Asgard NOTT: L-band nulling interferometry at the VLTI I Simulating the expected high-contrast performance by Romain Laugier et al. on Monday 21 November

Context: NOTT (formerly Hi-5) is a new high-contrast L' band (3.5-4.0 \textmu

m) beam combiner for the VLTI with the ambitious goal to be sensitive to young

giant exoplanets down to 5 mas separation around nearby stars. The performance

of nulling interferometers in these wavelengths is affected both by fundamental

noise from the background and by the contributions of instrumental noises. This

motivates the development of end-to-end simulations to optimize these

instruments. Aims: To enable the performance evaluation and inform the design

of such instruments on the current and future infrastructures, taking into

account the different sources of noise, and their correlation. Methods:

SCIFYsim is an end-to-end simulator for single mode filtered beam combiners,

with an emphasis on nulling interferometers. It is used to compute a covariance

matrix of the errors. Statistical detection tests based on likelihood ratios

are then used to compute compound detection limits for the instrument. Results:

With the current assumptions on the performance of the wavefront correction

systems, the errors are dominated by correlated instrumental errors down to

stars of magnitude 6-7 in the L band, beyond which thermal background from the

telescopes and relay system becomes dominant. Conclusions: SCIFYsim is suited

to anticipate some of the challenges of design, tuning, operation and signal

processing for integrated optics beam combiners. The detection limits found for

this early version of NOTT simulation with the unit telescopes are compatible

with detections at contrasts up to $10^5$ in the L band at separations of 5 to

80 mas around bright stars.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.09548v1