Synthetic Population of Binary Cepheids. II. The effect of companion light on the extragalactic distance scale

Abstract

Because of their period-luminosity relation (PLR), classical Cepheids play a key role in the calibration of the extragalactic distance scale and the determination of the Hubble-Lemaître constant $H_0$. Recent findings show that the majority of classical Cepheids should be in binary or multiple systems, which might undermine their accuracy, as the extra -- and unaccounted for -- light from the companions of Cepheids causes a shift in the PLR. We quantify this shift using synthetic populations of binary Cepheids that we developed for this purpose, as described in Paper I of this series. We find that while all PLRs are shifted toward brighter values due to the excess light from the companions, the bias in the relative distance modulus between two galaxies hosting binary Cepheids can be either positive or negative, depending on the percentage of binary Cepheids in them. If the binarity percentage in the two galaxies is similar, the effect of binarity is canceled. Otherwise, it introduces a shift in the distance modulus of the order of millimags in the near-infrared passbands and Wesenheit indices, and tens of millimags in the visual domain; its exact value depends on the variant of the synthetic population (a unique combination of metallicity, star formation history, shape and location of the instability strip, and initial parameter distributions). Such shifts in distance moduli to type Ia supernova host galaxies introduce an additional statistical error on $H_0$, which however does not prevent measuring $H_0$ with a precision of 1%.

16 pages, 11 figures, accepted for publication in The Astrophysical Journal

References in corpus (15)

• Array Programming with NumPy
• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM
• YBC, a stellar bolometric corrections database with variable extinction coefficients: an application to PARSEC isochrones
• Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2 - I. Binarity from proper motion anomaly
• An Improved Calibration of the Wavelength Dependence of Metallicity on the Cepheid Leavitt law
• A 0.9% Calibration of the Galactic Cepheid luminosity scale based on Gaia DR3 data of open clusters and Cepheids
• The influence of metallicity on the Leavitt Law from geometrical distances of Milky Way and Magellanic Clouds Cepheids
• Classical Cepheid period-Wesenheit-metallicity relation in the Gaia bands
• Vetting Galactic Leavitt Law Calibrators using Radial Velocities: On the Variability, Binarity, and Possible Parallax Error of 19 Long-period Cepheids
• The occurrence of classical Cepheids in binary systems
• Cepheids with giant companions. I. Revealing a numerous population of double-lined binary Cepheids
• On the dynamical evolution of Cepheids in star clusters
• Synthetic population of binary Cepheids. I. The effect of metallicity and initial parameter distribution on characteristics of Cepheids' companions
• Calibrating the Cepheid Period--Wesenheit Relation in the Gaia Bands using Galactic Open Cluster Cepheids

Cited by in corpus (5)

• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Period-Luminosity Relations for Galactic classical Cepheids in the Sloan bands
• The stellar evolution perspective on the metallicity dependence of classical Cepheid Leavitt laws
• Non-evolutionary effects on period change in Magellanic Cepheids I. New binary systems revealed from Light Travel Time Effect
• Orbit determination for the binary Cepheid V1344 Aql