Nonlinear Period-Luminosity Relation for the Large Magellanic Cloud Cepheids: Myths and Truths

Abstract

In this paper, we discuss and examine various issues concerning the recent findings that suggested the observed period-luminosity (P-L) relation for the Large Magellanic Cloud (LMC) Cepheids is nonlinear. These include (1) visualizing the nonlinear P-L relation; (2) long period Cepheids and sample selection; (3) outlier removal; (4) issues of extinction; (5) nonlinearity of the period-color (P-C) relation; (6) nonlinear P-L relations in different pass-bands; and (7) universality of the P-L relation. Our results imply that a statistical test is needed to detect the nonlinear PL relation. We then show that sample selection, number of long period Cepheids in the sample, outlier removal and extinction errors are unlikely to be responsible for the detection of the nonlinear P-L relation. We also argue for the existence of a nonlinear P-L relation from the perspective of the nonlinear P-C relation and the non-universality of the P-L relation. Combining the evidence and discussion from these aspects, we find that there is a strong indication that the observed LMC P-L relation is indeed nonlinear in the optical bands (however the K-band LMC P-L relation is apparently linear). This could be due to the internal physical reasons or the external hidden/additional factors. Compared to the non-linear P-L relation, the systematic error in distance scale introduced from using the (incorrect) linear P-L relation is at most at a few per cent level. While this is small compared to other systematic errors, it will be important in future efforts to produce a Cepheid distance scale accurate to one per cent in order to remove degeneracies presented in CMB results.

22 pages, 8 figures, 1 table, ApJ accepted

References in corpus (28)

• Cosmological parameters from SDSS and WMAP
• Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant
• The Magellanic Clouds Photometric Survey: The Large Magellanic Cloud Stellar Catalog and Extinction Map
• The HST Key Project on the Extragalactic Distance Scale XIII. The Metallicity Dependence of the Cepheid Distance Scale
• New Period-Luminosity and Period-Color Relations of Classical Cepheids: I. Cepheids in the Galaxy
• Cepheid Distances to SNe Ia Host Galaxies based on a Revised Photometric Zero-Point of the HST-WFPC2 and New P-L Relations and Metallicity Corrections
• Cepheid Period-Radius and Period-Luminosity Relations and the Distance to the LMC
• Intermediate-mass star models with different helium and metal contents
• New Period-Luminosity and Period-Color Relations of Classical Cepheids: II. Cepheids in LMC
• Theoretical Models for Classical Cepheids: II. Period-Luminosity, Period-Color and Period-Luminosity-Color Relations
• The effect of metallicity on the Cepheid Period-Luminosity relation from a Baade-Wesselink analysis of Cepheids in the Galaxy and in the Small Magellanic Cloud
• Direct Distances to Cepheids in the Large Magellanic Cloud: Evidence for a Universal Slope of the Period-Luminosity Relation up to Solar Abundance
• Cepheid Calibration of the Peak Brightness of SNe Ia. XI. SN 1998aq in NGC 3982
• Cepheid pulsation models at varying metallicity and DY/DZ
• Theoretical models for classical Cepheids. VIII. Effects of helium and heavy elements abundance on the Cepheid distance scale
• The Araucaria Project. The Distance to the Local Group Galaxy IC 1613 from Near-Infrared Photometry of Cepheid Variables
• Further empirical evidence for the non-linearity of the period-luminosity relations as seen in the Large Magellanic Cloud Cepheids
• Period-color and amplitude-color relations in classical Cepheid variables
• The extra-galactic Cepheid distance scale from LMC and Galactic period-luminosity relations
• The Linearity of the Wesenheit function for the Large Magellanic Cloud Cepheids
• The MACHO Project Large Magellanic Cloud Variable Star Inventory. VIII. The Recent Star Formation History of the LMC from the Cepheid Period Distribution
• GAIA and the Extragalactic Distance Scale
• Reddening map of the Large Magellanic Cloud bar region
• Period-color and amplitude-color relations in classical Cepheid variables III: The Large Magellanic Cloud Cepheid models
• Period-luminosity relations for Galactic Cepheid variables with independent distance measurements
• Period-colour and amplitude-colour relations in classical Cepheid variables IV: The multi-phase relations
• Period-colour and amplitude-colour relations in classical Cepheid variables II: the Galactic Cepheid model
• The Hubble Constant from Type Ia Supernova Calibrated with the Linear and Non-Linear Cepheid Period-Luminosity Relation

Cited by in corpus (20)

• The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 300
• Gaia Data Release 1. Testing the parallaxes with local Cepheids and RR Lyrae stars
• Classical Cepheid Pulsation Models. XI. Effects of convection and chemical composition on the Period-Luminosity and Period-Wesenheit relations
• Period-Luminosity Relations Derived from the OGLE-III Fundamental Mode Cepheids
• Large Magellanic Cloud Near-Infrared Synoptic Survey. II. The Wesenheit relations and their application to the Distance scale
• The Period-Luminosity Relation for the Large Magellanic Cloud Cepheids Derived from Spitzer Archival Data
• High-precision distance measurements with classical pulsating stars
• Large Magellanic Cloud Near-Infrared Synoptic Survey. III. A Statistical Study of Non-Linearity in the Leavitt Laws
• Testing the nonlinearity of the BVIcJHKs period-luminosity relations for the Large Magellanic Cloud Cepheids
• On Cepheid Distance Scale Bias due to Stellar Companions and Cluster Populations
• The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 55
• Temperature Differences in the Cepheid Instability Strip Require Differences in the Period-Luminosity Relation in Slope and Zero Point
• Testing Mass Loss in Large Magellanic Cloud Cepheids using Infrared and Optical Observations
• The Detailed Forms of the LMC Cepheid PL and PLC Relations
• Period-color and amplitude-color relations in classical Cepheid variables V: The Small Magellanic Cloud Cepheid models
• Concerning the Slope of the Cepheid Period-Luminosity Relation
• Investigations of the Non-Linear LMC Cepheid Period-Luminosity Relation with Testimator and Schwarz Information Criterion Methods
• Period-Luminosity Relations Derived From the OGLE-III Fundamental Mode Cepheids II: The Small Magellanic Cloud Cepheids
• A multiphase study of theoretical and observed light curves of classical Cepheids in the Magellanic Clouds
• Precision cosmological measurements: independent evidence for dark energy