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					    ASTROPHYSICAL HIGH-ENERGY PHENOMENA
     DETECTED IN THE EARTH’S IONOSPHERE



                              Jean-Pierre Raulin


   Centro de Radioastronomia e Astrofísica Mackenzie, Universidade
      Presbiteriana Mackenzie, Escola de Engenharia, São Paulo, SP, Brasil




4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
Scientific Research at CRAAM/EE/UPM

SOLAR PHYSICS
                                                                        CARPET + EFM 100



SOLAR-TERRESTRIAL RELATIONSHIP
                                     SST

IONOSPHERIC PHYSICS


      ROI                                                     ROEN
                      SAVNET

GALACTIC AND EXTRAGALACTIC RADIO ASTROPHYSICS
                                    SST                                 COMTE. FERRAZ



SPACE GEODESICS

      4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                                Photosphere




H = 500 km ; T ~ 6000 K
Few Gauss < B < ~ 2500 G
           4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                            << 1       TRACE         171 Ang.




                >> 1                                                                  = Pgas/Pmag




                           Few 104 km




         Solar Flares                                                                       Solar Flares
1032 erg in few sec. to few min.                                                       Eth  few 10 MK
      1041 e-/s > 20 keV                                                               Ek  few 10 MeV
                                                                                            Emec  CMEs
              4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                     Solar Flares




4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                  Solar Flares
Fast releases of energy in the solar atmosphere. Up to 1032-33 ergs
(1 J = 107 ergs) are dissipated in few seconds to few minutes. This
energy is observed as :
• thermal energy (few MK  tens of MK)
• kinetic energy (acceleration of particles)
• mechanical energy (mass motions - CMEs)

         3                                 Ne ~ 1010cm-3 ; Te ~ 5 MK ; R ~ 20”
 Eth      N e k BTV ~ 6.1021 J
         2

 E gr  Eth

      B2
 EB     V        ~ 1026 J - B ~ 100 G ; R ~ 20”
      8
             4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                Solar Flares
                                                    Coronal Mass Ejection (CME)
                                                    1 AU = 150 106 km ~ 110 solar Ø
                                                    Arrival time at 1 AU ~ 1.5 – 3 d


2003/10/28 11:10 UT
2003/11/02 17:15 UT
2003/11/04 19:40 UT


CMEs are fundamental for
Space Weather prediction




           4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                                            4 November 2003 solar flare


                                                                            CSR P1




                                                                                           ISR P1


                                                                CSR P4




Laboratory accelerators
                                                                                     ISR P4




                                                                                          ISR(?)
                                                                                          pulses




       4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
            The Earth Ionosphere


The ionization of the neutral component of the
Earth’s atmosphere is done through 2 processes

Photo-ionization (Chapman) and collision




      4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                           The Earth Ionosphere
Height
(km)




                                                                   Picos de Densidade Ocasionadas Pela Radiação Solar
              Intensidade da Atmosfera Neutra Decresce



1000
                                                                                                                                                                                   103




                                                                                                                        Picos de Densidade Ionosférica




                                                                                                                                                                                         Altitude (km)
400                                                                                                                                                                         F2
                                                                                                                                                                            F2


                                                                                                                                                                       F1



100                                                                                                                                                                E               102

                                                                                                                                                         D


 70
                                                                                                                                                             104             106
                                                                                                                                        Densidade Eletrônica (cm -3 )



                                                         Ionization due to solar radiation

         4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
             The Earth Ionosphere

Q:     Rate of e- - ion production (cm-3s-1)                        Sun
                                                                              s
I:     Intensity of radiation (energy flux in        eV/m2/s)

s:     Line-of-sight path length

:     Zenith angle                                                                           h

:     Photon absorption cross-section (m2)

Nn :    Density of neutral

        dh
ds  
       cos                                                                          Ground




       4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                   The Earth Ionosphere
      D and E regions
                                      Hot plasma heated during solar flares will emit a copious
Photo-ionization                      amount of X-rays


 X-rays (  < 10 Å)
     O2
     N2
                                                                           Solar Minimum
 Lyman- (  = 1216 Å)
     NO
     Low ionization
    potential component

 Ultraviolet (  < 1750 Å)
     Minor constituents                                                    Solar Maximum




             4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                   The Earth Ionosphere
Collisions                                             Computer anomaly locations experienced
                                                       by STS and TOPEX
 Solar Cosmic Rays

 Galactic Cosmic Rays

 Radiation belts particles

      High latitudes (auroral and sub-auroral);

      Regions of low magnetic field(AMAS)




             4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
           The Earth Ionosphere
                                                        For VLF waves (f between 3 –
                                                        30 kHz) the ionospheric D
                                                        region and the Earth’s surface
                                                        are good electrical conductors
                                                        and reflecting media. These
                                                        layers     forms  the   Earth-
                                                        Ionosphere Waveguide (EIW).
                                                        Electromagnetic energy can
                                                        therefore be guided and
                                                        propagate along the waveguide
                                                        long axis.

