1. COSMIC MAGNETIC FIELDS ElisaBete M. de Gouveia Dal Pino
IAG-USP
UFRRJ, October 2005

2. PREAMBLE
Most of visible matter in the Universe is in plasma state:
 composed of ionized or partially ionized gas permeated by magnetic fields
Alfvén, Biermann, Chandrasekhar and Parker knew that decades ago !
Mais de 90% da matéria visível do Universo encontra-se no estado de plasma, ou em outras palavras, é constituída de matéria parcial ou totalmente ionizada permeada por campos magnéticos. A importância dos campos magnéticos já era percebida a várias décadas atrás por visionários como Alfvén, Biermann, Chandrasekhar e Parker.

3. Charged Particle  Fluid immersed in B
WHY MAGNETIC FIELDS?
Charged Particle  Fluid immersed in B
v x B  J x B
Dessa forma: e de se esperar que B exerca forcas importantes sobre fluidos e fontes astrofisicas que irao afetar sua dinamica, evolucao e foramcao
nterstellar magnetic fields are strongest in massive spiral arms of galaxies ( muG) and in nuclear starburst regions (up to 100 muG). Processes related to star formation tangle the field lines, so that little polarization is observed in star-forming regions. The magnetic energy density in the inner disk of galaxies is larger than the thermal energy density, comparable to that of turbulent gas motions, and is dominant in the outer disk. Large-scale spiral patterns of the regular field are observed in grand-design, flocculent and even some irregular galaxies. In grand-design galaxies the regular fields are aligned parallel to the optical spiral arms, with the strongest regular fields (highest polarization) in interarm regions, sometimes forming magnetic spiral arms between the optical arms. Faraday rotation of the polarization vectors reveals patterns which are signatures of coherent large-scale fields in galactic disks, probably generated by dynamo action. The majority of field structures in galaxies requires a superposition of several dynamo modes. In barred galaxies the magnetic field is mostly aligned with the gas flow, deflected by shear and compressed in the shock. The regular field is already strong in the ``upstream'' region ahead of the shock. Within the circumnuclear ring the magnetic field is strong, with a regular component of spiral shape. Magnetic stress may drive inflow of gas towards the nucleus. -- Present-day radio polarimetry is limited by sensitivity. The next-generation radio telescope, the Square Kilometer Array (SKA), will be able to reveal the full wealth of magnetic structures in galaxies. Cosmic magnetism is one of the Key Science projects for the SKA.

4. Charged Particle  Fluid immersed in B
WHY MAGNETIC FIELDS?
Charged Particle  Fluid immersed in B
v x B  J x B
Dessa forma: e de se esperar que B exerca forcas importantes sobre fluidos e fontes astrofisicas que irao afetar sua dinamica, evolucao e foramcao
nterstellar magnetic fields are strongest in massive spiral arms of galaxies ( muG) and in nuclear starburst regions (up to 100 muG). Processes related to star formation tangle the field lines, so that little polarization is observed in star-forming regions. The magnetic energy density in the inner disk of galaxies is larger than the thermal energy density, comparable to that of turbulent gas motions, and is dominant in the outer disk. Large-scale spiral patterns of the regular field are observed in grand-design, flocculent and even some irregular galaxies. In grand-design galaxies the regular fields are aligned parallel to the optical spiral arms, with the strongest regular fields (highest polarization) in interarm regions, sometimes forming magnetic spiral arms between the optical arms. Faraday rotation of the polarization vectors reveals patterns which are signatures of coherent large-scale fields in galactic disks, probably generated by dynamo action. The majority of field structures in galaxies requires a superposition of several dynamo modes. In barred galaxies the magnetic field is mostly aligned with the gas flow, deflected by shear and compressed in the shock. The regular field is already strong in the ``upstream'' region ahead of the shock. Within the circumnuclear ring the magnetic field is strong, with a regular component of spiral shape. Magnetic stress may drive inflow of gas towards the nucleus. -- Present-day radio polarimetry is limited by sensitivity. The next-generation radio telescope, the Square Kilometer Array (SKA), will be able to reveal the full wealth of magnetic structures in galaxies. Cosmic magnetism is one of the Key Science projects for the SKA.
TENSION
PRESSURE

5. Charged Particle  Fluid immersed in B
WHY MAGNETIC FIELDS?
Charged Particle  Fluid immersed in B
v x B  J x B
Dessa forma: e de se esperar que B exerca forcas importantes sobre fluidos e fontes astrofisicas que irao afetar sua dinamica, evolucao e foramcao
nterstellar magnetic fields are strongest in massive spiral arms of galaxies ( muG) and in nuclear starburst regions (up to 100 muG). Processes related to star formation tangle the field lines, so that little polarization is observed in star-forming regions. The magnetic energy density in the inner disk of galaxies is larger than the thermal energy density, comparable to that of turbulent gas motions, and is dominant in the outer disk. Large-scale spiral patterns of the regular field are observed in grand-design, flocculent and even some irregular galaxies. In grand-design galaxies the regular fields are aligned parallel to the optical spiral arms, with the strongest regular fields (highest polarization) in interarm regions, sometimes forming magnetic spiral arms between the optical arms. Faraday rotation of the polarization vectors reveals patterns which are signatures of coherent large-scale fields in galactic disks, probably generated by dynamo action. The majority of field structures in galaxies requires a superposition of several dynamo modes. In barred galaxies the magnetic field is mostly aligned with the gas flow, deflected by shear and compressed in the shock. The regular field is already strong in the ``upstream'' region ahead of the shock. Within the circumnuclear ring the magnetic field is strong, with a regular component of spiral shape. Magnetic stress may drive inflow of gas towards the nucleus. -- Present-day radio polarimetry is limited by sensitivity. The next-generation radio telescope, the Square Kilometer Array (SKA), will be able to reveal the full wealth of magnetic structures in galaxies. Cosmic magnetism is one of the Key Science projects for the SKA.

