Effects of thermal and exozodiacal background on space telescope observations of exoEarths

One of the major goals of the exoplanet community in the coming decades is to detect Earth-like exoplanets (exoEarths) and look for biomarkers in their atmospheres. High-dispersion coronagraphy (HDC) may allow detection and characterization to be done simultaneously, as well as relax the starlight suppression requirements of the telescope and coronagraph. However, similar to other direct imaging techniques, HDC faces challenging thermal and/or exozodiacal background levels. In this paper, we present simulations of coronagraphic observations using a variety of space telescope apertures ranging in diameter from 1 to 15 m, specifically incorporating thermal and exozodiacal background. We investigate the effects of instrument temperature and aperture on the maximum usable wavelength, as well as the effects of exozodiacal disk inclination and thickness on observational SNR. We then identify the spectral resolutions which maximize observational SNR subject to detector noise and the required starlight suppression levels for the detection of various potential biomarker molecules (H_2O, O_2, CO_2, and CH_4)

Fast linearized coronagraph optimizer (FALCO) III: optimization of key coronagraph design parameters

Deformable mirrors (DMs) are increasingly becoming part of nominal coronagraph designs, such as the hybrid Lyot coronagraph, in addition to their role counteracting optical aberrations. Previous studies have investigated the effects of the inter-DM Fresnel number on achievable contrast, throughput, and tip/tilt sensitivity for apodized coronagraphs augmented with DMs to suppress diffraction from struts and segment gaps. In this paper, we build upon that previous work by directly suppressing tip/tilt sensitivity with the controller, both for coronagraphs with and without apodizers. We also explore the effects of other important design parameters such as actuator density and tip/tilt controller weighting on performance. These comprehensive coronagraph design studies are enabled by the Fast Linearized Coronagraph Optimizer (FALCO) software toolbox, which provides rapid re-calculation of the DM response matrix for a variety of coronagraphs

The high-contrast spectroscopy testbed for segmented telescopes (HCST): new wavefront control demonstrations

The High-Contrast Spectroscopy Testbed for Segmented Telescopes (HCST) in the Exoplanet Technology Laboratory (ET Lab) at Caltech is designed to test the technologies that will enable direct imaging and characterization of exoplanets with future segmented ground- and space-based telescopes. Wavefront sensing and control has been successfully implemented with electric field conjugation (EFC) using the FALCO Matlab package, yielding a baseline raw contrast of 1×10^(-8) in narrowband light with a Vector Vortex Coronagraph over a clear aperture. Here we report on progress towards our next HCST milestones: 1- Demonstration of 10^(-8) raw contrast levels in broadband light with the apodized vortex coronagraph using a LUVOIR B-like segmented aperture. 2- Integration of a fiber injection unit (FIU) and corresponding wavefront control algorithm to achieve 10^(-8) raw contrast in broadband light through a single mode fiber enabling high dispersion coronagraphy

Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-line Analysis for NGC 5548

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multiwavelength reverberation mapping campaign. The campaign spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes. The Hβ and He ii λ4686 broad emission-line light curves lag that of the 5100 +-optical continuum by 4.17+0.36-0.36 and 0.79+0.35-0.34 days, respectively. The Hβ lag relative to the 1158 ultraviolet continuum light curve measured by the Hubble Space Telescope is ∼50% longer than that measured against the optical continuum, and the lag difference is consistent with the observed lag between the optical and ultraviolet continua. This suggests that the characteristic radius of the broad-line region is ∼50% larger than the value inferred from optical data alone. We also measured velocity-resolved emission-line lags for Hβ and found a complex velocity-lag structure with shorter lags in the line wings, indicative of a broad-line region dominated by Keplerian motion. The responses of both the Hβ and He ii emission lines to the driving continuum changed significantly halfway through the campaign, a phenomenon also observed for C iv, Lyα, He ii(+O iii]), and Si iv(+O iv]) during the same monitoring period. Finally, given the optical luminosity of NGC 5548 during our campaign, the measured Hβ lag is a factor of five shorter than the expected value implied by the R BLR-L AGN relation based on the past behavior of NGC 5548