                                                 At 70 km  300 e-. cm-3  156 kHz
                                                 For 20 kHz  4.9 e-.cm-3

28    90     283      900     2846     9000      At 200 km  800000 e-. cm-3  8 MHz
           (kHz)


     4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
              The Earth Ionosphere
                    X                    k 2c 2
N 2  1                                         Appleton-Hartree, (Quemada, 1967)
           U  T  Y cos   T
                    2     2      2          2




  p2
               b                                        Y 2 sin 2 
X 2        Y          Z     U 1  iZ               T
                                                       2U  X 


                         2

             N  1
                2         p
                                 B = 0 ;  << 2
                         2
               The Earth Ionosphere
          p2
                     r
 N  1 i
  2
               1 i
                   
 r    Conductivity parameter (Wait & Spies, 1964)

          ( z  H ' ) Conductivity gradient  [km-1], Reference height H′ [km]
r  e


At 70 km (D region) we have
 ~ 5 MHz >> VLF

At 220 km (F region) we have
 ~ 50 Hz << VLF
                  The Earth Ionosphere
r   Conductivity parameter (Wait & Spies, 1964)

          ( z  H ' ) Conductivity Gradient (sharpness)  [km-1]
r  e            Reference height H′ [km]

Increases of incoming X-ray fluxes during flares and increasing particle
precipitations during geomagnetic storms produce ionization excesses and change
of the electrical properties of the lower ionosphere D region. Then changing:
         conductivity gradient  [km-1] and reference height H′ [km]
Excesses of ionization can be monitored using the phase of long distance VLF
propagating waves




            4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
        The Earth Ionosphere
           Wait 1950s-60s; Budden, 1961; Wait,1962

                                               Solar flare



                                       70 km                                  Ref. Height


                                                                Δh


                                       60 km                                  Perturbed
        60 km
                                                                              Ref. height

                                        The lowering of H produces a
                                        change  of the phase of the
90 km
                                        VLF wave. This change is
                                        measured by the VLF receiver,
                                        and can be expressed in terms of
                                        h. The change  is proportional
                                        to the VLF path.

4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                    The Earth Ionosphere
• Solar Flares (Chilton et al. 1965; Kaufmann & Paes de Barros 1969;
Mitra 1974; Muraoka et al. 1978, McRae et al. 2004)




                                                                                        Solar Flare




                                                                                 SPA
                                                                                 (Sudden Phase Anomaly)
           (h)



• Geomagnetic Storms (Spjeldvik & Thorne 1975; Kikuchi & Evans 1983)
• Supernova (Edwards 1987)
• Magnetar
• Nuclear explosions in the atmosphere(Jean & Wait, 1965; Carpenter et al. 1968;
          Mikhailov et al. 1999)
              4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
        The Earth Ionosphere Sensitivity
                 d 1   2 
           360  
                       t  RX ( , t )  ddt
                   2a 16h3 .h
                 
                       
                            
                            


        R > 0.95
                                                       For a given solar flare the lowering of the
                                                       reference height is higher (by about 1 km)
                                                       during solar minimum
                                                       The low ionosphere is more sensitive during
                                                       minimum of solar activity




                                                       Ionospheric indice for monitoring of the
                                                       long-term solar radiation

                                  ~ 1 km               McRae & Thomson 2000, 2004 showed that the
                                                       quiescent (undisturbed) ionospheric D region
                                                       reference height is higher during solar activity
Raulin et al. 2006; Pacini & Raulin 2006               minimum periods by about ~ 1 km

                   4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                            SAVNET
                                               CRAAM/EE
8 VLF tracking receiver stations deployed in
Brazil, Peru and Argentina.
3 years of operation since 2007

• Long-term and transient solar
activity (Ly- ; solar flares)

• mesospheric disturbances
(T, NO, O3)

• Physics of the lower
ionospheric (C/D) regions

• Atmos. Physics (TGFs)

• Subionospheric radio propagation
modeling

• Search for seismic-EM effects

• Detection of Remote
astrophysical objects



                   4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
      SAVNET: The basics




                                                                      Characteristics of
                                                                      the sensors
                                                                      b ; A ; Ae




4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                   SAVNET: Installation
 Punta Lobos, 2007, April 1- 8                  Piura, 2007, June
                                                5-11




                                                              São Martinho da Serra,
Palmas, TO, 2007, May 21-26                                   RS, 2007, May 1- 5

                           CASLEO, 2007, Julio 1- 07




             4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                        SAVNET: Design
         Pre-amp                                                                    Power supply




             to Audio                            to Audio                             to Ant. GPS


to
Antena                                                            Alimen.                           Alimen.
                           Alimen.



