KSwAGS: A Swift X-ray and UV Survey of the Kepler Field. I

TL;DR

KSwAGS is a pioneering simultaneous X-ray and UV survey of the Kepler field, detecting diverse sources and developing classification methods based on spectral energy distributions, with ongoing efforts to fully identify the sample.

Contribution

This paper introduces the first phase of KSwAGS, a novel survey combining X-ray and UV observations of the Kepler field, and demonstrates a new classification approach using SEDs.

Findings

Detected 93 X-ray sources with UV counterparts.

Constructed SEDs that differentiate source types.

Provided first X-ray and UV data for many variable stellar sources.

Abstract

We introduce the first phase of the Kepler-Swift Active Galaxies and Stars survey (KSwAGS), a simultaneous X-ray and UV survey of ~6 square degrees of the Kepler field using the Swift XRT and UVOT. We detect 93 unique X-ray sources with S/N>3 with the XRT, of which 60 have observed UV counterparts. We use the Kepler Input Catalog (KIC) to obtain the optical counterparts of these sources, and construct the X-ray to optical flux ratio as a first approximation of the classification of the source. The survey produces a mixture of stellar sources, extragalactic sources, and sources which we are not able to classify with certainty. We have obtained optical spectra for thirty of these targets, and are conducting an ongoing observing campaign to fully identify the sample. For sources classified as stellar or AGN with certainty, we construct SEDs using the 2MASS, UBV and GALEX data supplied for their optical counterparts by the KIC, and show that the SEDs differ qualitatively between the source types, and so can offer a method of classification in absence of a spectrum. Future papers in this series will analyze the timing properties of the stars and AGN in our sample separately. Our survey provides the first X-ray and UV data for a number of known variable stellar sources, as well as a large number of new X-ray detections in this well-studied portion of the sky. The KSwAGS survey is currently ongoing in the K2 ecliptic plane fields.