White Dwarfs with Infrared Excess from LAMOST Data Release 11

TL;DR

This study systematically identifies white dwarfs with infrared excess using LAMOST DR11 spectra combined with multiple IR surveys, discovering new candidate systems with companions or debris disks, and emphasizing the need for follow-up observations.

Contribution

First large-scale systematic search for IR excess in LAMOST DR11 white dwarfs, identifying new candidate systems with companions or debris disks using multi-survey data.

Findings

Identified 139 IR excess white dwarf candidates, including new systems.

Discovered 18 new WD + M dwarf binaries and 8 new WD + brown dwarf binaries.

Found 38 new dust disk candidates among white dwarfs.

Abstract

Infrared (IR) excess observed around white dwarfs (WDs) is typically attributed to companions or debris disks. These systems are interesting because they offer a unique opportunity to study the late stages of stellar evolution and the interactions between WDs and surrounding material. The 11th data release (DR11) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) - one of the largest spectroscopic surveys to date - has recently provided spectra for 3092 WDs, many of which have yet to be systematically investigated for IR excess. In this study, we cross-correlated the LAMOST DR11 WD catalog with optical and IR surveys, including the Sloan Digital Sky Survey (SDSS), Two Micron All-Sky Survey (2MASS), UKIRT Infrared Deep Sky Survey (UKIDSS), and Wide-field Infrared Survey Explorer (WISE). We performed spectral energy distribution fitting using the VOSA tool for 1818 WDs and identified 167 IR excess WD candidates. After excluding 23 sources with potential contamination within 6" and five additional sources identified through WISE ccf flag analysis, we identified 139 objects with candidate IR excess. These include 30 candidate WD + M dwarf binaries (18 new systems), 19 candidate WD + brown dwarf (BD) binaries (eight new systems), 66 candidate WD + dust disks (38 new systems), and 24 candidate either WD + BD or WD + dust disks (19 new systems). Given the limited spatial resolution of WISE, all candidate systems require follow-up IR observations for confirmation, such as high spatial resolution imaging or IR spectroscopy. This will help expand the parameter space of dust disks, allowing us to explore a broader range of possibilities.