Interview with Federica Tarsitano

Postdoctoral researcher at the University of Geneva

 

What is your current role within the ESA Euclid mission?

I am a post-doctoral researcher at the University of Geneva, and co-leader of the Euclid Morphology Active Galactic Nuclei (AGN) working group. I joined the Euclid collaboration in 2022, to contribute to the photometric redshift pipeline, which involves determining the distances of the galaxies observed by Euclid.

I am also leading various projects reflecting my main scientific interest: AGN. These are among the most interesting objects in the Universe, emitting vast amount of energy due to a central supermassive black hole that actively accretes matter.
We can consider AGN as polyglot citizens of the Universe, as their emitted radiation can be detected across multiple wavelengths. The Euclid telescope speaks well one of their languages, operating in the optical to near infrared. Furthermore, by offering unprecedented depth and high resolution, the Euclid survey can really play a key role in advancing our understanding of such phenomena.

As part of the Euclid Early Release Observations Team, I have been working on the very first images from the Euclid telescope, analysing the properties of AGN host galaxies in the Perseus Cluster, with a special focus on novel approaches to study dual and binary supermassive black holes (SMBH). Dual AGN are two actively accreting SMBHs in the same galaxy or in merging galaxy systems, representing an earlier stage in the evolution toward binary SMBHs. The latter are gravitationally bound systems which eventually inspiral and merge, emitting gravitational waves.
Just recently, using the Q1 data release, I lead the first systematic approach to identify red quasars in Euclid, using a colour-colour selection function and machine learning. Red quasars are a class of AGN where optical light is heavily attenuated. They own their red colour to either galaxy mergers or observational angles and represent a key phase in the co-evolutionary path of BH and their host galaxies.

I am also co-leading, together with Prof. Miyatake and Prof. Nishizawa, both Euclid members based in Japan, the design of a survey using a new set of medium-band filters of the Subaru telescope. The synergy between this survey and Euclid is set to bring improvements in the estimates of the photometric redshift and allow for various scientific analyses, both in galaxy evolution and cosmology.

Have there been any unexpected findings or surprises in the ESA Euclid mission so far?

I see Euclid as a gold mine of exceptionally high-resolution data. Such richness allows you to begin exploring a topic closely related to your scientific interests, and often, in the process, you find unexpected features - for instance, strong lensing signatures - that lead you to expand your research. I think it is a unique opportunity not only to deepen your work, but also to learn new things and spark new collaborations across the scientific community.

What part of the Q1 data release and your own research are you most excited about?

What I find particularly compelling about Euclid in relation to dual AGN systems is its potential to transform how we search for these objects and our understanding of them. Until now, studies of dual AGN have been limited by instrumental challenges, but Euclid offers an ideal framework for this kind of analysis, combining unprecedented depth and sky coverage. This gives us the chance to build the first large-scale atlas of dual AGN systems. Furthermore, this research could impact other surveys as well, since dual AGN are considered the precursors of merging supermassive black holes, releasing gravitational waves. In this sense, this line of research plays a fundamental role in the broader context of multi-messenger astronomy.

Based on the knowledge you have now from the Q1 data release, what are your main expectations from Euclid in the future?

Euclid core science is cosmology, as it is a mission to map the distribution of matter in the Universe and deepen our understanding of dark matter and dark energy. However, the vast amount of galaxies that will be surveyed over the next six years represents an unprecedented opportunity for legacy science. This includes the study of galaxies and their cosmic evolution.
So, for the future I see this dataset as a great chance to advance our knowledge and make new discoveries. I am enthusiast for the fact that this is happening now, but I think it is also important that the huge amount of data we receive will be available for future generations of scientists.

Do you have any advice for people who would like to follow a similar career path or to use Euclid data?

Euclid data is truly promising. As I mentioned earlier, there is no limit to how far we can advance our knowledge. It is just like the Universe itself: vast and full of possibilities. With Euclid, we will be able to observe billions of galaxies. This will require dedication, both now and in the years to come, as we work to explore this incredible dataset.

My advice to the next generation of scientists is to be passionate, stay curious, and keep asking questions. Don't be afraid to explore beyond your current expertise as Euclid science is inherently interdisciplinary. Learn the tools and methods that will allow you to study this data and embrace the incredible opportunities that the Euclid mission will represent for future research.

Above all, my suggestion is to take part. The Euclid mission offers an extraordinary framework not only for discovery today, but for shaping the research of tomorrow.

 

 

For further details on Federica Tarsitano's work on red quasars selection, please refer to the following scientific paper published in arXiv:

For more information about the Euclid Q1 release, visit the ESA press release: