The collaboration Estallidos has been working together for more than two decades. In the present edition, we have organised the research work into five Objectives which are described in the common MEMORIA presented by the coordination node (CIEMAT). The tasks proposed by the various nodes are closely intertwined. They are organised according to our scientific goals. Note that there is no one-toone correspondence between our five science goals and our four subprojects (nodes), as it is difficult to separate the objectives led by each one of the nodes. Here we summarize the particular activities to be carried out in the subproject led by the IAC. We also participate in other research activities taken over by the other nodes.

We will study Star Formation (SF) throughout the history of the Universe as described in Objective 3 of the common MEMORIA. SF will be followed in time from the early universe until today. SF requires gas, which was far more abundant early on, during the cosmic noon. It is not well understood what feeds the starbursts observed in our local Universe. Our team found evidence of the starburst being fed by cosmological gas accretion. This finding will be explored further as described in Objective 3.1, in which we will seek for the direct detection of almost pristine gas in the environment of nearby galaxies. Cosmological gas accretion also leaves a signature on the distribution of metals in galaxy disks, which will be exploited as a diagnostic tool.

Large galaxy samples are needed to get global relations, which are needed for a proper understanding of the process of galaxy formation. Photometric surveys are ideal to identify and characterize star-forming galaxies, and to follow them in time. We are experts in their exploitation and we plan to use the know-how developed for SHARDs and COSMOS to other surveys like PAU. By identifying emission line patterns, the surveys provide samples of young starbursts at redshift as high as 6. The characterization of such starbursts and their host galaxy will allow us to understand the relation between SF and the host galaxy, and to see whether it changes with cosmic time (Objective 3.2). According to all models of galaxy evolution, the feedback from SF is a key parameter. Usually, the kinetic energy deposited by young massive starbursts in the interstellar medium inhibits further SF, and the feedback is said to be negative. However, the theoretical models developed by our team have shown that in the case of massive and compact sources, the SF feedback can be positive (SF triggers SF). We will search for signs of positive feedback using diagnostic diagrams based on the analysis of emission lines (Objective 3.3). Our team will push the study of SF back in time to allow understanding SF in the epoch of re-ionization (Objective 3.4). We will test the hypothesis that clusters of low mass galaxies are responsible for the re-ionization. Clusters are needed to create large ionized bubbles so that the ionizing photons can scape further out. We will find and census the sources that produce the Lyman continuum photons.