                                                                    Computer
                                     to
                                     Antena

                                                                                  1 PPS to Audio
  Interface loop sensor               Interface vertical sensor                     Interface GPS
             4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
            SAVNET: Design




  Audio Card




4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                         SAVNET: Design


                                                      Loops (magnetic) or vertical (Ez) antennae




Phase anomalies to measure are very small (s)  cristal, atomic clocks

Cristal  10-8 – 10-6 this OK for fast phenomena, but not for solar flares, or for
         long-term monitoring
Atomic clocks  10-12 – 10-11 (for ex. GPS system)

Drift of 1 s at each 108 s  Drift of 0.000036 s in 1 hour
During 0.000036 s the phase of the wave at 24 kHz  24000 x 360 x 0.000036 > 300 grados


              4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
VLF REMOTE SENSING OF THE LOWER IONOSPHERE




           South America VLF NETwork (SAVNET; CRAAM/EE/UPM; Brasil)


     4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
     SENSITIVITY OF THE LOWER IONOSPHERE




(Raulin et al. 2010)

        4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
              SENSITIVITY OF THE LOWER IONOSPHERE




(Raulin et al. 2010)


                  4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                 SENSITIVITY OF THE LOWER IONOSPHERE
(Pacini, 2006)
                                                                Baker et al. 2004: Period of strong
                                                                 geomagnetic disturbances (Out-
                                                                Dez/2003): sucessive intense solar
                                                                events with particles, shock waves
                                                                              and CMEs

                                                                                     
                                                                  Important changes of Van Allen
                                                                    radiation belts and intense
                                                               precipitation of electrons from these
                                                                              regions.




                  4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                        GRBs and SGRs FLARES

• Soft Gamma-ray repeaters repeat sporadically from the same source (SNRs, AXPs), while Gamma-
Ray Bursts have never been verified to come more than once from the same spot in the sky
• GRB are numerous while we know about 6 SGRs sources
• SGR are softer than GRB (less mean energy per photon)
• photon flux is generally higher for SGR
• SGR outbursts occur in group
• duration ranges from < 1 s to few minutes in average
• SGRs do produce some spectacular giant flares (3 known in 30 years)
• SGRs more probably originate in Magnetars (rotating neutron stars with B ~ 1015 G)


Observing and instrumental limitations:
• saturation during giant flares  (problems to recover photon spectra)
• off-pointing  (problems to recover photon spectra)
• Earth occultation  (no observations)



            4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
        SENSITIVITY OF THE LOWER IONOSPHERE
• The daytime sensitivity of the low ionospheric plasma has been estimated for daytime
conditions, using solar flares as external forcing (Pacini & Raulin, 2006; Raulin et al. 2010)
   - Minimum peak power detected at Earth orbit for [1.5 – 24 keV] photons :
          2.7 10-4 erg/cm2/s (solar min.) and 10-3 erg/cm2/s (solar max.)
   - Fluence > 14 keV, for 10 min. accumulated times:
          ~ 10-7 erg/cm2 (solar min.) and few 10-7 erg/cm2 (solar max.)




• The nighttime sensitivity has been estimated to 10 times less than that during daytime
(Tanaka, Raulin, Bertoni et al. 2010).

 Therefore we do expect the VLF technique to detect intermediate-to-low SGRs
and GRBs outbursts.
           4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                      GIANT SGRs FLARES
So far (30 years) , we know of 3 giant flares from SGRs. The most spectacular event occurred on 2004,
December 27 at about 21:30 UT, from SGR 1806-20:
• estimated distance 15 kpc
                                                                                                RHESSI
• main peak (0.2 s) : rise < 1 ms, decay < 65 ms
• periodic tail (400 s), P ~ 7.56 s
• main peak satured all onboard -ray sensors
• Emain peak ~ total energy released by the Sun in
            250 .103 years ~ 1010 times E (largest solar flares)
• lowering of daytime ionosphere ~ 10 km
• Magnetar, B ~ 1015 G




                  4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
IONOSPHERIC OBSERVATIONS OF AXP 1E 1547-5408
(also known as SGR J1550-5418 , PSR J1550-5418) (Tanaka, Raulin, Bertoni et al. 2010, ApJL)



   22-Jan. 2009, 0648 UT, larger burst

                                                               VLF propagation path from NPM
                                                               transmitter    (Hawaii)     to   ATI
                                                               observing station (São Paulo,
                                                               Brazil). Also shown are the locations
                                                               of other four VLF transmitters
                                                               (NLK, NDK, NAA, and NAU).
                                                               Shaded hemisphere indicates the
                                                               night side part of the Earth at 06:48
                                                               UT, when the largest burst occurred.
                                                               The part of the Earth illuminated by
                                                               -rays at 6:48 UT is also drawn by
                                                               dashed area. Although not shown,
                                                               bursts were also detected by other
                                                               SAVNET bases at Palmas, TO
                                                               (PAL), São Martinho da Serra, RS
                                                               (SMS), and Piura, Peru (PIU).




