arXiv subjects

E. Zubieta

Publications and source records attributed to E. Zubieta.

5 recordsLinked to original sources

arXiv2026

Giant radio pulses in the magnetar XTE J1810-197 detected with the IAR's telescopes

[...] We observed XTE J1810-197 between 29 September 2022 and 14 July 2023 with the radio telescopes at the Argentine Institute of Radioastronomy (IAR). We searched for single pulses in time series at a DM range of 100-400 pc cm-3 , with a threshold in signal-to-noise ratio (S/N) of 8. [...] We found 249 giant pulses at a DM mean value of 178.8$\pm$0.1 pc cm-3 . We measured peak flux densities up to 119 Jy, and fluences up to 58 Jy ms. We fitted a power law distribution to the flux density, obtaining an index of -4.0$\pm$0.3. We observed a maximum rate of approximately 15 pulses per hour on 20 February 2023, followed by an abrupt disappearance of transient radio emission, indicating a transition to a less active state. The brightest single pulses are limited to a $\sim$2$\%$ of the rotational phase and have similar fluence values to the reported intermediate FRB-like bursts of SGR 1935+2154. No significant X-ray activity in the MAXI data was detected during the radio observing period. This is the first study of single radio pulses of a magnetar using IAR data, showing the potential of the upgraded telescopes for investigating the transient radio sky. The properties of the single pulses detected here show the magnetar transient nature and capability to emit high-luminosity pulses. We compared the detected emission to FRB-like bursts and single pulses emitted by SGR 1935+2154. Even though the mechanism producing all the events should be coherent, the luminosity of the events, features on the dynamic spectra, and the difference between being phase confined or not, indicate that XTE J1810-197 presents GP emission, while SGR 1935+2154 only shows normal single pulses or FRB bursts. This could indicate that the conditions for producing each type of event differ.

astro-ph.HE↗

arXiv2025

PSR J0537-6910: Exponential recoveries detected for 12 glitches

Pulsar glitches are unresolved increments of the rotation rate that sometimes trigger an enhancement of the spin-down rate. On occasions, the augmented spin-down decays gradually in an exponential manner, particularly after the largest glitch events. The young pulsar PSR J0537-6910 exhibits the highest known glitching rate, with 60 events detected in nearly 18 years of monitoring. Despite most PSR J0537-6910 glitches being large, only one exponential recovery has been reported, following its first discovered glitch. This is puzzling, as pulsars of similar characteristics typically present significant exponential recoveries. We aim to determine whether this reflects an intrinsic difference in PSR J0537-6910 or a detectability issue, for example due to its high glitch frequency. The full dataset, including recent NICER observations, was systematically searched for exponential relaxations. Each glitch was tested for evidence of a recovery over a broad range of trial timescales. Promising candidates were investigated further by comparing recovery models with and without an exponential term using Bayesian evidence. We discovered six new glitches, bringing the total to 66. Our criteria strongly indicates the presence of 11 previously undetected exponential recoveries. We presente updated glitch and timing solutions. Exponential recoveries are detected only for the largest glitches, though not all of them. The inferred timescales range from 4 to 37 d, with the decaying frequency increment generally below $1\%$ of the total. We find that $\ddotν$ can remain stable across several glitches, with persistent changes associated with only some events. In particular, it tends to be lowest after glitches with exponential recoveries, yielding inter-glitch braking indices between 6 and 9. Following glitches without recoveries, $\ddotν$ is higher, leading to braking indices between 10 and 35.