6. MAGNETIC FIELDS
 Crucial in: star formation, solar and stellar activity, pulsars, accretion disks, formation and stability of jets, formation and propagation of cosmic rays, galaxy structure.
 Probably crucial in: ISM, molecular clouds, supernova remnants, proto-planetary disks, and planetary nebulae, GRBs.
Importance not well understood in: stellar evolution, halos of galaxies, galaxy evolution, and structure formation in the early Universe.
Dessa forma: e de se esperar que B exerca forcas importantes sobre fluidos e fontes astrofisicas que irao afetar sua dinamica, evolucao e foramcao
nterstellar magnetic fields are strongest in massive spiral arms of galaxies ( muG) and in nuclear starburst regions (up to 100 muG). Processes related to star formation tangle the field lines, so that little polarization is observed in star-forming regions. The magnetic energy density in the inner disk of galaxies is larger than the thermal energy density, comparable to that of turbulent gas motions, and is dominant in the outer disk. Large-scale spiral patterns of the regular field are observed in grand-design, flocculent and even some irregular galaxies. In grand-design galaxies the regular fields are aligned parallel to the optical spiral arms, with the strongest regular fields (highest polarization) in interarm regions, sometimes forming magnetic spiral arms between the optical arms. Faraday rotation of the polarization vectors reveals patterns which are signatures of coherent large-scale fields in galactic disks, probably generated by dynamo action. The majority of field structures in galaxies requires a superposition of several dynamo modes. In barred galaxies the magnetic field is mostly aligned with the gas flow, deflected by shear and compressed in the shock. The regular field is already strong in the ``upstream'' region ahead of the shock. Within the circumnuclear ring the magnetic field is strong, with a regular component of spiral shape. Magnetic stress may drive inflow of gas towards the nucleus. -- Present-day radio polarimetry is limited by sensitivity. The next-generation radio telescope, the Square Kilometer Array (SKA), will be able to reveal the full wealth of magnetic structures in galaxies. Cosmic magnetism is one of the Key Science projects for the SKA.

7. Measuring magnetic fields
Polarization: by aligned dust grains with B of ISM B
Radiacao e polarizada direcao normal a propagacao (lv)
Em geral "Unpolarized" light is a random mixture of light of all polarizations. When light has an easily observed dominant polarization, we refer to it as polarized.
Quando luz nao polarizada de uma estrela atravessa poeira: graos com eixo menor alinhado com campo magnetico do MIS polarizam a radiacao, transmitindo radiacao polarizada na direcao paralela ao eixo menor do grao. Isso determina a distribuicao de B perpendicular a linha de visada.
Magalhães 2005

8. Measuring Magnetic fields
Zeeman effect (within galaxy):
 = e B║/2 me
Polarized synchrotron emission (Beck and Krause 2005):
I  ∫ nCR B┴1+α dl
Faraday rotation of the diffuse polarized emission:
RM  ∫ ne B║ dl
Alfa indice espectral da radiacao sincrotron det. Obs.
Radiacao de linhas ao atravessar campo ao longo da linha de visada se intenso o bastante pode causar splitting de niveis de energia degenerados: dando medida de B // linha de visada portanto.
Radiacao sincrotron: boa quando ha quantidade de eletrons relativisticos suficientes para produzir rad. Sincrotronica que e linearmente polarizada pois e produzida por eletrons acelerados ao longo de B. Como radiacao propaga normal ao plano de polarizacao, obtemos B normal a linha de visada e normal ao vetor polarizacao.
Metodo tambem permite determinar intensidade de B e nao apenas direcao. Fraqueza do metodo: assume-se equiparticao de en. Entre els. Relativisticos e campo B.Hipotese incerta
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, integral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.

9. Some Radio Telescopes
VLA
Effelsberg
ATCA

10. Outline Magnetic Fields in Stars and Compact Objects
Magnetic Fields in the ISM & Star Formation
Magnetic Fields in the Milky Way
Magnetic Fields in Galaxies, Clusters and IGM
Primordial Magnetic Fields
Future Needs and Perspectives

11. PART I: Magnetic Fields in Stars and Compact Objetcs

12. Solar Magnetic Fields In corona (2 x 106 K):
Associated to proeminence eruption and/or flares;
matter (electrons, protons, and ions) is thrown into the interplanetary medium;
In corona (2 x 106 K):
Magnetic arcs ( x 104 km)
Sunspots (B = G)

13. Solar Magnetic Fields
Silva, 2005
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
Magnetic arcs: rise by buoyancy due to convective motions (Parker-Rayleigh-Taylor instability)
sunspot

14. Sudden release of 1030-1032 erg (seconds to hours)
Solar Flares
Silva 2005
Sudden release of erg (seconds to hours)

15. Flares energized by magnetic reconnection
Solar Flares
CMEs
Shibata et al.
Flares energized by magnetic reconnection
EB released: heating, particle acceleration, coronal mass ejections (CMEs)

16. Flares energized by magnetic reconnection
Solar Flares
CMEs
Shibata et al.
Flares energized by magnetic reconnection
EB released: heating, particle acceleration, coronal mass ejections (CMEs)

17. What is the origin of solar magnetic activity?
Solar Magnetic Fields
What is the origin of solar magnetic activity?
Dynamo action:
 Conductive ionized flow
 Convective and turbulent motions
 Differential rotation
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
As in lab., where electric generator may spring to life if rotated fast: current will be created in the wires and then B is created .
The same ingredients in a star: conductive flow
Conversion of kinetic energy of these motions into EB

18. Magnetic Field Evolution
Fluid-B freezing
diffusion
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
As in lab., where electric generator may spring to life if rotated fast: current will be created in the wires and then B is created .
The same ingredients in a star: conductive flow
  BA = constant
diff = 4 L2 >> 1

19. Responsible for conversion of Ec  EB
Dynamo Mechanism
Responsible for conversion of Ec  EB
= 1/4: magnetic diffusivity
: field dissipation due to turbulent motion
-effect: vo=r differential rotation (Bp  BT)
-effect:
turbulent/convection motions (BT  Bp)
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
As in lab., where electric generator may spring to life if rotated fast: current will be created in the wires and then B is created .
The same ingredients in a star: conductive flow

20. Dynamo Mechanism Bp -effect BT -effect
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
As in lab., where electric generator may spring to life if rotated fast: current will be created in the wires and then B is created .
The same ingredients in a star: conductive flow BT
-effect

21. Dynamo Mechanism -effect -effect
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
As in lab., where electric generator may spring to life if rotated fast: current will be created in the wires and then B is created .
The same ingredients in a star: conductive flow

22. Magnetic Fields in other stars
Similar magnetic processes: in many stars (cool stars)
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
Shibata 2005
STARS

23. Magnetic Fields in Jets Jet from Active Galactic Nuclei (AGN)
ASTROPHYSICAL JETS
Jet from Active Galactic Nuclei (AGN)
EXTRAGALACTIC:  106 l.y., velocities  c, source mass 108 M, L ~ erg/s

24. Magnetic Fields in Jets Jet from Active Galactic Nuclei (AGN)
EXTRAGALACTIC:  106 l.y., velocities  c, source mass 108 M, L ~ erg/s

25. Magnetic Fields in Jets
GALACTIC:
~ 1 l.y., velocities  c, source mass 10 M, L ~ erg/s
Their proximity makes them one of the best labs. to investigate relativistic jet
also thanks to their proximity and scales we can see lifetime variations in them.

