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5 Publications visible to you, out of a total of 5
A Gaussian process cross-correlation approach to time-delay estimation in active galactic nuclei

Abstract

Not specified

Authors: F. Pozo Nunez, N. Gianniotis, K.L. Polsterer

Date Published: 18th Apr 2023

Publication Type: Journal

Modeling photometric reverberation mapping data for the next generation of big data surveys. Quasar accretion disks sizes with the LSST

Abstract (Expand)

Abstract Photometric reverberation mapping can detect the radial extent of the accretion disc (AD) in Active Galactic Nuclei by measuring the time delays between light curves observed in different …rves observed in different continuum bands. Quantifying the constraints on the efficiency and accuracy of the delay measurements is important for recovering the AD size-luminosity relation, and potentially using quasars as standard candles. We have explored the possibility of determining the AD size of quasars using next-generation Big Data surveys. We focus on the Legacy Survey of Space and Time (LSST) at the Vera C. Rubin Observatory, which will observe several thousand quasars with the Deep Drilling Fields and up to 10 million quasars for the main survey in six broadband filter during its 10-year operational lifetime. We have developed extensive simulations that take into account the characteristics of the LSST survey and the intrinsic properties of the quasars. The simulations are used to characterise the light curves from which AD sizes are determined using various algorithms. We find that the time delays can be recovered with an accuracy of 5 and 15% for light curves with a time sampling of 2 and 5 days, respectively. The results depend strongly on the redshift of the source and the relative contribution of the emission lines to the bandpasses. Assuming an optically thick and geometrically thin AD, the recovered time-delay spectrum is consistent with black hole masses derived with 30% uncertainty.

Authors: F Pozo Nuñez, C Bruckmann, S Desamutara, B Czerny, S Panda, A P Lobban, G Pietrzyński, K L Polsterer

Date Published: 6th Feb 2023

Publication Type: Journal

Accretion disks, quasars and cosmology: meandering towards understanding

Abstract (Expand)

Abstract As Setti and Woltjer noted back in 1973, one can use quasars to construct the Hubble diagram; however, the actual application of the idea was not that straightforward. It took years to implement …It took years to implement the proposition successfully. Most ways to employ quasars for cosmology now require an advanced understanding of their structure, step by step. We briefly review this progress, with unavoidable personal biases, and concentrate on bright unobscured sources. We will mention the problem of the gas flow character close to the innermost stable circular orbit near the black hole, as discussed five decades ago. This problem later led to the development of the slim disk scenario and is recently revived in the context of Magnetically Arrested Disks (MAD) and Standard and Normal Evolution (SANE) models. We also discuss the hot or warm corona issue, which is still under debate and complicates the analysis of X-ray reflection. We present the scenario of the formation of the low ionization part of the Broad Line Region as a failed wind powered by radiation pressure acting on dust (Failed Radiatively Driven Dusty Outflow – FRADO). Next, we examine the cosmological constraints currently achievable with quasars, primarily concentrating on light echo methods (continuum time delays and spectral-line time delays to the continuum) that are (or should be) incorporating the progress mentioned above. Finally, we briefly discuss prospects in this lively subject area.

Authors: Bożena Czerny, Shulei Cao, Vikram Kumar Jaiswal, Vladimír Karas, Narayan Khadka, Mary Loli Martínez-Aldama, Mohammad Hassan Naddaf, Swayamtrupta Panda, Francisco Pozo Nuñez, Raj Prince, Bharat Ratra, Marzena Sniegowska, Zhefu Yu, Michal Zajaček

Date Published: 1st Feb 2023

Publication Type: Journal

The EURONEAR Lightcurve Survey of Near Earth Asteroids 2017–2020

Abstract

Not specified

Authors: O. Vaduvescu, A. Aznar Macias, T. G. Wilson, T. Zegmott, F. M. Pérez Toledo, M. Predatu, R. Gherase, V. Pinter, F. Pozo Nunez, K. Ulaczyk, I. Soszyński, P. Mróz, M. Wrona, P. Iwanek, M. Szymanski, A. Udalski, F. Char, H. Salas Olave, G. Aravena-Rojas, A. C. Vergara, C. Saez, E. Unda-Sanzana, B. Alcalde, A. de Burgos, D. Nespral, R. Galera-Rosillo, N. J. Amos, J. Hibbert, A. López-Comazzi, J. Oey, M. Serra-Ricart, J. Licandro, M. Popescu

Date Published: 1st Oct 2022

Publication Type: Journal

An Absolute Calibration of the Near-infrared Period–Luminosity Relations of Type II Cepheids in the Milky Way and in the Large Magellanic Cloud

Abstract (Expand)

Abstract We present time-series photometry of 21 nearby type II Cepheids in the near-infrared J , H , and K s passbands. We use this photometry, together with the Third Gaia Early Data Release parallaxes, … K s passbands. We use this photometry, together with the Third Gaia Early Data Release parallaxes, to determine for the first time period–luminosity relations (PLRs) for type II Cepheids from field representatives of these old pulsating stars in the near-infrared regime. We found PLRs to be very narrow for BL Herculis stars, which makes them candidates for precision distance indicators. We then use archival photometry and the most accurate distance obtained from eclipsing binaries to recalibrate PLRs for type II Cepheids in the Large Magellanic Cloud (LMC). Slopes of our PLRs in the Milky Way and in the LMC differ by slightly more than 2 σ and are in a good agreement with previous studies of the LMC, Galactic bulge, and Galactic globular cluster type II Cepheids samples. We use PLRs of Milky Way type II Cepheids to measure the distance to the LMC, and we obtain a distance modulus of 18.540 ± 0.026(stat.) ± 0.034(syst.) mag in the W JK Wesenheit index. We also investigate the metallicity effect within our Milky Way sample, and we find a rather significant value of about −0.2 mag dex −1 in each band meaning that more metal-rich type II Cepheids are intrinsically brighter than their more metal-poor counterparts, in agreement with the value obtained from type II Cepheids in Galactic globular clusters. The main source of systematic error on our Milky Way PLRs calibration, and the LMC distance, is the current uncertainty of the Gaia parallax zero-point.

Authors: Piotr Wielgórski, Grzegorz Pietrzyński, Bogumił Pilecki, Wolfgang Gieren, Bartłomiej Zgirski, Marek Górski, Gergely Hajdu, Weronika Narloch, Paulina Karczmarek, Radosław Smolec, Pierre Kervella, Jesper Storm, Alexandre Gallenne, Louise Breuval, Megan Lewis, Mikołaj Kałuszyński, Dariusz Graczyk, Wojciech Pych, Ksenia Suchomska, Mónica Taormina, Gonzalo Rojas Garcia, Aleksandra Kotek, Rolf Chini, Francisco Pozo Nũnez, Sadegh Noroozi, Catalina Sobrino Figaredo, Martin Haas, Klaus Hodapp, Przemysław Mikołajczyk, Krzysztof Kotysz, Dawid Moździerski, Piotr Kołaczek-Szymański

Date Published: 8th Mar 2022

Publication Type: Journal

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