Pulsation Period Research Articles

Results of comparison of fast variations of geomagnetic field and ionospheric scintillations of 3C 144 radio source in the area of Odessa geomagnetic anomaly

From November 2017 to May 2019 at the Astronomical Observatory of Odessa I.I. Mechnikov National University, the variational component of the geomagnetic field was monitored to study short-periodic geomagnetic variations in the central part of the Odessa regional magnetic anomaly. The measurements were carried out using a LEMI-008 precision fluxgate magnetometer with a sampling rate of 1 Hz. The aim of this work is to compare the manifestation of short-periodic geomagnetic oscillations (which in some cases coincided with periods of geomagnetic pulsations) and ionospheric scintillations of the 3C 144 radio source (Taurus A) according to the data of URAN-4 low-frequency phased antenna array at frequencies of 20 and 25 MHz. The data obtained were processed on a daily basis using the method of continuous wavelet transform, as well as band-pass filtering based on Fourier transform, to select individual frequency bands containing irregular and quasi-harmonic variations in the geomagnetic field and radio flux density. The analysis of results of the observations, during geomagnetic disturbances, storms and in calm conditions, is carried out. The data from long-term monitoring of variational component of the geomagnetic field in the most interesting, central part of the Odessa magnetic anomaly, where such studies have not been conducted before, have been obtained. Observations of various manifestations of ionospheric scintillations were carried out both during magnetic storms and during a calm geomagnetic field. It is shown that during storms, main scintillation time scale of the 3C 144 radio source is 1–3 minutes. Ionospheric scintillations occasionally show a quasiperiodic structure.

New DA white dwarf models for asteroseismology of ZZ Ceti stars

Context. Asteroseismology is a powerful tool used to infer the evolutionary status and chemical stratification of white dwarf stars and to gain insights into the physical processes that lead to their formation. This is particularly true for the variable hydrogen-rich atmosphere (DA) white dwarfs, known as DAV or ZZ Ceti stars. They constitute the most numerous class of pulsating white dwarfs. Aims. We present a new grid of white dwarf models that take into account advances made over the last decade in modeling and input physics of both the progenitor and the white dwarf stars. As a result, it is possible to avoid several shortcomings present in the set of white dwarf models employed in the asteroseismological analyses of ZZ Ceti stars that we carried out in our previous works. Methods. We generate white dwarf stellar models appropriate for ZZ Ceti stars with masses from ∼0.52 to ∼0.83 M⊙, resulting from the whole evolution of initially 1.5–4.0 M⊙ mass star models. These new models are derived from a self-consistent way with the changes in the internal chemical distribution that result from the mixing of all the core chemical components induced by mean molecular-weight inversions, from 22Ne diffusion, Coulomb sedimentation, and from residual nuclear burning. In addition, the expected nuclear-burning history and mixing events along the progenitor evolution are accounted for, in particular the occurrence of third dredge-up, which determines the properties of the core and envelope of post-AGB and white dwarf stars, as well as the white dwarf initial-final mass relation. The range of hydrogen envelopes of our new ZZ Ceti models extends from the maximum residual hydrogen content predicted by the progenitor history, log(MH/M⊙)∼ − 4 to −5, to log(MH/M⊙) = − 13.5, thus allowing for the first stellar models that would enable the search for seismological solutions for ZZ Ceti stars with extremely thin hydrogen envelopes – if, indeed, they do exist in nature. We computed the adiabatic gravity(g)-mode pulsation periods of these models. Calculations of our new evolutionary and pulsational ZZ Ceti models were performed with the LPCODE stellar evolution code and the LP-PUL stellar pulsation code. Results. Our new hydrogen-burning post-AGB models predict chemical structures for ZZ Ceti stars that are substantially different from those we used in our previous works, particularly in connection with the chemical profiles of oxygen and carbon near the stellar centre. We also discuss the implications of these new models for the pulsational spectrum of ZZ Ceti stars. Specifically, we find that the pulsation periods of g modes and the mode-trapping properties of the new models differ significantly from those characterizing the ZZ Ceti models of our previous works, particularly for long periods. Conclusions. The improvements in the modeling of ZZ Ceti stars we present here lead to substantial differences in the predicted pulsational properties of ZZ Ceti stars, which are expected to impact the asteroseismological inferences of these stars. This is extremely relevant in view of the abundant amount of photometric data from current and future space missions, resulting in discoveries of numerous ZZ Ceti stars.