26. Jets: What are they? Supersonic collimated outflows carry:
mass, momentum, energy and magnetic flux from stellar, galactic and extragalactic objects to the outer medium
carrying out the angular momentum excess from the central star.
Particular features: knots, disks (seem by HST), wiggling
Their proximity makes them one of the best labs. to investigate jet
also thanks to their proximity and scales we can see lifetime variations in them.
EXTRAGALACTIC
GALACTIC

27. WHAT IS THE JET ORIGIN ?
carrying out the angular momentum excess from the central star.
Particular features: knots, disks (seem by HST), wiggling
Their proximity makes them one of the best labs. to investigate jet
also thanks to their proximity and scales we can see lifetime variations in them.
Magneto-centrifugal acceleration out off accretion disk around the source (Blandford & Payne)

28. Accretion Disks

29. Magnetic Fields in Accretion Disks
Similar magnetic processes in stars: in accretion disks, galactic disks
Wind/Jet
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
Shibata 2005
STARS
DISKS

30. Magnetic Fields in Accretion Disks
X-ray and radio flares: ejections accelerated during violent magnetic reconnection (de Gouveia Dal Pino & Lazarian 2001, 2005; de Gouveia Dal Pino 2006)
We went further in these magnetic ideas and recently Lazarian & I have suggested that

31. PART II: Magnetic Fields in the ISM & Star Formation
Radiacao de linhas ao atravessar campo ao longo da linha de visada se intenso o bastante pode causar splitting de niveis de energia degenerados: dando medida de B // linha de visada portanto.
Radiacao sincrotron: boa quando ha quantidade de eletrons relativisticos suficientes para produzir rad. Sincrotronica que e linearmente polarizada pois e produzida por eletrons acelerados ao longo de B. Como radiacao propaga normal ao plano de polarizacao, obtemos B normal a linha de visada e normal ao vetor polarizacao.
Metodo tambem permite determinar intensidade de B e nao apenas direcao. Fraqueza do metodo: assume-se equiparticao de en. Entre els. Relativisticos e campo B.Hipotese incerta
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, inegral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.
Em clusters gals: obtem-se ne de obs. Raio X gas quente;
MIG: muito rarfeito nao facil medir

32. ISM: Interstellar Medium
Radiacao de linhas ao atravessar campo ao longo da linha de visada se intenso o bastante pode causar splitting de niveis de energia degenerados: dando medida de B // linha de visada portanto.
Radiacao sincrotron: boa quando ha quantidade de eletrons relativisticos suficientes para produzir rad. Sincrotronica que e linearmente polarizada pois e produzida por eletrons acelerados ao longo de B. Como radiacao propaga normal ao plano de polarizacao, obtemos B normal a linha de visada e normal ao vetor polarizacao.
Metodo tambem permite determinar intensidade de B e nao apenas direcao. Fraqueza do metodo: assume-se equiparticao de en. Entre els. Relativisticos e campo B.Hipotese incerta
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, inegral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.
Em clusters gals: obtem-se ne de obs. Raio X gas quente;
MIG: muito rarfeito nao facil medir

33. ISM 21cm Emission from Perseus - Auriga
b=+4°
Observations of the diffuse polarized emission from our Galaxy are complementary to extragalactic observations as they trace structures of pc and sub-pc sizes (Fig. 5).
Faraday depolarization is strong at frequencies below about 1 GHz, so that only a nearby Faraday screen is visible in polarization.
features carry valuable information about the turbulent ISM in the Faraday screen.
The wavelength dependence of Faraday depolarization allows Faraday tomography of different layers when maps at several wavelengths are combined.
b=-4°
l=166°
l=150°
Polarized emission
Effelsberg 21cm (Reich et al 2003)

34. ISM 21cm Emission from Perseus - Auriga
b=+4°
ISM diffuse polarized emission: traces B structures of pc and sub-pc sizes
Carries information about the turbulent ISM
Observations of the diffuse polarized emission from our Galaxy are complementary to extragalactic observations as they trace structures of pc and sub-pc sizes (Fig. 5).
Faraday depolarization is strong at frequencies below about 1 GHz, so that only a nearby Faraday screen is visible in polarization.
features carry valuable information about the turbulent ISM in the Faraday screen.
The wavelength dependence of Faraday depolarizationallows Faraday tomography of different layers when maps at several wavelengths are combined.
b=-4°
l=166°
l=150°
Polarized emission
Effelsberg 21cm (Reich et al 2003)

35. Magnetic fields in the ISM
MHD turbulence distributes energy from SN explosions, jets and winds within the ISM
Magnetic fields control density and distribution of cosmic rays in the ISM and halo
EB  Eturb  ECR
Radiacao de linhas ao atravessar campo ao longo da linha de visada se intenso o bastante pode causar splitting de niveis de energia degenerados: dando medida de B // linha de visada portanto.
Radiacao sincrotron: boa quando ha quantidade de eletrons relativisticos suficientes para produzir rad. Sincrotronica que e linearmente polarizada pois e produzida por eletrons acelerados ao longo de B. Como radiacao propaga normal ao plano de polarizacao, obtemos B normal a linha de visada e normal ao vetor polarizacao.
Metodo tambem permite determinar intensidade de B e nao apenas direcao. Fraqueza do metodo: assume-se equiparticao de en. Entre els. Relativisticos e campo B.Hipotese incerta
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, inegral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.

