arXiv subjects

Santiago del Palacio

Publications and source records attributed to Santiago del Palacio.

At least 19 recordsLinked to original sources

arXiv2026

The influence of free-free absorption on the radio spectrum of Particle-Accelerating Colliding-Wind Binaries

The study of massive stars in binary and higher-multiplicity systems that participate in particle acceleration is a key topic at the crossroads of massive star physics, shock physics, and galactic cosmic ray astrophysics. From an observational perspective, radio measurements are our pri- mary tool for identifying these systems through their synchrotron radio emission. Out of the 54 such systems known to date, all but two have been discovered via their non-thermal radio emission. However, identifying these systems is not straightforward. The main challenge lies in free-free absorption, which can obscure the synchrotron signature and hinder detection. This paper summarizes recent developments in our understanding of these systems, with a particular focus on the strong observational bias introduced by free-free absorption. This bias significantly limits our ability to determine the true fraction of particle accelerators among colliding-wind binaries.

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arXiv2026

Radio Emission with Dust: A Bow-Shock Interpretation for the TDE Candidate AT 2019avd

Forward shocks produced by interactions between a single ejected blob and the circumnuclear medium (CNM) around a supermassive black hole are widely invoked to explain radio emission from tidal disruption events (TDEs). However, recent observational evidence such as rapidly rising radio emission, double-peaked broadband spectral energy distributions, and declining shock energies at late times poses challenges to this picture. Alternative scenarios have therefore been proposed, including bow shocks arising from outflows colliding with dense clouds, the production of new ejecta at late times, and variations in microphysical parameters. To investigate the roles of these factors, we analyze the long-lived radio flare of the TDE candidate AT 2019avd, for which dust has been identified through mid-infrared observations, using a radio dataset spanning more than five years. We find that a bow-shock scenario can account for the majority of the observed radio emission, while a forward shock, or an additional bow shock involving different clouds, may begin to dominate at late times. However, a forward-shock scenario remains viable when allowing for evolving microphysical parameters and more complex CNM structures. We discuss the remaining tensions in both the outflow-CNM and outflow-cloud interaction scenarios.

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arXiv2026

Single-pulse reanalysis of the 2024 Vela glitch and new observations of PSR~J0437$-$4715 and PSR~J1644$-$4559

The Pulsar Monitoring in Argentina (PuMA) collaboration systematically monitors southern glitching pulsars, maintaining high-cadence single-pulse records of the Vela pulsar. We present a pulse-per-pulse reanalysis of the 2024 major glitch of Vela (PSR~J0835$-$4510) with the 400~MHz-bandwidth ROACH backend of the Argentine Institute of Radioastronomy, and extend our machine-learning single-pulse pipeline---Isolation Forest outlier rejection, $β$-Variational-AutoEncoder denoising, and Self-Organizing-Map clustering---to new observations of PSR~J1644$-$4559 and the millisecond pulsar PSR~J0437$-$4715. For Vela, the 4- and 6-cluster decompositions of the eight days bracketing the glitch reproduce, with seven times the previous bandwidth, the behavior found with the narrow-band ETTUS receivers: higher-amplitude clusters peak earlier in phase, are narrower, more skewed, and less populated. With the glitch jump and its two exponential recovery terms included in the timing solution, the mean profile is stable to 1\% across all eight days (width change $-0.5\pm0.9$\% from pre- to post-glitch); omitting the recovery terms would mimic a post-glitch broadening of up to 55\% through a folding-frequency error at the $10^{-7}$ level. The clusters of PSR~J1644$-$4559 differ almost exclusively in amplitude, as expected for a scattering-dominated profile. For PSR~J0437$-$4715, retaining the 10\% of pulses with the highest peak-dominance score doubles the signal-to-noise ratio, and a five-cluster decomposition yields narrow, phase-ordered groups a factor $3.6\pm0.4$ narrower than the average profile, suggesting a $\sim$3.5-fold improvement in cluster-based timing precision for this pulsar-timing-array target, to be confirmed in a follow-up paper.

