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4 results on '"Rescigno, Umberto"'

1. The first quenched galaxies, when and how?

Author

Xie, Lizhi, De Lucia, Gabriella, Fontanot, Fabio, Hirschmann, Michaela, Bahé, Yannick M, Balogh, Michael L., Muzzin, Adam, Vulcani, Benedetta, Baxter, Devontae C., Forrest, Ben, Wilson, Gillian, Rudnick, Gregory H., Cooper, M. C., and Rescigno, Umberto

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Many quiescent galaxies discovered in the early Universe by \textit{JWST} raise fundamental questions on when and how these galaxies became and stayed quenched. Making use of the latest version of the semi-analytic model GAEA that provides good agreement with the observed quenched fractions up to $z\sim 3$, we make predictions for the expected fractions of quiescent galaxies up to $z\sim 7$ and analyze the main quenching mechanism. We find that in a simulated box of $685~{\rm Mpc}$ on a side, the first quenched massive ($M_{\star} \sim 10^{11} {\rm M}_{\odot}$), Milky Way mass, and low mass ($M_{\star} \sim 10^{9.5} {\rm M}_{\odot}$ ) galaxies appear at $z\sim 4.5$, $z\sim 6.2$, and before $z = 7$. Most quenched galaxies identified at early redshifts remain quenched for more than 1 Gyr. Independently of galaxy stellar mass, the dominant quenching mechanism at high redshift is accretion disk feedback (quasar winds) from a central massive black hole, which is triggered by mergers in massive and MW-mass galaxies, and by disk instabilities in low-mass galaxies. Environmental stripping becomes increasingly more important at lower redshift., Comment: 8 pages, 3 figures, Accepted publication in APJL

Published
2024

2. AN ACCURATE MASS MODEL OF THE GALAXY CLUSTER ABELL 2163 VIA STRONG GRAVITATIONAL LENSING

Author

RESCIGNO, UMBERTO

Abstract

The gravitational lensing effect is the phenomenon for which the electromagnetic radiation, departing from a luminous object is deflected in the proximity of a mass distribution (the gravitational lens), placed between the source and an observer. In the relativistic interpretation, massive objects curve the space-time continuum and light rays, which follow this curvature, are bent passing close to these deflectors. Thus, a gravitational lens essentially acts on light as a normal lens does in geometrical optics. Precise modeling of massive galaxy clusters acting as lenses is crucial: it would help to disentangle the discrepancies emerging between the predictions of the cosmological concordance model and the observations at the scale of collapsed structures. The gravitational lens which is the subject of the present thesis is Abell 2163, one of the most massive galaxy clusters known, at redshift 0.2. Abell 2163 is a challenging system and a goldmine for contemporary astrophysics: its complex structure shows a variety of interacting sub-systems manifesting their activity all over the electromagnetic spectrum. A missing key element to unveil the properties of this cluster is to map its mass distribution at high resolution. We perform such a reconstruction thanks to the presence, in its core, of the typical effects of the strong gravitational lensing regime, such as the presence of multiple images produced from single background sources. Using data from the Multi Unit Spectroscopic Explorer on the VLT, in Chile, we compile and release three astronomical catalogs, confirm known multiple images and discover new lensed galaxies. We then build, test and rank different mass models, using Hubble Space Telescope data and the positions of the observed multiple images as constraints. Finally, we provide the most precise strong lensing mass model of the Abell 2163 core: the model- predicted positions of the multiple images are, on average, only 2.5 pixels away from the observed ones. The precise results of the present thesis can improve a number of scientific programs and can contribute significantly to different lines of research, e.g., the definition of the Abell 2163 merging history and an initial test on a possible self-interaction of the dark matter.

Published
2019
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3. Degenerate dark matter halos of dwarf galaxies as a possible solution to the core-cusp problem

Author

Rescigno, Umberto, thesis supervisor: Nipoti, Carlo, Rescigno, Umberto, and thesis supervisor: Nipoti, Carlo

Abstract

Associating self-gravitating systems of degenerate fermionic matter to DM halos of dwarf galaxies leads to an interesting scenario (Destri et al.,2012), for which these kind of galaxies could be considered as astrophysical objects supported by a pressure having quantum origin. The inequality that defines the Pauli exclusion principle, in fact, can be propagated, in the sense that it can be used to derive other bounds on different quantities; they in turn can be exploited in order to solve some of the problems that the standard cosmological model is facing today, among them, the Core-Cusp Problem (CCP). By means of the semi-classical Thomas-Fermi model, Destri et al. developed a theoretical approach to solve this dichotomy and to test the above-mentioned scenario. Domcke and Urbano also were interested in the topic of degenerate DM halos and developed a procedure to test this possibility. We use their method in order to understand the feasibility of the proposed solution to the CCP and analyzed our results in the context of the Tremaine-Gunn bound on the dark matter particle mass. We suggest that, at least for the dwarf spheroidals analyzed, degenerate Dark matter halo cores are consistent with observations and at the same time are able to solve the CCP, if DM particle candidates have a mass of about 0.1-0.2 keV.

4. Degenerate dark matter halos of dwarf galaxies as a possible solution to the core-cusp problem

Author

Rescigno, Umberto, thesis supervisor: Nipoti, Carlo, Rescigno, Umberto, and thesis supervisor: Nipoti, Carlo

Abstract

Associating self-gravitating systems of degenerate fermionic matter to DM halos of dwarf galaxies leads to an interesting scenario (Destri et al.,2012), for which these kind of galaxies could be considered as astrophysical objects supported by a pressure having quantum origin. The inequality that defines the Pauli exclusion principle, in fact, can be propagated, in the sense that it can be used to derive other bounds on different quantities; they in turn can be exploited in order to solve some of the problems that the standard cosmological model is facing today, among them, the Core-Cusp Problem (CCP). By means of the semi-classical Thomas-Fermi model, Destri et al. developed a theoretical approach to solve this dichotomy and to test the above-mentioned scenario. Domcke and Urbano also were interested in the topic of degenerate DM halos and developed a procedure to test this possibility. We use their method in order to understand the feasibility of the proposed solution to the CCP and analyzed our results in the context of the Tremaine-Gunn bound on the dark matter particle mass. We suggest that, at least for the dwarf spheroidals analyzed, degenerate Dark matter halo cores are consistent with observations and at the same time are able to solve the CCP, if DM particle candidates have a mass of about 0.1-0.2 keV.

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