arXiv subjects

M. Berezina

Publications and source records attributed to M. Berezina.

10 recordsLinked to original sources

arXiv2026

The Northern High Time Resolution Universe pulsar survey: III. Single-pulse search continuation, follow-up observations, and initial results

We continued the search for single pulses (SPs) in the northern part of the all-sky High Time Resolution Universe survey, whose aim is to detect pulsars and other radio transients. This search is now about 21% complete and has yielded the first discovery of a fast radio burst (FRB) with the 100 m Effelsberg Radio Telescope. FRB20110220A was detected with an S/N-optimised dispersion measure of 501.0 pc/cm$^{3}$ and a width of 11.9 $\pm$ 3.5 ms, for a fluence of 0.6 $\pm$ 0.1 Jy ms. We obtained the first L-band detection of the rotating radio transient (RRAT) J2028+28, from which we obtained upper limits on the source's period and burst rate, as well as an improved position. We also discovered a new RRAT, J0404+53, which had previously been reported as an isolated SP candidate. Eight new SP trains and 272 faint isolated SP candidates were detected too. We used these candidates to demonstrate that their all-sky detection rates depend on Galactic latitude and longitude. This direction dependence suggests the existence of a faint Galactic SP population.

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arXiv2026

The Northern High Time Resolution Universe pulsar survey: II. Single-pulse search set-up and simulations

The High Time Resolution Universe (HTRU) survey is an all-sky survey looking for pulsars and other radio transients. A new single-pulse (SP) search pipeline is presented, tailored to the northern part of the HTRU survey collected with the 100m Effelsberg Radio Telescope. In a selection of this data, synthetic SPs are injected with frequency-time structures resembling those of the detected Fast Radio Burst (FRB) population and processed by the pipeline to characterize its performance. Therefore, several new software toolkits have been developed (FRBfaker and RFIbye) to enable the injection of SPs with complex frequency-time structures and cope with the Radio Frequency Interference (RFI) in the survey's data. The operation of these toolkits is described alongside the overall functionality of the SP pipeline. Qualification of the pipeline confirmed that it is ready to process all the HTRU-North data. Additionally, the survey's sensitivity to SPs, the impact of RFI thereon, the performance of the deep-learning classifier FETCH, and some insights that may be used to improve the pipeline's performance in the future are determined. Within the small data sample analysed, 21 known pulsars and a RRAT are detected. In addition, eight faint SP trains that might originate from yet undiscovered neutron stars and 141 isolated SP candidates were discovered.

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arXiv2024

A study of two FRBs with low polarization fractions localized with the MeerTRAP transient buffer system

Localisation of fast radio bursts (FRBs) to arcsecond and sub-arcsecond precision maximizes their potential as cosmological probes. To that end, FRB detection instruments are deploying triggered complex-voltage capture systems to localize FRBs, identify their host galaxy and measure a redshift. Here, we report the discovery and localisation of two FRBs (20220717A and 20220905A) that were captured by the transient buffer system deployed by the MeerTRAP instrument at the MeerKAT telescope in South Africa. We were able to localize the FRBs to a precision of $\sim$1 arc-second that allowed us to unambiguously identify the host galaxy for FRB 20220717A (posterior probability$\sim$0.97). FRB 20220905A lies in a crowded region of the sky with a tentative identification of a host galaxy but the faintness and the difficulty in obtaining an optical spectrum preclude a conclusive association. The bursts show low linear polarization fractions (10--17$\%$) that conform to the large diversity in the polarization fraction observed in apparently non-repeating FRBs akin to single pulses from neutron stars. We also show that the host galaxy of FRB 20220717A contributes roughly 15$\%$ of the total dispersion measure (DM), indicating that it is located in a plasma-rich part of the host galaxy which can explain the large rotation measure. The scattering in FRB 20220717A can be mostly attributed to the host galaxy and the intervening medium and is consistent with what is seen in the wider FRB population.