New technique for determining a pulsar period: Waterfall principal component analysis

Aims. This paper describes a new technique for determining the optimal period of a pulsar and consequently its light curve. Methods. The implemented technique makes use of the principal component analysis (PCA) applied to the so-called waterfall diagram, which is a bidimensional representation of the acquired data of the pulsar. In this context, we have developed the python package pywpf to easily retrieve the period with the presented method. Results. We applied this technique to sets of data of the brightest pulsars in visible light that we obtained with the fast photon counter Iqueye. Our results are compared with those obtained by different and more classical analyses (e.g., epoch folding), showing that the periods so determined agree within the errors, and that the errors associated with the waterfall-PCA folding technique are slightly smaller than those obtained by the x2 epoch-folding technique. We also simulated extremely noisy situations, showing that by means of a new merit function associated with the waterfall-PCA folding, it is possible to become more confident about the determined period with respect to the x2 epoch-folding technique.

Inferring Pulsar Periods from Synchro-curvature Spectra

The period and the period derivative of a pulsar are critical magnitudes for defining the properties of the magnetospheric size and plasma dynamics. The pulsar light cylinder, the magnetic field intensity nearby it, and the curvature radius all depend on these timing properties, and shape the observed high-energy synchro-curvature emission. Therefore, the radiative properties of pulsars are inextricably linked to them. This fact poses the question of how well does a given pulsar’s spectral energy distribution embed information of the timing parameters, and if so, whether we can deduce them if they have not been measured directly. This is relevant to possibly constrain the timing properties of potential pulsar candidates among unidentified γ-ray sources. We consider well-measured pulsar spectra blinding us from the knowledge of their timing properties, and address this question by using our radiative synchro-curvature model that was proven able to fit the observed spectra of the pulsar population. We find that in the majority of the cases studied (8 out of 13), the spin period is constrained within a range of about 1 order of magnitude, within which the real period lies. In the other cases, there is degeneracy and no period range can be constrained. This can be used to facilitate the blind search of pulsed signals.

Discovery of a Compact X-Ray Object with a 614 s Periodicity in the Direction of the Galactic Center

We report on analysis of X-ray, optical, and radio observations of the previously overlooked X-ray source 2CXO J174517.0–321356 located just 3.°2 away from the Galactic center. Timing analysis of X-ray observations of the source with XMM-Newton reveals periodic pulsations with periods of 1228 and 614 s, with the latter being tentatively considered fundamental. On the other hand, an observation of the object with NuSTAR reveals a hard thermal-bremsstrahlung spectrum. Inspection of the archival Very Large Telescope image reveals, however, no obvious optical counterpart down to R > 25 mag. Observations made with ATCA showed a possible faint radio counterpart with a positive spectral index (α > 0.51) between 1 and 3 GHz, but follow-up ATCA and Very Large Array observations at frequencies between 4.5–10 GHz and 3–22 GHz, respectively, could not detect it. Given the properties in these three bands, we argue that the most likely origin of the X-ray source is emission from a new intermediate polar close to the Galactic center. Alternatively, and less likely, it is an ultracompact X-ray binary, which is one of the most compact X-ray binaries.

Analysis of Surface Pressure Pulsation Characteristics of Centrifugal Pump Magnetic Liquid Sealing Film

In order to discuss the surface pressure pulsation characteristics of the magnetic-fluid sealing membrane of centrifugal pump, this paper studies the surface pressure pulsation characteristics of the shaft end sealing membrane under different flow operating conditions of centrifugal pump based on the combination of numerical calculation and experimental verification. The results show that the pressure value on the surface of the magnetic-fluid sealing film decreases with the increase of the flow rate of the centrifugal pump, and the pressure on the surface of the magnetic-fluid sealing film has periodic pulsation, and the period is the time required for a single blade to sweep the volute separating tongue. In one rotation cycle of the runner, the number of reciprocating movements of the magnetic-hydraulic sealing film is the same as the number of blades of the runner. The main reason for the pressure pulsation is that the impeller periodically sweeps the fixed surface of the centrifugal pump.

