Survey of compact sources for pulsars and exotic objects -- I. Overview and initial discoveries

TL;DR

This paper presents the initial results of the SCOPE survey, which uses interferometric and time-domain radio observations to discover and characterize pulsars and exotic sources, including two new millisecond pulsars.

Contribution

It introduces the SCOPE survey methodology, sample selection, and reports the discovery of two new millisecond pulsars with steep spectra.

Findings

Discovered two millisecond pulsars, J1840+1102 and J1827-0849.

Provided morphological classification and spectral modeling of sources.

Identified extragalactic sources and characterized their spectra.

Abstract

Targeted searches for pulsars based on their counterparts in radio images have resulted in the discovery of interesting pulsars including the first ever discovered millisecond pulsar (MSP). We are conducting an image-based pulsar survey, survey of compact sources for pulsars and exotic objects (SCOPE), that utilizes interferometric as well as time-domain observations to search for radio pulsations as well as characterize the sources in the image-domain to identify their true nature. In the first stage of the SCOPE survey, we have used the Giant Metrewave Radio Telescope (GMRT) and the Green Bank Telescope (GBT) to follow up a sample of 31 compact and steep-spectrum sources. We provide an overview of the survey, the sample selection, the search procedures, and present discoveries of two MSPs -- J1840+1102 and J1827-0849. J1840+1102 is a 1.6 ms pulsar at the edge of the Scutum-Centaurus arm, while J1827-0849 is the radio counterpart of a gamma-ray pulsar that was earlier thought to be radio-quiet, and both the sources have very steep radio spectra. Using the interferometric data, we also provide a morphological classification of all the sources, model and characterize their spectra and identify the resolved, extragalactic sources in our sample. We discuss these results in the context of future image-based pulsar surveys.