Imprints of nuclear burning on X-ray transients

In X-ray binaries, a neutron star accretes material from its companion star. Nuclear burning of accreted material on the surface of a neutron star leads to synthesis of heavier elements (burst ashes), and huge amounts of energy released over timescale of few seconds is observed as X-ray flashes or type-I X-ray bursts (XRBs). XRBs provide ideal astrophysical laboratories to study the properties of neutron stars through model-observation comparison. The crusts of transiently accreting neutron stars cool down during the quiescent phase, and observations encode a wealth of information about the properties of dense matter. Nuclear burning plays a crucial role in both burst phase and quiescent phase, and intricacies of this burning are imprinted on X-ray observations. Therefore, to decode these observations, the role of nuclear physics needs to be studied. Study of nuclear reactions on the surface of neutron star are crucial to facilitate the XRB light-curve model-observation comparison, and a lot of experimental efforts have gone into studying these reactions. This talk will highlight some of the major recent experimental results. Moving beyond the sensitivity studies, focus will be on impact of nuclear burning on photospheric radius expansion and under what conditions can burst ashes be exposed, especially what are nuclear imprints on recent observations. Role of burst ashes in the crust and impact of pycnonuclear burning, i.e., density-density fusion, on the observations in quiescent phase will be discussed, and the need for new nuclear data to decipher these X-ray transients will be highlighted.