36. Magnetic Fields in Molecular Clouds Regular B and disk-like morphology
L1544 Core
Red lines: B direction from dust measures. A regular field dominating a random field and an hourglass morphology toward cores are predictions of the strong magnetic field paradigm. However,
B projected onto the sky is observed to be not exaclty parallel to the minor axes of starless
cores as predicted by magnetic support (but makes an angle 29°. Initial conditions of cloud formation and turbulence could explain difference.
n(H2)  5  105 cm-3, N(H2)  4  1022,   13, Bpos  140 G (Crutcher et al. 2004)
Regular B and disk-like morphology

37. Magnetic Fields in Molecular Clouds
DR21OH core
L183 core
Blos = 0.4, 0.7 mG
high-mass star formation region DR21OH; consists of two compact cores witha total mass of » 100 Msolar
magnetic field direction in DR21OH is parallel to the CO polarization (red) and therefore parallel to the major axis of DR21OH. The dust polarization data north of the cores suggest that B is along the minor axis to the north of the cores. This morphology could be explained by a large-scale poloidal field with a toroidal field toward the cores produced by rotation of the double
The CO and dust polarization maps suggest that magnetic fields are remarkably uniform throughout the region. Both the dust emission and the CN lines sample a
Combining these results, Btotal = 1:2 mG
Bpos  0.7 mG
n(H2)  3  105, N(H2)  3  1022,   13, Bpos80 µG (Crutcher et al. 2004)
n(H2)  2  106, N(H2)  3  1023, Bpos  0.7 mG (Lai et al. 2001)

38. Magnetic Fields in Diffuse and Molecular Clouds
H I Clouds Molecular Clouds
Btotal (G) 6.0 – 3,000
M/(BA) < ~1
[B  ] ~ ~1/2
Pthermal/PB
Pturbulent/PB
Polarization maps of cores consistent with strong regular field dominating turbulent component
B not // to minor axes as predicted by ambipolar diffusion model (where the support of the cloud against colapse is believed to be due to magn. Pressure and ambipolar diffusion is important to provide star collapse).
Triaxial cloud morphology due to compressible turbulence can account for this.
Hybrid paradigm: compressible turbulence dominates in the diffuse ISM over gravity and magnetic B, sometimes form slef-gravitating clouds.
HI clouds are precursors of molecular clouds: dominated by turbulence
Turbulent flow: primarily along B lines (flux tubes)
Magnetic pressure: resists compression normal to B.
Aggregation of HI clouds into a single MC would lead to observed increase in M/(BA) ratio.
Turbulence driven ambipolar diffusion may also occur in this phase.
Residual effects of turbulence in MCs may explain why they are not simple oblate spheroids and some non-thermal velocity is observed and B not perfeclty // to the minor axis as expected in collapse of cloud dominated by regular B.
B-rho scaling with k=0.5 is expected from ambipolar B dominated collapse.
Crutcher 2005

39. Magnetic Fields in Diffuse and Molecular Clouds
Diffuse ISM and HI clouds: dominated by turbulence
Parker 1972
Molecular clouds: formed by HI clouds accumulation along field lines
Crutcher 2005

40. Star Formation in Molecular Clouds
Observations consistent with approximate magnetic support in molecular cores (gPB)
Ambipolar diffusion driving star formation on a fast (~few free-fall times) timescale
Li & Shu (1996)
Magnetic fields also essential for removal of angular momentum from protostellar cloud (magnetic braking!)

41. Phases of Star Formation
(a) Formation of cores in giant molecular clouds by ambipolar diffusion and decay of turbulence:
Δt = 1 – 3 Myr
(b) Rotating, magnetized gravitational collapse:
Δt = ?
(c) Strong jets & bipolar outflows; reversal of gravitational infall:
Δt = 0.1 – 0.4 Myr
(d) Star and protoplanetary disk with lifetime:
Δt = 1 – 5 Myr
Shu, Adams, & Lizano 1987

42. PART III: Magnetic Fields in the Milky Way
Radiacao de linhas ao atravessar campo ao longo da linha de visada se intenso o bastante pode causar splitting de niveis de energia degenerados: dando medida de B // linha de visada portanto.
Radiacao sincrotron: boa quando ha quantidade de eletrons relativisticos suficientes para produzir rad. Sincrotronica que e linearmente polarizada pois e produzida por eletrons acelerados ao longo de B. Como radiacao propaga normal ao plano de polarizacao, obtemos B normal a linha de visada e normal ao vetor polarizacao.
Metodo tambem permite determinar intensidade de B e nao apenas direcao. Fraqueza do metodo: assume-se equiparticao de en. Entre els. Relativisticos e campo B.Hipotese incerta
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, inegral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.

43. The Milky Way Nossa gal. Poderia ser assim ou assim.
Nao sabemos exatamente pois teriamos que sair dela para ver como e exatamente.

44. Magnetic fields in our Galaxy?
Galactic magnetic field is the existence of multiple reversals
along Galactic radius, derived from pulsar RM data [46], [30]. No such reversals were found so far in any external galaxy.
To account for several large-scale reversals, a
bisymmetric magnetic spiral with a small pitch angle (
However, the RM data from pulsars are still scarce. Only one large-scale reversal is statistically significant [24].
Furthermore, some of the field reversals may not be of galactic extent, but due to field distortions [42] or loops of the anisotropic turbulent field.
In summary, the pattern of the large-scale regular magnetic field of the MilkyWay is still unknown.
Sun is located between two spiral arms, the Sagittarius/Carina and the Perseus
Dynamo: standard model predicts even parity no reversals of B; a primordial origin from compression of Bo + diff. Rotation may wrap B into bysymmetric spiral with reversals (M81, MW).
Han et al. 2001

45. Magnetic fields in our Galaxy
Cosmic-ray energy density + radio synchrotron:
<B> 6 G
and in inner region:
<B> 10 G
Agrees with independent estimate of cosmic-ray electrons from bremsstrahlung γ-rays
(Strong et al. 2000)
The validity of the equipartition assumption can be tested in our Galaxy, because there is independent information about the local cosmic-ray energy density from in-situ measurements
and from -ray bremsstrahlung data. Combination with the radio synchrotron data yields a local strength of the total field
6 micro G and 10 micro G in the inner
Galaxy [56], similar to the values derived from energy equipartition (Berkhuijsen, in
[4]) and similar to the values in other galaxies (Sect. 3).
Rotation measure and dispersion measure data of pulsars give an average strength of the local regular field of 1.4 microG and 4.4 inner arrm (note measure from pulsar data is underestimated or overestimated if small-scale fluctuations in field strength and in electron
density are anticorrelated or correlated, respectively
Equipartition fields in the Galaxy (Berkhuijsen, priv. comm.)

