A sample of 554 white dwarfs showing infrared excess from Gaia EDR3 and CatWISE catalogs^★

¹ Departamento de Física de la Tierra y Astrofísica, Fac. CC. Físicas, Universidad Complutense de Madrid, Plaza de las Ciencias, 1, 28040 Madrid, Spain
e-mail: cmadurga@ucm.es
² Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
³ European Space Agency, Camino Bajo del Castillo, s/n. Urb. Villafranca del Castillo, 28692 Villanueva de la Canada, Madrid, Spain
⁴ Gemini Observatory/NSF’s NOIRLab, 670 N. A’ohoku Place, Hilo, HI 96720, USA
⁵ Institute of Astronomy, University of Cambridge, Madingley Rise, Cambridge CB3 0HA, UK

Received: 5 July 2023
Accepted: 29 May 2024

Abstract

Context. White dwarfs (WDs) are generally intrinsically faint in the infrared (IR). Excess emission in the infrared results from low-mass companions or dusty material, potentially linked to the on-going accretion of planetary material.

Aims. This work presents a new catalog of white dwarfs with (candidate) infrared excess.

Methods. The final sample comes from a cross-match between the Gaia Early Data Release (EDR3) white dwarf candidates, and the CatWISE catalog, with candidate infrared excesses determined considering both magnitude and color excess. A magnitude excess is found to be more reliable than a color excess.

Results. The final catalog contains 554 infrared excess candidates (446 are presented for the first time here) from 41 020 white-dwarf candidates with a Gaia magnitude of G < 18.5 mag. Our infrared excess candidate sample extends to a white-dwarf temperature range of 4500–98 000 K and a white-dwarf mass range of 0.1–1.2 M_⊙. We caution that these objects should be treated as infrared excess candidates until confirmed with other methods.

Conclusions. We present a three-fold increase in the sample of white dwarfs known to have infrared excesses. Among the sample applications is the study of the accretion of planetary material by white dwarfs and the identification of new white-dwarf-brown-dwarf pairs.