СMB anisotropy induced by a moving straight cosmic string

Sazhina O.S.Sazhin M.V.Sementsov V.N.Capaccioli M.Longo G.Riccio G.

Sternberg State Astronomical Institute of Moscow State University

15th International Seminar on High Energy Physics QUARKS’2008

Sergiev Posad, Russia May 23-29, 2008

The main results It was elaborated the method of searching

for cosmic strings based on analysis of the CMB anisotropy;

Moving straight cosmic string was shown to generate distinctive structures of enhanced and reduced temperature fluctuations on the surface of last scattering;

It was analized the conditions under which a cosmic string could be detected by both CMB anisotropy and gravitational lensing.

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Euclidean Universe

Conical Universe

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Cosmic string in the UniverseСosmic strings have been introduced in theoretical cosmology by Kibble, 1976; Zeldovich, 1980; Vilenkin, 1981

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Cosmic string in the Universe

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Cosmic string in the Universe

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Deficit angle

Cosmic string in the Universe

The conical Universe is equivalent to euclidean Universe with cut

The cosmic string status in modern theoretical cosmology

Among all possible types of topological defects, cosmic strings are particulary interesting and their existence finds support in superstring theories, both in compactification models and in theories with extended additional dimensions;

From theoretical point of view for cosmic strings it is available the large mass range: from the GUT to electroweak energies.

fundamental strings of

superstring theory

cosmic strings

The energy scale for cosmic strings is the scale of GUT or less

The energy scale for fundamental strings is Planck scale

GeV15102GeV1910

cosmic strings

fundamental strings of

superstring theory

GeV1910

Such heavy strings do not exist in our Universe today, and cannot have played any role in cosmological evolution except in the first few Planck times

cosmic strings

fundamental strings of

superstring theory

GeV1510

GeV1910Now we know models with large compact dimensions, in which the string scale may be much lower, down to the GUT scale or even less.

cosmic strings

fundamental strings of

superstring theory

Branes, which now play key role in superstring theory, can collide and generate cosmic strings.

cosmic strings branes

The cosmic string status in modern observational cosmologyThe current CMBR data exclude cosmic strings as source of primordial density perturbations. The data give the upper bound on the mass of cosmic strings but do not forbid their existence.

The methods were oriented to search string networks only, not individual strings as we now proposed.

The foreground-reduced internal linear combination map based on the 5 year WMAP data

The temperature power spectrum based on the 5 year WMAP data

Modern methods of cosmic string detection Optical surveys

Looking for gravitational lensing events

Radio surveys

The investigations of the structure of CMB anisotropy

Gravitational radiation from string loops

Interaction of string and black hole

Decay of heavy particles emitted by string

String + string interaction ...

The investigations of the structure of CMB anisotropy looking for cosmic string footprints

Looking for gravitational lensing events induced by cosmic string

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The cosmological model in use

The simplу simulation of a straight cosmic string moving with constant velocity

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CMB anisotropy induced by straight moving cosmic string

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CMB anisotropy induced by straight moving cosmic string. Results of preliminary simulations.

R – distance from observer to string (in units of SLS);

v – string velocity (in units of c); ψ – direction angle between line of sight

and velocity of string.

(R,v,ψ)

(R,v,ψ)=(0.9,0.9,90°)

v

(R,v,ψ)=(0.5,0.9,90°)

(R,v,ψ)=(0.1,0.9,90°)

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Time retardation over the string extension (A.Vilenkin, 1986)

If an infinite straight string moves past the observer, he sees its distant parts with a retardation, so that the string appears to him to be curved

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R=0.15 v=0.1 ψ=90°with retardation

R=0.15 v=0.4 ψ=90°with retardation

R=0.15 v=0.7 ψ=90°with retardation

(R,v,ψ)=(0.9,0.9,90°)

(R,v,ψ)=(0.9,0.5,90°)

(R,v,ψ)=(0.9,0.1,90°)

(R,v,ψ)=(0.9,0.9,45°)

(R,v,ψ)=(0.9,0.9,90°)

(R,v,ψ)=(0.9,0.9,120°)

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The low observational limit due the available resolution (Hubble Space Telescope) in optical searching of gravitational lensing events of galaxies by cosmic strings. “Superlight” strings could exist but can not be detected.

The upper bound on string deficit angle. The induced anisotropy (amplitude of spot) is compared with anisotropy due adiabatic fluctuations and could be detected.

Why strings with deficit angle more than 10” does not exist? Because we do not observe such structures.

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Minimal string number N ~ 10Maximal string number N ~ 1000

Main conclusions

We found the structure of the CMB anisotropy generated on a cosmic string for simple model of straight string moving with constant velocity;

The number of strings that could be detected by optical method is only 20%, therefore the gravitational lensing method has to be “completed” by CMB one;

For strings with deficit angle 1-2 arcsec the amplitude of generated anisotropy has to be 15-30 microK (the corresponding string linear density is and energy is GUT one, );

To use both radio and optical methods the deficit angle has to be from 0.1 arcsec to 5-6 arcsec.

If cosmic string could be detected by optical method, the hight of corresponding brightness spot of anisotropy has to be no less than 100°.

710~ G GeV1510

Thank you for attention