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arXiv2023

The MPIfR-MeerKAT Galactic Plane Survey II. The eccentric double neutron star system PSR J1208-5936 and a neutron star merger rate update

The MMGPS-L is the most sensitive pulsar survey in the Southern Hemisphere. We present a follow-up study of one of these new discoveries, PSR J1208-5936, a 28.71-ms recycled pulsar in a double neutron star system with an orbital period of Pb=0.632 days and an eccentricity of e=0.348. Through timing of almost one year of observations, we detected the relativistic advance of periastron (0.918(1) deg/yr), resulting in a total system mass of Mt=2.586(5) Mo. We also achieved low-significance constraints on the amplitude of the Einstein delay and Shapiro delay, in turn yielding constraints on the pulsar mass (Mp=1.26(+0.13/-0.25) Mo), the companion mass (Mc=1.32(+0.25/-0.13) Mo, and the inclination angle (i=57(12) degrees). This system is highly eccentric compared to other Galactic field double neutron stars with similar periods, possibly hinting at a larger-than-usual supernova kick during the formation of the second-born neutron star. The binary will merge within 7.2(2) Gyr due to the emission of gravitational waves. With the improved sensitivity of the MMGPS-L, we updated the Milky Way neutron star merger rate to be 25(+19/-9) Myr$^{-1}$ within 90% credible intervals, which is lower than previous studies based on known Galactic binaries owing to the lack of further detections despite the highly sensitive nature of the survey. This implies a local cosmic neutron star merger rate of 293(+222/-103} Gpc/yr, consistent with LIGO and Virgo O3 observations. With this, we predict the observation of 10(+8/-4) neutron star merger events during the LIGO-Virgo-KAGRA O4 run. We predict the uncertainties on the component masses and the inclination angle will be reduced to 5x10$^{-3}$ Mo and 0.4 degrees after two decades of timing, and that in at least a decade from now the detection of the shift in Pb and the sky proper motion will serve to make an independent constraint of the distance to the system.

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arXiv2023

The MPIfR-MeerKAT Galactic Plane survey I -- System setup and early results

Galactic plane radio surveys play a key role in improving our understanding of a wide range of astrophysical phenomena. Performing such a survey using the latest interferometric telescopes produces large data rates necessitating a shift towards fully or quasi-real-time data analysis with data being stored for only the time required to process them. We present here the overview and setup for the 3000 hour Max-Planck-Institut fuer Radioastronomie (MPIfR) MeerKAT Galactic Plane survey (MMGPS). The survey is unique by operating in a commensal mode, addressing key science objectives of the survey including the discovery of new pulsars and transients as well as studies of Galactic magnetism, the interstellar medium and star formation rates. We explain the strategy coupled with the necessary hardware and software infrastructure needed for data reduction in the imaging, spectral and time domains. We have so far discovered 78 new pulsars including 17 confirmed binary systems of which two are potential double neutron star systems. We have also developed an imaging pipeline sensitive to the order of a few tens of micro-Jansky with a spatial resolution of a few arcseconds. Further science operations with an in-house built S-Band receiver operating between 1.7-3.5 GHz are about to commence. Early spectral line commissioning observations conducted at S-Band, targeting transitions of the key molecular gas tracer CH at 3.3 GHz already illustrate the spectroscopic capabilities of this instrument. These results lay a strong foundation for future surveys with telescopes like the Square Kilometre Array (SKA).

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arXiv2020

Real-time triggering capabilities for Fast Radio Bursts at the MeerKAT telescope

Fast Radio Bursts (FRBs) are bright enigmatic radio pulses of roughly millisecond duration that come from extragalactic distances. As part of the MeerTRAP project, we use the MeerKAT telescope array in South Africa to search for and localise those bursts to high precision in real-time. We aim to pinpoint FRBs to their host galaxies and, thereby, to understand how they are created. However, the transient nature of FRBs presents various challenges, e.g. in system design, raw compute power and real-time communication, where the real-time requirements are reasonably strict (a few tens of seconds). Rapid data processing is essential for us to be able to retain high-resolution data of the bursts, to localise them, and to minimise the delay for follow-up observations. We give a short overview of the data analysis pipeline, describe the challenges faced, and elaborate on our initial design and implementation of a real-time triggering infrastructure for FRBs at the MeerKAT telescope.

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arXiv2020

A precise mass measurement of PSR J2045+3633

We present the results of a timing analysis undertaken with the goal of obtaining an improved mass measurement of the recycled pulsar J2045+3633. Using regular high-cadence observations with the Effelsberg, Nançay, and Lovell radio telescopes, together with targeted campaigns with the Arecibo Telescope and Effelsberg, we have assembled a 6-yr timing data set for this pulsar. We measure highly significant values for the proper motion and the related rate of change of orbital semi-major axis ($\dot{x}$), and have obtained high precision values of the rate of advance of periastron time ($\dotω$), and two of the Shapiro delay parameters ($h_{3}$ and $ς$). This has allowed us to improve the measurements of the pulsar and companion masses by an order of magnitude, yielding (with $1σ$ uncertainties) $1.251^{+0.021}_{-0.021}\,\text{M}_{\odot}$ for PSR J2045+3633, and $0.873^{+0.016}_{-0.014}\,\text{M}_{\odot}$ for its white dwarf companion, and has allowed us to place improved constraints on the geometrical orientation of the binary system. Using our measurements of the binary component masses and the orbital size, we consider possible evolutionary scenarios for the system.

