Evolution and Signatures of Helical Magnetic Fields Tina Kahniashvili McWilliams Center for...

Evolution and SignaturesEvolution and Signaturesofof

Helical Magnetic Fields Helical Magnetic Fields

Tina KahniashviliTina Kahniashvili

McWilliams Center for CosmologyMcWilliams Center for CosmologyCarnegie Mellon UniversityCarnegie Mellon University

&&Abastumani Astrophysical ObservatoryAbastumani Astrophysical Observatory

Ilia State UniversityIlia State University

NORDITANORDITAJune 24 2015June 24 2015

Based OnBased On

Kahniashvili, Maravin, Lavrelashvili, Kosowsky PRD 2014

Kahniashvili, Tevzadze, Brandenburg, Neronov, PRD 2013

Tevzadze, Kisslinger, Brandenburg, Kahniashvili, ApJ 2013

Ongoing CollaborationOngoing Collaboration(papers in preparation)(papers in preparation)

Axel Brandenburg, Ruth Durrer, Victoria Merten,

Alexander Tevzadze, Tanmay Vachaspati, Winston Yin

Cosmic Magnetic Fields

Sun MF

Galaxy MF

Earth MF

Interstellar MF

How do we observe cosmic magnetic fields?

Electromagnetic waves &Effects induced by magnetic fields

Magnetic HelicityMagnetic Helicity

DIFFICULT TO DETECT cosmic rays: Kahniashvili & Vachaspati 2006 gamma-rays: Tashiro and Vachaspati 2011

Solar activity: SunspotsSolar flaresCoronal mass ejectionSolar wind

Magnetic helicity reflects mirror symmetry (parity) breaking

Gamma Rays vs Magnetic HelicityGamma Rays vs Magnetic Helicity

Tashiro, Chen, Francesc, Vachaspati 2014

Tashiro and Vachaspati 2015

Chen, Chowdhury, Francesc, Tashiro, Vachaspati 2014

Primordial Magnetic Field Hypothesis

F. Hoyle in Proc. F. Hoyle in Proc. ““La structure et La structure et ll ’’evolution de levolution de l’’UniverseUniverse”” (1958) (1958)

InflationInflation Phase transitionsPhase transitions SupersymmetrySupersymmetry String CosmologyString Cosmology Topological defectsTopological defects

SpringelMillenium simulations

Magnetogenesis Inflation Inflation (Turner & Widrow 1988, Ratra 1992)(Turner & Widrow 1988, Ratra 1992)

• The correlation length larger The correlation length larger than horizonthan horizon

• Scale invariant spectrumScale invariant spectrum• Well agree with the lower Well agree with the lower

boundsbounds DiffucultiesDiffuculties

• BackreactionBackreaction• Symmetries violationSymmetries violation

Phase TransitionsPhase Transitions

((Harrisonl 1970, Vachaspati 1991Harrisonl 1970, Vachaspati 1991))• Bubble collisions – first order Bubble collisions – first order

phase transitionsphase transitions QCDPTQCDPT EWPTEWPT

• Causal fields Causal fields • Limitation of the correlation Limitation of the correlation

lengthlength Smoothed and effective fields Smoothed and effective fields

approachesapproaches

Cosmological vs. Astrophysical Magnetogenesis

MHD Simulations by Donnert et al. 2008

Z=4

Z=0

Z=4

Z=0

Ejection Primordial

Cosmological Magnetic Fields(Obvious Limits)

BBN limits: 10% of BBN limits: 10% of additional additional relativistic relativistic component component • 0.1 – 1 microGauss0.1 – 1 microGauss

(comoving value)(comoving value) Grasso and Rubistein Grasso and Rubistein

20002000 Yamazaki and Yamazaki and

Kusakabe 2012Kusakabe 2012 Kawasaki and Kawasaki and

Kusakabe 2012Kusakabe 2012

Faraday Rotation Faraday Rotation Measure Measure • At z~2-3 At z~2-3

microGauss microGauss Bernet et al. 2009Bernet et al. 2009 Kronberg et al. 2008Kronberg et al. 2008

Magnetized CMB Perturbations Magnetized CMB Perturbations

Density perturbations - scalar mode Density perturbations - scalar mode • Fast and slow magnetosound wavesFast and slow magnetosound waves

Adams et al. 1996 Adams et al. 1996 Jedamzik, Katalinic, Olinto, 1996Jedamzik, Katalinic, Olinto, 1996

Vorticity perturbations - vector mode Vorticity perturbations - vector mode • Alfven wavesAlfven waves

Subramanian and Baroow, 1998Subramanian and Baroow, 1998 Durrer, Kahniashvili, and Yates, 1998Durrer, Kahniashvili, and Yates, 1998

Gravitational waves - tensor ModeGravitational waves - tensor Mode Deryagin et al. 1986Deryagin et al. 1986 Durrer, Ferreira, Kahniashvili 2000Durrer, Ferreira, Kahniashvili 2000

Faraday rotation does not depend on magnetic helicity

Modeling Helical Magnetic Field Modeling Helical Magnetic Field

Kahniashvili, Kosowsky, Lavrelashvili, Maravin, 2014 Kahniashvili, Kosowsky, Lavrelashvili, Maravin, 2014

