Searching for the Origin of UHECR with Michael Hillas (Aug 2014- Dec - PowerPoint PPT Presentation

Searching for the Origin of UHECR with Michael Hillas (Aug 2014- Dec 2016) Andrew Taylor Hillas Symposium Andrew Taylor

Michael’s PainEng- Renoir’s Nightmare! Andrew Taylor Hillas Symposium Andrew Taylor

MeeEng at Dunsink (2014) Hillas Symposium Andrew Taylor

Cosmic Ray Spectrum It is surprising how much detail lurks here

Enlarged Plot To Show Bend in Spectrum KNEE ANKLE Extragalactic? Galactic/SNR? The knee and ankle bends show up, but it is probable that this traditional interpretation of the ankle greatly underestimates the low energy presence of extragalactic cosmic rays.

. . An Obvious Interpretation of a Graph is Not Always Right! KNEE ANKLE Extragalactic? Galactic/SNR? Observations at Haverah Park and elsewhere looked for signs (anisotropy) that the Galactic particles were increasingly leaking away, but found none. Michael thought the particles were already largely extragalactic- why?

Particles From Extragalactic Sources pion production pair-production losses S normalised here SF W C Spectrum of protons after struggling through the microwave treacle: If initial spectrum dN/dE ~ E -2.3 , Production rate in universe: SF = like Porciani-Madau star formation rate SF2; C =constant; W =PM 0.5 ; S = PM 1.5 The (e + e - )energy losses in CMBR produce an ANKLE in right place.

Particles From Extragalactic Sources And this is the flux that reaches us if one starts with He or O nuclei instead if protons: they also suffer nuclear fragmentation. (Reaction thresholds at different place.) NOTE- the energy losses do not produce the ankle feature.

Can We Detect The Change To Light Nuclei Near 3x10 17 eV? p He C Equivalent mass The x max test (depth of maximum of extensive air shower) (If the primary particle is a large nucleus, the individual nucleons have less energy and their showers die out at a lesser atmospheric depth.) Here, “ x max ” – a – b.logE is plotted to make the line horizontal if the nuclear mass is unchanged with energy. (b is the “ elongation rate ” ; a is arbitrary.) (Line is “ best spectrum fit ” 5%-of-normal He and metals.) The older pioneering “ Stereo Fly ’ s Eye ” data look discordant: there does appear to be a rapid change to light nuclei here.

Michael’s Conclusion! Michael’s poignant wit! Hillas Symposium Andrew Taylor

My Own Motivation for Considering Extragalactic Cosmic Rays Below the Ankle Liu et al. (2016), 1603.03223 GiacinE et al. (2011), 1112.5599 Pierre Auger Collab. (2012), 1212.3083 1 Upper Limit - Dipole Amplitude λ -1 10 Z=1 Z=26 -2 10 1 10 Hillas Symposium Andrew Taylor E [EeV]

Cross Check of Nuclei Propagation Results...Michael learnt this very quickly! 10000 E 2 dN/dE [arb. units] 100 1 Michael- A=1-2 Andrew- A=1-2 0.01 Michael- A=3-5 Andrew- A=3-5 Michael- A=6-13 Andrew- A=6-13 0.0001 Michael- A=14 Andrew- A=14 16.5 17 17.5 18 18.5 19 19.5 20 20.5 21 log 10 (E) Hillas Symposium Andrew Taylor

Low Energy CR Composition Investigation composi?on ra?os of CR at 10~GeV per nucleon proton He C O Si Fe 1.0 0.04 0.001 0.001 0.0002 0.0002 x i ATIC data CREAM data 10 0 10 0 E CR dN CR /dE CR [cm -2 s -1 sr -1 ] E CR dN CR /dE CR [cm -2 s -1 sr -1 ] p p He He C C 10 -2 10 -2 O O Ne Ne Mg Mg Si Si 10 -4 10 -4 Fe Fe p p 10 -6 10 -6 10 -8 10 -8 10 -10 10 -10 10 9 10 10 10 11 10 12 10 13 10 14 10 15 10 9 10 10 10 11 10 12 10 13 10 14 10 15 E CR [eV] E CR /A [eV per nucleon] Hillas Symposium Andrew Taylor

