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Table 2:

Birth rates, local densities and numbers of DWDs.
  Bulge Thin disc Thick disc Halo Galaxy

$\nu-\xi$ 		$8.0\times10^{-3}$ a $2.1\times10^{-2}$ $1.4\times10^{-3}$ $1.7\times10^{-3}$ a $3.21\times10^{-2}$
    b $2.7\times10^{-2}$     b $3.81\times10^{-2}$
N $7.6\times10^{7}$ a $1.7\times10^{8}$ $1.2\times10^{7}$ $1.9\times10^{7}$ a $2.76\times 10^{8}$
    b $2.3\times10^{8}$     b $3.37\times10^{8}$
$N_{\rm o}$ $8.0\times10^{5}$ a $2.1\times10^{6}$ $1.4\times10^{5}$ $1.7\times10^{5}$ a $3.21\times10^{6}$
    b $2.7\times10^{6}$     b $3.81\times10^{6}$
$\xi$ $4.0\times10^{-4}$ a $1.4\times10^{-3}$ $1.1\times10^{-4}$ $8.3\times10^{-4}$ a $2.74\times10^{-3}$
    b $1.5\times10^{-3}$     b $2.84\times10^{-3}$
X $5.4\times10^{6}$ a $1.1\times10^{7}$ $1.2\times10^{6}$ $1.2\times10^{6}$ a $1.88\times10^{7}$
    b $1.1\times10^{7}$     b $1.88\times10^{7}$
$\rho_{\rm LD}$ - a $2.1\times10^{-4}$ $4.4\times10^{-6}$ $4.1\times10^{-7}$ a $2.2\times10^{-4}$
    b $2.8\times10^{-4}$     b $2.9\times10^{-4}$

SNe Ia 		        $\nu=$ a $1.3\times10^{-3}$
resolved 14800 a18870     a $N_{\rm r}=$ 33 670
    b22670     b $N_{\rm r}=$ 37 470

Notes. $\nu$ = current birth rate, $\xi$= current merger rate, N = total number, $N_{\rm o}$ = the number for DWDs with a detectable component, X = merger number, $\rho_{\rm LD}$=local density of DWDs. The last two rows represent the current birth rate of supernovae Ia and the number of resolved DWDs detectable by LISA. Different thin disc models are denoted by (a) Z=0.02; (b) Z=0.001. Rates $\nu,\xi$ are in yr-1, $\rho_{\rm LD}$ in pc-3.
A DWD is deemed detectable for 108 yr after the second star became a WD. This definition follows Iben et al. (1997) and the values are given for comparison with Han (1998).


Source LaTeX | All tables | In the text

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