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arXiv2026

Upstream neutrino production and delayed jet emission in the blazar GB6 J1542+6129

We present a multimessenger case study of the blazar GB6 J1542+6129, examining whether its multiwavelength behavior is consistent with neutrino production in a compact region near the central black hole, or with the parsec-scale radio jet. We perform a multimessenger analysis combining ~17 years of Fermi-LAT gamma-ray data with ~14 years of VLBI/MOJAVE. These are compared to the temporal properties of a suspected IceCube neutrino flare with a duration of $147^{+110}_{-25}$ days, enabling a direct test of spatial and causal connections between neutrino and electromagnetic emission regions. We find that the suspected neutrino flare appears to precede both a $γ$-ray flare and a pronounced increase in the VLBI core Doppler factor by up to ~1 year. The duration of the post-flare $γ$-ray activity is comparable to that of the neutrino flare, which, in our framework, is consistent with both signatures originating from a single propagating disturbance whose temporal structure is preserved during the propagation. The gamma-ray spectral energy distribution remains consistent in shape across the full, flare, and post-flare intervals, indicating stable particle acceleration conditions. The temporal ordering, taken at face value, places the neutrino production site upstream of the VLBI core. The observations of GB6 J1542+6129 are consistent with a disturbance-driven, multi-zone scenario in which neutrinos are produced in a compact, photon-rich inner region upstream of the parsec-scale VLBI core, plausibly at the coronal region, while the same disturbance later enhances Doppler-boosted leptonic emission once it reaches the radio core. While the data alone do not strictly establish this scenario on a population level, they show how time-domain multimessenger observations of a single AGN can localize neutrino emission relative to the parsec-scale radio jet in a particular source.

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arXiv2026

First fast radio burst search campaign at the Argentine Institute of Radio Astronomy

Fast radio bursts (FRBs) are intense millisecond-duration radio transients of extragalactic origin whose physical nature remains under active investigation, and which also serve as probes of the intergalactic medium. We report on the first FRB search campaign carried out at the Argentine Institute of Radio Astronomy (IAR) between December 2024 and March 2026, targeting nearby galaxy superclusters in the southern sky. We observed fields in the Ophiuchus, Shapley, and Sculptor/Phoenix supercluster regions with one of the two 30~m antennas of the IAR, using a ROACH-based backend with 400~MHz of bandwidth centred at 1400~MHz and a time resolution of 41--82~$μ$s, for a total net observing time of 212~h. The data were searched for dispersed single pulses with \texttt{PRESTO} in the dispersion measure range $100 \leq \mathrm{DM} \leq 500$, and candidates were classified with the FETCH machine learning classifier. The pipeline was validated on archival Parkes data containing known FRBs and on synthetic bursts injected into IAR observations. One FRB candidate, FRB~20251018, was identified on 18 October 2025 in an observation pointed towards the galaxy cluster A2870, in the Phoenix supercluster, with a dispersion measure of $243$, a signal-to-noise ratio of 8.2, and a FETCH probability of $p=0.99$. To the best of our knowledge, this would be the first FRB detected from South America. A set of more marginal candidates is also presented. These results demonstrate the capability of the IAR antennas to detect FRBs and support the continuation and extension of the monitoring campaign, including coincident dual-antenna observations and cross-matches with gravitational-wave events and electromagnetic transients.

