The Abundance of Clustered Primordial Black Holes from Quasar Microlensing

Fuente: arXiv
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Auteurs principaux: Heydenreich, Sven, Mediavilla, Evencio, Jiménez-Vicente, Jorge, Vives-Arias, Héctor, Muñoz, Jose A.
Format: Preprint
Publié: 2024
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author Heydenreich, Sven
Mediavilla, Evencio
Jiménez-Vicente, Jorge
Vives-Arias, Héctor
Muñoz, Jose A.
author_facet Heydenreich, Sven
Mediavilla, Evencio
Jiménez-Vicente, Jorge
Vives-Arias, Héctor
Muñoz, Jose A.
contents While elementary particles are the favored candidate for the elusive dark matter, primordial black holes (PBHs) have also been considered to fill that role. Gravitational microlensing is a very well-suited tool to detect and measure the abundance of compact objects in galaxies. Previous studies based on quasar microlensing exclude a significant presence of substellar to intermediate-mass BHs ($\lesssim 100\,\mathrm{M}_\odot$). However, these studies were based on a spatially uniform distribution of BHs while, according to current theories of PBHs formation, they are expected to appear in clusters. We study the impact of clustering in microlensing flux magnification finding that at large scales clusters act like giant pseudo-particles, strongly affecting the emission coming from the Broad Line Region, which can no longer be used to define the zero microlensing baseline. As an alternative, we set this baseline from the intrinsic magnification ratios of quasar images predicted by macro lens models and compare them with the observed flux ratios in emission lines, infrared (IR), and radio. The (magnitude) differences are the flux-ratio anomalies attributable to microlensing, which we estimate for 35 image pairs corresponding to 12 lens systems. A Bayesian analysis indicates that the observed anomalies are incompatible with the existence of a significant population of clustered PBHs. Furthermore, we find that more compact clusters exhibit a stronger microlensing impact. Consequently, we conclude that clustering makes the existence of a significant population of BHs in the substellar to intermediate mass range even more unlikely.
format Preprint
id arxiv_https___arxiv_org_abs_2409_04534
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Abundance of Clustered Primordial Black Holes from Quasar Microlensing
Heydenreich, Sven
Mediavilla, Evencio
Jiménez-Vicente, Jorge
Vives-Arias, Héctor
Muñoz, Jose A.
Cosmology and Nongalactic Astrophysics
While elementary particles are the favored candidate for the elusive dark matter, primordial black holes (PBHs) have also been considered to fill that role. Gravitational microlensing is a very well-suited tool to detect and measure the abundance of compact objects in galaxies. Previous studies based on quasar microlensing exclude a significant presence of substellar to intermediate-mass BHs ($\lesssim 100\,\mathrm{M}_\odot$). However, these studies were based on a spatially uniform distribution of BHs while, according to current theories of PBHs formation, they are expected to appear in clusters. We study the impact of clustering in microlensing flux magnification finding that at large scales clusters act like giant pseudo-particles, strongly affecting the emission coming from the Broad Line Region, which can no longer be used to define the zero microlensing baseline. As an alternative, we set this baseline from the intrinsic magnification ratios of quasar images predicted by macro lens models and compare them with the observed flux ratios in emission lines, infrared (IR), and radio. The (magnitude) differences are the flux-ratio anomalies attributable to microlensing, which we estimate for 35 image pairs corresponding to 12 lens systems. A Bayesian analysis indicates that the observed anomalies are incompatible with the existence of a significant population of clustered PBHs. Furthermore, we find that more compact clusters exhibit a stronger microlensing impact. Consequently, we conclude that clustering makes the existence of a significant population of BHs in the substellar to intermediate mass range even more unlikely.
title The Abundance of Clustered Primordial Black Holes from Quasar Microlensing
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2409.04534