46. PART IV: Magnetic Fields in Galaxies, Clusters and IGM
Radiacao de linhas ao atravessar campo ao longo da linha de visada se intenso o bastante pode causar splitting de niveis de energia degenerados: dando medida de B // linha de visada portanto.
Radiacao sincrotron: boa quando ha quantidade de eletrons relativisticos suficientes para produzir rad. Sincrotronica que e linearmente polarizada pois e produzida por eletrons acelerados ao longo de B. Como radiacao propaga normal ao plano de polarizacao, obtemos B normal a linha de visada e normal ao vetor polarizacao.
Metodo tambem permite determinar intensidade de B e nao apenas direcao. Fraqueza do metodo: assume-se equiparticao de en. Entre els. Relativisticos e campo B.Hipotese incerta
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, inegral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.

47. Magnetic fields in Galaxies
B2 = Bt2 + Br2
Polarized synchrotron: measures Br
M51

48. Magnetic fields in Galaxies
Spiral patterns of regular B:
observed in grand-design, flocculent and even in some irregular galaxies.
Large-scale spiral patterns of the regular field are observed in grand-design, flocculent
and even some irregular galaxies. In grand-design galaxies the regular fields are aligned parallel to
the optical spiral arms, with the strongest regular fields (highest polarization) in interarm regions,
sometimes forming magnetic spiral arms between the optical arms.

49. Magnetic fields in Galaxies
Spiral patterns of regular B observed in
Grand-design galaxies
Large-scale spiral patterns of the regular field are observed in grand-design, flocculent
and even some irregular galaxies. In grand-design galaxies the regular fields are aligned parallel to
the optical spiral arms, with the strongest regular fields (highest polarization) in interarm regions,
sometimes forming magnetic spiral arms between the optical arms.
M51

50. indicate dynamo works without assistance of density waves!
Flocculent galaxies:
spiral field without
spiral arms !
indicate dynamo works without assistance of density waves!
NGC4414
(Soida et al. 2002)

51. Large Irregulars: some traces of spiral field NGC4449 (Chyzy et al.
2000)

52. Regular fields follow the shearing gas flow around massive bars
Barred Spiral galaxies:
Regular fields follow the shearing gas flow around massive bars
Resolution 10”
NGC1097
(Beck et al. 2004)

53. Organized B inside and outside of the circumnuclear “ring” !
Magnetic fields in Galaxies
M31
Organized B inside and outside of the circumnuclear “ring” !

54. Magnetic fields in Galaxies
Turbulent fields are strongest in spiral arms (20 G): due to intense star formation, SN shocks.
Regular fields are strongest in interarm regions (15 G)
M51

55. Magnetic fields in Galaxies
Survey of 74 S galaxies (Niklas):
<Btot> = 9 μG
Starburst galaxies:
B ≥ μG
Nuclear starburst regions:
B ≥ 100μG!
Suggests B is essential in the deflagration of SBs and since SBs are believed to be the progenitors of spheroidal gals. And bulges, hence in the formation of spheroidal gals.!
Why B intensity in gals. Concentrate in few microGauss?
Totani suggested and generally agreeded that spheroidal gal. Formation occurs as a consequence of SBs triggered by strong Bs!
Based this in 2 arguments: 1.B is around few microGauss always; 2. SF activity observed to be correlated with local B intensity!.
Correlation may be due to magnetic braking: i.e., in order for the protogalaxy cloud to collapse a significant amount of angular momentum must be transferred outwards.
Totani suggests that SBs, hence massive galaxy formation takes place only where B strong enough to provide magnetic braking and allow colapse at a critical value that happens to be of the order of few microGauss! A seed field could have been produced by a battery and then amplified by dynamo!
Correlation B and SF!
NGC1067: nuclear SB region

56. Magnetic fields in Galaxies
Outer regions:
EB > Etherm :
B affects gas rotation curve !?
(Battaner & Florido 2000)
Large-scale patterns in Faraday rotation measures RM, as observed e.g. in M 31 [14],
show that the regular field in these galaxies has a coherent direction and hence is not
generated by compression or stretching of turbulent fields in gas flows. The turbulent
dynamo mechanism [9] is able to generate and preserve coherent magnetic fields, and
these are of appropriate spiral shape.
Battaner et al: in MW and NGC6946: clearly determined that magnetic field forces outside regions cannot be neglected in the dynamics and is competitive candidate to explain flatness of rotation curves !!
 consistent with dynamo!
EB ≈ Eturb

57. M31: very regular (coherent) field revealed by Faraday rotation
The coherent
magnetic field
in M31 is the
best evidence
so far for
dynamo action !
Fletcher et al. 2004

58. Magnetic fields in Galaxy Halos
B in Halos of galaxies with high SFR:
correlated to diffuse ionized gas and X-rays (up to z=5 kpc)
Several halos:
v/z < 0
contribute to excitation of dynamo!
Gaseous DIG halos are found in galaxies with sufficiently high SFR per unit area.
Typically these layers of extraplanar DIG can be traced out to distances of z 1–2 kpc
– sometimes even up to 5 kpc or more – from the mid-plane of the disk.
In several galaxies the halo gas is observed to rotate slower than the gas in the disk with NGC5775 showing the largest
gradient. This velocity gradient could contribute to the excitation of a global dynamo in disk galaxies.
The highly structured dust distribution in the halos of some galaxies could be influenced by magnetic fields due the coupling of charged dust to both the radiation and magnetic fields.
NGC (Dettmar 2005)

59. Magnetic fields in Galaxy Halos
The highly structured dust distribution in the halos of some galaxies could be influenced by magnetic fields due the coupling of charged dust to both the radiation
and magnetic fields.
NGC891 (Rossa et al. 2005)
B filaments and loops coupled with charged dust in halo!

60. Do dynamos work in galaxies ?
YES:
+ Spiral fields occur almost everywhere, even in irregular galaxies and central rings
++ Magnetic arms occur between gas arms
++ Large-scale coherent fields exist
++ There is at least one case of a dominating axisymmetric mode (M31)
The fact that there are magnetic arms between gas arms: suggests that a global dynamo mechanism is necessary. Reason: B fields could be produced by stars winds, jets and SN explosions but these are more intense within the arms;
Coherent fileds mored difficult to produce in turbulent media. Require a dynamo action to produce large scale regular coherence.