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arXiv2026

Correlation Between Hard X-Ray and Cosmic Neutrino Sources: From Obscured AGN to Blazars

The origin of high-energy astrophysical neutrinos remains a key open question in multimessenger astrophysics. A correlation between unabsorbed hard X-ray and high-energy neutrino luminosity has been reported in six active galactic nuclei with the highest individual IceCube significances, linking neutrino production to compact, photon-rich environments near supermassive black holes. We study whether the threshold-near IceCube excesses associated with seven NuSTAR-observed blazars are statistically consistent with that relation. Calibrating the $L_\mathrm{hX}$-$L_ν$ relation on the six published sources via a Bayesian regression with errors on both axes, the slope is consistent with $β= 1$ and the intrinsic scatter is $\sim 0.6$\,dex. All seven new blazars are posterior-predictively consistent with this calibration ($χ^2_7 = 1.58$, $p = 0.98$) under the working hypothesis that the published IceCube $\hat{n}_s$ values reflect the signal. A null-injection test confirms that, at the present calibration sample size, the consistency test does not by itself adjudicate between signal and selected-background origins. A distance-free $L_\mathrm{hX}/L_ν$ ratio diagnostic places both populations within the photohadronic prediction band, statistically indistinguishable. Two diagnostics that control the common $d_L^{\,2}$ distance bias, a redshift-partial rank correlation ($τ|z = 0.69$, $\sim\!2.7\,σ$) and a flux-space permutation test on the 13-source joint sample ($p = 6.3\times10^{-4}$, $3.23\,σ$), indicate a residual $L_\mathrm{hX}$-$L_ν$ association beyond the distance-induced trend. We interpret these results as a conditional consistency check; a detection-level statement requires either an enlarged calibration set or an X-ray-weighted IceCube stacking likelihood with internal data.

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arXiv2026

The PARADIGM Project II: Characterising Nuclear and Diffuse Radio Components in Local U/LIRGs

Disentangling SF and AGN emission is essential for understanding galaxy evolution, yet remains challenging in merging systems where both processes are enhanced and spatially intertwined. Galaxy mergers drive gas inflows that simultaneously fuel nuclear SBs and BH accretion, shaping morphology from nuclear ($\lesssim 250$~pc) to large-scale ($\gtrsim 500$~pc) regions. Radio interferometry provides an unobscured view, but separating compact nuclear SBs, AGN, and diffuse SF requires multiscale, multi-frequency observations. We present a systematic method to characterise multiscale radio properties in 15 local ($z\lesssim 0.1$) U/LIRGs ($L_{\mathrm{IR}} > 10^{11}\mathrm{L}_{\odot}$). Using \emph{e}-MERLIN and VLA at 1.4, 6.0 and 33.0~GHz, we probe physical scales from $\sim 10$--$250$~pc to $\sim 0.5$--$3.0$~kpc. We decompose radio emission into nuclear (compact cores and nuclear extended) and large-scale (total and diffuse) components, comparing morphological properties (emission fractions, sizes, luminosities, surface densities) and investigating correlations with source classes, merger stages, and $L_{\mathrm{IR}}$. We find: i) nuclear emission contributes $\sim$50\% of total radio emission on average; ii) total multiscale diffuse emission (SF-related) contributes $\sim$80\% to total power; iii) nuclear emission components act together to correlate with total radio and infrared luminosities, which increase with merger stage, whilst diffuse emission at larger scales shows no clear dependence on nuclear processes; iv) sources with radio excess (lower $q_{\mathrm{IR}}$) show lower nuclear luminosity ratios $L_{\mathrm{R,33}}^{\mathrm{N}}/L_{\mathrm{R,6}}^{\mathrm{N}}$, indicating a deficit of high-$ν$ radio emission; since 33.0~GHz traces recent SF, this suggests the radio excess is dominated by non-thermal emission at lower $ν$, likely AGN-related, rather than enhanced SF.

