Juan G. Lebron Medina

arXiv2026

An Extreme Scattering Event Toward PSR J2313+4253

We present evidence of an extreme scattering event (ESE) toward PSR J2313+4253 using high-cadence observations taken with the Green Bank Observatory 20m telescope. The high density of observations in time allow for detailed tracking of the event. We observe a pair of spikes along with the characteristic drop in scintillation bandwidth that is expected during an ESE. This pattern implies that the structures predominantly responsible for scattering occur at different distances than those from previous and subsequent epochs. A secondary spectrum processed during the event shows a detached feature similar to those found in double lensing events from previously observed ESEs. We measure this event as originating from a scattering region with a distance of 1.04(1) kpc, a transverse size of 15 AU, and a duration of approximately 220 days. These rare events provide opportunities to study the properties of small-scale structures in the ISM.

astro-ph.HE↗

arXiv2024

The Pulsar Science Collaboratory: Multi-Epoch Scintillation Studies of Pulsars

We report on findings from scintillation analyses using high-cadence observations of eight canonical pulsars with observing baselines ranging from one to three years. We obtain scintillation bandwidth and timescale measurements for all pulsars in our survey, scintillation arc curvature measurements for four, and detect multiple arcs for two. We find evidence of a previously undocumented scattering screen along the line of sight (LOS) to PSR J1645$-$0317, as well as evidence that a scattering screen along the LOS to PSR J2313$+$4253 may reside somewhere within the Milky Way's Orion-Cygnus arm. We report evidence of a significant change in the scintillation pattern in PSR J2022$+$5154 from the previous two decades of literature, wherein both the scintillation bandwidth and timescale decreased by an order of magnitude relative to earlier observations at the same frequencies, potentially as a result of a different screen dominating the observed scattering. By augmenting the results of previous studies, we find general agreement with estimations of scattering delays from pulsar observations and predictions by the NE2001 electron density model but not for the newest data we have collected, providing some evidence of changes in the ISM along various LOSs over the timespans considered. In a similar manner, we find additional evidence of a correlation between a pulsar's dispersion measure and the overall variability of its scattering delays over time. The plethora of interesting science obtained through these observations demonstrates the capabilities of the Green Bank Observatory's 20m telescope to contribute to pulsar-based studies of the interstellar medium.

astro-ph.HE↗