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arXiv2017

The discovery of two mildly-recycled binary pulsars in the Northern High Time Resolution Universe pulsar survey

We report the discovery and the results of follow-up timing observations of PSR J2045+3633 and PSR J2053+4650, two binary pulsars found in the Northern High Time Resolution Universe pulsar survey being carried out with the Effelsberg radio telescope. Having spin periods of 31.7 ms and 12.6 ms respectively, and both with massive white dwarf companions, $M_{c}\, > \, 0.8\, M_{\odot}$, the pulsars can be classified as mildly recycled. PSR J2045+3633 is remarkable due to its orbital period (32.3 days) and eccentricity $e\, = \, 0.01721244(5)$ which is among the largest ever measured for this class. After almost two years of timing the large eccentricity has allowed the measurement of the rate of advance of periastron at the 5-$σ$ level, 0.0010(2)$^\circ~\rm yr^{-1}$. Combining this with a detection of the orthometric amplitude of the Shapiro delay, we obtained the following constraints on the component masses (within general relativity): $M_{p}\, = \, 1.33^{+0.30}_{-0.28}\, M_{\odot}$, and $M_{c}\, = \, 0.94^{+0.14}_{-0.13}\, M_{\odot}$. PSR J2053+4650 has a 2.45-day circular orbit inclined to the plane of the sky at an angle $i\, = \, 85.0^{+0.8}_{-0.9}\,{^\circ}$. In this nearly edge-on case the masses can be obtained from the Shapiro delay alone. Our timing observations resulted in a significant detection of this effect giving: $M_{p}\, = \, 1.40^{+0.21}_{-0.18}\, M_{\odot}$, and $M_{c}\, = \, 0.86^{+0.07}_{-0.06}\, M_{\odot}$.

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arXiv2016

A Massive Millisecond Pulsar in an Eccentric Binary

The recent discovery of a population of eccentric (e ~ 0.1) millisecond pulsar (MSP) binaries with low-mass white dwarf companions in the Galactic field represents a challenge to evolutionary models that explain MSP formation as recycling: all such models predict that the orbits become highly circularised during a long period of accretion. The members of this new population exhibit remarkably similar properties (orbital periods, eccentricities, companion masses, spin periods) and several models have been put forward that suggest a common formation channel. In this work we present the results of an extensive timing campaign focusing on one member of this new population, PSR J1946+3417. Through measurement of the both the advance of periastron and Shapiro delay for this system, we determine the mass of the pulsar, companion and the inclination of the orbit to be 1.828(22) Msun, 0.2656(19) Msun and 76.4(6) , under the assumption that general relativity is the true description of gravity. Notably, this is the third highest mass measured for any pulsar. Using these masses and the astrometric properties of PSR J1946+3417 we examine three proposed formation channels for eccentric MSP binaries. While our results are consistent with eccentricity growth driven by a circumbinary disk or neutron star to strange star phase transition, we rule out rotationally delayed accretion-induced collapse as the mechanism responsible for the configuration of the PSR J1946+3417 system.

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arXiv2016

A Fast Radio Burst Host Galaxy

In recent years, millisecond duration radio signals originating from distant galaxies appear to have been discovered in the so-called Fast Radio Bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity which, in tandem with a redshift measurement, can be used for fundamental physical investigations. While every fast radio burst has a dispersion measurement, none before now have had a redshift measurement, due to the difficulty in pinpointing their celestial coordinates. Here we present the discovery of a fast radio burst and the identification of a fading radio transient lasting $\sim 6$ days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be $z=0.492\pm0.008$. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionised baryons in the intergalactic medium of $Ω_{\mathrm{IGM}}=4.9 \pm 1.3\%$, in agreement with the expectation from WMAP, and including all of the so-called "missing baryons". The $\sim6$-day transient is largely consistent with a short gamma-ray burst radio afterglow, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting there are at least two classes of bursts.

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