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Sesto

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Franco Vazza

on 18 May 2018

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Transcript of Sesto

Radio-X synergies in the detection of the shocked cosmic web
Mag.Fields
Detectability with incoming radio surveys
FV, Ferrari, Brüggen+2015 AA
The shocked cosmic web
Temperature & Mag.Fields
Synchrotron from
shock-accelerated
electrons:
Main assumptions:
The amplification of magnetic fields across environment
~ MHD picture (on >100 kpc scales)
Diffusive shock acceleration is operating
0
-11
The "CHRONOS++ suite"
(~32 million core hours)
Large survey of models for the origin of cosmic magnetism
ENZO-MHD (Dedner) , cooling, star formation, AGN feedback
PDF of B-fields
Cluster properties
Magnetic fields from SF
Trend with resolution
B-field & RM properties well converged
for r>R200
Summary:
MAGCOW
The Magnetised Cosmic Web
2017-2022
Cosmic baryons were there at high redshift in the low density Universe...
The cosmic web of galaxies
~90 % of cosmic (DM+ordinary) matter in the cosmic web
~6% of total matter locked in ALL ~ 10 galaxies in the Universe
11
(Nicastro+16)

WHIM & filaments in simulations
B) Gas isodensity reconstruct.
(+shape analysis & halo removal)
parallel implementation in VisIT
Gheller, FV et al. 2015, 2016
Thermal and non-thermal properties of filaments
A) N-body based: topological or morphological analysis.
10 Mpc
transverse profiles
phase diagrams
- mostly filled by WHIM gas
-small but non-negligible impact of cooling/heating

Thermal and non-thermal properties of filaments
Density sorting for ~100 filaments
Temperature:
~10-30% of cluster outskirts

Lx ~ 10% CL.out.
velocity~CL.out
Bfield~30%CL.out

-> non thermal energy is filaments >> than in cluster outskirts

Galaxies in filaments
-> assuming a typical M*- Mtot relation (Hahn+15)
observed & simulated filaments agree well

Thermal and non-thermal properties of filaments
Temp vs Mass MaxB vs Mass
In clusters : T ~ M^2/3
in filaments : T ~ M^1/2
-> cylindrical collapse, not in virial eq.
Magnetic field mostly grows via compression
Amplification ~10 seed field

WHIM
WHIM
(see Cen+2006,Roncarelli+12)
(see Stoica+,Hahn+,Cautun+)
DM halos in filaments compared to galaxies in filaments in GAMA (Alpaslan+15)
SKA-ATHENA synergies on the cosmic web
Challenges:
Problem#1 : unknown metallicity
Metallicity in cluster
outskirts still uncertain!
at r~R180 :
~0.3 solar Werner+13
~0.03-0.26 Molendi+16
Problem#2 : impact of feedback
what is the sphere of influence of
AGN feedback?
(e.g.Roncarelli+12; Biffi+16)
star feedback stars+AGN feedb.
Matching emissions in ATHENA & SKA
Including: galactic absorpion (5e20 atoms/cm^2), background, pixelisation 27" x 27"
FV, Ettori, et al to be submitted
Non-radiative run, Z=0.3 Zsolar, 1 Megasecond, 0.8-1.2keV
-> Only a 4.5% of cluster outskirts may be detectable by both.
Traces of magnetogenesis on ~10-100 Mpc scales
- Differences in RM and sync. em. for r>R200 in massive clusters
- Statistical differences in correlation functions ~1-10Mpc
-> Vernstrom et al. 2017 MNRAS
- The cosmic web: a shrine for the study of baryon physics & magnetism
Two complementary & interconnected problems.
we know they were there (z=1000) and we don't know where they ended up.
Magnetic fields:
Baryons:
we see them at z~0 but we don't know where they come from.
Problem#3 : realistic mock observations (SIXTE, SIMX)
THE COMPLEXITY OF COSMIC STRUCTURE (FV+17 MNRAS)
Kolmogorov (algorithmic) complexity:
how many bits of information are necessary to perfectly reproduce a data (e.g. loss-less compression)
Statistical complexity:
how many bits of information are necessary to produce statistically similar data (e.g. you download the wrong movie)
THE COMPLEXITY OF COSMIC STRUCTURE (FV+17 MNRAS)
Basic idea:
- thermal/kinetic/magnetic energy binned into
E1...En
states
- transition probability
P(E2|E1)
between states at each timestep
- Shannon entropy of each transition
THE COMPLEXITY OF COSMIC STRUCTURE (FV+17 MNRAS)
Complexity phase diag.
Time evolution (block entropy)
AGN feedback
WHIM
Potentially a very powerful tool to analyse
simulations (and even design new ones)
The cosmic web and the neuronal network: equally complex systems?
(FV & A. Feletti to appear in Nautil.us)
The cosmic web and the neuronal network: equally complex systems?
(FV & A. Feletti to appear in Nautil.us)
~10 halos
11
~10 neurons
11
simulated real
Complexity of the observable Universe (at ~100kpc) : ~1-10 Pb
Memory capacity of the human brain: ~2.5 Pb
interesting....
Detecting cluster outskirts & filaments with SKA
FV, Ferrari+2015 SKA White Book
Can we detect the cosmic
web with SKA?
Low frequency (<200 Mhz) is best ; sensitivity ~muJy/arcsec^2 necessary
Cosmological MHD & numerical implementations
The CHRONOS++ suite of simulations (Vazza+14,15,16...)
extra slide
extra slide
primordial additional seeding from stars
Simulated global star formation
"Computationally-Intensive, High-Impact Research on Novel Outstanding Science"@CSCS
>50 million CPU hours in total ( ~45 @ CSCS, ~5 @ Juelich)
ENZO-MHD on the GPU + code implementations
largest survey of magnetic fields in cosmology
Volumes: 50-200 cubic Mpc, resolution=1-80 kpc
Scientific products made public via EUDAT
Seeding from galactic dynamos
Enzo-MHD
(Bryan+14)






