The SPanD project has been focused on two complementary research lines. The first one is a rather direct approach to constrain and study IMF variations in nearby galaxies. I joined the F3D team as an expert on stellar population analysis with the goal of characterize the IMF variations using state-of-the-art spectroscopic data. I have developed faster and more robust analysis tools, which are now fully tested. The outcome of this efforts are summarized in Martin-Navarro 2019a, where we showed for the first time the full, two-dimensional IMF map of a nearby massive galaxy. This unprecedented analysis has also allowed us to demonstrate that, contrary to what it was believed, the local metallicity is not the main driver of the observed IMF variations. Moreover, a striking connection between the IMF and the orbital structure of the galaxy was found, further probing into the connection between stellar dynamics and IMF studies. Period 2 has been mostly dedicated to apply these newly developed tools to a large sample of galaxies. This work is currently on its final stages and it will be published by the end of the year. Additionally, we have upgraded our modelling techniques to deal with more complex stellar populations, which has lead to the first simultaneous measurement of the high- and low-mass end of the IMF in a star-forming galaxy.
The second research line developed within the SPanD project is related to one of the most fundamental yet open questions in Astronomy: why do galaxies stop forming new stars? Within the SPanD framework I was able to develop a new observational approach that lead to the first direct evidence supporting the effect of black hole feedback in driving the evolution of massive galaxies (Martin-Navarro et al. 2018b, Nature). We expanded this idea to low-mass galaxies, a regime where the effect of the IMF should become more important, finding indeed that black holes do not seem to regulate star formation in these low-mass systems. The SPanD project has lead to two more paper where I further studied how stellar and black hole feedback processes alter the stellar population properties and the evolution of galaxies. I have also shown the relation between black hole growth and therefore feedback on galaxy cluster scales. In Period 2 these ideas have been further developed, finding a striking dependence of the star formation rate of satellites and their position with respect to the plane defined by the central galaxy. This signal is also seen in cosmological simulations but, interestingly, as an emerging process, at subgrid physics in simulations is fundamentally isotropic.
The dissemination of all these results has been done through two main channels. First, among colleagues, the results of the SPanD project have been presented internationally in numerous conferences, workshops, and invited talks. I have recently organized a conference where we brought together the expertise of different communities to understand the chemical enrichment of galaxies, which is ultimately set by the slope of the IMF. Complementary, a bi-yearly collaboration with a Spanish newspaper was established and four articles have been published so far. In addition to this, two press releases have been published. These press releases led two several interviews for newspapers and outreach journals both in the United States of America, Spain, and France. Moreover, I also participated in public outreach talks, and I also try to engage younger generations of high-schoolers. I was also involved in activities to promote scientific career path among under-represented groups, in particular the Hispanic community in the Bay Area.
