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Ricardo Heras

Publications and source records attributed to Ricardo Heras.

20 records · Page 2Linked to original sources

The magnetar origin of pulsars

This paper suggests the idea that all neutron stars experienced at birth an ultrafast decay of their magnetic fields from their initial values to their current surface values. If the electromagnetic energy radiated during this field decay is converted into kinetic and rotational energies of the neutron star then the decay time is of the order of 10^(-4) s provided that the initial magnetic fields lie in the range of 10^(15)-10^(16) G and the initial periods in the range 1-20 ms. This means that all neutron stars are born with magnetic fields typical of magnetars and periods typical of millisecond pulsars. More explicitly, energy considerations and a birth-ultrafast-magnetic-field decay imply a model that consistently relates birth properties of neutron stars such as the initial period and the initial magnetic field with current properties such as the observed period, the surface magnetic field and the transverse velocity. This model provides a solution to the long-standing problem of finding a physical explanation for the observed high velocities of neutron stars. These stars acquire their space velocities during the birth ultrafast decay of their magnetic fields. The origin of this field decay points to magnetic instabilities, which are inevitable if neutron stars are born as magnetars.

astro-ph.GA↗

Initial accelerations of pulsars caused by external kicks

Using energy conservation we show that if a sudden external force of unknown nature causes a newborn pulsar of mass $M=1.4 M_\odot$ and radius R=10 km to have the acceleration $a_0$ then we can derive the relation $a_0\simeq k^{-1}vB_0^{-2/3},$ where $v$ is the velocity of the pulsar, $B_0$ its initial magnetic field and $k\approx 10^{-17}$G$^{-2/3}$s. This relation predicts that a newborn pulsar with $v=450$ km experienced the acceleration $a_0\simeq10^{13}$g when $B_0\simeq10^{13}$G. An external force producing such an acceleration seems not to be physically feasible. This pulsar could have experienced the more realistic acceleration $a_0\simeq10^{9}$g if $B_0\simeq10^{18}$G. But this huge magnetic field seems to be unrealistic.

physics.class-ph↗