The primary components of two new candidate events (GW190403 051519 and GW190426 190642) fall in the mass gap predicted by pair-instability supernova theory. We also expand the population of binaries with significantly asymmetric mass ratios reported in GWTC-2 by an additional two events (q < 0.61 and q < 0.62 at 90% credibility for GW190403 051519 and GW190917 114630 respectively), and find that 2 of the 8 new events have effective inspiral spins χ eff > 0 (at 90% credibility), while no binary is consistent with χ eff < 0 at the same significance.

We report the observation of gravitational waves from two compact binary coalescences in LIGO's and Virgo's third observing run with properties consistent with neutron star-black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115; the first was observed by LIGO Livingston and Virgo and the second by all three LIGO-Virgo detectors. The source of GW200105 has component masses -+ 8.9 1.5 1.2 and 130 Gpc yr 69 112 3 1 under the assumption of a broader distribution of component masses.

Radio pulsars provide us with some of the most stable clocks in the universe. Nevertheless several pulsars exhibit sudden spin-up events, known as glitches. More than forty years after their first discovery, the exact origin of these phenomena is still open to debate. It is generally thought that they an observational manifestation of a superfluid component in the stellar interior and provide an insight into the dynamics of matter at extreme densities. In recent years there have been several advances on both the theoretical and observational side, that have provided significant steps forward in our understanding of neutron star interior dynamics and possible glitch mechanisms. In this article we review the main glitch models that have been proposed and discuss our understanding, in the light of current observations.Radio pulsars are thought to be rotating magnetised neutron stars (NS). The huge moment of inertia (of the order of 10 45 g cm 2 ) leads to exceptionally stable rotation rates and provides us with some of the most precise clocks in the universe. The best timed millisecond pulsars are stable to a precision which rivals that of atomic clocks [1]. Nevertheless radio pulsars exhibit several timing irregularities, the most striking of which are the so-called glitches. While most objects are observed to steadily spin-down due to the emission of electromagnetic and, possibly, gravitational waves, many pulsars show sudden increases in their spin, in some cases followed by an increase in their spin-down rate, i.e. glitches. Most pulsars also show slower, long-term, stochastic deviations from a regular spin-down law, that are generally classed as 'timing noise' and are not the main focus of this review article.Soon after the discovery of the first glitches in the Vela [2,3] and Crab [4,5] pulsars in 1969, several mechanisms were suggested to explain these phenomena. Although some initial suggestions featured external mechanisms, such as plasma explosions in the magnetosphere [6] or planets around the pulsar [7], the lack of radiative and pulse profile changes associated with these events was taken as evidence for an internal origin. The situation is different for rotating radio transients (RRATs) and magnetars, which are now known to glitch and do exhibit, amongst other peculiar traits, radiative changes associated with these events [8][9][10][11]. Magnetospheric activity is likely to play a role in these objects, as we discuss below.There are two main internal glitch mechanisms that have been examined in the literature. The first set of models relies on the fact that the outer layers of a neutron star form a crystalline crust that can support stress. As the NS spins down, the liquid core adjusts its shape to the rotation rate, while the solid crust maintains the shape appropriate for the previous, higher, spin rate. This leads to an increasing amount of strain building up in the crust, which is eventually released in the form of a star quake. The quake causes a sudden rearrangement of the moment of inertia and...

Rotating deformed neutron stars are important potential sources for groundbased gravitational-wave interferometers such as LIGO, GE0600 and VIRGO. One mechanism that may lead to significant non-asymmetries is the internal magnetic field. It is well known that a magnetic star will not be spherical and, if the magnetic axis is not aligned with the spin axis, the deformation will lead to the emission of gravitational waves. The aim of this paper is to develop a formalism that would allow us to model magnetically deformed stars, using both realistic equations of state and field configurations. As a first step, we consider a set of simplified model problems. Focusing on dipolar fields, we determine the internal magnetic field which is consistent with a given neutron star model. We then calculate the associated deformation. We conclude by discussing the relevance of our results for current gravitational-wave detectors and future prospects