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arXiv2026

The Inner and Outer Shock Layers of Bow Shocks in Cataclysmic Variables

Bow shocks around cataclysmic variables (CVs) have traditionally been identified with a single bright optical arc. This feature has been interpreted as the bow shock formed by the interaction between a sustained outflow and the interstellar medium (ISM). We show that this interpretation is incomplete. Generic wind-ISM interaction theory predicts a two-shock configuration consisting of an inner terminal wind (reverse) shock and an outer forward shock, separated by a hot, low-density shocked wind cavity. Using archival ultraviolet, optical, and infrared imaging of the nova-like systems BZ Cam and V341 Ara, and the polar 1RXS J052832.5+283824, we find that the nebulae around all three systems exhibit this layered structure. In each case, the previously identified bow shock bright in Halpha and [OIII] corresponds to a compact inner arc, while additional emission components reveal a more extended morphology. Specifically, each system shows an outer arc detected in mid-infrared images, and the region between the optical and infrared arcs is filled with faint Halpha emission and, where available, far ultraviolet emission. We identify this infrared arc, reported here for the first time in these systems, as the sweep-up boundary of the forward shock, while the bright inner optical arc corresponds to the terminal wind shock rather than the forward shock as previously assumed. These results reveal that the true extent and layered structure of bow shocks around CVs only become apparent when observations extend beyond the optical band.

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arXiv2026

Bayesian parameter study of the Seyfert-starburst composite galaxies NGC 1068 and NGC 7469

Multimessenger observation of the Seyfert-starburst composite galaxies NGC 1068 and NGC 7469 indicate a characteristic feature in the radio band (the so-called mm-bump) as well as indication of high-energy neutrinos by the AGN corona. Moreover, also the starburst ring of these sources is bright in the radio and hence, a potential source of $γ$-rays and neutrinos. We aim to explain the non-thermal features of these two sources with our homogeneous steady-state Seyfert-starburst composite model, which we refined in this work. Hereby, we account for stochastic diffuse acceleration and energy losses within the corona and $γγ$-pair attenuation of the escaping $γ$-rays. Since the non-thermal features of Seyfert sources contribute only marginally to the electromagnetic spectrum, only few data points can be assigned to the starburst ring or the AGN corona. Hence, prior information on the physical parameters is incorporated within a Markov Chain Monte Carlo approach to avoid overfitting. Based on this Bayesian parameter study we show, that the non-thermal features of NGC 1068 can be explained well. Still a more detailed treatment of the spatial inhomogeneities in the central region of the AGN could further improve the fit results. This manifests itself even more clearly in the case of NGC 7469, where the mm-bump needs to emerge from a coronal size $R_{\rm c}>100\,\mathcal{R}_{\rm s}$, whereas (TeV-PeV)-neutrino emission requires $R_{\rm c}< 10\,\mathcal{R}_{\rm s}$. Similar to what has previously been shown in other wavebands, our analysis highlights that the spatial extension of the so-called AGN corona depends the considered energy of the messenger. Hence, it seems that there is not a unique edge of the corona and a substantial progress in the understanding of these phenomena is expected if future analysis account for these spatial inhomogeneities.

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arXiv2026

Investigating particle acceleration in the Wolf-Rayet bubble NGC 2359

Massive stars have been proposed as candidates to be major factories of Galactic cosmic rays (GCRs). However, this claim lacks enough empirical evidence, especially for isolated stars. The powerful stellar winds from massive stars impact the ambient medium producing strong shocks suitable for accelerating relativistic particles. The detection of non-thermal emission-particularly synchrotron emission in low radio frequencies-serves as a key proof of particle acceleration sites. We aim to assess the potential of isolated massive stars as sources of GCRs. We observed the Wolf-Rayet bubble, NGC 2359, using the upgraded Giant Metrewave Radio Telescope at Band 3 (250-500 MHz) and Band 4 (550-950 MHz). Additionally, we used complementary archival radio datasets at different frequencies to derive the broad spectral energy distribution (SED) for several regions within the bubble. To further characterize the interaction between the stellar wind and the ambient medium, we introduced a composite SED model including synchrotron and free-free emission, and two low-frequency turnover processes, the Razin-Tsytovich (RT) effect and free-free absorption (FFA).We used a Bayesian inference approach to fit the SEDs and constrain the electron number density and magnetic field strength. The SEDs of several regions reveal spectral indices steeper than -0.5, indicative of synchrotron emission. and show a turnover below ~1 GHz. Our SED modelling suggests that the observed turnover is primarily caused by the RT effect, with a minor contribution from internal FFA. Our analysis confirms the presence of synchrotron radiation within NGC 2359. This is the second detection of non-thermal emission in a stellar bubble surrounding a WR star, reinforcing the idea that such environments are sites of relativistic particle acceleration and supporting the hypothesis that isolated massive stars are sources of GCRs of at least GeV energies.

