Type I X-ray bursts are thermonuclear explosions on the neutron star (NS) surface by mass accretion from a companion star. Observation of X-ray bursts provides valuable information on X-ray binary systems, e.g., binary parameters, the chemical compos
ition of accreted matter, and the nuclear equation of state (EOS) of NSs. There have been several theoretical studies to constrain the physics of X-ray bursters. However, they were mainly focused on the burning layers above the NS surface. The effects of the EOS and the heating and cooling processes inside the NS are still unknown. In this study, we calculated a series of X-ray bursts using a general relativistic stellar-evolution code with several NS EOSs. We compared the X-ray burst models with the burst parameters of a clocked burster associated with GS 1826-24. We found a monotonic correlation between the NS radius and the light-curve profile. A larger radius shows a higher recurrence time and a large peak luminosity. In contrast, the dependence of light curves on the NS mass becomes more complicated, where the neutrino cooling suppress the efficiency of nuclear ignition. We also constrained the EOS and mass of GS~1826-24, i.e., stiffer EOSs, corresponding to larger NS radii, are unpreffered due to a too high peak luminosity. The EOS and the cooling and heating of NSs are important to discuss the theoretical and observational properties of X-ray bursts.
We investigated coherent betatron oscillations of a deuteron beam in the storage ring COSY, excited by a detuned radio-frequency Wien filter. These beam oscillations were detected by conventional beam position monitors, read out with lock-in amplifie
rs. The response of the stored beam to the detuned Wien filter was modelled using the ring lattice and time-dependent 3D field maps of the radio-frequency Wien filter. The influence of uncertain system parameters related to manufacturing tolerances and electronics was investigated using the polynomial chaos expansion. With the currently available apparatus, we show that oscillation amplitudes down to $SI{1}{micro meter}$ can be detected. Future measurements of the electric dipole moment of protons will, however, require control of the relative position of counter-propagating beams in the sub-picometer range. Since the stored beam can be considered as a rarefied gas of uncorrelated particles, we moreover demonstrate that the amplitudes of the zero-point betatron oscillations of individual particles are within a factor of 10 of the Heisenberg uncertainty limit. As a consequence of this, we conclude that quantum mechanics does not preclude the control of the beam centroids to sub-picometer accuracy. The smallest Lorentz force exerted on a single particle that we have been able to determine is $SI{10}{aN}$.
Coronal holes (CHs) are darker than quiet Sun (QS) when observed in coronal channels. This study aims to understand the similarities and differences between CHs and QS in the transition region using the ion{Si}{4}~1394~{AA} line recorded by the Inter
face Region Imaging Spectrograph (IRIS) by considering the distribution of magnetic field measured by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We find that ion{Si}{4} intensities obtained in CHs are lower than those obtained in QS for regions with identical magnetic flux densities. Moreover, the difference in intensities between CHs and QS increases with increasing magnetic flux. For the regions with equal magnetic flux density, QS line profiles are more redshifted than those measured in CHs. Moreover, the blue shifts measured in CHs show an increase with increasing magnetic flux density unlike in the QS. The non-thermal velocities in QS, as well as in CHs, show an increase with increasing magnetic flux. However, no significant difference was observed in QS and CHs, albeit a small deviation at small flux densities. Using these results, we propose a unified model for the heating of the corona in the QS and in CHs and the formation of the solar wind.
Using the N-body+Smoothed particle hydrodynamics code, ChaNGa, we identify two merger-driven processestextemdash disk disruption and supermassive black hole (SMBH) feedbacktextemdash which work together to quench L$^*$ galaxies for over 7 Gyr. Specif
ically, we examine the cessation of star formation in a simulated Milky Way (MW) analog, driven by an interaction with two minor satellites. Both interactions occur within $sim$100 Myr of each other, and the satellites both have masses 5 to 20 times smaller than that of their MW-like host galaxy. Using the genetic modification process of cite{Roth2016}, we generate a set of four zoom-in, MW-mass galaxies all of which exhibit unique star formation histories due to small changes to their assembly histories. In two of these four cases, the galaxy is quenched by $z = 1$. Because these are controlled modifications, we are able to isolate the effects of two closely-spaced minor merger events, the relative timing of which determines whether the MW-mass main galaxy quenches. This one-two punch works to: 1. fuel the primary halos supermassive black hole (SMBH) at its peak accretion rate; and 2. disrupt the cold, gaseous disk of the host galaxy. The end result is that feedback from the SMBH thoroughly and abruptly ends the galaxys star formation by $zapprox1$. We search for and find a similar quenching event in {sc Romulus25}, a hydrodynamical $(25,mathrm{Mpc})^3$ volume simulation, demonstrating that the mechanism is common enough to occur even in a small sample of MW-mass quenched galaxies at $z=0$.
The effects of parity violation in the interaction of relativistic polarized protons and deuterons are discussed. Within Glaubers approach, estimates are obtained for P-odd asymmetries in the total and elastic scattering cross sections, in the deuter
on dissociation cross section, and in the inelastic cross section with meson production in a final state. It is shown that, from the point of view of the magnitude of the P-odd effects, the interaction of polarized deuterons with unpolarized protons has an advantage over the interaction of polarized protons with unpolarized deuterons. A significant P-odd asymmetry was found in the dissociation channel of the polarized deuteron.
