1. Department of Mathematical and Physical Sciences, College of Arts and Sciences, University of Nizwa, Nizwa, Sultanate of Oman
2. Department of Mathematics, Institute of Applied Sciences and Humanities, GLA University, Mathura-281 406, Uttar Pradesh, India
3. Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu, Natal, Private Bag X54001, Durban 4000, South Africa
4. Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
5. Centro de Astrofísica e Gravitação, CENTRA, Instituto Superior Técnico-IST, Universidade de Lisboa-UL, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
6. Departamento de Ciencias Físicas, Universidad de la Frontera, Casilla 54-D, 4811186 Temuco, Chile