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arXiv2025

A Seyfert galaxy as a hidden counterpart to a neutrino-associated blazar

The origin and production mechanisms of high-energy astrophysical neutrinos remain open questions in multimessenger astronomy. Previous studies have hinted at a possible linear correlation between the hard X-ray and high-energy neutrino emission in active galactic nuclei. New \textit{NuSTAR} observations, first presented here, reveal that blazar PKS 1424+240, located within a prominent IceCube neutrino hotspot, is far fainter in hard X-rays than expected from this trend. Motivated by this apparent ambiguity, we identify the nearby Seyfert galaxy NGC 5610, also coincident with the hotspot, whose unabsorbed hard X-ray flux exceeds that of PKS 1424+240 by about an order of magnitude. When the local IceCube neutrino flux is apportioned between the two AGN in proportion to their hard X-ray emission, both align with the previously suggested X-ray-neutrino correlation. This suggests that certain IceCube hotspots may be unresolved blends of multiple AGN, and supports a multimessenger scenario in which high-energy neutrinos and hard X-rays originate from the same hadronic interactions, with the X-ray emission produced through cascade reprocessing.

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arXiv2025

Detection of disk-jet co-precession in a tidal disruption event

Theories and simulations predict that intense spacetime curvature near black holes bends the trajectories of light and matter, driving disk and jet precession under relativistic torques. However, direct observational evidence of disk-jet co-precession remains elusive. Here, we report the most compelling case to date: a tidal disruption event (TDE) exhibiting unprecedented 19.6-day quasi-periodic variations in both X-rays and radio, with X-ray amplitudes exceeding an order of magnitude. The nearly synchronized X-ray and radio variations suggest a shared mechanism regulating the emission regions. We demonstrate that a disk-jet Lense-Thirring precession model successfully reproduces these variations while requiring a low-spin black hole. This study uncovers previously uncharted short-term radio variability in TDEs, highlights the transformative potential of high-cadence radio monitoring, and offers profound insights into disk-jet physics.

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arXiv2025

Monte Carlo parameter study for Seyfert AGN-starburst composite galaxies NGC1068 and NGC7469

Seyfert-starburst composite galaxies host two promising phenomena of non-thermal high-energy radiation. In this regard the IceCube observation of high-energy neutrinos from the direction of the Seyfert-starburst composite galaxy NGC 1068 is not surprising. More recently, another Seyfert-starburst composite galaxy, NGC 7469, has shown hints for neutrino emission at even higher energies. Theoretical investigations could clarify that their so-called AGN corona is the most-likely origin of these neutrinos due to the need of being partially $γ$-ray opaque. In this work, we present an updated version of our Seyfert-starburst composite model from 2022, that accounts for a proper treatment of the stochastic acceleration processes in the AGN corona and the secondary electrons and positrons from leptonic radiation processes. Moreover, we use a Markov Chain Monte Carlo (MCMC) approach to study the parameter space of these two potential high-energy neutrino sources under consideration of the given prior knowledge. In the case of NGC 1068, we can successfully explain its non-thermal observational features, where both its AGN corona and starburst ring are needed to account for the observations at high- energies. In the case of NGC 7469, the high-energy signatures can only be explained assuming a small coronal radius and the including external $γγ$-pair attenuation. In general, both sources exhibit a strong influence of the $γ$-ray opaqueness on the results, highlighting the need for an accurate treatment of the intrinsic coronal X-ray field and the spatial extent of the $γ$-ray production site.

