Overview of non-transient γ-ray binaries and prospects for the Cherenkov Telescope Array

¹ School of Physical Sciences and CfAR, Dublin City University, Dublin 9, Ireland
e-mail: masha.chernyakova@dcu.ie
² Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
³ Institut für Astronomie und Astrophysik Tübingen, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
⁴ INAF – IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy
⁵ INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, Italy
⁶ Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
⁷ Max-Planck-Institut für Physik, 80805 München, Germany
⁸ INAF – IAPS Roma, Italy
⁹ ISDC, University of Geneva, Switzerland
¹⁰ Astronomical Observatory of Taras Shevchenko National University of Kyiv, 3 Observatorna str. Kyiv, 04053, Ukraine
¹¹ University of the Free State Department of Physics, PO Box 339, 9300 Bloemfontein, South Africa
¹² Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, 08028 Barcelona, Spain
¹³ Dept of Physics and Astronomy, University of Manitoba, Winnipeg R3T 2N2, Canada
¹⁴ Unidad de Partículas y Cosmología (UPARCOS), Universidad Complutense, 28040 Madrid, Spain
¹⁵ EPS Jaén, Universidad de Jaén, Campus Las Lagunillas s/n, 23071 Jaén, Spain
¹⁶ Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Rua Arlindo Bettio 1000, 03828-000 São Paulo, Brazil

Received: 13 August 2019
Accepted: 22 September 2019

Abstract

Aims. Despite recent progress in the field, there are still many open questions regarding γ-ray binaries. In this paper we provide an overview of non-transient γ-ray binaries and discuss how observations with the Cherenkov Telescope Array (CTA) will contribute to their study.

Methods. We simulated the spectral behaviour of the non-transient γ-ray binaries using archival observations as a reference. With this we tested the CTA capability to measure the spectral parameters of the sources and detect variability on various timescales.

Results. We review the known properties of γ-ray binaries and the theoretical models that have been used to describe their spectral and timing characteristics. We show that the CTA is capable of studying these sources on timescales comparable to their characteristic variability timescales. For most of the binaries, the unprecedented sensitivity of the CTA will allow studying the spectral evolution on a timescale as short as 30 min. This will enable a direct comparison of the TeV and lower energy (radio to GeV) properties of these sources from simultaneous observations. We also review the source-specific questions that can be addressed with these high-accuracy CTA measurements.