61. Do dynamos work in galaxies ?
NO:
- Single dominating modes are rare (nonlinear multiple dynamos? – Subramanian 1988)
- Coherent fields surprisingly weak in galaxies with strong density waves (M51) (strong compression and/or shear?)
Spiral fields extend well into the centers
Fields are still strong in outer regions of galaxies (magneto-rotational instability?)
Turbulent dynamo (Subramanian 1988): considers the standard dynamo model acting in different scales, of multiple cells, these micro-dynamos combine to build a large scale B

62. Dynamo in Galaxies
Beck 2005

63. Magnetic fields in Clusters
A Coma
Galaxies: aggregate in clusters in the large scale structure of Universe. MW for ex., belongs to a local group of gals. That belong to Virgo cluster. A cluster has typically 100 Mpc (3 million light-years). Can be regular (left) or irregular (right).
B fields may have been generated by batteries powered by SBs, jet-lobe radio sources. Colgate & Li, proposed strong B in clusters produced by a dynamo operating in the accretion disk of the massive black hole in AGNs. However, the dynamics of process leading to the formation of BHs is still unclear and pre-existing Bs may be required to carry away the huge angular momentum of the falling matter. For the same reason pre-existing Bs may be required to trigger SBs.
This suggests that seed fields before recombination may be required.

64. Rotation Measures in Clusters
RMs of polarized synchrotron radiation from background or embedded radio galaxies

65. Rotation Measures in Regular Clusters Hydra A Taylor & Perley (1993)
Lane et al. (2004)
Rad/m/m
+5000 Rad/m/m

66. Rotation Measures in Irregular Clusters
A400 (3C75) Eilek & Owen (2002)
-170 Rad/m/m
+170 Rad/m/m

67. Magnetic fields in Clusters
X-rays observations Abel clusters (e.g., Grasso & Rubinstein 2001):
Coma cluster: B  8.3 G ! (tangled in L ~1 kpc)
Clusters central regions with radio sources (Govoni et al. 2005):
Govoni 2005:
Magnetic fields in IRREGULAR clusters ~5μG
Magnetic fields in REGULAR clusters are higher ~10-30μG
B  G  PB > Ptherm!

68. Origin of B in Clusters ?
B fields powered by jets from radio sources (Colgate & Li 2003, Kato et al. 2005).
But: pre-existing B may be required!
Numerical Simulations of Kato et al. 2004: B generation from accretion disk (Shibata et al.) and injection into the intra-cluster medium.
Hydra
Numerical simulation (Kato et al 2005)

69. Magnetic fields in IGM BIGM  10-9 G, for L  1 Mpc
B probably pervades entire Universe
IGM: rarefied ionized gas and coherence L of B poorly known
Faraday rotation of polarized emission from distant quasars (up to z=2.5):
For diffuse IGM: We assume a reversal scale of B similar to the maximum measured in Clusters: L = 1 Mpc
BIGM  10-9 G, for L  1 Mpc

70. PART V: Primordial Magnetic Fields
Rotacao Faraday do angulo de polarizacao em relacao a linha de visada, de radiacao linearmente polarizada : quando onda eletromagnetica (especialmente radio grande lamda) linearmente polarizada atravessa campo // REGULAR aa linha de visada , determinando a densidade dos els. Termicos ao longo da linha de visada, inegral (ne dl), obtem-se B//.
Para obter integral (ne dl): mede-se na nossa gal. Medida de dispersao dos tempos de chegada dos sinais dos pulsares de diferentes lambdas devido aa densidade colunar.

71. Magnetic fields in Early Universe
Universe History
B fields may have been generated by batteries powered by SBs, jet-lobe radio sources. Colgate & Li, proposed strong B in clusters produced by a dynamo operating in the accretion disk of the massive black hole in AGNs. However, the dynamics of process leading to the formation of BHs is still unclear and pre-existing Bs may be required to carry away the huge angular momentum of the falling matter. For the same reason pre-existing Bs may be required to trigger SBs.
This suggests that seed fields before recombination may be required.

72. Magnetic fields in Early Universe
RMs of distant quasars (z>1)  B in the past (Kronberg et al. 1992)
3C191 (z=1.945):
B  G in L  15 kpc (galaxy size!)
Young spiral galaxy (z=0.395):
B  G
B in gals. At high z’s (Kim 2005):
Microgauss levels of the observed B-fields in radio gals at z=2 shorten the time available for dynamo action.
To amplify a seed field by the alpha-omega dynamo mechanism with ~Gyr growth time, the strength of the seed field should be stronger than G.
The growth time of B-field by SN-driven turbulence at least at a 100 pc scale is ~ 10 Myr.
SN-driven turbulence may possibly amplify kpc-scale B-fields, which should be confirmed by numerical experiments with a bigger computational domain.
SN-driven turbulence may play an important role in amplifying B-fields in many interesting astrophysical systems.
B fields may have been generated by batteries powered by SBs, jet-lobe radio sources. Colgate & Li, proposed strong B in clusters produced by a dynamo operating in the accretion disk of the massive black hole in AGNs. However, the dynamics of process leading to the formation of BHs is still unclear and pre-existing Bs may be required to carry away the huge angular momentum of the falling matter. For the same reason pre-existing Bs may be required to trigger SBs.
This suggests that seed fields before recombination may be required.
What is the origin of these B fields in early Universe ?

73. Primordial Magnetic fields?
Strong B in galaxy clusters and in galaxies at high redshifts:
Are the magnetic fields primordial ?
Pros:
Large conductivity of plasma in Universe:
diff = 4 L2 >> to    BA = constant
Alternative to dynamo: If B is primordial  Bgal 10-6 G results from compression of primordial B:
From B flux conservation and mass conservation we find eq. above. For adiabatically compressed primordial Bo
B primordial 10-9 G: would affect structure formation dynamically!
Also primordial Universe: RM >> Re>> 1: early Universe very turbulent!
Bprim,o  10-9 G !