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arXiv2025

Millimeter VLBI constraints on the central magnetic field and symmetric jet production in the twin-jet galaxy NGC 1052

This paper investigates the symmetry and magnetic field properties of the jets in the radio galaxy NGC 1052, with particular attention to the impact of the ionized torus that surrounds the central region on the emitted radiation. Our study is based on three new 43 GHz Very-Long-Baseline Interferometry (VLBI) observations and one 86 GHz observation conducted between April 2021 and April 2022. We derive key jet parameters, such as speed, width, and flux density for both jets at the two frequencies and compare them with those obtained from previous VLBI campaigns. Additionally, we present the first (43-86) GHz spectral index image of NGC 1052, which is crucial to assess the role of the torus at high frequencies. Finally, we leverage the derived observational parameters to constrain the magnetic field strength and configuration in the launched jets. We observe variability in the jet morphology at 43 GHz across the three epochs, which can be associated with the propagation of jet knots launched from the nuclear region. The stacked 43 GHz image reveals that the western and receding jet is approximately three times fainter than its eastern (approaching) counterpart in the sub-mas region. This asymmetry, together with the (43-86) GHz spectral index map, suggests that free-free absorption may affect the 43 GHz emission. On the contrary, the jets appear highly symmetric at 86 GHz. From the stacked images at 43 GHz and 86 GHz, we extract the jet width, which is consistent with previous VLBI studies and supports the presence of a parabolic jet profile on very compact scales. Overall, our results suggest that the jets are intrinsically launched symmetrically, and that the observed time-dependent asymmetries may result from free-free absorption by the torus and the downstream propagation of jet components, a scenario supported by previous theoretical studies.

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arXiv2025

Probing the detectability of electromagnetic signatures from Galactic isolated black holes

Context: A large number of isolated black holes (IBHs) are expected to populate the Galaxy. However, only one has been confirmed by the analysis of a microlensing event, and no confirmed emission detection from an IBH has been reported so far. Aims: We analysed the detectability of electromagnetic signatures from IBHs moving in the Galaxy. Methods: We considered accretion from the interstellar medium onto an IBH and assumed the formation of an outflow. We modelled the accretion process and the interaction of the outflow with the surrounding medium on large scales, including mechanical feedback on the accretion process. Furthermore, we also calculated the emission from three different regions: the accretion region, the radiation from the outflow medium interaction structure, and the emission of relativistic particles that diffuse in the surrounding medium. Results: Multiwavelength emission associated with Galactic IBHs can be detected in systems moving through a very dense medium. Thermal emission from accretion could be observed in the mid infrared and in hard X rays with current and forthcoming observatories. Thermal and non thermal emission from the outflow medium shock could also be detected in the radio and millimetre ranges. Moreover, detection of the emission from particles diffusing in a dense medium could be feasible in gamma rays. Applying our model to the IBH associated with the gravitational microlensing event MOA2011BLG191 OGLE2011BLG0462, we inferred that radio and infrared detection of the IBH is plausible. Also, we derived that IBHs could be modest Galactic cosmic ray contributors, potentially reaching a 1% contribution at 1 PeV. Finally, by extending our model to primordial black holes, we conclude that efficient leptonic acceleration in their outflow medium interactions would rule them out as a major dark matter component.

