Monthly Proton Flux Veronica Bindi, AMS Collaboration Physics and - PowerPoint PPT Presentation

Solar modulation, Forbush decreases and Solar Energetic Particles with AMS Monthly Proton Flux Veronica Bindi, AMS Collaboration Physics and Astronomy Department University of Hawaii at Manoa Honolulu, Hawaii, US 1

AMS on the ISS May 19, 2011 and for the duration of the ISS. 2

Particle Identification with AMS AMS is a general purpose detector which measures particles in the GV-TV rigidity range More details ICRC 2017 highlight talk: A. Kounine 3

Particle identification with AMS In 6 years of operation, AMS has measured over 100 billion events. More details ICRC 2017 CR-D session: A. Oliva, Q. Yan. 4

AMS Scientific Goals Indirect Dark Matter search Galactic Cosmic Rays study M. Aguilar (AMS collaboration) PRL110,141102 (2013) Interesting features have been measured at high energies and more has to come in the near future. New Goal: Study of the time variation of the low energy part of the spectrum. 5

Solar modulation: Dark Matter search Uncertainties at low energies M. Aguilar (AMS collaboration) PRL110,141102 (2013) due to the effects of Solar modulation, increase the errors on theoretical models used for Dark Matter interpretation of the excess in the antimatter channels and in evaluation of the secondary background. Charge sign effects affect the DM signatures expected at low energies (anti-deuteron). More details ICRC 2017 CR-D session: Z. Li, W. Xu 6

Solar Modulation: GCR in heliosphere Precise measurements of the time-dependent GCRs spectra are important: • to understand the propagation of GCRs in the heliosphere. • to test theories of particles diffusion (charge and mass) and drift (charge-sign). • to study the effect on cosmic rays due to the reversal in the solar polarity. 7

Solar activity measured by AMS The Sun goes through an 11-year activity cycle shown by sunspots number. At each solar maximum the Sun flips its magnetic field polarity (A>0, A<0) showing a periodicity of 22 years. Cycle 22 Cycle 23 Cycle 24 NM Counts/sec SSN NM The flux of galactic cosmic rays is anti-correlated with the intensity of the solar activity. 8 Daily sunspot number: http://www.sidc.be/silso/datafiles

AMS Monthly Proton Flux five years of data Flux Intensity More details ICRC 2017 CR-D session: C. Consolandi 9

Monthly Proton & Helium Fluxes Minimum of the flux around Feb 2014 for most of rigidities Monthly fluxes 10

Monthly Proton & Helium Fluxes ) ) -1 50 340 -1 p GV He [3.29-3.64]GV GV -1 320 -1 s s -1 45 -1 sr 300 sr -2 Proton Flux (m -2 Helium Flux (m 280 40 260 240 35 220 30 200 Apr Sep Apr Jan Jun Feb Nov Jul Dec 2011 2012 2012 2013 2014 2014 2015 2016 2016 AMS will study how solar modulation affects all different cosmic ray species. 11

Electron & Positron Fluxes Each color represents a 27 days integration flux. Electrons Positrons 10 1 Energy (GeV) -1 10 2 3 4 5 6 7 8 910 12

Monthly e+ and e- flux Time profile 13

Change of Solar Polarity and Particle Drift [1.0 -1.2]GV Electrons A >0 Electrons A <0 A <0 A >0 AMS e+/e- ratio clearly shows the charge-sign dependence of [2.0 -2.3]GV solar modulation. A <0 A >0 Repeat the study with pbar/p. AMS will measure the drift of positive vs negative particles during a solar minimum with positive polarity A>0. 14 Polarity inversion period from: X. Sun et al., Astroph. J., 798, 114 (2015)

Short term solar activity 15

Solar Events measured by AMS March 7, 2012 Two Solar Flares of class X5.4 and X1.3 (XRT Flare catalog). Two Coronal Mass Ejections with linear speeds of 2684 km/s and 1825 km/s (SOHO LASCO CME catalog). AMS daily Normalized Flux Solar Energetic Particles Forbush Decrease More details ICRC 2017 SH session: M. Palermo 16

Normalized daily proton flux Daily fluxes 17

Forbush Decreases Characteristics FD with long duration (20 days) and maximum decrease at 2 GV of 40% 18

FD event List 19

FD Characteristics for Selected Events 20

SEP Observed as an Excess above the GCR Background AMS Proton daily flux 21

AMS Daily Proton Flux May 17, 2012 - Ground Level Enhancement (GLE) Solar Flare of class M5.1 (XRT Flare catalog). Coronal Mass Ejection with linear speeds of 1582 km/s (SOHO LASCO CME catalog). May 17, 2012 May 16 , 2012 (quiet day) 22

Solar Energetic Particle Flux SEP flux obtained subtracting the galactic cosmic ray background May 17, 2012 AMS SEP 23

IGRF Geomagnetic Cutoff in the AMS field of view 27% of orbiting period GV GV SEPs can be observed in the part of the orbit close to geomagnetic poles 24

AMS Multi-orbit Observations Time evolution May 17, 2012 Average integration time about 10 minutes SEP AMS data provide information at high rigidity with fine resolution. 25

SEP flux May 17, 2012 AMS data, combined with other instruments at lower energy, will provide a baseline for the modeling of SEP production. GOES SOHO GOES AMS 26

SEP events Observed by AMS AMS observed 27 high energy SEP events at ~ 1 GV from GLE May 2011 to May 2016. AMS SEP events are typically associated with M and X class flares and fast CMEs. Ground Level Enhancement (GLE) 27

AMS data taking till 2024 - Agenda Cycle 24 Cycle 25 Years : 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Polarity: A<0 Reversal A>0 A>0 A>0 Reversal Polarity: A<0 Reversal A>0 A>0 A>0 Reversal ascending solar maximum descending solar minimum ascending solar maximum phase phase phase AMS will measure the Comparing data collected AMS will compare drift of positive vs before, during and after the solar maximum of DRIFT : negative particles during solar maximum AMS can cycles 25 (A>0) and e-, e+ , p, pbar the solar minimum with study in details the effects 24 (A<0) and the positive polarity A>0. due to the solar polarity solar polarity reversal. reversal. DIFFUSION : AMS is measuring the modulation of different nuclei during a solar cycle. All species of GCR Lots of new SEPs Measured 27 SEPs and Not expected major FD and SEP : and FDs. identified so far 33 FDs. events during minimum

Summary & Conclusions A new era in galactic cosmic rays understanding has started, not only at high energy, but also at low energy in the region affected by the solar modulation thanks to the precise and continuous observations from space by PAMELA in solar cycle 23 and now AMS-02 in solar cycle 24 and 25. New and precise measurements are increasing our knowledge of important effects such as diffusion and drift in the heliosphere, allowing the detailed study of propagation. These measurements will serve as a high-precision baseline for continued studies of GCR solar modulation, SEPs, space radiation hazards, magnetospheric effects, trapped particles and in many other fields. Near future forthcoming AMS publications on solar modulation: time evolution of proton and helium fluxes, electron and positron fluxes, and antiproton/proton ratio. 29

AMS FD Relationship with Solar Wind Parameters AMS 30