74. Primordial Magnetic fields?
Constraints:
CMBR: Primordial B would influence CMBR via:
 breaking spatial isotropy
 MHD effects temperature and polarization fluctuations CMBR
CMB spectrum  Bo(50 Mpc) < 10-8 –10-9 G
CMB: constrains B at the time of recombination el-proton
Accoustic peaks: Primordial density fluctuations (necessary to explain obs. structures formation in the Universe) distort CMB spectrum introducing T fluctuationns , gravitational Doppler shift of photons in grav. Potential well (Sachs.Wolfe effect)
B may introduce effects on small scale fluctuations :
P magnetic may reduce acoustic peak by opposing infall of photon-baryons in grav. potential of the fluctuation.
BBN provides constraint on B atearlier time of nucleosynthesis primordial when radius universe: 100 pc << protogalaxy sizes 1-10 Mpc. Thus, progenitor B of gal. Fields must be average of tangled B (Grasso e Rubinstein)
BB Nucleosynthesis: Primordial B could change expansion rate of the Universe and 4He abundance
BBN  B(100pc, T=109K) < 1011 G
 Bo(1Mpc)<10-10 G

75. Primordial Magnetic fields?
CMBR and BBB constraints:
Imply B strengths  the required by IGM today
diff >> to: diffusion length lo < 109 cm:
Small scale fields produced in early Universe survived and left no significant imprints on BBN or CMB (perhaps!)
CMB: constrains B at the time of recombination el-proton
Accoustic peaks: Primordial density fluctuations (necessary to explain obs. structures formation in the Universe) distort CMB spectrum introducing T fluctuations , gravitational Doppler shift of photons in grav. Potential well (Sachs.Wolfe effect)
B may introduce effects on small scale fluctuations :
P magnetic may reduce acoustic peak by opposing infall of photon-baryons in grav. potential of the fluctuation.
BBN provides constraint on B atearlier time of nucleosynthesis primordial when radius universe: 100 pc << protogalaxy sizes 1-10 Mpc. Thus, progenitor B of gal. Fields must be average of tangled B (Grasso e Rubinstein)
Only fields with scales >109 cm can survive, or there is no constraint on scale of primordial Bs: all can survive: primordial plasma can be magnetized without leaving inprint on CMB (only very small scales are dumped away)

76. Models for Primordial Magnetic fields
Inflation (breaking conformal invariance of electromagnetic field): Bo(1Mpc)  G! Too small to seed galactic dynamo
QCD Phase transition (quarks combine to form hadrons, T= K): Bo(100kpc)  10-9 G (under extreme conditions! Sigl et al.)
Biermann Batery (pxn≠0): Bo G (pre-galactic seed field is exponentially amplified by dynamo)
Harrison effect: Bo G (pre-galactic seed field is amplified by dynamo)
SN-driven turbulence (may amplify seed B-fields in 10 Myr only; Kim 2005)
Why do we care about primordial magnetic fields? (shaposhnikov, 2004)
Origin of galactic and cluster magnetic field?
Probably, amplification of seed magnetic fields via galactic dynamo.
Astrophysic origin of seeds:
Biermann battery in intergalactic shocks, Harrison effect,
stellar magnetic fields, supernova explosions, galactic outflows into
intergalactic medium, quasar outflow of magnetized plasma,...
Cosmology:
Perhaps, seeds are coming from some peculiar processes
in the early universe (primordial magnetic fields prior to
recombination)?
Magnetized plasma at early times?
Change of a standard view on the evolution of the universe: inflation,
cosmological phase transitions, baryogenesis, nucleosynthesis...
Harison: Vorticidade do plasma primordial pre-estruturas and pressao de radiacao atuando mais fortemente sobre els que protons: geraria correntres e portanto campos B sementes.
Problem with primordial Bs:
the coherence length L at the time of generation cannot exceed radius of the Universe<<< when adiabatically scheduled for today the obtained cell sizes of coherence << cell sizes of B today observed in gals. And ICM
Helicity may ease this problem: magnetic helicity
(rotB. B) may help formation of large scale B structures starting from small ones ( INVERSE CASCADE)
INFLATION:
Offers solution to horizon flatness and homogeneity of the universe , quantum fluctuations produce large scale density perturbations drho/rho = 10-5.
Quantum fluctuations of electromagnetic field could produce large scales Bs?
Small coherence problem of primordial Bs: may be circumvented if production mechanism was not causal: possible if B produced during inflation by superadiabatic amplification of pre-exisiting quantum fluctuations IF gauge invariance of electromagnetic field is BROKEN
QCD: bubble nucleation . As T cools below Tqcd, bubbles with hadrons grow as burning deflagration fronts and become supersonic ; shock re-heat the plasma stopping bubble grow. Transition ends when expansion wins and quark pockets are hadronized. E fields develop behind the shock fronts ahead of expanding bubbles create currencts and B=Ev is generated in small scales. Volume average of these fields Bqcd = 108G and under very special conditions with amplification by hydromagnetic instabilities, dynamo operation during QCD and inverse cascade: Sigl et al obtain Bqcd = 1017 G and today: 10-9 G
B in gals. At high z’s (Kim 2005):
Microgauss levels of the observed B-fields in radio gals at z=2 shorten the time available for dynamo action.
To amplify a seed field by the alpha-omega dynamo mechanism with ~Gyr growth time, the strength of the seed field should be stronger than G.
The growth time of B-field by SN-driven turbulence at least at a 100 pc scale is ~ 10 Myr.
SN-driven turbulence may possibly amplify kpc-scale B-fields, which should be confirmed by numerical experiments with a bigger computational domain.
SN-driven turbulence may play an important role in amplifying B-fields in many interesting astrophysical systems.
On the other hand, B fields may be important to drive SF and starbursts!
What came first?

77. Future Needs & Perspectives
Higher radio polarization sensitivity
Higher angular resolution (to map wealth of magnetic structures in galaxies)
High-frequency radio polarization observations have revealed the large-scale properties of the interstellar magnetic fields in many galaxies. Observations at better angular resolution
are needed to map the full wealth of magnetic structures in galaxies. Furthermore,
the velocity field of the gas should be measured in more detail, to provide input for dynamo
and MHD models. In our Galaxy, we need polarization maps of selected regions
at high frequencies and a much larger sample of RM data from pulsars.
The Square Kilometer Array (SKA) will detect more than pulsars in our Galaxy
and allow to detect their rotation measures. The SKA will be able to map nearby galaxies
with at least 10x better angular resolution compared to present-day radio telescopes,
or 10x more distant galaxies with similar spatial resolution as today [7]. Magnetic
field structures will illuminate the dynamical interplay of cosmic forces. The SKA’s
sensitivity will allow to detect synchrotron emission from the most distant galaxies in
the earliest stage of evolution and to search for the earliest magnetic fields and their
origin. Cosmic Magnetism is one of the Key Science Projects for the SKA [26].
Beck 2005

78. Square Kilometer Array (SKA)
Total effective collecting area: 1 Km2 (100 MHz to 25 GHz)
Stations of ~100 m diameter stations – accounting for half the SKA area – will be distributed across continental distances (~3000 km).
Remaining area will be concentrated within a central region of 5 km diameter (2020).
International radio telescope for 21st century
The Square Kilometer Array (SKA) will detect more than pulsars in our Galaxy and allow to detect their rotation measures.
The SKA will be able to map nearby galaxies with at least 10x better angular resolution compared to present-day radio telescopes, or 10x more distant galaxies with similar spatial resolution as today [7].
Magnetic field structures will illuminate the dynamical interplay of cosmic forces.
The SKA’s sensitivity will allow to detect synchrotron emission from the most distant galaxies in the earliest stage of evolution and to search for the earliest magnetic fields and their origin.
Cosmic Magnetism is one of the Key Science Projects for the SKA [26].
SKA goals mean that with a canonical 50 kelvin system temperature, one million square metres (or 1km2 ) of effective collecting area will be needed. How will the collecting area be arranged? Antennas will be grouped in patches, or stations, of ~100 m diameter. About 150 stations – accounting for half the SKA area – will be distributed across continental distances (~3000 km). The remaining area will be concentrated within a central region of 5 km diameter.

