We will present new constraints on the physics of magnetar outbursts from recent observations of peculiar events, among which the long-term evolution of the Galactic center magnetar.
In this talk, I will focus on the peculiar case of the magnetar 1E 1547.0-5408. This source underwent three outbursts, with the latest having onset in 2009. By analysing new and archival observations, we measured a steady flux over the last 9 years (about a factor 30 larger than its quiescent level and an order of magnitude fainter than the peak of the 2009 outburst). Moreover, we observed...
We model numerically the process of formation of proto-magnetars resulting from the collapse of the very compact, low-metallicity cores of high-mass stars. We explore the dependence of the proto-magnetar properties on the stellar progenitor rotational and magnetic properties as well as small variations thereof. These variations aim to parametrize the uncertainties with which 1D stellar...
The magnetic field is believed to play an important role in at least some core-collapse supernovae when its magnitude reaches $10^{15}$ G, which is typical of the most magnetic neutron stars called magnetars. In the presence of fast rotation, such a strong magnetic field can drive powerful jet-like explosions if it has the large-scale coherence of a dipole. The topology of the magnetic field...
The presence of strong magnetic fields in many compact objects, neutron stars in particular, as well as accretion disks, is key to understand their dynamical evolution and to explain the properties of their high-energy emission. The magnetic evolution inside the hosting relativistic plasma, is subject of complex behaviours: dynamo or chiral processes that can amplify any initial seed fields...
The plateau phases in the X-ray light curves of gamma-ray burst afterglows are explained by the presence of newly-born millisecond magnetars that are slowing down under the action of the spin-down component of the magnetic dipole radiation torque. The alignment component of this torque affects the angle between the magnetic dipole moment and rotation axis of the star, i.e., the inclination...
Neutron star in the center of young (330 yr) supernova remnant Cassiopeia A is thought to demonstrate enhanced cooling inconsistent with the standard neutron star cooling via the modified Urca processes. One of the possible explanations of this phenomenon is a recent (approx. 80 yr ago) transition of the neutron liquid in the neutron star interior to the superfluid state [1]. Recently [2] the...
The formation of neutron stars is an extremely complex problem involving many field of physics : general relativity, relativistic fluid mechanics, nuclear matter equation of state, neutrino-matter interactions...
This diversity makes neutron stars the ideal target for the era of multimessenger astronomy, but progress has to be made also on the theoretical aspects of the problem.
In this...
The interior of a neutron star is usually assumed to be made of cold catalysed matter. However, the outer layers are unlikely to remain in full thermodynamic equilibrium during the neutron-star formation and cooling, especially after crystallization occurs.
In this contribution, we present a study of the evolution of the nuclear distributions of the hot dense multicomponent Coulomb plasma and...
We constrain the profiles of nucleon critical temperatures with a recently developed model of resonance stabilization of r-modes (Gusakov, Chugunov, Kantor PRL 112, 151101, 2014). To this end, we calculate the finite-temperature r-mode spectrum of a superfluid neutron star under realistic microphysics assumptions. Namely, we, for the first time, account for both muons and entrainment between...
With their ultra-strong magnetic fields and densities exceeding that found inside heavy atomic nuclei, magnetars offer unique possibilities to study matter under extreme conditions that cannot be reproduced in the laboratory. We have determined the equilibrium properties of magnetar crusts taking into account the Landau-Rabi quantization of electron motion. Both the outer and inner crusts were...
With the recent, first detection of a binary neutron-star merger by gravitational-wave detectors, it proves timely to consider how the internal structure of neutron stars affects the way in which they are deformed. Such deformations will leave measurable imprints on gravitational-wave signals and can be sourced through tidal interactions or the formation of mountains. In this talk, I will...
Gravitational waves can provide unique insight into the interiors of neutron stars. The signal types and timescales accessible to ground-based detectors range from the final orbits of binary mergers to continuous waves from mature spinning objects, with various long-duration transients in between. In this presentation I will focus on pulsar glitches as possible sources of long-duration...
A small fraction of neutron stars that can be timed to high precision lend themselves to the scientific endeavors of pulsar timing array (PTA) experiments, which have the primary goal of directly detecting low-frequency gravitational waves. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is one such PTA experiment and has been in operation for more than fifteen...
GrailQuest (Gamma-ray Astronomy International Laboratory for Quantum Exploration of Space-Time) is an ambitious astrophysical mission concept that uses a fleet of small satellites, whose scientific objectives are discussed below.
Within Quantum Gravity theories, different models for space-time quantisation predict an energy dependent speed for photons. Although the predicted discrepancies are...
The Fermi Space Telescope is an important tool in the growing area of multimessenger astronomy. The Fermi Gamma-ray Burst Monitor (GBM) has nearly full-sky continuous coverage allowing for simultaneous observations of gamma-ray bursts (GRBs) with gravitational-wave candidates from the Advanced LIGO and Advanced Virgo instruments. The power of these observations was shown with the detection...
Core collapse supernovae is among the most exciting events that we expect to observe in the future by gravitational wave interferometers. They provide a unique multi messenger opportunity with the combined emission of gravitational waves, neutrinos and electromagnetic waves. In this talk I will focus in the current understanding of core-collapse GW signals and how they can be modelled in terms...
The spin frequencies of the neutron stars in low-mass X-ray binaries may be limited by the emission of gravitational waves, potentially making them an interesting target for continuous gravitational wave searches. The gravitational waves may be produced by an asymmetry in the star’s mass distribution. Such “mountains” could be created by temperature asymmetries within the stellar crust. ...
Recent advances in realistic descriptions of pulsar magnetosphere with regions of finite conductivity allow for the predictions of the gamma-ray intensity over the observer sky in the form of a sky map. Such models incorporate trends of conductivity $\sigma$ with spin-down power $\dot E$, cut-off energies $\epsilon_{\rm cut}$ with $\dot E$, and the gamma-ray luminosity $L_\gamma$ with...
The Fast Folding Algorithm (FFA) is a fully phase-coherent search technique for periodic pulsar signals dating back to 1969, which consists of folding the input data at all distinguishable signal periods. It has historically seen limited use, having been dismissed in favour of the less computationally expensive Fast Fourier Transform (FFT) on which the standard search method is based. Interest...
We are using the central "Superterp" core of the LOw Frequency ARray (LOFAR) to perform the LOFAR Tied-Array All-sky Survey (LOTAAS) for pulsars and fast radio transients. Each pointing of the survey covers 67 square degrees of sky in the range of 119 to 151 MHz and is observed for one hour. We then employ both periodicity and single pulse searching codes to look for astrophysical signals....
MeerTRAP is a commensal program running on the MeerKAT telescope to look for Fast Radio Bursts and other radio transients. It simultaneously searches the sky in more than 400 beams using the sensitivity of MeerKAT to probe the furthest FRBs. It also has the capability to record the raw data from the telescopes to be able to form offline images to precisely localise any FRBs or other transients...
One way to probe the still unknown nature of fast radio bursts (FRBs) progenitors is to investigate how their sources are distributed in space. With this aim we have applied the luminosity–volume test, also known as $\langle V/V_{\rm max} \rangle$ test, to two samples of FRBs detected by ASKAP and Parkes, respectively. These samples have different flux limits and correspond to different...
