Estimation of possible additional acceleration of CR particles in the Galaxy

According to data on the relative content of Be10 the life-time of CR particles in our Galaxy is (Berezinsky et al., M1990)

where Td and Th are the times of CR particles living in the disk and in the halo, respectively. on the other hand, from data on the chemical and isotopic composition of CR it follows that in average CR particles crossed some

X g/cm2 of matter. If the density of matter in disk is Pd and in halo Ph we obtain

where v = c is the velocity of CR particles. From Eq. 4.20.24 and Eq. 4.20.25 follows that

Th = (TgVPd - X)x [v(pd - Ph )]-1; Td = Tg - Th . (4.20.26)

For particles with energy E ~ l0 GeV/nucleon the value X ~ 7 g/cm2 . If pd = 10-24 g/cm3 and ph = 10-26g/cm3 then according to Eq. 4.20.24 and Eq.

4.20.26 will be Td = 7 X106 years and Th = 2.3 X107 years. In the disk (the depth of which is Ld ~ 1 kpc) the expected transport path \d = ¿dfevTd ~ 0.2 pc. In the halo (the dimension Lh ~ 15 kpc) the expected transport path / = l|/2vTh ~ 15 pc.

Let us take into account that in many regions of the Galaxy's disk there are shock waves, extended supernova remnants and strong stellar winds (which we consider as scatters) moving relative to interstellar matter with a velocity |u2o -U10| ~ 108 cm/s. We expect that the transport path i^d on these scatters is much bigger than i . Let us suppose that i^d ~ 20 id • In this case, according to Eq. 4.20.21, we obtain Tac ~ 106 years for the time of acceleration. It means that in the disk according to Eq. 4.20.23 effective additional acceleration with increasing of energy up to exp(d /Tac) ~ 103 times can be realized.

Some part of shock waves, extended supernova remnants and strong stellar winds are also in the halo moving relative to the galactic wind with a velocity |u2o -U10| < l07 cm/sec. We expect that the transport path i^h on these scatters is not smaller than i . In this case according to Eq. 4.20.21 we obtain for the time of acceleration Tac > 6 X10 years. This means that in the halo according to Eq. 4.20.23 can not be realized additional acceleration by considered mechanism because Th /Tac << 1

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