Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-06-14
Abstract: The evolution of dislocation loops in austenitic steels irradiated with Fe+ is investigated using cluster dynam ics (CD) simulations by developing a CD model. The CD predictions are compared with experimental results in the literature. The number density and average diameter of the dislocation loops obtained from the CD simula tions are in good agreement with the experimental data obtained from transmission electron microscopy (TEM) observations of Fe+-irradiated Solution Annealed 304, Cold Worked 316, and HR3 austenitic steels in the liter ature. The CD simulation results demonstrate that the diffusion of in-cascade interstitial clusters plays a major role in the dislocation loop density and dislocation loop growth; in particular, for the HR3 austenitic steel, the CDmodel has verified the effect of temperature on the density and size of the dislocation loops.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: We conduct a systematic search for quasars with periodic variations from the archival photometric data of the Zwicky Transient Facility (ZTF) by cross matching with the quasar catalogues of the Sloan Digital Sky Survey and V\'eron-Cetty & V\'eron. We first select out primitive periodic candidates using the methods of the generalized Lomb-Scargle periodogram and auto-correlation function, and then estimate the false-alarm probability of the periodicity and calculate the Bayesian information criterion to compare between periodic and purely stochastic models. As such, we finally identify a sample of 127 candidates with the most significant periodic variations out of 143,700 quasars. This is the largest periodic quasar sample so far, thus providing a useful guiding sample for studying origins of quasar periodicity considering the moderate sampling rate and high-quality photometry of the ZTF data. We summarize the basic properties of the sample and briefly discuss the implications.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: In this third paper of the series reporting on the reverberation mapping (RM) campaign of active galactic nuclei with asymmetric H$\beta$ emission-line profiles, we present results for 15 Palomar-Green (PG) quasars using spectra obtained between the end of 2016 to May 2021. This campaign combines long time spans with relatively high cadence. For 8 objects, both the time lags obtained from the entire light curves and the measurements from individual observing seasons are provided. Reverberation mapping of 9 of our targets has been attempted for the first time, while the results for 6 others can be compared with previous campaigns. We measure the H$\beta$ time lags over periods of years and estimate their black hole masses. The long duration of the campaign enables us to investigate their broad line region (BLR) geometry and kinematics for different years by using velocity-resolved lags, which demonstrate signatures of diverse BLR geometry and kinematics. The BLR geometry and kinematics of individual objects are discussed. In this sample, the BLR kinematics of Keplerian/virialized motion and inflow is more common than outflow.
Peer Review Status:Awaiting Review