We explored the role of X-ray binaries composed by a black hole and a massive stellar companion (BHXs) as sources of kinetic feedback by using hydrodynamical cosmological simulations. Following previous results, our BHX model selects low metal-poor s
tars ($Z = [0,10^{-4}]$) as possible progenitors. The model that better reproduces observations assumes that a $sim 20%$ fraction of low-metallicity black holes are in binary systems which produce BHXs. These sources are estimated to deposit $sim 10^{52}$ erg of kinetic energy per event. With these parameters and in the simulated volume, we find that the energy injected by BHXs represents $sim 30%$ of the total energy released by SNII and BHX events at redshift $zsim7$ and then decreases rapidly as baryons get chemically enriched. Haloes with virial masses smaller than $sim 10^{10} ,M_{odot}$ (or $T_{rm vir} lesssim 10^5 $ K) are the most directly affected ones by BHX feedback. These haloes host galaxies with stellar masses in the range $10^7 - 10^8$ M$_odot$. Our results show that BHX feedback is able to keep the interstellar medium warm, without removing a significant gas fraction, in agreement with previous analytical calculations. Consequently, the stellar-to-dark matter mass ratio is better reproduced at high redshift. Our model also predicts a stronger evolution of the number of galaxies as a function of the stellar mass with redshift when BHX feedback is considered. These findings support previous claims that the BHXs could be an effective source of feedback in early stages of galaxy evolution.
Recent theoretical works claim that high-mass X-ray binaries (HMXBs) could have been important sources of energy feedback into the interstellar and intergalactic media, playing a major role in the reionization epoch. A metallicity dependence of the p
roduction rate or luminosity of the sources is a key ingredient generally assumed but not yet probed. Aims: Our goal is to explore the relation between the X-ray luminosity (Lx) and star formation rate of galaxies as a possible tracer of a metallicity dependence of the production rates and/or X-ray luminosities of HMXBs. Methods: We developed a model to estimate the Lx of star forming galaxies based on stellar evolution models which include metallicity dependences. We applied our X-ray binary models to galaxies selected from hydrodynamical cosmological simulations which include chemical evolution of the stellar populations in a self-consistent way. Results: Our models successfully reproduce the dispersion in the observed relations as an outcome of the combined effects of the mixture of stellar populations with heterogeneous chemical abundances and the metallicity dependence of the X-ray sources. We find that the evolution of the Lx as a function of SFR of galaxies could store information on possible metallicity dependences of the HMXB sources. A non-metallicity dependent model predicts a non-evolving relation while any metallicity dependence should affect the slope and the dispersion as a function of redshift. Our results suggest the characteristics of the Lx evolution can be linked to the nature of the metallicity dependence of the production rate or the Lx of the stellar sources. By confronting our models with current available observations of strong star-forming galaxies, we find that only chemistry-dependent models reproduce the observed trend for z < 4.
We analyse the spatial distribution within host galaxies and chemical properties of the progenitors of Long Gamma Ray Bursts as a function of redshift. By using hydrodynamical cosmological simulations which include star formation, Supernova feedback
and chemical enrichment and based on the hypothesis of the collapsar model with low metallicity, we investigate the progenitors in the range 0 < z < 3. Our results suggest that the sites of these phenomena tend to be located in the central regions of the hosts at high redshifts but move outwards for lower ones. We find that scenarios with low metallicity cut-offs best fit current observations. For these scenarios Long Gamma Ray Bursts tend to be [Fe/H] poor and show a strong alpha-enhancement evolution towards lower values as redshift decreases. The variation of typical burst sites with redshift would imply that they might be tracing different part of galaxies at different redshifts.
