Coronagraphic time-delay interferometry: characterization and updated geometric properties

TL;DR

This paper explores a novel coronagraphic TDI variable for LISA that can potentially improve sky localization of gravitational wave sources by exploiting its unique signal-canceling properties, validated through simulations.

Contribution

It introduces and validates the use of the coronagraphic TDI variable $$ for practical sky localization of LISA GW sources, expanding its application beyond theoretical considerations.

Findings

Coronagraphic TDI can effectively localize GW sources like GBs and MBHBs.

The method shows promise for low-latency GW source localization.

Potential for glitch vetoing in LISA data analysis.

Abstract

The Laser Interferometer Space Antenna (LISA) will be a space-borne gravitational wave (GW) detector to be launched in the next decade. Central to LISA data analysis is time-delay interferometry (TDI), a numerical procedure which drastically reduces otherwise overwhelming laser frequency noise. LISA data analysis is usually performed on sets of TDI variables, e.g. Michelson variables $(X, Y, Z)$ or quasiorthogonal variables $(A, E, T)$. We investigate a less standard TDI variable denoted $\kappa$ which depends on time, or frequency, and two parameters $(\beta, \lambda)$. This so-called coronagraphic TDI variable has the singular property of canceling GW signal when $(\beta, \lambda)$ tend to the sky position of the GW source. Thanks to this property, coronagraphic TDI has the potential to be an efficient model-agnostic method for sky localization of GW sources with LISA. Those characteristics make it relevant for low-latency searches and a possible glitch veto. Although briefly discussed in the literature, coronagraphic TDI has only been tested on theoretical grounds. In this paper we validate the applicability of $\kappa$ to sky localization of typical LISA sources, namely Galactic binaries (GBs) and massive black hole binaries (MBHBs), when considering a simplified LISA instrument. The goal of this paper is to pave the way for applications of coronagraphic TDI to practical LISA data analysis problems.