Hydrodynamic modelling of pulsation period decrease in the Mira-type variable T UMi

ABSTRACT Pulsation period decrease during the initial stage of the thermal pulse in the helium-burning shell of the Mira-type variable T UMi is investigated with numerical methods of stellar evolution and radiation hydrodynamics. To this end, a grid of evolutionary tracks was calculated for stars with masses on the main sequence $1\, \mathrm{M}_{\odot }\le M_\mathrm{ZAMS}\le 2.2\, \mathrm{M}_{\odot }$ and metallicity Z = 0.01. Selected models of AGB evolutionary sequences were used for determination of the initial conditions and the time-dependent inner boundary conditions for the equations of hydrodynamics describing evolutionary changes in the radially pulsating star. The onset of period decrease during the initial stage of the thermal pulse is shown to nearly coincide with the peak helium-burning luminosity. The most rapid decrease of the period occurs during the first three decades. The pulsation period decreases due to both contraction of the star and mode switching from the fundamental mode to the first overtone. The time-scale of mode switching is of the order of a few dozen pulsation cycles. The present-day model of the Mira-type variable T UMi is the first-overtone pulsator with small-amplitude semiregular oscillations. Theoretical estimates of the pulsation period at the onset of period decrease and the rate of period change three decades later are shown to agree with available observational data on T UMi for AGB stars with masses $1.04\, \mathrm{M}_{\odot }\le M\le 1.48\, \mathrm{M}_{\odot }$.

Initial periods and magnetic fields of neutron stars

ABSTRACT Initial distributions of pulsar periods and magnetic fields are essential components of multiple modern astrophysical models. Not enough work has been done to properly constrain these distributions using direct measurements. Here, we aim to fill this gap by rigorously analysing the properties of young neutron stars (NSs) associated to supernova remnants (SNRs). In order to perform this task, we compile a catalogue of 56 NSs uniquely paired to SNRs with known age estimate. Further, we analyse this catalogue using multiple statistical techniques. We found that distribution of magnetic fields and periods for radio pulsars are both well described using the lognormal distribution. The mean magnetic field is log10[B/G] = 12.44 and standard deviation is σB = 0.44. Magnetars and central compact objects do not follow the same distribution. The mean initial period is $\log _{10} P_0 [P / \mathrm{s}] = -1.04_{-0.2}^{+0.15}$ and standard deviation is $\sigma _{\rm p} = 0.53_{-0.08}^{+0.12}$. We show that the normal distribution does not describe the initial periods of NSs sufficiently well. Parameters of the initial period distribution are not sensitive to the exact value of the braking index.

The OGLE Collection of Variable Stars: Nearly 66,000 Mira Stars in the Milky Way

We present a collection of 65,981 Mira-type variable stars found in the Optical Gravitational Lensing Experiment (OGLE) project database. Two-thirds of our sample (40,356 objects) are located in the Galactic bulge fields, whereas 25,625 stars are in the Galactic disk. The vast majority of the collection (47,532 objects) comprises new discoveries. We provide basic observational parameters of the Mira variables: equatorial coordinates, pulsation periods, I-band and V-band mean magnitudes, I-band brightness amplitudes, and identifications in other catalogs of variable stars. We also provide the I-band and V-band time-series photometry collected since 1997 during the OGLE-II, OGLE-III, and OGLE-IV phases. The classical selection process, i.e., being mostly based on the visual inspection of light curves by experienced astronomers, has led to the high purity of the catalog. As a result, this collection can be used as a training set for machine-learning classification algorithms. Using overlapping areas of adjacent OGLE fields, we estimate the completeness of the catalog to be about 96%. We compare and discuss the statistical features of Miras located in different regions of the Milky Way. We show examples of stars that change their type over time, from a semiregular variable to Mira and vice versa. This data set is perfectly suited to studying the three-dimensional structure of the Milky Way, and it may help to explain the puzzle of the X-shaped bulge.

