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Lens candidates in the Capodimonte Deep Field in the vicinity of the CSL1 object

M. V. Sazhin, O. S. Khovanskaya, M. Capaccioli, G. Longo, J. M. Alcala, R. Silvotti, M. V. Pavlov

TL;DR

CSL1 is investigated as a potential gravitational lens produced by a cosmic string. The authors combine deficit-angle lensing theory, simulations, and multi-band OACDF photometry to search for a statistical excess of lens-like images near CSL1 and to test a predicted angular separation versus flux-ratio signature. Simulations indicate $ angle N \rangle$ of 7–9 lenses for a straight string (and up to ~200 for curved strings with $a \in [0,1]$), while observations yield 11 strong candidates, exceeding the conventional lens expectation of $\langle N \rangle \lesssim 2$; spectroscopic confirmation remains essential. If confirmed, these findings would provide indirect evidence for cosmic strings and demonstrate a practical method to detect non-local lensing effects using deep, multi-band imaging.

Abstract

CSL1 is a peculiar object discovered in the OACDF. Photometric and spectroscopic investigation strongly suggest that it may be the first case of gravitational lensing by cosmic string. In this paper we derive and discuss a statistical excess of a gravitational lens candidates present in OACDF region surrounding CSL1. This excess cannot be explained on the basis of conventional gravitational lens statistic alone, but is compatible with the proposed cosmic string scenario.

Lens candidates in the Capodimonte Deep Field in the vicinity of the CSL1 object

TL;DR

CSL1 is investigated as a potential gravitational lens produced by a cosmic string. The authors combine deficit-angle lensing theory, simulations, and multi-band OACDF photometry to search for a statistical excess of lens-like images near CSL1 and to test a predicted angular separation versus flux-ratio signature. Simulations indicate of 7–9 lenses for a straight string (and up to ~200 for curved strings with ), while observations yield 11 strong candidates, exceeding the conventional lens expectation of ; spectroscopic confirmation remains essential. If confirmed, these findings would provide indirect evidence for cosmic strings and demonstrate a practical method to detect non-local lensing effects using deep, multi-band imaging.

Abstract

CSL1 is a peculiar object discovered in the OACDF. Photometric and spectroscopic investigation strongly suggest that it may be the first case of gravitational lensing by cosmic string. In this paper we derive and discuss a statistical excess of a gravitational lens candidates present in OACDF region surrounding CSL1. This excess cannot be explained on the basis of conventional gravitational lens statistic alone, but is compatible with the proposed cosmic string scenario.

Paper Structure

This paper contains 5 sections, 5 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Criteria for candidates identification
  3. Simulations
  4. The case of OACDF
  5. The angular separation vs magnitude difference test

Figures (2)

  • Figure 1: Spectral distribution derived from OACDF multiband photometry. The solid line refers to the primary object, while the dashed line refer to the secondary (i.e. fainter) component. The vertical lines give the error bars for the different spectral bands.
  • Figure 2: Here correlation of angular distance versus ratio of fluxes of two images is presented. Diamonds show position of experimental dots, while solid line present expected theoretical function obtained in simulations