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Community Profile: Oscar Macias

Name: Oscar Macias

Current position: Postdoc

Affiliation: GRAPPA (University of Amsterdam)

Field of research: Astroparticle Physics, Indirect Dark Matter Searches


What is your career trajectory to date?

I am originally from Colombia. I completed my undergraduate and master's degrees at the National University of Colombia in 2011 and my doctoral work in astrophysics at the University of Canterbury in 2014 under the direction of Chris Gordon. I was a postdoctoral researcher at the Center for Neutrino Physics in Virginia Tech from 2015-2018, and moved to another postdoctoral position to the Kavli Institute for the Physics and Mathematics of the Universe in Tokyo University from 2018-2021. I am now a GRAPPA Fellow at the University of Amsterdam.

What are the most exciting open questions in your research area?

In my opinion, the single most important question in modern science corresponds to the nature of dark matter. It is the most abundant substance in the entire Universe, and yet we don't have a clue of what it is, how it interacts with normal matter, what is its lifetime, etc. Currently, we can only observe dark matter through its gravitational interactions. But what would be ground breaking is if Dark Matter particles could produce observable non-gravitational signals such as photons, neutrinos, and charged cosmic rays as the result of collisions with each other. Now, a quick survey to the literature on the subject for the last 10 years would reveal there are a few tentative detections of dark matter emission in various astrophysical datasets. Examples include: the so-called Galactic Center gamma-ray excess seen by the Fermi telescope, the positron/antiproton excess seen by PAMELA/AMS-02 instruments, and the 3.5 keV line observed by variuos X-ray telescopes; to name only a few of the most famous ones. I think there is an imperative need in our field to resolve these puzzles and figure out whether what we are seen are mere false positives or something more interesting!

What do you like and dislike about being a scientist?

I love the fact that every time I get to the office, I know I will be working on something new and exciting. I truly enjoy the freedom that we researchers are given to work on whatever we think is interesting and cool. However, not everything in science is rosy: there are difficult long-standing problems in our field such as discrimination. We all would be better off with a lot less of that stuff!

In your career so far, at what point were you the most excited, and what were you excited about?

Back in 2012, Christoph Weniger wrote a paper claiming the detection of a gamma-ray line at ~130 GeV. Back then, it was pretty clear that gamma-ray lines are close-to-impossible to be produced by standard astrophysical objects. So, I seriously believed that we had seen dark matter for the first time! - The moment I read that paper, I abandoned everything I was doing and started doing Galactic Center research. In the end it turned out to be just an instrumental artifact. However, mother nature has been kind to us and has given us the Galactic Center gamma-ray excess, which we are not completely sure what it is yet, but it most certainly is not a statistical fluctuation!

What’s your favorite food?

My favorite food is "Colombian Tamales" :). A tamale is a traditional dish, made of corn dough, and various veggies (the traditional also contains a lot of beef, but I'm nowadays into vegetarian tamales) which is steamed in a banana leaf. The Mexican Tamales are pretty tasty as well. If you ever go to a Colombian/Mexican restaurant, don't hesitate to ask for a Tamale, you won't regret it ;).

How do you like to relax after a hard day of work?

I like to take a dive into my favorite high-fantasy novels. I only recently discovered that there is much more than "The Lord of the Rings" out there. I just finished reading the amazing "The Stormight Archive", and am currently fully immersed in the fantastic world of "The Sword of Truth".

What do you hope to see accomplished scientifically in the next 50 years? I would like to see particle dark matter in the "periodic table" (A.k.a the "particle data group"), of course!


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