e-VLBI with the SFXC correlator

oS(EXPReS09)04

The 60 pc Environment of FRB 20180916B

Fast Radio Burst FRB 20180916B in its host galaxy SDSS J015800.28+654253.0 at 149 Mpc is by far the closest-known FRB with a robust host galaxy association. The source also exhibits a 16.35-day period in its bursting. Here we present optical and infrared imaging as well as integral field spectroscopy observations of FRB 20180916B with the WFC3 camera on the Hubble Space Telescope and the MEGARA spectrograph on the 10.4-m Gran Telescopio Canarias. The 60-90 milliarcsecond (mas) resolution of the Hubble imaging, along with the previous 2.3-mas localization of FRB 20180916B, allow us to probe its environment with a 30-60 pc resolution. We constrain any point-like star-formation or HII region at the location of FRB 20180916B to have an H$\alpha$ luminosity $L_\mathrm{H\alpha} \lesssim 10^{37}\,\mathrm{erg\,s^{-1}}$ and, correspondingly, constrain the local star-formation rate to be $\lesssim10^{-4}\,\mathrm{M_\odot\,yr^{-1}}$. The constraint on H$\alpha$ suggests that possible stellar companions to FRB 20180916B should be of a cooler, less massive spectral type than O6V. FRB 20180916B is 250 pc away (in projected distance) from the brightest pixel of the nearest young stellar clump, which is $\sim380$\,pc in size (full-width at half maximum). With the typical projected velocities of pulsars, magnetars, or neutron stars in binaries (60-750 km s$^{-1}$), FRB 20180916B would need 800 kyr to 7 Myr to traverse the observed distance from its presumed birth site. This timescale is inconsistent with the active ages of magnetars ($\lesssim10$ kyr). Rather, the inferred age and observed separation are compatible with the ages of high-mass X-ray binaries and gamma-ray binaries, and their separations from the nearest OB associations.Comment: Updated version: Updated Figure 2. 16 pages, 4 figures, 1 table. Published in ApJ Letters. Comments welcom

Implementation of a Geodetic Path at the JIVE Correlator

This paper reports on the progress towards the implementation of a complete geodetic path for the EVN Software Correlator at JIVE (SFXC). It is con-ducted as part of the JUMPING JIVE project funded by the Horizon 2020 Framework Programme of the EU.JUMPING JIVE is dedicated to enhance the position of JIVE and the European VLBI Network (EVN) within the future of radio astronomy. This includes implementation of new capabilities, among which is the possibility to correlate geodetic-type experiments and export them in a standard fashion so that they can be further processed by the usual geodetic software packages.The implementation of this new capability requires (i)to make SFXC able to handle complex geodetic-like schedules with sub-netting, and (ii) to incorporate total quantities and measured phase-cal values in the data provided to the users. To facilitate post-processing, it was also decided to convert the correlator output to the standard geodetic Mark4 format. All such developments are now complete. To test the implementation,we have reprocessed IVS session R1872 and compared the output from SFXC with that obtained at the DIFX correlator in Bonn, where the session was originally processed. The methodology is explained here and partial results of the comparison are given. These indicate a 5.5 ps wrms for the Total Multiband Delay difference between the two correlator

Geodesy at K-band with the European VLBI Network

The paper presents the current status of adding geodetic capabilities to the European VLBI Network (EVN) software correlator at JIVE (SFXC), which is accomplished as part of the JUMPING JIVE project. Even though the EVN is not a geodetic array, there are many reasons why accurate radio telescope positions are desirable, including frequent observations using the phase-referencing technique to detect weak radio sources. Several changes were made at the SFXC so that the correlator can successfully correlate geodetic experiments. Detailed testing using data from the International VLBI Service for geodesy and astrometry (IVS) was performed to check the implementation. Additionally, a non-standard geodetic VLBI experiment was carried out at K-band (22 GHz) in June 2018 using 14 radio telescopes from the EVN. The purpose of this experiment was to determine accurate geodetic positions for those EVN telescopes that do not possess S/X receivers and hence do not participate in regular experiments organized by the IVS.The experiment was fully correlated with SFXC and exported into Mk4 format so that it can be further processed with standard geodesy software packages. That experiment is used as another means to demonstrate the full geodetic capabilities of the JIVE correlator