# Stochastic Speckle Discrimination with Time-Tagged Photon Lists: Digging Below the Speckle Noise Floor

## TL;DR

This paper introduces a photon timing-based algorithm that distinguishes speckles from incoherent sources in high contrast images, enabling detection of exoplanets closer to stars by overcoming speckle noise limitations.

## Contribution

The novel algorithm leverages photon arrival time distributions to separate speckles from incoherent sources, improving high contrast imaging capabilities at small angular separations.

## Key findings

- Can overcome speckle noise limit in simulated data
- Effective when a coronagraph reduces diffraction patterns
- Allows subsequent application of differential imaging techniques

## Abstract

We present an algorithm that uses the distribution of photon arrival times to distinguish speckles from incoherent sources, like planets and disks, in high contrast images. Using simulated data, we show that our approach can overcome the noise limit from fluctuating speckle intensity. The algorithm is likely to be most advantageous when a coronagraph limits the coherent diffraction pattern in the image plane but the intensity is still strongly modulated by fast-timescale uncorrected stellar light, for example from atmospheric turbulence. These conditions are common at small inner working angles and will allow probing of exoplanet populations at smaller angular separations. The technique requires a fast science camera that can temporally resolve the speckle fluctuations, and the detection of many photons per speckle decorrelation time. Since the algorithm directly extracts the incoherent light, standard differential imaging post-processing techniques can be performed afterwards to further boost the signal.