All Figures

$\begin{figure} \par\resizebox{8.3cm}{!}{\includegraphics[clip]{0387f1.eps}}\end{figure}$ Figure 1: Equations of state of hyperonic matter calculated by Balberg & Gal (1997); and used in this paper. Our notation is a close analogue of that introduced by Balberg et al. (1999). Our labels N1, N1H1, and N1H2 are their EoS1 N, EoS1 N $\Lambda \Xi$ , and EoS1 N $\Lambda \Sigma \Xi$ , respectively. Our N2H1 and N2H2 are their EoS2 N $\Lambda \Xi$ and EoS2 N $\Lambda \Sigma \Xi$ , respectively. For further explanations see the text.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0387f2.eps}}\end{figure}$ Figure 2: The difference between the back-bending curves J(f) and I(f). The spin-evolution track is calculated for $M_{\rm B}=2.15~M_{\odot}$ and N2H1 EOS. Upper panel presents the dependence J(f). The thicker segment AB represents stable back-bending evolution, while dotted segment to the right of the minimum at B consists of configurations unstable with respect to axisymmetric perturbation. The lower panel represents the I(f) spin evolution track, considered in the previous work; the back-bending behavior occurs apparently along the whole AC branch. Actually, the BC segment of the I(f) is astrophysically irrelevant, because configurations to the right of B are unstable.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f3.eps}\end{figure}$ Figure 3: Total baryon mass $M_{\rm B}$ vs circumferential equatorial radius $R_{\rm eq}$ for stationary configurations rotating at a fixed frequency, for the N2H1 EOS. The curves are labeled by the rotational frequency $f=\Omega /2\pi$ [Hz]. The dotted line corresponds to the onset of instability with respect to axi-symmetric (quasi-radial) perturbations. All curves terminate on the large-radius side at the mass-shedding (Keplerian) configurations. The maximum baryon mass of non-rotating stars, $M_{\rm B,max}^{\rm stat}$ , is marked by a dash-dotted line.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f4.eps}\end{figure}$ Figure 4: The enlarged region of the back-bending phenomenon (corresponding to the box in Fig. 3). For fixed rotational frequency $f_{\rm 1,infx}\simeq 880$ Hz and $f_{\rm 2,infx}\simeq 1320$ Hz the ${M}_{\rm B}(R_{\rm eq})$ dependence has an inflexion point (corresponding to the masses $M_{\rm B}^{\rm (1,infx)}=1.91~M_{\odot}$ and $M_{\rm B}^{\rm (2,infx)}=2.17~M_{\odot}$ , respectively) resulting in a region where the curve is nearly flat. For $f \in [f_{\rm 1,infx},f_{\rm 2,infx}]$ there exists a local minimum of $M_{\rm B}$ . Dashed curves correspond to a fixed total angular momentum J. The configurations close to the local maxima are obviously stable (for a fixed J, $M_{\rm B}$ is monotonic). The evolution of an isolated star which is losing its angular momentum is represented by the motion along a horizontal line from right to the left (decreasing J). The loss of J in the back-bending regime is associated with a spin up of the star.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f5.eps}\end{figure}$ Figure 5: Same as in Fig. 3 but for the N1H1 EOS.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f6.eps}\end{figure}$ Figure 6: The enlarged region of the back-bending phenomenon (corresponding to the box in Fig. 5).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{0387f7.eps}\end{figure}$ Figure 7: Angular momentum of the star J versus rotation frequency f, for the N2H1 EOS. Each curve corresponds to a fixed $M_{\rm B}$ , whose value in $M_{\odot }$ is displayed. Along each curve, the central density increases downwards. The dotted segments correspond to configurations which are unstable with respect to axi-symmetric perturbations whereas the thick lines correspond to spin-up by angular momentum loss. An enlarged view of the rectangular region within which the back-bending occurs is shown in Fig. 8.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{0387f8.eps}\end{figure}$ Figure 8: Enlargement of Fig. 7.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{0387f9.eps}\end{figure}$ Figure 9: Same as Fig. 7 but for N1H1 EOS. The dash-dotted line is the J(f) curve for the N1 EOS (i.e., not allowing for the presence of the hyperons).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{0387f10.eps}\end{figure}$ Figure 10: Angular momentum of the star as a function of frequency for the N1H1 EOS, in the region where the back-bending phenomenon with stable termination ( ${\rm BB_{st}}$ , see the text) occurs. Each curve corresponds to a fixed value of $M_{\rm B}$ (in $M_{\odot }$ ). Along each curve, the central density increases downwards. Segments along which the angular momentum loss is associated with a spin up are indicated by a thick solid line. All configuration on the S-shaped thick segments are stable. The dash-dotted line describes a J(f) trajectory for the EOS of matter in which hyperons are not allowed (N1 EOS, see the text). This curve illustrates the dramatic effect of the hyperon softening of the EOS on the pulsar spin-evolution.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{0387f11.eps}\end{figure}$ Figure 11: Angular momentum of a star with fixed baryon mass $M_{\rm B}$ as a function of frequency for the N1 EOS. Segments constraining unstable configurations are dotted, those corresponding to the spin-up by the angular momentum loss are indicated by a thick solid line.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f12.eps}\end{figure}$ Figure 12: Model N2H2. Baryon-mass versus circumferential equatorial radius for fixed frequency. The minimum for fixed $M_{\rm B}$ appears approximately at the same frequency at which the decreasing part for large $R_{\rm eq}$ (close to Keplerian configurations) disappears, i.e. this limiting case correspond to the nearly flat curve ( ${M}_{\rm B}={\rm const}$ ) up to the Keplerian configuration. There is no maximum for fixed frequency.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{0387f13.eps}\end{figure}$ Figure 13: Model N2H2. The enlarged region marked by the rectangular box in Fig. 12. For $f\simeq 920$ Hz there exist region where the curve is nearly flat ( $M_{\rm B}$ does not change) up to the Keplerian configurations. For higher f there exist a minimum of $M_{\rm B}$ . The evolution of the isolated star which is losing its angular momentum is represented by the motion along horizontal line from right to the left (decreasing J). For ${M}_{\rm B}>1.82~M_{\odot}$ angular momentum loss leads to spin up. For explanation of the "way features'' of most curves see the text.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f5.eps}\end{figure}$	Figure 5: Same as in Fig. 3 but for the N1H1 EOS.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=-90,width=8.3cm,clip]{0387f6.eps}\end{figure}$	Figure 6: The enlarged region of the back-bending phenomenon (corresponding to the box in Fig. 5).
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{0387f8.eps}\end{figure}$	Figure 8: Enlargement of Fig. 7.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{0387f9.eps}\end{figure}$	Figure 9: Same as Fig. 7 but for N1H1 EOS. The dash-dotted line is the J(f) curve for the N1 EOS (i.e., not allowing for the presence of the hyperons).
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{0387f11.eps}\end{figure}$	Figure 11: Angular momentum of a star with fixed baryon mass $M_{\rm B}$ as a function of frequency for the N1 EOS. Segments constraining unstable configurations are dotted, those corresponding to the spin-up by the angular momentum loss are indicated by a thick solid line.
Open with DEXTER