Dedner method
(2002) for MHD, ported on the GPU by Wang et al.(2010)

ORIGINAL CODE IMPLEMENTATIONS:
Tailored adaptive mesh refinement for shocks & turbulent motions (Vazza+09)
2-fluid model for cosmic rays (Vazza et al. 2012,13,14,15,16)
Magnetic field injection coupled to star formation and AGN feedback (Vazza+16)
Magnetic seeding from star formation
Vazza et al. 2014 MNRAS
Vazza et al. 2015 A&A
Large volumes, large uniform grids (2400^3)
Subvolumes, high resolution with AMR (5kpc)
5Mpc
-> radio survyes
-> deflection of UHECRs
-> study of axionlike particle oscillations
-> dynamo in clutsers
-> Faraday tomography
-> radio emission in clusters
Vazza et al. submitted
Data used
to study:
Data used
to study:
Overview of Sub-project #1
extra slide
Notes:
simulations are ~80% completed (May 2016)
new suite of "Constrained" MHD simulations of the local Universe allotted @ Juelich (800,000 hours)
submitted 30 million hours proposal for AMR @ CSCS-ETHZ
"Primordial" scenario B0=1nG (comoving)
most of volume follows adiabatic B ~ n relation
Non-radiative MHD (Dedner). 2400^3 cells. ~2.5Mh on 1024 nodes on PizDaint
temperature
mag.field
in clusters: magnetic fields probe plasma turbulence
in filaments: magnetic fields carry memory of seeding
ICM
:
solenoidal turbulence
~10 Gyrs timescales
-> small-scale dynamo

WHIM
:
compressive turbulence
~1Gyr timescales
-> no dynamo
Clusters vs filaments
Vazza+14MNRAS
- Simulations are establishing the link btw galaxies, baryon & mag.fields
- Next radio/X-ray/optical surveys: fundamental for these quests
- My ERC-funded group on these themes will begin in Sept.2017 @
Bologna Univ. & Hamburg Univ.