Neutrino Rocket Jet Model: An Explanation of High-velocity Pulsars and Their Spin-down Evolution

The fact that the spatial velocity of pulsars is generally higher than that of their progenitor stars has bothered astronomers for nearly 50 years. It has been extensively argued that the high pulsar velocity should be acquired during a natal kick process on a timescale of 100 ms–10 s in the supernova explosion, in which some asymmetrical dynamical mechanism plays a key role. However, a satisfactory picture generally is still lacking. In this study, it is argued that the neutrino rocket model can well account for the high speed as well as the long-term evolution behaviors of pulsars. The neutrinos are emitted from superfluid vortex neutrons through the neutrino cyclotron radiation mechanism. The unique characters of left-handed neutrinos and right-handed antineutrinos resulting from the nonconservation of parity in weak interactions play a major role in the spatial asymmetry. The continuous acceleration of pulsars can be naturally explained by this model, which yields a maximum velocity surpassing 1000 km s−1. The alignment between the spinning axis and the direction of motion observed for the Crab pulsar (PSR 0531) and the Vela pulsar (PSR 0833) can be well accounted for. The observed correlation between the spin-down rate and the period of long-period pulsars with P ≳ 0.5 s can also be satisfactorily explained.

Control and Dynamic Characteristics Analysis for the Double-Compound Axial Piston Pump Based on Working Conditions

The periodic flow and pressure pulsation of the axial piston pump can lead to periodic vibration, noise, and even damage to various components in the hydraulic system. Therefore, the dynamic characteristics analysis of the axial piston pump in the hydraulic system is of great significance for reducing vibration and noise in the hydraulic system and improving efficiency. The double-compound axial piston pump is the key component of a high power and large flow hydraulic power system, which has a special power control mode. In this paper, the working and control principles of the double-compound axial piston pump are analyzed, the numerical model of the double-compound axial piston pump is established, and the effectiveness of the model is verified through experimental tests. The constant power control characteristics of the double-compound axial piston pump under different power settings and the variable power control characteristics under the rated load pressure are analyzed. By analyzing the dynamic characteristics of the double-compound axial piston pump, the influence of different working conditions on the dynamic characteristics is investigated. The results show that the output efficiency of the double-compound axial piston pump is higher when the output flow is larger. When the piston chamber works in the closed pre-compression pressure zone and the closed pre-release pressure zone, oil backflow occurs. The oil backflow in the piston chamber seriously intensifies the outlet flow pulsation of the double-compound axial piston pump. The flow pulsation rate is positively correlated with load pressure and power control pilot pressure, while negatively correlated with spindle speed. The paper provides a basis for the analysis and optimization of power control, flow pulsation, fluid vibration, and noise of the double-compound axial piston pump.

The specifics of pulsar radio emission

Abstract A characteristic property of pulsars is pulsed periodic radio emission, which has a high stability of periods. Despite the high stability of the emission periods of pulsars, monitoring the time of arrival of pulses (timing) shows the presence of different types of irregularities: variations of residual deviations, changes in the shape of the pulse, switching on and off of radio emission, and rotation discontinuities. Numerous observations of the radio emission of pulsars indicate that they are caused mainly by processes occurring in the pulsar’s magnetosphere. The special interest causes the observations of a pulsar in the Crab Nebula, performed, in particular, at Jodrell Bank and Pushchino Radio Astronomy Observatory of Lebedev Physical Institute. The connection between the scattering of radio pulses and the measure of the pulsar dispersion, which was established earlier in Pushchino together with Jodrell Bank, has been confirmed. The observed variations in the scattering of radio pulses and their partial correlation with the dispersion measure are explained by the eclipse of the pulsar by plasma clouds with electron density fluctuations significantly exceeding the corresponding fluctuations in the interstellar medium. The question of a possible connection between glitches, dispersion measure variations, radio pulses scattering, and gamma-ray flares is discussed.

Low-frequency observations of giant pulses from ordinary pulsars

ABSTRACTWe present the results of an investigation of the giant radio pulse (GRP) generation rate from five radio pulsars (B0301+19, B0950+08, B1112+50, B1133+16, and B1237+25) and anomalous intensity pulse generation rate from B0809+74. All data used were obtained with the Large Phased Array radio telescope at the Pushchino Radio Astronomy Observatory at 111 MHz from 2012 to 2021. In addition to the analysis of the rate of generation of bright pulses, we analyse the distribution of bright pulses in the phase of the pulsar period and search for clusters of bright pulses – several bright pulses emitted in adjacent pulsar periods. It is found that pulsars B0301+19, B1112+50, B1133+16, and B1237+25 demonstrate different generation rates and generation of clusters. Pulsar B1112+50 generates GRP clusters more often than the other pulsars studied. The longest cluster of GRPs containing four single pulses is detected from this pulsar. GRPs from the pulsars studied are distributed along the longitudes of the main components of the average pulses of these pulsars. This distribution is 1.5–2 times narrower than the phase distribution of non-giant pulses. It is found that the distance between the components of the average GRP profile and the distance between the components of the average non-giant profile differ substantially for pulsars with multicomponent average profiles.