79. Square Kilometer Array (SKA)
Map nearby galaxies 10x better angular resolution of present radio telescopes
10x more distant galaxies with similar spatial resolution as today
detect synchrotron emission from galaxies and structures in the earliest stage of evolution
search for the earliest magnetic fields and their origin
proto-planets
black-holes
pulsars (>10000)
The Square Kilometer Array (SKA) will detect more than pulsars in our Galaxy and allow to detect their rotation measures.
The SKA will be able to map nearby galaxies with at least 10x better angular resolution compared to present-day radio telescopes, or 10x more distant galaxies with similar spatial resolution as today [7].
Magnetic field structures will illuminate the dynamical interplay of cosmic forces.
The SKA’s sensitivity will allow to detect synchrotron emission from the most distant galaxies in the earliest stage of evolution and to search for the earliest magnetic fields and their origin.
Cosmic Magnetism is one of the Key Science Projects for the SKA [26].
SKA goals mean that with a canonical 50 kelvin system temperature, one million square metres (or 1km2 ) of effective collecting area will be needed. How will the collecting area be arranged? Antennas will be grouped in patches, or stations, of ~100 m diameter. About 150 stations – accounting for half the SKA area – will be distributed across continental distances (~3000 km). The remaining area will be concentrated within a central region of 5 km diameter.
Cordes 2001

80. Square Kilometer Array (SQA)
Magnetic Fields in the Universe: from Laboratory and Stars to primordial Structures
American Inst. Phys., Conf. Procs., AIP, vol. 784
Aqui no Brasil: crescente interesse por Bs no cosmos: tanto de uma perspectiva teorica como observacional, do sol a estruturas primordiais:
IAG, INPE, Mackenzie, UFMG, Rio, RN, mas pode e DEVE crescer considerando-se a importancia de B no cosmos, como vimos.
Nesse sentido: organizamos no ultimo ano a 1 conferencia internacional:
E e uma satisfacao anunciar que os procs. Aparecerao publicados pela AIP ao final deste mes:
Contem mais de 40 artigos de revisao de todas as areas espaco, objetos compactos ao plasma primordial, alem de mais de 45 contribuicoes:
Voces encontrarao o que foi disuctido e mais nesse livro!

81. Square Kilometer Array (SQA)
Thank you !
Aqui no Brasil: crescente interesse por Bs no cosmos: tanto de uma perspectiva teorica como observacional, do sol a estruturas primordiais:
IAG, INPE, Mackenzie, UFMG, Rio, RN, mas pode e DEVE crescer considerando-se a importancia de B no cosmos, como vimos.
Nesse sentido: organizamos no ultimo ano a 1 conferencia internacional:
E e uma satisfacao anunciar que os procs. Aparecerao publicados pela AIP ao final deste mes:
Contem mais de 40 artigos de revisao de todas as areas espaco, objetos compactos ao plasma primordial, alem de mais de 45 contribuicoes:
Voces encontrarao o que foi disuctido e mais nesse livro!

82. Origin of B in Clusters ?
B fields powered by jets from radio sources (Colgate & Li 2003, Kato et al. 2005). But pre-existing B may be required!
Numerical Simulations of Kato et al. 2004: B generation from accretion disk (Shibata et al.) and injection into the intra-cluster medium.
Kato et al 2005

83. Dynamo Mechanism Bp -effect BT -effect
Magnetic fields are created by dynamo action in the convection zone, and rise up to the surface by magnetic
buoyancy. In the atmosphere, plasma beta (pgas/pmag) becomes less than unity, i.e., a magnetically dominated gas layer is created, so that once magnetic energy is released,
violent heating and mass ejection occur. This is why flares, corona, CMEs, and even solar wind occur.
The same physical processesare expected to be occurring in many stars (especially in cool stars). Similar, but more
violent activity may be occurring in accretion disks and galactic disks (Fig. 1).
As in lab., where electric generator may spring to life if rotated fast: current will be created in the wires and then B is created .
The same ingredients in a star: conductive flow BT
-effect

84. Magnetic fields at Early Universe
RMs of distant quasars (z>1)
 B in the past (Kronberg et al. 1992)
3C191 (z=1.945):
B  G in L  15 kpc (galaxy size!)
Young spiral galaxy (z=0.395):
B  G
B in gals. At high z’s (Kim 2005):
Microgauss levels of the observed B-fields in radio gals at z=2 shorten the time available for dynamo action.
To amplify a seed field by the alpha-omega dynamo mechanism with ~Gyr growth time, the strength of the seed field should be stronger than G.
The growth time of B-field by SN-driven turbulence at least at a 100 pc scale is ~ 10 Myr.
SN-driven turbulence may possibly amplify kpc-scale B-fields, which should be confirmed by numerical experiments with a bigger computational domain.
SN-driven turbulence may play an important role in amplifying B-fields in many interesting astrophysical systems.
B fields may have been generated by batteries powered by SBs, jet-lobe radio sources. Colgate & Li, proposed strong B in clusters produced by a dynamo operating in the accretion disk of the massive black hole in AGNs. However, the dynamics of process leading to the formation of BHs is still unclear and pre-existing Bs may be required to carry away the huge angular momentum of the falling matter. For the same reason pre-existing Bs may be required to trigger SBs.
This suggests that seed fields before recombination may be required.
What is the origin of these B fields in early Universe ?

85. VLA observations of 15 radio galaxies with z>2
Athreya et al. 1998
VLA observations of 15 radio galaxies with z>2
Four gals show intrinsic RMs in excess of 1000 rad m-2
The environs of the gals at z>2 have B-fields with micro-G strength
Kim 2005.