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29.09.26, 11:25
Ultralight axions are a well-motivated dark matter candidate whose large de Broglie wavelength suppresses the growth of structure on small scales, making cosmological observations a powerful probe of their existence. Realizing the full constraining power of current and upcoming surveys, however, requires accurate predictions of nonlinear structure formation in mixed cold dark matter–ultralight...
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29.09.26, 11:45
Parity violation provides a new probe of fundamental physics in the primordial Universe. Recent hints of parity-odd signals in large-scale structure motivate a careful connection between primordial parity-violating non-Gaussianity and late-time observables. We derive the parity-odd matter trispectrum at one-loop order, including the effects of nonlinear gravitational evolution. We then extend...
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29.09.26, 12:00
Detecting the global 21-cm signal from Cosmic Dawn and the Epoch of Reionization requires extremely precise calibration, since instrumental systematics can easily mimic or obscure the cosmological signal. In this work, we investigate the numerical stability of the Bayesian calibration pipeline used by the REACH experiment, which models receiver noise using the noise wave formalism. We identify...
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29.09.26, 12:15
We apply for the first time an alternative approach based on the Renormalization Group (RG) formalism, proposed in Rubira and Schmidt 2023, in which the bias parameters become explicitly dependent on the cut-off scale and are naturally suited for EFT-based field-level inference. Specifically, we use the Lagrangian perturbation theory forward-modeling code $\texttt{LEFTfield}$ to generate mock...
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30.09.26, 09:35
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30.09.26, 09:50
We report the first measurement of the Hubble constant 𝐻_0 using the stochastic gravitational-wave background arising from binary black hole mergers. This astrophysical background is sensitive to the expansion history of the Universe and, thus, can be used for cosmological parameter inference independently of not only electromagnetic methods, but also gravitational-wave standard siren...
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30.09.26, 10:10
Large-scale structure is a powerful probe of dark matter beyond the standard cold paradigm, since even a subdominant warm component can leave observable signatures through its free-streaming effects. In mixed dark matter cosmologies, where cold and warm components evolve jointly, these effects generate not only total density fluctuations but also relative density and velocity perturbations...
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30.09.26, 10:25
Testing the expansion history beyond the redshift range densely sampled by Type Ia supernovae requires independent distance probes with distinct astrophysical systematics. Wide-field time-domain surveys now deliver light curves for hundreds of thousands of quasars, making AGN variability a viable survey-scale distance indicator via the optical/UV variability–luminosity anti-correlation: at...
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117. Yunhe Wang - "Testing HEFT counterterm modeling of baryon feedback with Magneticum simulations"30.09.26, 10:40
Baryon feedback in galaxy-galaxy lensing (GGL) and the combination with galaxy clustering and cosmic shear (3x2pt), and its measurement in hydrodynamical simulations, are much less studied than in cosmic shear alone. Modeling baryonic feedback with counterterms in the hybrid effective field theory (HEFT) has not been tested against realistic baryonic effects from simulations.
This project...
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01.10.26, 14:00
TBC (LSS related)
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01.10.26, 14:20
Upcoming and ongoing large-scale structure surveys are probing the Universe across increasingly large volumes, opening a new window onto relativistic effects that become important on horizon scales. In this talk, I will discuss how these effects enter observed galaxy clustering statistics in redshift space. While the standard Kaiser contribution captures the dominant Newtonian redshift-space...
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01.10.26, 14:40
The cosmological bispectrum is a powerful probe of non-Gaussianity, sensitive to both nonlinear structure formation and primordial physics from inflation. However, measuring the bispectrum in large-scale structure surveys is computationally challenging due to its high dimensionality and observational effects.
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In this talk I present ongoing work extending the MODAL bispectrum estimator to... -
01.10.26, 14:55
Extracting precise cosmological constraints from cosmic shear observations requires accurate modeling of the non-linear matter power spectrum, which is suppressed at small scales ($k\sim$1 to 10$\,h~$Mpc$^{-1}$) due to baryonic feedback. Various hydrodynamical simulations predict different levels of matter power spectrum suppression based on the type and strength of the feedback mechanisms...
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01.10.26, 15:15
Scale-dependent bias, a result of nonlinear modulation of small-scale statistics by long-wavelength modes, is a tell-tale sign of inflationary physics. Through the squeezed-limit bispectrum, the nonlinear coupling depends on both the magnitude ratio and the relative angle between the long and short modes, the latter largely disregarded as inaccessible through two-point correlations of the...
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Fast Radio Bursts (FRBs) are very short transients bright enough to be detected at large cosmological distances. Their source is still unknown, but the radio pulse undergoes dispersion caused by free electrons associated with halos and the large-scale structure. This makes FRBs a sensitive probe of the baryon content in the Universe.
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As the dispersion depends on the frequency, the...
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