The onset of turbulence in pulsating flows in smooth pipes

Experimental study examines the structure of nominally laminar flows subjected to sinusoidal variation of flow rate in smooth pipes. An experimental setup employed for this purpose provides high stability of flow rate variation pattern and is able to reproduce flow reversal during a fraction of pulsation period. The Reynolds number based on the highest cross-section average velocity over the pulsation period is 1200. SIV technique is used to measure the instantaneous vector fields of velocity in two regimes of pulsating flow. While there is no flow reversal in the first regime, it occupies approximately 0.4 of the pulsation period in the second regime. The increase in the amplitude of high-frequency fluctuation of velocity is documented in both regimes near the pipe wall within the Stokes layer. Evolution of the shape of velocity profiles and fluctuation amplitude profiles depending on the pulsation phase is presented. Our analysis suggests that forced sinusoidal pulsation of flow rate at the considered parameters results in the onset of instability and signs of transition to turbulence in the near-wall flow in the smooth pipe. We describe possible mechanism of turbulization of the near-wall flow under the impact of forced flow rate pulsation.

Study on flow characteristics of bidirectional sinusoidal liquid pulsed gas-liquid-solid multiphase fluidized bed

Gas-liquid-solid three-phase fluidized bed has been widely used in chemical, biotechnology and environmental industries for its advantages of large inter-phase contact area, high heat/mass transfer efficiency and intense reaction process. In this work, the bidirectional sinusoidal liquid pulsed GLS fluidized bed was proposed to improve the interphase relative velocity and reaction efficiency. The effects of particle properties and pulsed liquid amplitude/frequency on the flow characteristics were studied by numerical simulations and experiments. In a complete circulation period, the average axial solids holdup is larger near the middle region of the fluidized bed and gradually decreases along the upper and lower inlets. With the increase of pulsation amplitude or period, the axial average gas holdup distribution uniformity and the liquid-solid relative velocity increase significantly. Compared with the conventional upward gas-liquid-solid fluidized bed, the bidirectional fluidized bed can further improve the liquid-solid relative velocity and reaction efficiency. The obtained studies have important implications for better design, scale-up and operation of gas-liquid-solid multiphase fluidization systems.

Slow Magnetoacoustic Oscillations in Stellar Coronal Loops

Slow magnetoacoustic oscillations in stellar coronal loops with gravitational stratification are analyzed with a numerical solution of the boundary value problem for eigenvalues and eigenfunctions. In this study, we only focus on the resonant periods. The effects of the gravitational stratification, star mass, loop temperature, and loop length on the properties of slow magnetoacoustic oscillations are investigated. It is shown that the discrepancy between stratified and nonstratified loops is higher in density perturbations than in velocity perturbations. When the star has a larger mass, higher coronal temperature, and longer loop, the density perturbations in the stratified loop are significantly different from the harmonic functions. The periods in the stratified loop are slightly longer than in the nonstratified loop. The periods calculated in our model (14–644 minutes) are consistent with the periods of stellar quasi-periodic pulsations observed in both soft X-rays (2–70 minutes) and white lights (8–390 minutes).

Intra-pulse variability induced by plasmoid formation in pulsar magnetospheres

Context. Pulsars show irregularities in their pulsed radio emission that originate from propagation effects and the intrinsic activity of the source. Aims. In this work, we investigate the role played by magnetic reconnection and the formation of plasmoids in the pulsar wind current sheet as a possible source of intrinsic pulse-to-pulse variability in the incoherent, high-energy emission pattern. Methods. We used a two-dimensional particle-in-cell simulation of an orthogonal pulsar magnetosphere restricted to the plane perpendicular to the star spin axis. We evolved the solution for several tens of pulsar periods to gather a statistically significant sample of synthetic pulse profiles. Results. The formation of plasmoids leads to strong pulse-to-pulse variability in the form of multiple short, bright subpulses, which appear only on the leading edge of each main pulse. These secondary peaks of emission are dominated by the dozen plasmoids that can grow up to macroscopic scales. They emerge from the high end of the hierarchical merging process occurring along the wind current layer. The flux of the subpulses is correlated with their width in phase. Although the full-scale separation is not realistic, we argue that the simulation correctly captures the demographics and the properties of the largest plasmoids, and therefore of the brightest subpulses. Conclusions. The prediction of subpulses at specific pulse phases provides a new observational test of the magnetic reconnection scenario as the origin of the pulsed incoherent emission. High-time-resolution observations of the Crab pulsar in the optical range may be the most promising source to target for this purpose.