Search for the Electric Dipole Moment of nuclear particles is at the forefront of incessant quest for CP violation beyond Standard Model. The ultimate target is to reach a sensitivity to the electric dipole moment of neutrons, protons, deuterons etc.
at the level of $sim 10^{-15}$ nuclear magnetons. Defying the common lore on weakness of gravity, spurious signals induced by curved space-time in the gravity field of the rotating Earth become quite substantial at such a daunting sensitivity. We review the recent development in the field with an emphasis on the geometric magnetic field in pure electrostatic systems at rest on the rotating Earth.
We report ground-based transmission spectroscopy of the highly irradiated and ultra-short period hot-Jupiter WASP-103b covering the wavelength range $approx$ 400-600 nm using the FORS2 instrument on the Very Large Telescope. The light curves show sig
nificant time-correlated noise which is mainly invariant in wavelength and which we model using a Gaussian process. The precision of our transmission spectrum is improved by applying a common-mode correction derived from the white light curve, reaching typical uncertainties in transit depth of $approx$ 2x10$^{-4}$ in wavelength bins of 15 nm. After correction for flux contamination from a blended companion star, our observations reveal a featureless spectrum across the full range of the FORS2 observations and we are unable to confirm the Na absorption previously inferred using Gemini/GMOS or the strong Rayleigh scattering observed using broad-band light curves. We performed a Bayesian atmospheric retrieval on the full optical-infrared transmission spectrum using the additional data from Gemini/GMOS, HST/WFC3 and Spitzer observations and recover evidence for H$_2$O absorption at the 4.0$sigma$ level. However, our observations are not able to completely rule out the presence of Na, which is found at 2.0$sigma$ in our retrievals. This may in part be explained by patchy/inhomogeneous clouds or hazes damping any absorption features in our FORS2 spectrum, but an inherently small scale height also makes this feature challenging to probe from the ground. Our results nonetheless demonstrate the continuing potential of ground-based observations for investigating exoplanet atmospheres and emphasise the need for the application of consistent and robust statistical techniques to low-resolution spectra in the presence of instrumental systematics.
We report on a comprehensive characterization of the newly synthesized Cu$^{2+}$-based molecular magnet [Cu(pz)$_2$(2-HOpy)$_2$](PF$_6$)$_2$ (CuPOF), where pz = C$_4$H$_4$N$_2$ and 2-HOpy = C$_5$H$_4$NHO. From a comparison of theoretical modeling to
results of bulk magnetometry, specific heat, $mu^+$SR, ESR, and NMR spectroscopy, this material is determined as an excellent realization of the 2D square-lattice $S=1/2$ antiferromagnetic Heisenberg model with a moderate intraplane nearest-neighbor exchange coupling of $J/k_mathrm{B} = 6.80(5)$ K, and an extremely small interlayer interaction of about 1 mK. At zero field, the bulk magnetometry reveals a temperature-driven crossover of spin correlations from isotropic to $XY$ type, caused by the presence of a weak intrinsic easy-plane anisotropy. A transition to long-range order, driven by the low-temperature $XY$ anisotropy under the influence of the interlayer coupling, occurs at $T_mathrm{N} = 1.38(2)$ K, as revealed by $mu^+$SR. In applied magnetic fields, our $^1$H-NMR data reveal a strong increase of the magnetic anisotropy, manifested by a pronounced enhancement of the transition temperature to commensurate long-range order at $T_mathrm{N} =2.8$ K and 7 T.
The detailed nature of type Ia supernovae (SNe Ia) remains uncertain, and as survey statistics increase, the question of astrophysical systematic uncertainties arises, notably that of the evolution of SN Ia populations. We study the dependence on red
shift of the SN Ia light-curve stretch, a purely intrinsic SN property, to probe its potential redshift drift. The SN stretch has been shown to be strongly correlated with the SN environment, notably with stellar age tracers. We modeled the underlying stretch distribution as a function of redshift, using the evolution of the fraction of young and old SNe Ia as predicted using the SNfactory dataset, and assuming a constant underlying stretch distribution for each age population consisting of Gaussian mixtures. We tested our prediction against published samples that were cut to have marginal magnitude selection effects so that any observed change is indeed astrophysical and not observational in origin. In this first study, there are indications that the underlying SN Ia stretch distribution evolves as a function of redshift, and that the age drifting model is a better description of the data than any time-constant model, including the sample-based asymmetric distributions that are often used to correct Malmquist bias at a significance higher than 5 $sigma$. The favored underlying stretch model is a bimodal one, composed of a high-stretch mode shared by both young and old environments, and a low-stretch mode that is exclusive to old environments. The precise effect of the redshift evolution of the intrinsic properties of a SN Ia population on cosmology remains to be studied. The astrophysical drift of the SN stretch distribution does affect current Malmquist bias corrections and hence the distances that are derived using SNe that are affected by observational selection effects. This bias increases with surveys covering larger redshift ranges.
Time-reversal breaking and parity-conserving millistrong interactions, suggested in 1965, still remain a viable mechanism of CP-violation beyond the Standard Model. One of its possible manifestations is the T-odd asymmetry in the transmission of tens
or-polarized deuterons through a vector-polarized hydrogen gas target. Upon the rotation of the deuteron polarization from the vertical direction into the ring plane, the T-odd asymmetries, odd against the reversal of the proton polarization in the target, will continuously oscillate with first or second harmonics of the spin precession frequency. The Fourier analysis of the oscillating T-odd asymmetries allows for an easy separation from background persistent in conventional experiments employing static vector and tensor polarizations.