Low Energy CR Composition Investigation 10 0 E CR dN CR /dE CR [cm -2 s -1 sr -1 ] p compensated for solar abundance ratios He C 10 -1 O Si Fe 10 -2 p 10 -3 solar system abundance ra?os proton He C O Si Fe 10 -4 1.0 0.1 0.0004 0.0008 0.00003 0.00003 x i 10 -5 10 -6 10 9 10 10 10 11 10 12 10 13 10 14 10 15 E CR /A [eV per nucleon] ✓ E A ◆ dN A dN p = f A E p ( E p ) E A dE A A dE p f A = Z 2 A f SA Hillas Symposium Andrew Taylor

Cosmic Ray Spectrum from Cen A? Abundance by Mass Abundance by Number astro-ph: 1706.08229 Hillas Symposium Andrew Taylor

Cosmic Ray Spectrum from Local Sources Like Cen A 10000 E 2 dN/dE [eV cm -2 s -1 sr -1 ] E Fe, max =10 20.40 eV 1000 p=2.25 100 10 1 He 0.1 C O Ne 0.01 17.5 18 18.5 19 19.5 20 20.5 log 10 Energy [eV] *Note- no hardening of the spectrum at low energies has here been taken into account* Hillas Symposium Andrew Taylor

Step 2: Galactic B-field Interaction with Cen A CR Flux Toroidal field component z=2 kpc 15 1 0.9 10 0.8 0.7 5 z=-2 kpc 0.6 0 0.5 y 20 0.8 0.4 -5 15 0.7 0.3 0.2 10 0.6 -10 0.1 5 0.5 -15 0 0 0.4 -15 -10 -5 0 5 10 15 y -5 0.3 x -10 0.2 -15 0.1 -20 0 -20-15-10 -5 0 5 10 15 20 x Hillas Symposium Andrew Taylor

Galactic B-field Interaction with Cen A CR Flux X-field component y=0 kpc 15 1.6 1.4 10 1.2 1 5 0.8 z 0 0.6 0.4 -5 0.2 -10 0 -15 -10 -5 0 5 10 15 x Hillas Symposium Andrew Taylor

“Low Energy” Spectral Suppression of CR from Cen A System'Setup' z" Cen"A" Injec2on"Site" y" 90"kpc" θ" ϕ " Hillas Symposium Andrew Taylor

Galactic Magnetic Field “Shadowing” = 8 × 10 53 erg U disk B System'Setup' = 4 × 10 54 erg U toroid B = 3 × 10 54 erg U X − field B z" U CR ≈ 10 55 erg E p = 3 × 10 18 eV 80 5 Injec2on"Site" 60 0 40 -5 y" 90"kpc" 20 -10 y [kpc] 0 -15 -20 θ" " ϕ -20 -40 -25 -60 Milky"Way" x" -80 -30 -80 -60 -40 -20 0 20 40 60 80 x [kpc] Hillas Symposium Andrew Taylor

Galactic Magnetic Field “Shadowing” = 8 × 10 53 erg U disk System'Setup' B = 4 × 10 54 erg U toroid B z" = 3 × 10 54 erg U X − field B Injec2on"Site" y" 90"kpc" θ" " ϕ Milky"Way" x" Michael & I had intended to produce a short Hillas Symposium Andrew Taylor paper on this “shadowing” effect

