Performance simulations tools for Space Telescopes applied to Ariel space mission.

2021 ◽  
Author(s):  
Lorenzo V. Mugnai ◽  
Enzo Pascale ◽  
Billy Edwards ◽  
Andreas Papageorgiou ◽  
Subhajit Sarkar
Keyword(s):  
Software Architecture ◽  
Time Domain ◽  
Data Reduction ◽  
Time Scale ◽  
Space Mission ◽  
Space Telescopes ◽  
Space Instruments ◽  
Future Space ◽  
Candidate Target ◽  
Early Phases

<p>Since the very early phases of designing and developing space instruments, we need fast and reliable tools to validate and optimise the projects. In the framework of the Ariel Space Mission, we developed novel, versatile tools to estimate space instruments performance. </p> <p>ExoSim, a transiting exoplanet observation simulator, is a time domain simulator for space telescopes, that has been developed inside the Ariel framework, but already adapted to both HST and JWST, proving its versatility and its capability to accurately predict science products. It can be used to develop the data reduction pipeline, and to optimise systematics removal techniques.</p> <p>ArielRad, the Ariel radiometric model, is a simulator able to accurately predict the telescope performance in observing a candidate target for all the mission photometric and spectroscopic channels. The software inputs are a target description and a parameterization of the payload, allowing the investigation of different design performance. The software is also able to simulate entire target lists, predicting the observing time and the resulting SNR vs wavelength. Analysing 1000 candidate targets in a 20 minutes time scale, it allows the validation of different observational strategies. The software architecture is based on ExoRad 2, that is publicly available and can be easily adapted to perform the same tasks for other future space missions.</p>

scholarly journals When did Population III star formation end?

2020 ◽  
Vol 497 (3) ◽  
pp. 2839-2854 ◽  
Author(s):  
Boyuan Liu ◽  
Volker Bromm
Keyword(s):  
Star Formation ◽  
Direct Detection ◽  
Analytical Models ◽  
Space Telescopes ◽  
Detection Rates ◽  
Metal Free ◽  
Detection And Identification ◽  
Future Space ◽  
Study Population ◽  
Population Iii

ABSTRACT We construct a theoretical framework to study Population III (Pop III) star formation in the post-reionization epoch (z ≲ 6) by combining cosmological simulation data with semi-analytical models. We find that due to radiative feedback (i.e. Lyman–Werner and ionizing radiation) massive haloes ($M_{\rm halo}\gtrsim 10^{9}\ \rm M_{\odot }$) are the major (≳90 per cent) hosts for potential Pop III star formation at z ≲ 6, where dense pockets of metal-poor gas may survive to form Pop III stars, under inefficient mixing of metals released by supernovae. Metal mixing is the key process that determines not only when Pop III star formation ends, but also the total mass, MPopIII, of active Pop III stars per host halo, which is a crucial parameter for direct detection and identification of Pop III hosts. Both aspects are still uncertain due to our limited knowledge of metal mixing during structure formation. Current predictions range from early termination at the end of reionization (z ∼ 5) to continuous Pop III star formation extended to z = 0 at a non-negligible rate $\sim \!10^{-7}\ \rm M_{\odot }\ yr^{-1}\ Mpc^{-3}$, with $M_{\rm PopIII}\sim 10^{3}-10^{6}\ \rm M_{\odot }$. This leads to a broad range of redshift limits for direct detection of Pop III hosts, zPopIII ∼ 0.5–12.5, with detection rates $\lesssim 0.1-20\ \rm arcmin^{-2}$, for current and future space telescopes (e.g. HST, WFIRST, and JWST). Our model also predicts that the majority (≳90 per cent) of the cosmic volume is occupied by metal-free gas. Measuring the volume-filling fractions of this metal-free phase can constrain metal-mixing parameters and Pop III star formation.

scholarly journals Characteristic Variability Time Scales of Long Gamma-Ray Bursts

2003 ◽  
Vol 214 ◽  
pp. 339-340
Author(s):  
Rongfeng Shen ◽  
Liming Song
Keyword(s):  
Power Density ◽  
Time Scales ◽  
Time Domain ◽  
Time Scale ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Time Dilation ◽  
Dilation Effect ◽  
The Time Domain ◽  
Intrinsic Characteristic

We determine the characteristic variability time scales for 410 bright long GRBs by locating the maximums of their Power Density Spectra (PDSs) defined and calculated in the time domain. The averaged characteristic variability time scale decreases with peak fluxe. This is consistent with the time dilation effect expected by cosmological origin of GRBs. The occurrence distribution of the characteristic variability time scale shows bimodality, which might be interpreted as that the long GRB sample is composed of two sub-classes with different intrinsic characteristic variability time scales.

scholarly journals Thin glass shells for active optics for future space telescopes