Observed extragalactic fields
magnetic fields ~unknown for >99.99% of cosmic volume
"ITASCA" SIMULATIONS, FV, Jones et al. 2017 MNRAS
Detectability with incoming radio surveys
now ~2017 >2020
Traces of magnetogenesis on ~10-100 Mpc scales
"Tip of the iceberg" detectable !
CHALLENGES:
* Polarisation
* Confusion noise
* Statistical techniques
- Differences in RM and sync. em. for r>R200 in massive clusters
- Statistical differences in correlation functions ~1-10Mpc
2/3
Franco Vazza
Università Bologna
Universität Hamburg
IRA-INAF
+ S.Ettori
+S. Brüggen
+C.Gheller
+C.Ferrari
+G.Brunetti
+A.Bonafede
Sesto, 8-13 Jan 2018
Matching emissions in ATHENA & SKA
FV, Ettori, et al to be submitted
Matching emissions in ATHENA & SKA
FV, Ettori, et al to be submitted
Matching emissions in ATHENA & SKA
FV, Ettori, et al to be submitted
...Magnetic fields emerged at high density and low redshift.
Cluster outskirts in ATHENA & SKA
FV, Ettori, et al to be submitted
Target: a ~1e15 major merger cluster @200Mpc
Z=0.3Zol constant
Coma-like magnetic field, 0.1nG initial field
Cluster outskirts in ATHENA & SKA
FV, Ettori, et al to be submitted
Target: a ~1e15 relaxed cluster @200Mpc
Z=0.3Zol constant
Coma-like magnetic field, 0.1nG initial field
Cluster outskirts in ATHENA & SKA
FV, Ettori, et al to be submitted
Target: a ~1e15 major merger cluster, @200Mpc , Z=0.3Zol constant
emission + absorption + (instrumental+astroph.) background
*=wrong angular scale, sorry
*
(same saturated maps)
300Mpc
Structure formation, shocks and magnetic field
SKA-LOW XIFU Pressure
contours=double detections
Detectability of emission from different cosmic objects
The value of synergy
1. Testing the "WHIM picture": is there really shocked gas with T~1e5-1e7 ?
2. Best targets for long XIFU search of
emission
lines (complementary to probing
absorption
with GRB/AGN)
4. Electron acceleration efficiency at strong shocks
3. Constraining the Mach number of strong shocks : temp. jump better vs radio spectrum
5. Metallicity of shocked WHIM: is Z~0.3Zsol?
Properties of detectable cluster outskirts
in X-ray:
T>5e6K

in Radio
B>10nG

Uncertainties/todo list
metallicity...
magnetic fields...
feedback...
Inverse Compton...
more sophisticated Xray/radio simulators (SIXTE..)
detectability for varying metallicty
and magnetic fields
no feedback star/AGN feedback
Which objects are good for synergies?
Final message: in the cosmic web SKA & ATHENA will only overlap in the tip of the iceberg
Simulating the cosmic web and magnetogenesis with supercomputers
ENZO-MHD grid simulations
>40 million core hours on Piz-Daint @CSCS (Lugano)
Largest MHD cosmological simulations to date 2400^3 cells
A fraction of kinetic energy remain turbulent
- pressure support
- magnetic field dynamo
- possibly CR re-acceler.
~3%
~0.001%
primordial seeding AGN/SFR seeding
(FV,Ettori et al. to be submitted)
SKA-LOW survey
120 MHz
beam ~ 10"
sensitivity ~0.02 mJy/beam
detect.threshold~0.03 muJy/arcsec^2
(initial B=1nG seed field)
Radio emission X-ray emission
However, double detections will test the pillars of the WHIM paradigm for missing baryons
Questions?
FV+14,+15,FV16, Gheller+16,Hacsktein+17
Supersonic gas motions inject:
- Mach>10 accretion shocks
- Mach<5 merger shocks
- possibly cosmic rays
Gas Pressure
Mach number
Vorticity
Goal:
- can we use SKA to enable ATHENA detections?
- best targets for long XIFU exposures of the WHIM

ATHENA (XIFU) 1 Ms
[0.8-1.0]keV
5'x5' pixel binning
absorp. nH=1e20
Bg ~ 1.7e4 cts/arcmin^2/Ms
(Z=0.3 Zsolar)
>3*max(confusion,rms)
>3f*S/sqrt[f*S+2*BG]
Eckert+15
~10%
SKA :
reduced Bmax 65->40km

ATHENA :
x2 reduced effective area

~800
~80
Simulated X-ray observations of the Cosmic Web ~1Ms
>3f*S/sqrt[f*S+2*BG]
"Primordial" vs "Astrophysical" scenarios to the test
new ENZO simulations using MHD on Piz-Daint (~32 Million core hours)
>20 seeding models magnetic fields.
Cosmogensis on supercomputers
ENZO-MHD simulations using MHD on Piz-Daint (~8 Million core hours)
2400^3 : largest (grid) simulations of magnetism to-date (FV+14 MNRAS)
FV, Brüggen,Gheller et al. 2017
"Sparsity" (e.g. M50/M100) as an indicator?
Total mass as an indicator?
Profile of counts in massive clusters
Simulated X-ray observations of the Cosmic Web ~1Ms
Close interacting pairs (?)
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