Cosmic Ray Anisotropy from Cen A? Angular arrival distribu?on of parallel beam from Cen A fired at Galac?c magne?c field 9 observer position- (-8.5 kpc, 0.0 kpc, 0.0 kpc) 80 80 spatial bin size- 1.0 kpc, E p =3.2E+18 eV 8 full Bfield 60 60 7 40 40 6 20 20 b [deg] 5 0 0 4 -20 -20 3 -40 -40 2 -60 -60 1 -80 -80 0 150 150 100 100 50 50 0 0 -50 -50 -100 -100 -150 -150 l [deg] Hillas Symposium Andrew Taylor

Cosmic Ray Anisotropy from Cen A? Importance in role of X-field component of the Galac?c Magne?c in shi_ing posi?on of Cen A in arriving flux from beam injected Only Toroidal + Disk Fields Only X-field 6 1.2 observer position- (-8.5 kpc, 0.0 kpc, 0.0 kpc) 80 80 observer position- (-8.5 kpc, 0.0 kpc, 0.0 kpc) 80 80 spatial bin size- 1.0 kpc, E p =3.2E+18 eV spatial bin size- 1.0 kpc, E p =3.2E+18 eV x-field wo x-field 60 60 5 60 60 1 40 40 40 40 4 0.8 20 20 20 20 b [deg] b [deg] 0 0 3 0 0 0.6 -20 -20 -20 -20 2 0.4 -40 -40 -40 -40 -60 -60 1 -60 -60 0.2 -80 -80 -80 -80 0 0 150 150 100 100 50 50 0 0 -50 -50 -100 -100 -150 -150 150 150 100 100 50 50 0 0 -50 -50 -100 -100 -150 -150 l [deg] l [deg] Hillas Symposium Andrew Taylor

How Isotropic Cosmic Rays at Earth Sample the Isotropic Extragalactic Sky … .and lastly, back-tracking isotropic par?cles from Earth to see which parts of extragalac?c sky are preferen?ally sampled at these energies 1 1 800 full Bfield, r max =32.0 kpc 700 E p =3.2E+18 eV 0.5 0.5 600 500 sin(b) 0 0 400 300 -0.5 -0.5 200 100 -1 -1 0 150 150 100 100 50 50 0 0 -50 -50 -100 -100 -150 -150 l [deg] Michael named this effect “tunnel vision”! Hillas Symposium Andrew Taylor

How Isotropic Cosmic Rays at Earth Sample the Isotropic Extragalactic Sky Importance in role of Toroidal Field in Selec?ng Extragalac?c Regions Probed Only Disk + X-Field Only Toroidal Field 1 1 800 1 1 1200 toroidal field, r max =32.0 kpc wo toroidal field, r max =32.0 kpc 700 E p =3.2E+18 eV E p =3.2E+18 eV 1000 0.5 0.5 600 0.5 0.5 800 500 sin(b) sin(b) 0 0 400 0 0 600 300 400 -0.5 -0.5 200 -0.5 -0.5 200 100 -1 -1 0 -1 -1 0 150 150 100 100 50 50 0 0 -50 -50 -100 -100 -150 -150 150 150 100 100 50 50 0 0 -50 -50 -100 -100 -150 -150 l [deg] l [deg] Hillas Symposium Andrew Taylor

Farewell to Michael I wanted to finish with an effort to convey the joy that it was to work with Michael. I only knew him in the evening of his life, but s?ll his enthusiasm for astrophysics was infec?ous and his tenaciousness remarkable (emails with right arm “out of ac?on” following car crash!). He will be sorely missed, but I’m grateful for having known him. Hillas Symposium Andrew Taylor

Extra Slides Hillas Symposium Andrew Taylor

10 0 E CR dN CR /dE CR [cm -2 s -1 sr -1 ] p compensated for solar abundance ratios He C 10 -1 O Si Fe 10 -2 p 10 -3 10 -4 10 -5 10 -6 10 9 10 10 10 11 10 12 10 13 10 14 10 15 E CR /A [eV per nucleon] Hillas Symposium Andrew Taylor

Anatomy Of The Knee showing some component nuclei • TG indicates how the total of “ galactic ” components could thus appear