2019 ◽  
Vol 11 (4) ◽  
pp. 533-541
Author(s):  
G. Vecchi ◽  
S. Basso ◽  
M. Civitani ◽  
M. Ghigo ◽  
G. Pareschi ◽  
...  
Keyword(s):  
Space Telescopes ◽  
Thin Glass ◽  
Active Optics ◽  
Future Space

scholarly journals An elastic model of Phobos’ libration

2020 ◽  
Vol 636 ◽  
pp. A27
Author(s):  
Yongzhang Yang ◽  
Jianguo Yan ◽  
Xi Guo ◽  
Qingbao He ◽  
Jean-Pierre Barriot
Keyword(s):  
Numerical Model ◽  
Gravity Field ◽  
Numerical Integration ◽  
Elastic Properties ◽  
Rotational Motion ◽  
Space Mission ◽  
Elastic Model ◽  
Shape Model ◽  
Future Space ◽  
Least Squares Fit

Context. Study the rotation of a celestial body is an efficient way to infer its interior structure, and then may give information of its origin and evolution. In this study, based on the latest shape model of Phobos from Mars Express (MEX) mission, the polyhedron approximation approach was used to simulate the gravity field of Phobos. Then, the gravity information was combined with the newest geophysical parameters such as GM and k2 to construct the numerical model of Phobos’ rotation. And with an appropriate angles transformation, we got the librational series respect to Martian mean equator of date. Aims. The purpose of this paper is to develop a numerical model of Phobos’ rotational motion that includes the elastic properties of Phobos. The frequencies analysis of the librational angles calculated from the numerical integration results emphasize the relationship between geophysical properties and dynamics of Phobos. This work will also be useful for a future space mission dedicated to Phobos. Methods. Based on the latest shape model of Phobos from MEX mission, we firstly modeled the gravity field of Phobos, then the gravity coefficients were combined with some of the newest geophysical parameters to simulate the rotational motion of Phobos. To investigate how the elastic properties of Phobos affect its librational motion, we adopted various k2 into our numerical integration. Then the analysis was performed by iterating a frequency analysis and linear least-squares fit of Phobos’ physical librations. From this analysis, we identified the influence of k2 on the largest librational amplitude and its phase. Results. We showed the first ten periods of the librational angles and found that they agree well with the previous numerical results which Phobos was treated as a perfectly rigid body. We also found that the maximum amplitudes of the three parameters of libration are also close to the results from a rigid model, which is mainly due to the inclination of Phobos and moments of inertia. The other amplitudes are slightly different, since the physics contained in our model is different to that of a previous study, specifically, the different low-degree gravity coefficients and ephemeris. The libration in longitude τ has the same quadratic term with previous numerical study, which is consistent with the secular acceleration of Phobos falling onto Mars. We investigated the influence of the tidal Love number k2 on Phobos’ rotation and found a detectable amplitude changes (0.0005°) expected in the future space mission on τ, which provided a potential possibility to constrain the k2 of Phobos by observing its rotation. We also studied the influence of Phobos’ orbit accuracy on its libration and suggested a simultaneous integration of orbit and rotation in future work.

Development of a prototype active optics system for future space telescopes

2018 ◽  
Vol 57 (22) ◽  
pp. E101 ◽  
Author(s):  
Nicholas Devaney ◽  
Fiona Kenny ◽  
Alexander V. Goncharov ◽  
Matthias Goy ◽  
Claudia Reinlein
Keyword(s):  
Space Telescopes ◽  
Active Optics ◽  
Future Space

Thermoacoustic interplay between intrinsic thermoacoustic and acoustic modes: non-normality and high sensitivities

2019 ◽  
Vol 878 ◽  
pp. 190-220 ◽  
Author(s):  
Francesca M. Sogaro ◽  
Peter J. Schmid ◽  
Aimee S. Morgans
Keyword(s):  
Time Domain ◽  
Time Scale ◽  
Initial Conditions ◽  
Normal Modes ◽  
Time Domain Analysis ◽  
Normal Behaviour ◽  
Optimal Perturbation ◽  
Acoustic Modes ◽  
Energy Growth ◽  
The Time Domain

This study analyses the interplay between classical acoustic modes and intrinsic thermoacoustic (ITA) modes in a simple thermoacoustic system. The analysis is performed using a frequency-domain low-order network model as well as a time-domain spatially discretised model. Anti-correlated modal sensitivities are found to arise due to a pairwise interplay between acoustic and ITA modes. The magnitude of the sensitivities increases as the interplay between the modes grows stronger. The results show a global behaviour of the modes linked to the presence of exceptional points in the spectrum. The time-domain analysis results in a delay-differential equation and allows the investigation of non-normal behaviour and its consequences. Pseudospectral analysis reveals that energy amplification is crucially linked to an interplay between acoustic and ITA modes. While higher non-orthogonality between two modes is correlated with peaks in modal sensitivity, transient energy growth does not necessarily involve the most sensitive modes. In particular, growth estimates based on the Kreiss constant demonstrate that transient amplification relies critically on the proximity of the non-normal modes to the imaginary axis. The time scale for transient amplification is identified as the flame time delay, which is further corroborated by determining the optimal initial conditions responsible for the bulk of the non-modal energy growth. The flame is identified as an active and dominant contributor to energy gain. The frequency of the optimal perturbation matches the acoustic time scale, once more confirming an interplay between acoustic and ITA structures. Flame-based amplification factors of two to five are found, which are significant when feeding into the acoustic dynamics and eventually triggering nonlinear limit-cycle behaviour.

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