Related papers: Impact of axions on the Cassiopea A neutron star c…
Cooling of neutron stars (NSs) with superfluid cores is simulated taking into account neutrino emission produced by Cooper pairing of nucleons. The critical temperatures of neutron and proton superfluidities, $T_{cn}$ and $T_{cp}$, are…
Cooling simulations of neutron stars (NSs) are performed assuming that stellar cores consist of neutrons, protons and electrons and using realistic density profiles of superfluid critical temperatures $T_{cn}(\rho)$ and $T_{cp}(\rho)$ of…
We present results of a recent Chandra X-ray Observatory observation of the central compact object (CCO) in the supernova remnant Cassiopeia A. This observation was obtained in an instrumental configuration that combines a high spatial…
We found simultaneous decrease of Fe-K line and 4.2-6 keV continuum of Cassiopeia A with the monitoring data taken by Chandra in 2000-2013. The flux change rates in the whole remnant are $-$0.65$\pm$0.02 \% yr$^{-1}$ in the 4.2--6.0 keV…
We present the first results of an XMM-Newton observation of the central X-ray source in the Cas A supernova remnant. The spectrum can be fit equally well with an absorbed steep power law (alpha~3, N_H~1.5x10^22 cm^-2) or with a…
The observations combined with theory of neutron star (NS) cooling play a crucial role in achieving the intriguing information of the stellar interior, such as the equation of state (EOS), composition and superfluidity of dense matter. The…
We investigate axion emission from singlet proton Cooper pairs in neutron stars, a process that dominates axion emission in young neutron stars in the KSVZ model. By re-deriving its emissivity, we confirm consistency with most existing…
The existence of light QCD axions, whose mass depends on an additional free parameter, can lead to a new ground state of matter, where the sourced axion field reduces the nucleon effective mass. The presence of the axion field has…
In this study, we present the first multidimensional core-collapse supernovae (CCSNe) simulations including QCD axions in order to assess the impact on the CCSN explosion mechanism. We include axions in our simulations through the…
The high temperature and electron degeneracy attained during a supernova allow for the formation of a large muon abundance within the core of the resulting proto-neutron star. If new pseudoscalar degrees of freedom have large couplings to…
Thermal evolution of neutron stars (NSs) is studied as a probe of physics beyond the standard model. We first review the standard cooling theory of NSs in detail, with an emphasis on the roles of nucleon superfluidity. Then we discuss…
We study the impact of axion emission in simulations of massive star explosions, as an additional source of energy loss complementary to the standard neutrino emission. The inclusion of this channel shortens the cooling time of the nascent…
The rapid cooling observed in the Cassiopeia~A neutron star (Cas~A NS) is one of the most stringent tests for neutron-star cooling theory. While Cooper-pair breaking and formation (PBF) neutrino emission is a leading candidate,…
The surface of hot neutron stars is covered by a thin atmosphere. If there is accretion after neutron star formation, the atmosphere could be composed of light elements (H or He); if no accretion takes place or if thermonuclear reactions…
We analyse the cooling of white dwarfs in the globular cluster 47 Tucanae to look for evidence of axion emission affecting the rate of white dwarf cooling. If axions exist and couple to electrons, then axions could be produced at an…
We study the thermal evolution of neutron stars containing deconfined quark matter in their core. Such objects are generally referred to as quark-hybrid stars. The confined hadronic matter in their core is described in the framework of…
A new classification of neutron star cooling scenarios, involving either ``minimal'' cooling or ``enhanced'' cooling is proposed. The minimal cooling scenario replaces and extends the so-called standard cooling scenario to include neutrino…
Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a mild preference for a non-standard cooling mechanism when compared with theoretical…
We present a new model-independent (applicable for a broad range of equations of state) analysis of the neutrino emissivity due to triplet neutron pairing in neutron star cores. We find that the integrated neutrino luminosity of the Cooper…
We demonstrate that the existing neutron-star cooling data can be appropriately described within "the nuclear medium cooling scenario" including hyperons under the assumption that different sources have different masses. We use a stiff…