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arXiv2025

A consistent radio to sub-mm pc-scale study of the nucleus of NGC 1068

The origin of radio emission in radio-quiet (RQ) AGN remains a long-standing mystery. We present a detailed study of the cm to sub-mm emission from the nucleus of the nearby prototypical RQ Seyfert 2 galaxy, NGC 1068. We analyse observations between 4.5-706 GHz using $e$-MERLIN, VLA and ALMA. We restricted all data used for imaging to a matching $uv-$range of 15$-$3300 k$λ$, to ensure that all data sampled the same spatial scales. All images were restored with a $\sim$ 0.06$''$ beam. To derive the spectral energy distribution (SED), we fit synchrotron, free-free, dust and coronal component models to these data. We report that the sub-mm excess between $\sim$ 200-700 GHz is consistent with synchrotron emission from a compact and optically thick corona with a radius $R_\mathrm{c}\approx 70\pm5 \,R_\mathrm{g}$, a fraction of $\sim$\,$10\pm2$% of the energy density in the form of non-thermal electrons, and a magnetic field strength $B\approx 148$ G. The luminosity of the corona is roughly consistent with -- though higher than -- the expected from mm--X-ray correlations derived in recent studies of RQ AGN. This difference is likely due to the corona SED peaking at ($\approx$550 GHz). Between 10 and $\sim$ 200 GHz, the SED is dominated by free-free emission. High angular resolution observations at frequencies below 5 GHz are needed to constrain a putative optically thin synchrotron component and the amount of free-free absorption.

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arXiv2025

Radio study of the colliding wind binary HD93129A near periastron and its surroundings

HD93129A is an O+O stellar system whose CWR has been mapped by high angular resolution observations at cm wavelengths. The synchrotron nature of the radio emission confirms its particle accelerator status. According to astrometric measurements since 1996, the system has an orbital period of ~120 yr and recently went through its periastron passage. We characterize the radio emission during the epoch of periastron passage, when the particle density and the local magnetic energy density in the CWR increase. We monitored HD93129A and surroundings at 2.1, 5.5 and 9 GHz with the ATCA over 17 months, with a ~2-month cadence. Previous ATCA data and data collected using other radio observatories were also included. We obtained radio light curves in subbands per band per epoch. The flux densities show an average rise of a factor four from 2003 to 2018, with the caveat that the 2009-2018 time lapse is devoid of data, and a similar decay between 2018 to 2020. We fit the spectral energy distribution of quasi-simultaneous data at three epochs and find that the magnetic-to-thermal pressure ratio does not remain constant along the orbit, possible suggesting magnetic field amplification close to periastron. In the 2019 epoch, we estimate a magnetic field strength of ~1.1G in the apex of the CWR. The evolution of the SED and spectral index is also presented. By combining ATCA and ASKAP images a spectral index map was obtained in an area of 30' size. The radio emission in the direction of other massive binary systems in the field (WR22, WR25 and HD93250) was measured and briefly discussed. Intensive radio monitoring allows us to track the evolution of physical conditions in the shocks. The general trend of decreasing emission of HD93129A in the high-frequency bands in 2019-2020 suggests that the system is at post-periastron, consistent with model predictions. (Abridged)

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arXiv2025

Study of the 2024 major Vela glitch at the Argentine Institute of Radioastronomy

We report here on new results of the systematic monitoring of southern glitching pulsars at the Argentine Institute of Radioastronomy. In particular, we study in this work the new major glitch in the Vela pulsar (PSR J0835$-$4510) that occurred on 2024 April 29. We aim to thoroughly characterise the rotational behaviour of the Vela pulsar around its last major glitch and investigate the statistical properties of its individual pulses around the glitch. We characterise the rotational behaviour of the pulsar around the glitch through the pulsar timing technique. We measured the glitch parameters by fitting timing residuals to the data collected during the days surrounding the event. In addition, we study Vela individual pulses during the days of observation just before and after the glitch. We selected nine days of observations around the major glitch on 2024 April 29 and studied their statistical properties with the Self-Organizing Maps (SOM) technique. We used Variational AutoEncoder (VAE) reconstruction of the pulses to separate them clearly from the noise. We obtain a precise timing solution for the glitch. We find two recovery terms of $\sim 3~\mathrm{days}$ and $\sim 17~\mathrm{days}$. We find a correlation of high amplitude with narrower pulses while not finding notable qualitative systematic changes before and after the glitch.

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