Judit Prat

I am a Schmidt AI in Science Postdoctoral fellow at the University of Chicago.

Judit Prat

I am a Schmidt AI in Science Postdoctoral fellow at the University of Chicago, where I am part of the Survey Science Group. Before being a researcher at the University of Chicago I did my PhD at the Autonomous University of Barcelona. I am interested constraining cosmological parameters from the late-time Universe with galaxy surveys, in particular with galaxy clustering and weak graviational lensing measurements. These direct cosmological measurements from the late-time Universe can be compared with the predictions from the current Standard Cosmological Model (LCDM) assuming the initial cosmological parameters measured from observations of the early Universe, in particular from the Cosmic Microwave Background (CMB), and in such a way we can stress-test the current standard cosmological model.

I am also excited about sharing the science I am doing with the broader community through outreach activities. Moreover, I am part of the community engagement group of the Astronomy and Astrophysics, dedicated to support Black Astronomers and Physicists at the University of Chicago. Other random facts about me include that I love making plots, flowcharts and infographics — choosing the colors is the best part ;) — doing sports and being outdoors, and generally just being around and talking to people!

Research

Cosmology from galaxy surveys

Data analysis with current surveys

A major part of my research has consisted of extracting cosmological information from large-scale structure and weak gravitational lensing measurements. In particular I have used observations from the Dark Energy Survey (DES), a photometric galaxy survey that covers ~5000 sq. deg. of the southern sky, and that has measured the positions and shapes of over one hundred million galaxies. Specifically, I have been part of the core team that has performed a so-called 3x2pt analysis, which stands for the combination of three two point correlation functions: one from position-position correlations (galaxy clustering), one from shear-shear correlations (cosmic shear), and one from position-shear correlations (galaxy-galaxy lensing). Below you can find some of the main results of the DES Y3 3x2pt analysis:

  • Dark Energy Survey Year 3 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing.
  • Preparation for future surveys

    Besides this, I am also a member of the Dark Energy Science Collaboration (DESC) within the Vera Rubin Observatory's Legacy Survey of Space and Time, where I am developing and validating the pipelines that will be used when the data arrives. I have helped to develop and validate TXPipe, a modular pipeline for generating robust data vectors in cosmology analyses for the LSST.

    The galaxy-matter connection

    Extracting useful cosmological information from small scale two-point measurements is complicated due to non-linearities and baryonic effects that impact the matter power spectrum and the relation between the matter and galaxy power spectrum (i.e. the galaxy bias). Because of these limitations, it is common that cosmological analyses using galaxy surveys data discard scales under a given threshold, throwing out a lot of signal-to-noise (for instance, ~50% of the total S/N was discarded in the DES Y3 3x2pt analysis). Thus, the biggest gain in constraining power for future cosmological analyses could come from including smaller scales. Actually, even using the same range of scales will be challenging since reduced statistical uncertainties will require greater precision in the modeling. Therefore, it has become essential to improve the understanding of the galaxy-matter connection, including non-linearities in the galaxy and halo biases and baryonic feedback effects. During my career, I have been part of several efforts that are working towards this goal including this work we recently published on the galaxy-halo connection from galaxy-galaxy lensing.

    List of publications

    To follow my latest papers, check the following ADS libraries:
  • All my papers.
  • Corresponding author papers.
  • CV
    Equity, diversity and inclusion

    Equity, diversity and inclusion

    Throughout my career, I have been part of the following groups:
  • IDEA group within the Astronomy and Astrophysics Department (A & A) at UChicago (2021 - Present): It is a grassroots group of early career astronomers and physicsts in A & A and the Kavli Institute for Cosmological Physics (KICP) at the University of Chicago.
  • Community Engagement Working Group of the A & A Department at UChicago (2020 - Present): This group is dedicated to support Black Astronomers and Physicists at the University of Chicago.
  • The Gender Equality Committee at Institut de Física d'Altes Energies (IFAE) (2018 - 2019): This committee is dedicated to assess and improve the gender balance at IFAE.

  • Talks and initiatives

  • Community Conversations (sponsored by PSD Inclusive Climate Grant): We invited several speakers to talk about the South Side of Chicago from different perspectives.
  • Oral presentation on the report of the Gender Equality Committee activities, IFAE. May 2019.

    Resources

  • Cool places to visit in the South Side of Chicago.

  • Outreach

    Outreach talks

  • Talk within the Life-long Learning Fermilab progam. Sep 2021.
  • Talk at High School IES Matadepera, Barcelona. Jan 2019.
  • Talk in "Mad for Science" High School program, Barcelona. Mar 2018.
  • Public talk, Astronomical Association of Sant Cugat - Valldoreix (AASCV), Barcelona. Oct 2017.

    Participation in videos

  • Participation in Outreach Youtube channel Ani the Anisotropia.
  • Recording of a video with High School students about Maps of dark matter, emitted on local Barcelona TV. May 2017.

    Other

  • I was part of the organizer team for the first KICP Outreach Symposium, at the University of Chicago. Sep 2020.
  • Organizer of an activity to measure the Hubble Constant for the "Mad for Science" High School program, Barcelona. May 2017.
  • Local radio interview by college students about the Dark Energy Survey. Oct 2017.
  • Together with Chihway Chang, we created an infographic for the Dark Energy Survey, which you can find below. Jan 2021.

