Cool white dwarfs as standards for infrared observations

Abstract

In the era of modern digital sky surveys, uncertainties in the flux of stellar standards are commonly the dominant systematic error in photometric calibration and can often affect the results of higher-level experiments. The Hubble Space Telescope (HST) spectrophotometry, which is based on computed model atmospheres for three hot (Teff > 30,000 K) pure-hydrogen (DA) white dwarfs, is currently considered the most reliable and internally consistent flux calibration. However many next generation facilities (e.g. Harmoni on E-ELT, Euclid and JWST) will focus on IR observations, a regime in which white dwarf calibration has not yet been robustly tested. Cool DA white dwarfs have energy distributions that peak close to the optical or near-IR, do not have shortcomings from UV metal line blanketing, and have a reasonably large sky density ($\simeq$ 4 deg${}^{-2}$ at G < 20), making them, potentially, excellent calibrators. Here we present a pilot study based on STIS+WFC3 observations of two bright DA white dwarfs to test whether targets cooler than current hot primary standards (Teff < 20,000 K) are consistent with the HST flux scale. We also test the robustness of white dwarf models in the IR regime from an X-shooter analysis of Paschen lines and by cross-matching our previously derived Gaia white dwarf catalogue with observations obtained with 2MASS, UKIDSS, VHS, and WISE.

12 pages, 8 figures, 2 tables. Accepted for publication in MNRAS. The best fitting models to the two white dwarfs analyzed are available from \<http://deneb.astro.warwick.ac.uk/phrhcc/WD_models.tar>

References in corpus (31)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• Gaia Data Release 2. Summary of the contents and survey properties
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• Gaia Data Release 2: Photometric content and validation
• Automated data reduction workflows for astronomy
• The Pan-STARRS1 Surveys
• The Formation Rate, Mass and Luminosity Functions of DA White Dwarfs from the Palomar Green Survey
• An Improved Spectroscopic Analysis of DA White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• A $Gaia$ Data Release 2 catalogue of white dwarfs and a comparison with SDSS
• Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements
• Spectroscopic Analysis of DA White Dwarfs: Stark Broadening of Hydrogen Lines Including Non-Ideal Effects
• A Spectroscopic Survey & Analysis of Bright, Hydrogen-Rich White Dwarfs
• Spectroscopic analysis of DA white dwarfs with 3D model atmospheres
• Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared
• Tests of the Accelerating Universe with Near-Infrared Observations of a High-Redshift Type Ia Supernova
• Simulations of the WFIRST Supernova Survey and Forecasts of Cosmological Constraints
• A Dusty Disk Around GD 362, a White Dwarf With a Uniquely High Photospheric Metal Abundance
• Systematic Uncertainties Associated with the Cosmological Analysis of the First Pan-STARRS1 Type Ia Supernova Sample
• On the Measurement of Fundamental Parameters of White Dwarfs in the Gaia Era
• Scientific Discovery with the James Webb Space Telescope
• Fundamental parameter accuracy of DA and DB white dwarfs in Gaia Data Release 2
• The Euclid mission design
• 3D Model Atmospheres for Extremely Low-Mass White Dwarfs
• A New Generation of Cool White Dwarf Atmosphere Models. IV. Revisiting the Spectral Evolution of Cool White Dwarfs
• The Gaia DR1 Mass-Radius Relation for White Dwarfs
• Sub-percent Photometry: Faint DA White Dwarf Spectophotometric Standards for Astrophysical Observatories
• A possible solution to the Lyman/Balmer line problem in hot DA white dwarfs

Cited by in corpus (19)

• A catalogue of white dwarfs in Gaia EDR3
• The Dark Energy Survey Data Release 2
• $Gaia$ white dwarfs within 40 pc II: the volume-limited northern hemisphere sample
• New Grids of Pure-Hydrogen White-Dwarf NLTE Model Atmospheres \newline and the HST/STIS Flux Calibration
• The 40 pc sample of white dwarfs from Gaia
• $\text{Gaia}$ white dwarfs within 40 pc I: spectroscopic observations of new candidates
• $\text{Gaia}$ white dwarfs within 40 pc III: spectroscopic observations of new candidates in the southern hemisphere
• 3D spectroscopic analysis of helium-line white dwarfs
• Spectral analysis of ultra-cool white dwarfs polluted by planetary debris
• The spectral evolution of white dwarfs: where do we stand?
• J-PLUS: Spectral evolution of white dwarfs by PDF analysis
• A New Method for Finding Nearby White Dwarf Exoplanets and Detecting Biosignatures
• The entry geometry and velocity of planetary debris into the Roche sphere of a white dwarf
• Infrared Absolute Calibration I: Comparison of Sirius with Fainter Calibration Stars
• Serendipitous discovery of a dusty disc around WDJ181417.84-735459.83
• A network of cooler white dwarfs as infrared standards for flux calibration
• The miniJPAS survey: White dwarf science with 56 optical filters
• J-PLUS: The fraction of calcium white dwarfs along the cooling sequence
• J-PLUS: Understanding outlier white dwarfs in the third data release via dimensionality reduction