Scaling properties of the cosmic background plasma and radia

Scaling properties of the cosmic microwave background (CMB) radiation are studied using satellite (COBE-DMR maps), balloon-borne and ground-based (combined QMASK map) data. Quantitative consistency is found between the multiscaling properties of the COBE-D

a r X i v :a s t r o -p h /0305433v 1 22 M a y 2003Scaling properties of the cosmic background plasma and radiation A.Bershadskii February 2,2008ICAR,P.O.Box 31155,Jerusalem 91000,Israel Abstract Scaling properties of the cosmic microwave background (CMB)radiation are studied using satellite (COBE-DMR maps),balloon-borne and ground-based (combined QMASK map)data.Quantita-tive consistency is found between the multiscaling properties of the COBE-DMR and QMASK CMB maps.Surprisingly,it is found that the observed CMB temperature multiscaling resembles quantitatively the multiscaling properties of ?uid turbulence,that indicates primor-dial plasma turbulence as an origin of the CMB temperature space anisotropy.PACS numbers:98.70.Vc,98.80Es,95.30Qd

1

Scaling properties of the cosmic microwave background (CMB) radiation are studied using satellite (COBE-DMR maps), balloon-borne and ground-based (combined QMASK map) data. Quantitative consistency is found between the multiscaling properties of the COBE-D

1Introduction

In the last few years the interest in nonlinear(turbulent)processes in pri-mordial plasma has been renewed in relation to the origin of magnetic?elds observed in galaxies(see,for instance[1]-[6]and references therein).It has been suggested that primordial magnetic?elds might arise during the early cosmic phase transitions.The plasma of the early universe has a high con-ductivity so that a primordial magnetic?eld would be imprinted on the co-moving plasma and would dissipate very slowly.Such a?eld could then contribute to the seed needed to understand the presently observed galactic magnetic?elds,which have been measured in both the Milky Way and other spiral galaxies,including their halos.At earliest times,the magnetic?elds are generated by particle physics processes,with length scales typical of par-ticle physics.If the in?ation hypothesis is correct,long correlation lengths can be expected following the in?ation.It is shown in[1]that turbulence with its cascade processes is operative,and hence the scale of magnetic?elds is considerably larger than would be the case if turbulence were ignored. The turbulent nature of the magnetic?eld may have interesting e?ects on various phase transitions in the early universe.Also,the inherent shift of energy from small to large scales may be of interest in connection with den-sity?uctuations due to the magnetic energy.In particular,it is shown in [3],[4]that rotational velocity perturbations,induced by a tangled magnetic ?eld can produce signi?cant angular scale anisotropies in cosmic microwave background(CMB)radiation through the Doppler e?ect.The conclusions are relevant to arcminute scales[3]and to l>1000[4].These scales will be available for observation with the new MAP and Planck space missions.On the other hand,the authors of[5]and[6]consider early universe turbulence and its imprint on the cosmic background on larger angular scales via a tensor mode contribution.The question then is:Can one use the modern data on the CMB radiation(see for recent reviews[7],[8])to?nd out the?ngerprints of the primordial turbulence?The?rst attempt to?nd such?ngerprints was performed in[9].However,a CMB map used in Ref.[9]was one of the earliest of the COBE-satellite CMB maps and,therefore,the preliminary investigation of Ref.[9]gave a qualitative picture only.In present paper to obtain quantitative results we will use the improved four-year COBE-satellite CMB maps.Moreover,we have now a new generation of balloon-borne and ground-based CMB data obtained with angular resolution of the order of a degree(the angle resolution for COBE data,in contrast,was～70).We

2

Scaling properties of the cosmic microwave background (CMB) radiation are studied using satellite (COBE-DMR maps), balloon-borne and ground-based (combined QMASK map) data. Quantitative consistency is found between the multiscaling properties of the COBE-D

choose so-called QMASK map representing the data in a form suitable for our purpose.The QMASK map is a combination of QMAP(balloon-borne) and Saskatoon(ground-based)data[10]-[13].Using the three CMB maps (two COBE-DMR and one QMASK)we study the structure functions of the CMB temperature space increments and moments of CMB dissipation rate for frequency ranges:31.5,53,and90GHz(COBE-DMR data),26-46GHz (QMASK map).

The main results of our investigation are:

1)The CMB temperature structure functions and dissipation rate mo-ments are found exhibiting multiscaling properties.

2)The observed multiscaling resembles quantitatively the multiscaling properties of?uid turbulence,that indicates its primordial turbulence origin.

3)Comparison of the results obtained for the COBE-DMR and for the QMASK shows quantitative consistency of their CMB maps.

2Structure functions of QMASK map

Let us start from the QMASK CMB map.The QMAP(balloon)and Saska-toon(ground-based)data were used to construct this map[10]-[13].The ob-servations were made in Ka and Q bands(26-36GHz and36-46GHz respec-tively)for di?erent polarization channels.QMAP was designed to measure the CMB anisotropy by direct mapping.The Saskatoon data set is di?erent in the sense that it does not contain simple sky temperature measurements. Instead,it contains di?erent linear combinations of sky temperatures with complex set of weighting functions.The QMAP and Saskatoon data were combined to produce a CMB map named QMASK.The map was generated by subpiding the sky into square pixels of sideΘ?0.3o and consists of 6495pixels.The data are represented using three coordinates x,y,z of a unit vector R in the direction of the pixel in the map(in equatorial …… 此处隐藏：18050字，全部文档内容请下载后查看。喜欢就下载吧 ……