Discovery of delayed spin-up behavior following two large glitches in the Crab pulsar, and the statistics of such processes. (arXiv:2004.00791v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ge_M/0/1/0/all/0/1">M. Y. Ge</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_S/0/1/0/all/0/1">S. N. Zhang</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Lu_F/0/1/0/all/0/1">F. J. Lu</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Li_T/0/1/0/all/0/1">T. P. Li</a> (1,2,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Yuan_J/0/1/0/all/0/1">J. P. Yuan</a> (4,5), <a href="http://arxiv.org/find/astro-ph/1/au:+Zheng_X/0/1/0/all/0/1">X. P. Zheng</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_Y/0/1/0/all/0/1">Y. Huang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Zheng_S/0/1/0/all/0/1">S. J. Zheng</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_Y/0/1/0/all/0/1">Y. P. Chen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chang_Z/0/1/0/all/0/1">Z. Chang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Tuo_Y/0/1/0/all/0/1">Y. L. Tuo</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Cheng_Q/0/1/0/all/0/1">Q. Cheng</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Gungor_C/0/1/0/all/0/1">C. Güngör</a> (1,8), <a href="http://arxiv.org/find/astro-ph/1/au:+Song_L/0/1/0/all/0/1">L. M. Song</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Xu_Y/0/1/0/all/0/1">Y. P. Xu</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Cao_X/0/1/0/all/0/1">X. L. Cao</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_Y/0/1/0/all/0/1">Y. Chen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_C/0/1/0/all/0/1">C. Z. Liu</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_S/0/1/0/all/0/1">S. Zhang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Qu_J/0/1/0/all/0/1">J. L. Qu</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Bu_Q/0/1/0/all/0/1">Q. C. Bu</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Cai_C/0/1/0/all/0/1">C. Cai</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_G/0/1/0/all/0/1">G. Chen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_L/0/1/0/all/0/1">L. Chen</a> (9), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_M/0/1/0/all/0/1">M. Z. Chen</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_T/0/1/0/all/0/1">T. X. Chen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_Y/0/1/0/all/0/1">Y. B. Chen</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Cui_W/0/1/0/all/0/1">W. Cui</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Cui_W/0/1/0/all/0/1">W. W. Cui</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Deng_J/0/1/0/all/0/1">J. K. Deng</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Dong_Y/0/1/0/all/0/1">Y. W. Dong</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Du_Y/0/1/0/all/0/1">Y. Y. Du</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Fu_M/0/1/0/all/0/1">M. X. Fu</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_G/0/1/0/all/0/1">G. H. Gao</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_H/0/1/0/all/0/1">H. Gao</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_M/0/1/0/all/0/1">M. Gao</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Gu_Y/0/1/0/all/0/1">Y. D. Gu</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Guan_J/0/1/0/all/0/1">J. Guan</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Guo_C/0/1/0/all/0/1">C. C. Guo</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Han_D/0/1/0/all/0/1">D. W. Han</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Hao_L/0/1/0/all/0/1">L. F. Hao</a> (10), <a href="http://arxiv.org/find/astro-ph/1/au:+Huo_J/0/1/0/all/0/1">J. Huo</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Jia_S/0/1/0/all/0/1">S. M. Jia</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Jiang_L/0/1/0/all/0/1">L. H. Jiang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Jiang_W/0/1/0/all/0/1">W. C. Jiang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Jin_C/0/1/0/all/0/1">C. J. Jin</a> (11), <a href="http://arxiv.org/find/astro-ph/1/au:+Jin_J/0/1/0/all/0/1">J. Jin</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Jin_Y/0/1/0/all/0/1">Y. J. Jin</a> (15), <a href="http://arxiv.org/find/astro-ph/1/au:+Kong_L/0/1/0/all/0/1">L. D. Kong</a> (1,3), <a href="http://arxiv.org/find/astro-ph/1/au:+Li_B/0/1/0/all/0/1">B. Li</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Li_D/0/1/0/all/0/1">D. Li</a> (11), <a href="http://arxiv.org/find/astro-ph/1/au:+Li_C/0/1/0/all/0/1">C. K. Li</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Li_G/0/1/0/all/0/1">G. Li</a> (1), et al. (83 additional authors not shown)
Glitches correspond to sudden jumps of rotation frequency ($nu$) and its
derivative ($dot{nu}$) of pulsars, the origin of which remains not well
understood yet, partly because the jump processes of most glitches are not well
time-resolved. There are three large glitches of the Crab pulsar, detected in
1989, 1996 and 2017, which were found to have delayed spin-up processes before
the normal recovery processes. Here we report two additional glitches of the
Crab pulsar occurred in 2004 and 2011 for which we discovered delayed spin up
processes, and present refined parameters of the largest glitch occurred in
2017. The initial rising time of the glitch is determined as $<0.48$ hour. We
also carried out a statistical study of these five glitches with observed
spin-up processes. The two glitches occurred in 2004 and 2011 have delayed
spin-up time scales ($tau_{1}$) of $1.7pm0.8$,days and $1.6pm0.4$,days,
respectively. We find that the $Delta{nu}$ vs. $|Delta{dotnu}|$ relation
of these five glitches is similar to those with no detected delayed spin-up
process, indicating that they are similar to the others in nature except that
they have larger amplitudes. For these five glitches, the amplitudes of the
delayed spin-up process ($|Delta{nu}_{rm d1}|$) and recovery process
($Delta{nu}_{rm d2}$), their time scales ($tau_{1}$, $tau_{2}$), and
permanent changes in spin frequency ($Delta{nu}_{rm p}$) and total frequency
step ($Delta{nu}_{rm g}$) have positive correlations. From these
correlations, we suggest that the delayed spin-up processes are common for all
glitches, but are too short and thus difficult to be detected for most
glitches.
Glitches correspond to sudden jumps of rotation frequency ($nu$) and its
derivative ($dot{nu}$) of pulsars, the origin of which remains not well
understood yet, partly because the jump processes of most glitches are not well
time-resolved. There are three large glitches of the Crab pulsar, detected in
1989, 1996 and 2017, which were found to have delayed spin-up processes before
the normal recovery processes. Here we report two additional glitches of the
Crab pulsar occurred in 2004 and 2011 for which we discovered delayed spin up
processes, and present refined parameters of the largest glitch occurred in
2017. The initial rising time of the glitch is determined as $<0.48$ hour. We
also carried out a statistical study of these five glitches with observed
spin-up processes. The two glitches occurred in 2004 and 2011 have delayed
spin-up time scales ($tau_{1}$) of $1.7pm0.8$,days and $1.6pm0.4$,days,
respectively. We find that the $Delta{nu}$ vs. $|Delta{dotnu}|$ relation
of these five glitches is similar to those with no detected delayed spin-up
process, indicating that they are similar to the others in nature except that
they have larger amplitudes. For these five glitches, the amplitudes of the
delayed spin-up process ($|Delta{nu}_{rm d1}|$) and recovery process
($Delta{nu}_{rm d2}$), their time scales ($tau_{1}$, $tau_{2}$), and
permanent changes in spin frequency ($Delta{nu}_{rm p}$) and total frequency
step ($Delta{nu}_{rm g}$) have positive correlations. From these
correlations, we suggest that the delayed spin-up processes are common for all
glitches, but are too short and thus difficult to be detected for most
glitches.
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