Gaia white dwarfs with infrared excess I. The 100 pc catalogue

TL;DR

This work targets the incidence and nature of infrared excess around nearby white dwarfs to probe circumstellar disks and remnants of planetary systems. It builds deep, 100 pc volume-limited SEDs by combining Gaia DR3-based 56-filter J-PAS synthetic photometry with VO infrared data, and then fits white dwarf atmospheres (DA and non-DA) using VOSA, followed by meticulous contamination checks. The study yields 456 infrared-excess white dwarfs (292 robust, 164 tentative), of which ~75% are new identifications, corresponding to a fraction of $5.9\pm0.3\%$ (reliable) and $9.2\pm0.4\%$ (total); the non-DA fraction shows a color-dependent rise, though with caveats. This catalog, the largest and most complete local sample to date, provides prime targets for follow-up to characterize disks, companions, and the composition of accreted planetary material, with data publicly available for community use.

Abstract

The presence of infrared excess flux observed in white dwarfs (WDs) is related to the existence of debris disks or substellar companions. These systems provide important clues in the study of extrasolar planetary material and binary evolution. However, fully characterising their properties requires a statistically significant, complete sample. This work aims to identify a complete sample of WDs with infrared excess emission within 100 pc of the Sun. We built the spectral energy distributions (SEDs) of the WDs using synthetic photometry in 56 optical filters of the J-PAS system, generated from Gaia Data Release 3 low-resolution spectra and complemented with the latest infrared photometry available at the Virtual Observatory (VO). VOSA was used to fit the SEDs with different atmospheric WD models depending on the source spectral type. We visually checked optical and infrared images to identify contaminated photometry. We built a catalogue of 456 infrared excess WDs, of which 292 are robust identifications, and 164 are candidates. 351 ($\sim$75%) are new identifications. This implies a fraction of infrared excess WDs between 5.9$\pm$0.3% and 9.2$\pm$0.4%, higher than previous works, but in agreement with some more recent estimates. Furthermore, for the sample of infrared excess WDs, the fraction of sources with non-hydrogen atmosphere increases with the Gaia GBP-GRP colour, contrary to the general WD population. However, this result should be interpreted with caution. Additionally, a thorough comparison of our catalogue with those of previous studies was performed. The sample of WDs with infrared excess emission within 100 pc presented in this work is the largest, most complete and reliable to date. Due to their proximity, they are ideal targets for follow-up studies aimed at characterising circumstellar disks, substellar companions, and the composition of accreted planetary material.

Figures (5)

• Figure 1: SEDs of two white dwarfs (Gaia DR3 1900545847646195840 and Gaia DR3 5187830356195791488) showing infrared excess emission. The left-hand panel shows an example of a DA model fit, and the right-hand panel an example of a non-DA model fit. Models are shown with blue lines, and the photometric data with black or red points depending on whether excess flux emission with respect to the model is detected or not, respectively.
• Figure 2: Example of a white dwarf SED with contaminated photometry, Gaia DR3 5793469226531573376. Left panel: SED with the photometric data shown with different colours and symbols: J-PAS with green points, 2MASS with orange diamonds, VISTA with blue ovals, and WISE with red squares. The grey line corresponds to the non-DA model that best fits the photometric data. Middle and right panels: DESI (optical) and 2MASS (near-infrared) images, respectively, centred at the Gaia DR3 position of the white dwarf at epoch J2000 (magenta cross), and showing the white dwarf and a nearby field star at the southeast. Gaia DR3 counterparts at epochs J2000 and J2015.4 are shown with green solid and empty circles, respectively. Gaia DR3 proper motion directions are shown with green lines. The line running from south to north is for the white dwarf, while the line running from northeast to southwest is for the nearby field star. The 2MASS counterpart is shown as an orange diamond, the WISE counterpart is shown as a red square, and the VISTA counterparts are shown as blue ovals.
• Figure 3: Gaia Hertzsprung-Russell diagrams for the DAs (left panel) and non-DAs (right panel) with reliable and tentative infrared excess detections. For comparative purposes, we show the 100 pc white dwarf DAs (left panel) and non-DAs (right panel) population from 2023MNRAS.518.5106J.
• Figure 4: Distribution of the fraction of non-DAs with infrared excess relative to the total number of white dwarfs with infrared excess as a function of the Gaia colour. The reliable sample is shown in the left panel, and the total infrared excess sample in the right panel. For comparative purposes, the same ratio for the general population of white dwarfs at 100 pc is shown in grey.
• Figure 5: Distribution of the fraction of white dwarfs with infrared excess with respect to the number of white dwarfs with enough infrared photometry data in function of the Gaia colour.