In this talk we will discuss boson star configurations in quantum field theory using the semiclassical gravity approximation. Restricting our attention to the static case, we show that the semiclassical Einstein- Klein-Gordon system for a single real quantum scalar field whose state describes the excitation of N identical particles, each one corresponding to a given energy level, can be reduced to the Einstein- Klein-Gordon system for N complex classical scalar fields. Particular consideration is given to the spherically symmetric static scenario, where energy levels are labeled by quantum numbers n, l and m. When all particles are accommodated in the ground state n = l = m = 0, one recovers the standard static boson star solutions. On the other hand, for the case where all particles have fixed radial and total angular momentum numbers n and l, but are homogeneously distributed with respect to their magnetic number m, one obtains the l-boson stars, whereas when l = m = 0 and n takes multiple values, the multi-state boson star solutions are obtained.Thus, we have shown that in semiclassical gravity, Boson Stars relatives arise naturally as the quantum fluctuations associated with the state of a single field describing a many-body system.

# Boson stars and their relatives in semiclassical gravity

## Next Seminar

## New post-Newtonian results for compact binaries in general relativity and scalar-tensor theories

## Next Journal Club

## Discussion of the paper "Impact of theoretical uncertainties on model parameter reconstruction from GW signals sourced by cosmological phase transitions", by Marek Lewicki, et al.

## Black Hole Workshops

Next workshop:

XVII Black Holes Workshop, Aveiro,

19-20 December 2024

Previous workshops in the series:

I Black Holes Workshop, Porto, 2008

II Black Holes Workshop, Lisbon, 2009

III Black Holes Workshop, Minho, 2010

IV Black Holes Workshop, Aveiro, 2011

V Black Holes Workshop, Lisbon, 2012

VI Black Holes Workshop, Minho 2013

VII Black Holes Workshop, Aveiro 2014

VIII Black Holes Workshop, Lisbon 2015

IX Black Holes Workshop, Minho 2016

X Black Holes Workshop, Aveiro 2017

XI Black Holes Workshop, Lisbon, 2018

XII Black Holes Workshop, Minho, 2019

XIII Black Holes Workshop, Lisbon, 2020

XIV Black Holes Workshop, Aveiro, 2021

XV Black Holes Workshop, Lisbon, 2022

XVI Black Holes Workshop, Porto, 2023

## Numerical data

## NewFunFICO network

Our group coordinates the Marie Sklodowska Curie Staff Exchange NewFunFiCO network (Jan 2023- Dec 2026)

More info here

## FunFiCO Network

Our group coordinates the Marie Curie RISE FunFiCO network (Dec 2017- Dec 2023)

More info here

## EuCAPT Consortium

## GWVerse COST

## StronGrHEP Network

Our group was part of the RISE StronGrHEP network (2016-2019)

Meetings:

Paris, 12-13 May 2016

Azores, 3-8 July 2017

Osaka, 4-8 September 2017

## NRHEP Network Meetings

Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:

First Meeting:

9-13 July 2012, Aveiro, Portugal

Second Meeting:

11-14 March 2013, Lisbon, Portugal

Third Meeting:

6-10 January 2014, Mississippi, USA

Fourth Meeting:

7-10 July 2015, Rome, Italy

Fifth Meeting:

28 Sep-2 Oct 2015, Belém, Brazil

## Ph.D. and Post-doctoral opportunities

Contact us If you are interested in pursuing graduate studies/research in our group.

Information for prospective Ph.D. students can be found here.

Past Ph.D. theses from our group can be found here.

Working as a researcher in Portugal - a quick guide.