Gravitational Lensing By a Massive Object in a Dark Matter Halo. I. Critical Curves and Caustics

Abstract

We study the gravitational lensing properties of a massive object in a dark matter halo, concentrating on the critical curves and caustics of the combined lens. We model the system in the simplest approximation by a point mass embedded in a spherical Navarro$-$Frenk$-$White density profile. The low number of parameters of such a model permits a systematic exploration of its parameter space. We present galleries of critical curves and caustics for different masses and positions of the point in the halo. We demonstrate the existence of a critical mass, above which the gravitational influence of the centrally positioned point is strong enough to eliminate the radial critical curve and caustic of the halo. In the point-mass parameter space we identify the boundaries at which critical-curve transitions and corresponding caustic metamorphoses occur. The number of transitions as a function of position of the point is surprisingly high, ranging from three for higher masses to as many as eight for lower masses. On the caustics we identify the occurrence of six different types of caustic metamorphoses. We illustrate the peculiar properties of the single radial critical curve and caustic appearing in an additional unusual non-local metamorphosis for a critical mass positioned at the halo center. Although we constructed the model primarily to study the lensing influence of individual galaxies in a galaxy cluster, it can also be used to study the lensing by dwarf satellite galaxies in the halo of a host galaxy, as well as (super)massive black holes at a general position in a galactic halo.

arXiv comment23 pages, 13 figures, accepted to ApJ

References in corpus (31)

• Planck 2015 results. XIII. Cosmological parameters
• The Structure of Cold Dark Matter Halos
• Detection of lensing substructure using ALMA observations of the dusty galaxy SDP.81
• The distribution of dark matter in galaxies
• The Density Profiles of Massive, Relaxed Galaxy Clusters. I. The Total Density Over Three Decades in Radius
• Cluster Lenses
• The Frontier Fields Lens Modeling Comparison Project
• A New Sample of (Wandering) Massive Black Holes in Dwarf Galaxies from High Resolution Radio Observations
• CLASH: The Concentration-Mass Relation of Galaxy Clusters
• The Mass Profile and Accretion History of Cold Dark Matter Halos
• An excess of small-scale gravitational lenses observed in galaxy clusters
• Mass profiles of Galaxy Clusters from X-ray analysis
• Pseudo Elliptical Lensing Mass Model: Application to the NFW Mass Distribution
• Cluster-galaxy weak lensing
• Extended-Source Effect and Chromaticity in Two-Point-Mass Microlensing
• LoCuSS: The Mass Density Profile of Massive Galaxy Clusters at z=0.2
• Dark matter halos of massive elliptical galaxies at $z\sim 0.2$ are well described by the Navarro-Frenk-White profile
• Lensing Constraints on the Mass Profile Shape and the Splashback Radius of Galaxy Clusters
• Two families of astrophysical diverging lens models
• The concentration-mass relation of clusters of galaxies from the OmegaWINGS survey
• The Influence of Central Black Holes on Gravitational Lenses
• Growing a `Cosmic Beast': Observations and Simulations of MACS J0717.5+3745
• Evidences against cuspy dark matter halos in large galaxies
• Gravitational Lensing Signatures of Supermassive Black Holes in Future Radio Surveys
• Hunting for wandering massive black holes
• Mass Modeling of Frontier Fields Cluster MACS J1149.5+2223 Using Strong and Weak Lensing
• Strong Lensing by Binary Galaxies Modelled as Isothermal Spheres
• A Simple Model for Lensing by Black Holes in Galactic Nuclei
• Lensing by a singular isothermal sphere and a black hole
• Critical Lines in Gravitational Lenses and the Determination of Cosmological Parameters
• Analytic Solutions for Navarro--Frenk--White Lens Models for Low Characteristic Convergences