ASTROPHYSICAL HIGH-ENERGY PHENOMENA DETECTED IN THE EARTH’S IONOSPHERE 4th School on Cosmic Rays...

ASTROPHYSICAL HIGH-ENERGY PHENOMENA DETECTED IN THE EARTH’S

IONOSPHERE

4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/20104th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010

Jean-Pierre RaulinJean-Pierre Raulin

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

Scientific Research at CRAAM/EE/UPM

SOLAR PHYSICS

IONOSPHERIC PHYSICS

GALACTIC AND EXTRAGALACTIC RADIO ASTROPHYSICS

SPACE GEODESICS

SOLAR-TERRESTRIAL RELATIONSHIP

ROEN

SST

ROI

COMTE. FERRAZ

SAVNET

CARPET + EFM 100

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

SST

Photosphere

H = 500 km ; T ~ 6000 K

Few Gauss < B < ~ 2500 G


TRACE 171 Ang. << 1

>> 1 = Pgas/Pmag

Solar Flares

1032 erg in few sec. to few min.

1041 e-/s > 20 keV

Solar Flares

Eth few 10 MK

Ek few 10 MeV

Emec CMEs4th School on Cosmic Rays and Astrophysics – UFABC – Sto André – 28/08/2010

Few 104 km


Solar Flares

Solar Flares

JTVkNE Beth2110.6~

2

3

thgr EE

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)

Ne ~ 1010cm-3 ; Te ~ 5 MK ; R ~ 20”

VB

EB 8

2

~ 1026 J - B ~ 100 G ; R ~ 20”


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

Solar Flares


CSR P4

CSR P1

ISR P1

ISR P4

ISR(?) pulses

Laboratory accelerators

4 November 2003 solar flare


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

Photo-ionization (Chapman) and collision


The Earth Ionosphere

Inte

nsid

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da

Atm

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Pic

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Rad

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olar

D en sid a d e E le trô n ica (cm -3 )

Alt

itud

e (k

m)

1 0 4 1 0 6

10 2

10 3

F 2

F 1

E

D

Pic

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Inte

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Pic

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Alt

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1 0 4 1 0 6

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10 3

F 2

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Pic

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Inte

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Ionization due to solar radiation

70

100

400

1000

Height (km)



cos

:

:

:

:

:

:

dhds

N

s

I

Q

n

Rate of e- - ion production (cm-3s-1)

Intensity of radiation (energy flux in eV/m2/s)

Line-of-sight path length

Zenith angle

Photon absorption cross-section (m2)

Density of neutral

Ground

Sun

h

s



Hot plasma heated during solar flares will emit a copious amount of X-raysPhoto-ionization

X-rays ( < 10 Å) O2 N2

Lyman- ( = 1216 Å) NO Low ionization potential component

Ultraviolet ( < 1750 Å) Minor constituents

Solar Minimum

Solar Maximum

D and E regions



Collisions

Solar Cosmic Rays

Galactic Cosmic Rays

Radiation belts particles

High latitudes (auroral and sub-auroral);

Regions of low magnetic field(AMAS)

Computer anomaly locations experienced by STS and TOPEX



28 90 283 900 2846 9000 (kHz)

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

At 200 km 800000 e-. cm-3 8 MHz

XU

YT

2

sin 22 2

2

pX iZU 1

Z

Appleton-Hartree, (Quemada, 1967)

bY

2

22

222

2

cos1

ck

TYTU

XN

2

22 1

pN B = 0 ; << 2


rp iiN

112

2

r Conductivity parameter (Wait & Spies, 1964)

)( 'Hzr e Conductivity gradient [km-1], Reference height H′ [km]

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

At 220 km (F region) we have ~ 50 Hz << VLF


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

r Conductivity parameter (Wait & Spies, 1964)

)( 'Hzr e Conductivity Gradient (sharpness) [km-1]

Reference height H′ [km]



Wait 1950s-60s; Budden, 1961; Wait,1962

60 km

90 km

70 km

60 km

Δh

Solar flare

Ref. Height

Perturbed Ref. height

The lowering of H produces a change of the phase of the 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.



• Solar Flares (Chilton et al. 1965; Kaufmann & Paes de Barros 1969; Mitra 1974; Muraoka et al. 1978, McRae et al. 2004)

• 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)

(h)

Solar Flare

SPA(Sudden Phase Anomaly)



Raulin et al. 2006; Pacini & Raulin 2006

R > 0.95

~ 1 km

The low ionosphere is more sensitive during minimum of solar activity

Ionospheric indice for monitoring of the long-term solar radiation

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

For a given solar flare the lowering of the reference height is higher (by about 1 km) during solar minimum

hha

d

.

162

1360

3

2

t

dtdtRX

),(


The Earth Ionosphere Sensitivity

SAVNETCRAAM/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)

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

• mesospheric disturbances (T, NO, O3)

• Detection of Remote astrophysical objects

• Subionospheric radio propagation modeling

• Search for seismic-EM effects


• Atmos. Physics (TGFs)

Characteristics of the sensorsb ; A ; Ae


SAVNET: The basics

São Martinho da Serra, RS, 2007, May 1- 5

Punta Lobos, 2007, April 1- 8

Palmas, TO, 2007, May 21-26

Piura, 2007, June 5-11

CASLEO, 2007, Julio 1- 07


SAVNET: Installation

toAntena

toAntena

to Audio to Audio

1 PPS to Audio

Alimen.

Alimen.

Computer

to Ant. GPS

Alimen.

Interface GPSInterface loop sensor Interface vertical sensor

SAVNET: DesignPre-amp Power supply


SAVNET: Design

Audio Card


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 hourDuring 0.000036 s the phase of the wave at 24 kHz 24000 x 360 x 0.000036 > 300 grados

SAVNET: Design


VLF REMOTE SENSING OF THE LOWER IONOSPHERE

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


SENSITIVITY OF THE LOWER IONOSPHERE


(Raulin et al. 2010)



(Raulin et al. 2010)



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.

(Pacini, 2006)

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)



• 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.


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

• 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

GIANT SGRs FLARES

RHESSI


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).

22-Jan. 2009, 0648 UT, larger burst

IONOSPHERIC OBSERVATIONS OF AXP 1E 1547-5408(also known as SGR J1550-5418 , PSR J1550-5418) (Tanaka, Raulin, Bertoni et al. 2010, ApJL)



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.

22-Jan. 2009 bursts



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 ionospheric reference (reflection) height, after -ray photons enter the Earth’s atmosphere and ionize the neutral component at and below ~ 85 km.

INTEGRALSPI-ACS



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.



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.


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.


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ASTROPHYSICAL HIGH-ENERGY PHENOMENA DETECTED IN THE EARTH’S IONOSPHERE 4th School on Cosmic Rays...

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