Magnetic Helicity Effects on CMBMagnetic Helicity Effects on CMB

• Parity-even fluctuationsParity-even fluctuations Temperature - TemperatureTemperature - Temperature Temperature - E polarizationTemperature - E polarization E-polarization – E-polarizationE-polarization – E-polarization B-polarization – B-polarization B-polarization – B-polarization

• Parity-odd fluctuationsParity-odd fluctuations Temperature – B-polarizationTemperature – B-polarization E-polarization – B-polarization E-polarization – B-polarization

Pogosian, Vachaspati, and Winitski 2000, Caprini, Durrer, and Pogosian, Vachaspati, and Winitski 2000, Caprini, Durrer, and Kahniashvili, 2003, Kahniashvili and Ratra 2005, Kunze 2012, Kahniashvili, 2003, Kahniashvili and Ratra 2005, Kunze 2012, Kahniashvili, et al. 2014, Balardini, Finelli, and Paoletti, 2014Kahniashvili, et al. 2014, Balardini, Finelli, and Paoletti, 2014

Magnetic Helicity vs. WMAP 9 years Magnetic Helicity vs. WMAP 9 years datadata


Magnetic Helicity EffectsMagnetic Helicity Effects

Magnetic Helicity LimitsMagnetic Helicity Limits


Phenomenology

If the magnetic field has been generated If the magnetic field has been generated through a causal process in the early through a causal process in the early universe ituniverse it’’s correlation length could not s correlation length could not exceed the Hubble horizon at the moment exceed the Hubble horizon at the moment of the generation of the generation

MHD Modeling

Coupling of the magnetic Coupling of the magnetic field with primordial field with primordial plasmaplasma

Injection of the magnetic Injection of the magnetic energy at a given scale energy at a given scale (phase transition bubble)(phase transition bubble)

Brandenburg, Kahniashvili, Tevzadze 2014

Modeling Magnetic FieldModeling Magnetic Field

smoothed vs. effective smoothed vs. effective magnetic fieldmagnetic field

one-scale (delta function)one-scale (delta function)magnetic field magnetic field

Kahniashvili, Tevzadze, Brandenburg, Neronov 2013

Non-helical fieldNon-helical field

Helical fieldHelical field• Helicity conservation law Helicity conservation law

"»M E3=2Ma2

Phase Transitions Generated Magnetic Field Phenomenology

a2

Kahniashvili, Tevzadze, Brandenburg, Neronov 2013

Magnetic field from QCD Phase Transitions

Tevzadze, Kisslinger, Brandenburg, Kahniashvili 2012

Our analysis show that in the most optimistic scenario the magnetic correlation length in the comoving frame can reach 10 kpc with the amplitude of the effective magnetic field being 0.007 nG. We demonstrate that the considered model of magneto-genesis can provide the seed magnetic field for galaxies and clusters.

Magnetic Helicity GrowthTevzadze, Kisslinger, Brandenburg, Kahniashvili 2012

The correlation length The correlation length should satisfy: should satisfy:

Fractional magnetic Fractional magnetic helicity grows until it helicity grows until it reaches its maximal valuereaches its maximal value

Helical Magnetic Fields DecayHelical Magnetic Fields Decay


Causal fields – correlation length limitationCausal fields – correlation length limitationnnBB=2 or n=2 or nBB=0=0

Inverse CascadeInverse Cascade

Helical Magnetic Fields Helical Magnetic Fields DecayDecay Vachaspati 2001Vachaspati 2001

Helical Magnetic FieldHelical Magnetic Field


Inflationary Magnetic HelicityInflationary Magnetic Helicity

Magnetic field correlation length might be as large Magnetic field correlation length might be as large as the Hubble horizon today or even larger as the Hubble horizon today or even larger (infinity)(infinity)

Can we see the imprints of an a-causal field?Can we see the imprints of an a-causal field?

Kahniashvili, Brandenburg, Durrer, Tevzadze, Yin, 2015 Kahniashvili, Brandenburg, Durrer, Tevzadze, Yin, 2015

Inflation Generated Helical Magnetic FieldInflation Generated Helical Magnetic Field

Kahniashvili, Brandenburgh, Durrer, Tevzadze, Yin 2015

The absence of inverse cascade for Inflation generated magnetic fields

Helical Magnetic FieldsHelical Magnetic FieldsScaling LawsScaling Laws


ConclusionConclusion

The lower bound of the extragalactic magnetic field The lower bound of the extragalactic magnetic field favorsfavors a primordial magnetogenesis approach (in a primordial magnetogenesis approach (in particular, helical magnetic fields)particular, helical magnetic fields)

The primordial magnetic field might be a plausible The primordial magnetic field might be a plausible explanation for the galaxy magnetic fieldexplanation for the galaxy magnetic field

Cosmological magnetic field order of 0.1 nanoGauss Cosmological magnetic field order of 0.1 nanoGauss can be detectable by the nearest future CMB can be detectable by the nearest future CMB polarization and LSS measurementspolarization and LSS measurements

On the other hand, if the field is significantly On the other hand, if the field is significantly smaller – it would satisfy the LOWER limit bound but smaller – it would satisfy the LOWER limit bound but would not been observable through cosmological would not been observable through cosmological observations observations

Evolution and Signatures of Helical Magnetic Fields Tina Kahniashvili McWilliams Center for...

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