astro-ph.HE↗

arXiv2024

Glitch-induced pulse profile change of PSR J0742-2822 observed from the IAR

The radio pulsar PSR J0742-2822 is known to exhibit rapid changes between different pulse profile states that correlate with changes in its spin-down rate. However, the connection between these variations and the glitch activity of the pulsar remains unclear. We aim to study the evolution of the pulse profile and spin-down rate of PSR J0742-2822 in the period MJD 58810-60149 (November 2019 to July 2023), which includes the glitch on MJD 59839 (September 2022). In particular, we look for pulse profile or spin-down changes associated with the 2022 glitch. We observed PSR J0742-2822 with high cadence from the Argentine Institute of Radio astronomy (IAR) between November 2019 and July 2023. We used standard timing tools to characterize the times of arrival of the pulses and study the pulsar rotation, and particularly, the oscillations of $\dot ν$. We also study the evolution of the pulse profile. For both of them, we compare their behavior before and after the 2022 glitch. With respect to $\dot ν$, we found oscillations diminished in amplitude after the glitch. We found four different components contributing to the pre-glitch $\dot ν$ oscillations, and only one component after the glitch. About the emission, we found the pulse profile has two main peaks. We detected an increase in the $W_{50}$ of the total pulse profile of $\sim$12% after the glitch and we found the amplitude of the trailing peak increased with respect to the amplitude of the leading one after the glitch. We found significant changes in the pulse profile and the spin-down rate of PSR J0742-2822 after its 2022 glitch. These results suggest that there is a strong coupling between the internal superfluid of the neutron star and its magnetosphere, and that pulse profile changes may be led by this coupling instead of being led purely by magnetospheric effects.

astro-ph.HE↗

arXiv2024

Timing irregularities and glitches from the pulsar monitoring campaign at IAR

Context. Pulsars have a very stable rotation. However, sudden increases in their rotation frequency known as glitches, perturb their evolution. While large glitches are commonly detected, small glitches are harder to detect because of the lack of daily-cadence observations over long periods of time. Aims. We aim to explore the timing behaviour of young pulsars at daily timescales looking for small glitches and other irregularities. This will further our comprehension of the distribution of glitch sizes, which has also consequences for the theoretical modeling of the glitch mechanism. Methods. We observed six pulsars with up to daily cadence during 5 years with the antennas of the Argentine Institute of Radio Astronomy (IAR). We used standard pulsar timing tools to characterise the rotation of pulsars and developed an algorithm to look for small timing events in the data and calculate the changes in $ν$ and $\dotν$ at those epochs. Results. We found that the rotation of pulsars in this dataset is affected by small step changes in $ν$ and $\dotν$. We found three glitches that had not been reported before: two in PSR J1048-5832 with relative sizes $Δν/ ν= 9.1(4) \times 10^{-10}$ and $Δν/ ν= 4.5(1) \times 10^{-10}$, and one in the Vela pulsar with a size $Δν/ ν= 2.0(2) \times 10^{-10}$. We also report new decay terms on the 2021 Vela giant glitch, and on the 2022 giant glitches in PSR J0742-2822 and PSR J1740-3015 respectively. Besides, we found that the red noise contribution significantly diminished in PSR J0742-2822 after its giant glitch in 2022. Conclusions. Our results highlight the importance of high-cadence monitoring with an exhaustive analysis of the residuals to better characterize the distribution of glitch sizes and to deepen our understanding of the mechanisms behind glitches, red noise and timing irregularities.

astro-ph.HE↗

arXiv2023

Pulsar Observations at low latitudes and low frequencies

The Pulsar Monitoring in Argentina (PuMA) is a collaboration between the Argentine Institute for Radioastronomy (IAR) and the Rochester Institute of Technology (RIT) that since 2017 has been observing southern sky pulsars with high cadence using the two restored IAR antennas in the L-Band (1400MHz). We briefly review the first set of results of this program to study transient phenomena, such as magnetars and glitching pulsars, as well as to perform precise timing of millisecond pulsars. Access to lower frequency bands, where most of the pulsars are brighter, would allow us to reach additional pulsars, currently buried into the background noise. We identify two dozen additional glitching pulsars that could be observable in the 400MHz band by the IAR's projected Multipurpose Interferometer Array (MIA). We also discuss the relevance and challenges of single-pulse pulsar timing at low frequencies and the search for Fast Radio Burst (FRB) in the collected data since 2017 using machine learning techniques.

astro-ph.IM↗