni, MB, et al. (2019) The bridge in the Coma cluster seen with LOFAR
Halo front
Streams
Bonafede, MB, et al. (2020) Turbulent power in bridge volume V:
If group injects turbulence
A fraction can be converted to mildly relativistic electrons:
where
Mach number of turbulence for given efficiency
For radio halos so is enough to power radio bridge
Bonafede, MB, et al. (2020) A giant radio bridge connecting two galaxy clusters in Abell 1758 Emission is volume-filling
Botteon et al. (2019) ART-XC (IKI)
Navigator (NPO Lavochkin) eROSITA (MPE)
Спектр-РГ
Navigating the eROSITA X-ray sky Coma Cluster Sco X-1 z=3.1 QSO [26 Gpc] Cygnus Cyg X-1 [99 Mpc] [2.8 kpc] Virgo Cluster [17 Mpc] Shapley Supercluster Superbubble [1.9 kpc] [200 Mpc] Cas A [1-2 kpc] Centaurus Cluster [3.4 kpc] [41 Mpc] Crab Pulsar [~2 kpc]
North Polar Spur
Orion Nebula G156.2+05.7 [412 pc] Vela SNR SNR Perseus Cluster [250 pc] [1.7-3 kpc] Fornax Cluster [74 Mpc] Cyg X-2 Cygnus Loop [19 Mpc] [600 pc?] [770 pc] Large Magellanic Cloud IKI [50 kpc] MPE
Merloni, AAL-eROSITA, 2/2021 18 Data Release Plan
• Early Data Release (EDR): PV/Cal data: July 1st, 2021 • 2 Survey fields: • eFEDS (140 deg2; 2.5 ks) • Eta Chamaleontis (25 deg2; 5 ks) • 6 deep pointings in the LMC/SMC • 10 Extra-galactic fields (including A3391/3395) • 13 galactic fields • All calibrated events, exposure maps and source catalogs • eSASS software and Calibration DB. • All-sky Survey (TBC): • eRASS:1 (DR1: Q4 2022); eRASS:4 (DR2: Q2 2024); eRASS:8 (DR3: Q2 2026)
Merloni, AAL-eROSITA, 2/2021 25 SRG/eROSITA 0.2-2.0 keV SRG/eROSITA 0.2-2 keV
MPE/IKI
T Reiprich, M Ramos-Ceja, F Pacaud, N Ota, J Sanders, D Eckert, E Bulbul, V Ghirardini MPE/IKI Brüggen et al. (2020) At high redshift, radio halos are expected to be faint, due to the Inverse Compton losses and dimming effect with distance.
19 galaxy clusters in z range of ∼0.6−0.9 with masses MSZ,500 ∼ 4-8×1014 M⊙.
Di Gennaro, MB, et al. (2020) similar radio luminosities imply that the product of the number of the radio-emitting electrons and magnetic field (Ne × B2) in high-redshift clusters is similar to that in lower-redshift systems of comparable mass.
Di Gennaro, MB, et al. (2020) Equatorial Field Depth Survey Field (PV Phase)
Credits: Jeremy Sanders, Miriam Ramos-Ceja, Sebastian Grandis Ghirardini et al. (2020) Ghirardini, MB, et al. (2020) Summary
• Radio telescopes have revealed electron acceleration on Megaparsec scales
• Electrons get accelerated by shocks and turbulence
• Very deep LOFAR observations have shown that relativistic electrons in merging clusters fill vast volumes: MEGAHALOS
• Large-scale magnetic fields produced by turbulent dynamo
• Seeds for particle acceleration could come from radio galaxies
• Cosmological bridges: re-acceleration by solenoidal turbulence
• Future instruments, such as the SKA & LOFAR upgrade, will map extragalactic distribution of magnetic fields and cosmic rays. Ghirardini et al. (2020)