Astro-Cosmo Journal Club – CFT PAN – Centrum Fizyki Teoretycznej Polskiej Akademii Nauk

Central Engine of AGNs through Optical Spectroscopy

cft — Mon, 23 Feb 2026 13:35:17 +0000

Abstract: Supermassive black holes (SMBHs) are known to co-evolve with their host galaxies, yet the central regions that regulate this co-evolution, specifically the accretion disc and the broad-line region (BLR), are beyond the spatial resolution limits of current telescopes. Reverberation mapping (RM) provides a powerful indirect method for studying unresolved regions by measuring the time delay between variations in the accretion disc continuum and the response of broad emission lines from the BLR. This time delay determines the characteristic size of the BLR and underlies the empirical BLR size–luminosity (R_BLR–L) relation, which is widely used to estimate black hole masses from single-epoch spectra. However, this calibration is weakest at the extremes of the AGN population. At low luminosities, intermediate-mass black holes (IMBHs) are poorly sampled and may not follow the canonical R–L relation. At high luminosities, especially in radio-loud quasars, relativistic jet emission contaminates the optical continuum, biasing luminosity estimates and therefore BLR radius measurements. Furthermore, classical reverberation mapping campaigns require long-term spectroscopic monitoring, making them observationally demanding.

I will present a set of targeted RM studies designed to address these limitations. These include short-timescale RM campaigns of nearby IMBHs, jet–disc decomposition analyses in radio-loud AGNs to quantify how jets bias BLR measurements, and pilot spectrophotometric campaigns to develop geometric distance measurements using AGNs. Together, these efforts improve the calibration of the R_BLR–L relation across a wide luminosity range and explore the potential of AGN-based distance indicators to measure the Hubble constant H₀ with better than 3% precision, providing an independent probe of the ongoing H₀ tension.

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CFT PAN, room 203

Anisotropic cosmography

dev — Fri, 27 Dec 2024 12:19:37 +0000

Abstract: Cosmological data is typically analysed under the model assumptions of exact spatial homogeneity and isotropy in the space-time description of our Universe. However, such symmetries are in reality broken due to the presence of cosmic structure.
I will present cosmographic strategies for analysing data while remaining agnostic about the form of the metric of space-time and the field equations prescribing it.
I will discuss standardisable objects and redshift drift signals as model-independent probes of the kinematics of our Universe. The developed frameworks allow for consistent analyses of anisotropic features in cosmological data.

Speaker: Dr. Asta Heinesen from CRAL-ENS Lyon.

Time and day: November 8th 14:00hrs

Zoom: https://us06web.zoom.us/j/95520345926?pwd=UC8wVnFtTWxpOFdUOUhmZWlZTWFWUT09

Correlations between tiltmeter data and Virgo’s gravitational-wave data

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: Correlations between tiltmeter data and Virgo’s gravitational-wave data

Speaker: Dr. Przemyslaw Figura, Warsaw Astronomical Observatory

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Monday, June 28, 14:00 CET.

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Full sky Integrated Sachs-Wolfe maps for the MICE Grand Challenge lightcone simulation

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: Full sky Integrated Sachs-Wolfe maps for the MICE Grand Challenge lightcone simulation
Speaker: Dr. Krishna Naidoo, Center for Theoretical Physics – CFT PAN
Link: https://arxiv.org/abs/2103.14654

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How gas flows shape the stellar-halo mass relation in the EAGLE simulation

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: How gas flows shape the stellar-halo mass relation in the EAGLE simulation

Speaker: Dr. Peter D. Mitchell, Leiden Observatory – Leiden University

Link: https://arxiv.org/abs/2103.10966

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Including beyond-linear halo bias in halo models

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: Including beyond-linear halo bias in halo models

Speaker: MSc Suhani Gupta, PhD student at Center for Theoretical Physics PAN, Warsaw

Link: https://arxiv.org/abs/2011.08858

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One parameterisation to fit them all

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: One parameterisation to fit them all

Speaker: Dr. Mariana Jaber, Institute for Astronomy, Nicolaus Copernicus University

Link: https://arxiv.org/abs/2102.08561

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The possible astrophysical consequences of a new ultra-diluted gas optical transmittance model

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: The possible astrophysical consequences of a new ultra-diluted gas optical transmittance model

Speaker: MSc Jakub Ratajczak, Centre of New Technologies, University of Warsaw

Abstract

This talk discusses a new model of optical transmittance of ultra-diluted gas. The model considers individual gas particles’ non-locality, the quantum effect of wave function spreading derived from solving the Schrödinger equation for a free particle. I indicate some quantitative and qualitative consequences of this model. One of them is that measured transmittance depends on the detector size. Namely, for small detectors, such a gas’s optical transmittance increases significantly, up to 100%, compared to the classical predictions. The mathematical foundation of the model reveals how the transmittance of a closed system may rise to compare to classic models. I show the connection with classical models by deriving the Beer-Lambert law equation within its applicability range. I also show the relationship with some interpretations of quantum mechanics.

I briefly refer to the conducted lab experiment that measures gas transmittance in parallel with a pair of detectors with different diameters. I discuss results that are in agreement with the model.

Dark and thin interstellar and intergalactic regions seem to be natural regions for such a gas to occur. The transmittance model is a part of the radiation transfer equation. Besides, the model predicts the gas density depends on the intensity of the background radiation field. In this regard, the talk concludes by indicating the possible related astrophysical phenomena.

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Toward a more stringent test of gravity with redshift space power spectrum: simultaneous probe of growth and amplitude of large-scale structure

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: Toward a more stringent test of gravity with redshift space power spectrum: simultaneous probe of growth and amplitude of large-scale structure

Link: https://arxiv.org/abs/2102.01785

Speaker: Dr. Jorge García-Farieta, Center for Theoretical Physics CFT PAN

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Monday, March 8th, 14:00 CET.

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Unfolding the mystery of the galactic halo

dev — Fri, 27 Dec 2024 12:19:37 +0000

Paper: Unfolding the mystery of the galactic halo

Speaker: PhD(c) Manami Roy, Raman Research Institute, Bangalore, India

Abstract: Galaxies have three components: galactic disk, dark matter halo, and diffuse gaseous halo which is also known as Cicumgalactic medium (CGM). It is still a mystery how the different properties (e.g density, temperature, non-thermal component, etc.) of these galactic halos are structured. Due to its diffuse nature, it is very difficult to observe it with emission studies. But observations of absorption lines, gamma-ray background, and radio background come to the rescue here. I am mainly going to talk about theoretical models of CGM and how the observations of the absorption line, gamma-ray background, and radio background unfold the mystery of these galactic halos.

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