Investigation of the Effect of Nozzle on Underwater Detonation Shock Wave and Bubble Pulsation

The subject of a gas jet generated by underwater detonation is an important issue in the field of underwater propulsion. The experimental system of underwater detonation is established, which utilizes a high-speed camera to record the morphological changes in bubbles and various pressure sensors to measure the flow field pressure. The effect of nozzles and the pressure of the flow field are analyzed thoroughly. The comparison of the bubble and field pressure shows that the shrinking nozzle increases the peak pressure of the transmitted shock wave generated by underwater detonation compared with that of the straight nozzle. Simultaneously, the water–air mixing phenomenon caused by the gas jet is enhanced. Under the influence of the reflected shock wave and the converging angle of the nozzle, the pulsation process of the bubble is inhibited enormously, which results in the bubble energy being substantially below that of the straight nozzle. The bubble pulsation period is 24.2 ms when the shrinking nozzle is installed, and the pressure of the bubble pulsation is quite small, only 9.8 kPa. On the contrary, the expansion angle increases the velocity of the gas jet, suppressing the water–gas mixing phenomenon while enhancing the bubble pulsation process. The bubble pulsation period is 33.0 ms when the expanding nozzle is equipped, which is larger than the 31.2 ms of the straight nozzle and the bubble pulsation pressure is higher, at 26.1 kPa. Although the bubble energy is increased when the expanding nozzle is installed, thus generating a higher pulsation pressure, the peak pressure and direction of the shock wave are changed in the water.

Analysis of Cylinder Block Torque Characteristics of Dual-Drive Axial Piston Motor

A mathematical model of the cylinder block moment of a dual-drive axial piston motor considering the dynamic pressure in the piston chamber is developed. The influence of the number of plugs, staggering angle, inlet pressure and swashplate inclination on the individual moments applied to the cylinder block was analyzed. The results show: when the number of pistons in the inner and external emissions is the same, the cylinder block is subjected to a periodic pulsation of each moment and odd-numbered pistons have a higher frequency of torque fluctuations than even-numbered pistons. With increasing intersection angle, the pulsation rate of the torque around the x and y axes tends to increase and then decrease but the output torque varies in the opposite direction; The inlet pressure can increase the torque pulsation rate of the cylinder block in equal proportion. When the inclination angle of the inner and external swashplate is not the same, the reasonable selection of different inner and external swashplate inclination angles can make the overturning torque generated by the inner and external emissions offset and increase, so that the overturning torque of the cylinder block is reduced.

Four pulsar discoveries in NGC 6624 by TRAPUM using MeerKAT

ABSTRACT We report four new pulsars discovered in the core-collapsed globular cluster (GC) NGC 6624 by the TRAPUM Large Survey Project with the MeerKAT telescope. All of the new pulsars found are isolated. PSR J1823−3021I and PSR J1823−3021K are millisecond pulsars with period of respectively 4.319 and 2.768 ms. PSR J1823−3021J is mildly recycled with a period of 20.899 ms, and PSR J1823−3022 is a long period pulsar with a period of 2.497 s. The pulsars J1823−3021I, J1823−3021J, and J1823−3021K have position and dispersion measure (DM) compatible with being members of the GC and are therefore associated with NGC 6624. Pulsar J1823−3022 is the only pulsar bright enough to be re-detected in archival observations of the cluster. This allowed the determination of a timing solution that spans over two decades. It is not possible at the moment to claim the association of pulsar J1823−3022 with the GC given the long period and large offset in position (∼3 arcmin) and DM (with a fractional difference of 11 percent compared the average of the pulsars in NGC 6624). The discoveries made use of the beamforming capability of the TRAPUM backend to generate multiple beams in the same field of view which allows sensitive searches to be performed over a few half-light radii from the cluster centre and can simultaneously localize the discoveries. The discoveries reflect the properties expected for pulsars in core-collapsed GCs.