          4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
IONOSPHERIC OBSERVATIONS OF AXP 1E 1547-5408
(also known as SGR J1550-5418 , PSR J1550-5418) (Tanaka, Raulin, Bertoni et al. 2010, ApJL)



            22-Jan. 2009 bursts



                                                                Over 100 -ray bursts were observed
                                                                in the (South America) night of 22
                                                                January, 2009. Amplitude and phase
                                                                variations of a VLF signal from
                                                                NPM transmitter (21.4 kHz) are
                                                                shown, which were observed at ATI
                                                                from 04:00 UT to 10:00 UT. Lower
                                                                figures are background-subtracted
                                                                blown-ups at time ranges during
                                                                which short repeated SGR bursts
                                                                were detected.




          4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
IONOSPHERIC OBSERVATIONS OF AXP 1E 1547-5408
(also known as SGR J1550-5418 , PSR J1550-5418) (Tanaka, Raulin, Bertoni et al. 2010, ApJL)




                                                      Detailed amplitude time profiles on NPM-
                                                      ATI (a) and NPM-SMS (b) VLF
                                                      propagation paths during the largest 06:48
                                                      UT -ray burst, are compared with the > 25
                                                      keV INTEGRAL/SPI-ACS signal. Dashed
                                                      lines suggest common temporal fine
                                                      structures. The spin period of the remote
                                                      object (P ~ 2.07 s) can be seen in the
                                                      INTEGRAL -ray time profile .

                                                      Phase and amplitude variations are
                                                      interpreted in terms of the lowering of the
          INTEGRAL                                    ionospheric reference (reflection) height,
          SPI-ACS
                                                      after -ray photons enter the Earth’s
                                                      atmosphere and ionize the neutral
                                                      component at and below ~ 85 km.




          4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
IONOSPHERIC OBSERVATIONS OF AXP 1E 1547-5408
(also known as SGR J1550-5418 , PSR J1550-5418) (Tanaka, Raulin, Bertoni et al. 2010, ApJL)




          Main result of this study: The amplitude and phase variations detected
          using NPM – ATI VLF propagation path, during 8 gamma-ray bursts
          on 22 January 2009, are well correlated with the photon (> 25 keV)
          fluences.


          4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
IONOSPHERIC OBSERVATIONS OF AXP 1E 1547-5408
(also known as SGR J1550-5418 , PSR J1550-5418) (Tanaka, Raulin, Bertoni et al. 2010, ApJL)




          Main result of this study: The amplitude and phase variations detected
          using NPM – ATI VLF propagation path, during 8 intermediate-to-low
          gamma-ray bursts on 22 January 2009, are well correlated with the
          photon (> 25 keV) fluence.


          4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010
                                       SUMMARY

            The lower ionosphere plasma is a very sensitive medium to external forcing:
radiation, energetic particle fluxes, atmospheric variability. It is therefore a unique laboratory
to better track the Space Weather conditions and study the coupling with the upper and lower
atmosphere.
            The timescales involved give new insights on the monitoring of the long-term and
transient solar activities, the episodic geomagnetic disturbances, and upper propagating
phenomena in the neutral atmosphere.
            We have detected, for the first time, ionospheric disturbances caused by
intermediate-to-low short repeated gamma-ray bursts from a Magnetar. Amplitude and
phase changes of Very Low Frequency propagating waves are well correlated with gamma-
ray fluences. This can be understood in terms of the lowering of the ionospheric reflection
height due to excesses of ionization at and below ~ 85 km.
            While satellites in space cannot continuously observe the whole sky due to Earth
occultation, the Earth’s ionosphere can monitor it without interruption. Very Low Frequency
observations provide us with a new method, cheap and easy to implement, to monitor high
energy transient phenomena of astrophysical importance.
            Therefore, the Very Low Frequency diagnostic of high-energy astrophysical
processes is, at least, a complementary information to space detections, and, sometimes, it
may be the only way of recovering the incident photon spectrum at low energies.


           4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010

				
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