  • Portfolio

    Chicago Photography

    I like taking minimalist pictures of Chicago, where I currently live. Here's a selection of my favorites.

    Portfolio

    Creative Portfolio

    News

    Latest News

    • Just because we can't get out and about like we normally would, doesn’t mean we have to stop taking pictures. There’s still plenty you can do, provided you're prepared to use some imagination. Here are a few ideas to keep you shooting until normal life resumes.

      Most photographers love to shoot the unusual, and you don’t get much more unusual than These Unprecedented Times. Right now everything counts as out of the ordinary. There are a number of remarkable things about these lockdown days that are worth photographing now so we can remember them when it is all over.

      Most photographers find it hard to see interesting pictures in places in which they are most familiar. A trip somewhere new seems always exactly what our photography needed, as shooting away from home consistently inspires us to new artistic heights.

      Streets empty that are usually busy are remarkable and can evoke the sense of historical pictures from before the invention of the motorcar. Other things that are different at the moment will be queues to get into stores and the lines marked out on the floor to show how far apart we should be.

      Pretend everything is new and that you haven’t seen it before, and then you will be free to notice the leading lines, the places where one edge meets another in delightful geometric harmony, and how the ordinary things in the kitchen are transformed when the light is on or off.

      The trick here is to look slowly, and then look again. Take the time to look in detail and to look at the same thing from different angles, with different light, long lenses and wide lenses. Then move to the left a bit. You may never feel the need to leave the house again.

    • Just because we can't get out and about like we normally would, doesn’t mean we have to stop taking pictures. There’s still plenty you can do, provided you're prepared to use some imagination. Here are a few ideas to keep you shooting until normal life resumes.

      Most photographers love to shoot the unusual, and you don’t get much more unusual than These Unprecedented Times. Right now everything counts as out of the ordinary. There are a number of remarkable things about these lockdown days that are worth photographing now so we can remember them when it is all over.

      Most photographers find it hard to see interesting pictures in places in which they are most familiar. A trip somewhere new seems always exactly what our photography needed, as shooting away from home consistently inspires us to new artistic heights.

      Streets empty that are usually busy are remarkable and can evoke the sense of historical pictures from before the invention of the motorcar. Other things that are different at the moment will be queues to get into stores and the lines marked out on the floor to show how far apart we should be.

      Pretend everything is new and that you haven’t seen it before, and then you will be free to notice the leading lines, the places where one edge meets another in delightful geometric harmony, and how the ordinary things in the kitchen are transformed when the light is on or off.

      The trick here is to look slowly, and then look again. Take the time to look in detail and to look at the same thing from different angles, with different light, long lenses and wide lenses. Then move to the left a bit. You may never feel the need to leave the house again.

    • Just because we can't get out and about like we normally would, doesn’t mean we have to stop taking pictures. There’s still plenty you can do, provided you're prepared to use some imagination. Here are a few ideas to keep you shooting until normal life resumes.

      Most photographers love to shoot the unusual, and you don’t get much more unusual than These Unprecedented Times. Right now everything counts as out of the ordinary. There are a number of remarkable things about these lockdown days that are worth photographing now so we can remember them when it is all over.

      Most photographers find it hard to see interesting pictures in places in which they are most familiar. A trip somewhere new seems always exactly what our photography needed, as shooting away from home consistently inspires us to new artistic heights.

      Streets empty that are usually busy are remarkable and can evoke the sense of historical pictures from before the invention of the motorcar. Other things that are different at the moment will be queues to get into stores and the lines marked out on the floor to show how far apart we should be.

      Pretend everything is new and that you haven’t seen it before, and then you will be free to notice the leading lines, the places where one edge meets another in delightful geometric harmony, and how the ordinary things in the kitchen are transformed when the light is on or off.

      The trick here is to look slowly, and then look again. Take the time to look in detail and to look at the same thing from different angles, with different light, long lenses and wide lenses. Then move to the left a bit. You may never feel the need to leave the house again.

    • Just because we can't get out and about like we normally would, doesn’t mean we have to stop taking pictures. There’s still plenty you can do, provided you're prepared to use some imagination. Here are a few ideas to keep you shooting until normal life resumes.

      Most photographers love to shoot the unusual, and you don’t get much more unusual than These Unprecedented Times. Right now everything counts as out of the ordinary. There are a number of remarkable things about these lockdown days that are worth photographing now so we can remember them when it is all over.

      Most photographers find it hard to see interesting pictures in places in which they are most familiar. A trip somewhere new seems always exactly what our photography needed, as shooting away from home consistently inspires us to new artistic heights.

      Streets empty that are usually busy are remarkable and can evoke the sense of historical pictures from before the invention of the motorcar. Other things that are different at the moment will be queues to get into stores and the lines marked out on the floor to show how far apart we should be.

      Pretend everything is new and that you haven’t seen it before, and then you will be free to notice the leading lines, the places where one edge meets another in delightful geometric harmony, and how the ordinary things in the kitchen are transformed when the light is on or off.

      The trick here is to look slowly, and then look again. Take the time to look in detail and to look at the same thing from different angles, with different light, long lenses and wide lenses. Then move to the left a bit. You may never feel the need to leave the house again.

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