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Simran Nerval

Université de Toronto

Simran a récemment obtenu sa maîtrise à l'Université Queen's et est maintenant doctorante à l'Université de Toronto. Elle estime qu'il est essentiel d'accroître la visibilité des groupes minoritaires, d'accroître la diversité et de contribuer à faire du milieu universitaire un lieu plus accueillant et tolérant. Parallèlement à ses recherches, elle est très engagée dans la sensibilisation du public. Elle est directrice des affaires externes de l'initiative IDEAS (Innovation, Diversité, Exploration et Avancement en STIM) et représentante des étudiants diplômés en éducation et sensibilisation du public à la CASCA, où elle s'efforce de susciter l'enthousiasme des jeunes pour les sciences et de défendre la diversité.


En reliant les observations cosmologiques à la théorie, ses recherches explorent les signaux des premiers instants de notre Univers. Si la cosmologie du Big Bang explique une grande partie de l'histoire de notre Univers, elle n'explique pas certaines caractéristiques, comme la planéité et l'uniformité spatiales de notre Univers. L'inflation cosmologique est une explication largement étudiée de ces caractéristiques. L'objectif de sa thèse de master était de simuler les spectres d'ondes gravitationnelles générés par les configurations de champ d'inflaton oscillant après l'inflation pour les modèles E, T et GRIPI (General Renormalizable Inflection Point Inflation), à l'aide de simulations sur réseau. Sa thèse a montré que ces spectres d'ondes gravitationnelles donnent accès à des modèles d'inflation inaccessibles aux expériences de fond diffus cosmologique (CMB) prévues, telles que LiteBIRD, Simons Observatory et CMB-S4. Plus précisément, alors que ces expériences seront en mesure de résoudre le rapport tenseur/scalaire du spectre de puissance primordial (r) jusqu'à 10−3, elle a montré que les mesures du fond d'ondes gravitationnelles stochastiques (SGWB) ont le potentiel de sonder certains modèles d'inflation pour des valeurs jusqu'à 10−14.


Figure 1 shows stochastic gravitational wave spectra from inflation and sensitivity curves for upcoming and current gravitational wave experiments. The E-Model SGWB spectra sourced by oscillating inflatons are givenforr= 10−4,10−6,10−8,10−10as shown. The T-Models are given forr= 10−4,10−6,10−8,10−10,10−12,10−14as indicated. Also, GRIPI is plotted forr= 1.152×10−3. Sensitivity curves are also shown, both for direct gravitational wave observatories such as BBO, LISA, LIGO, and aLIGO, as well as indirect cosmological probes. Dashed-dotted projected sensitivity curves include the contribution of astrophysical foregrounds while dotted curves do not include astrophysical foregrounds. Solid curves represent bounds on SGWB. The sensitivity curves forBBO, LISA, and aLIGO were taken from [1] and take into account the number of detectors, mission observation time, and the overlap reduction function of each detector pair. The BBO and LISA curves additionally take into account astrophysical foregrounds. The LIGO sensitivity curve for the first observing run (O1), the first and second observing run (O1+O2), and the design sensitivity is taken from the data supplement to [2]. A bound on SGWB contributions to relativistic degrees of freedom, derived from a fit to CMB power, baryon acoustic oscillations, lensing, and primordial nuclear abundances and prospects for an improvement of this cosmologicalSGWB bound, using projected constraints from the COrE and EUCLID satellites is taken from [3]. Importantly, all the inflationary gravitational wave spectra lie in the MHz-GHz frequency range, motivating the development of gravitational wave detectors in this range.
Figure 1 shows stochastic gravitational wave spectra from inflation and sensitivity curves for upcoming and current gravitational wave experiments. The E-Model SGWB spectra sourced by oscillating inflatons are givenforr= 10−4,10−6,10−8,10−10as shown. The T-Models are given forr= 10−4,10−6,10−8,10−10,10−12,10−14as indicated. Also, GRIPI is plotted forr= 1.152×10−3. Sensitivity curves are also shown, both for direct gravitational wave observatories such as BBO, LISA, LIGO, and aLIGO, as well as indirect cosmological probes. Dashed-dotted projected sensitivity curves include the contribution of astrophysical foregrounds while dotted curves do not include astrophysical foregrounds. Solid curves represent bounds on SGWB. The sensitivity curves forBBO, LISA, and aLIGO were taken from [1] and take into account the number of detectors, mission observation time, and the overlap reduction function of each detector pair. The BBO and LISA curves additionally take into account astrophysical foregrounds. The LIGO sensitivity curve for the first observing run (O1), the first and second observing run (O1+O2), and the design sensitivity is taken from the data supplement to [2]. A bound on SGWB contributions to relativistic degrees of freedom, derived from a fit to CMB power, baryon acoustic oscillations, lensing, and primordial nuclear abundances and prospects for an improvement of this cosmologicalSGWB bound, using projected constraints from the COrE and EUCLID satellites is taken from [3]. Importantly, all the inflationary gravitational wave spectra lie in the MHz-GHz frequency range, motivating the development of gravitational wave detectors in this range.

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