Jonas Chaves-Montero

Jonás Chaves-Montero

Jonás is a postdoctoral appointee in the CPAC group. His scientific interests cover a broad range of topics in observational cosmology and galaxy formation physics. Specifically, his work focuses on harnessing the full power of galaxy surveys by characterizing the impact of theoretical shortcomings and systematics on cosmological constraints. His current lines of work are forward-modeling the galaxy-halo connection, cross-correlating large-scale structure (LSS) and cosmic microwave background (CMB) observations, and improving the precision of photometric redshift estimation.

  • Galaxy-halo connection. Through his Ph.D., Jonás studied the connection between galaxies and dark matter haloes using state-of-the-art cosmological hydrodynamical simulations, finding that subhalo abundance matching, a commonly used technique to assign galaxies to halos, suffers from important systematic uncertainties (Chaves-Montero et al. 2016). Currently, he is developing a new approach for forward-modeling the galaxy-halo connection using machine-learning techniques; this model will enable setting joint constraints on galaxy formation physics and cosmology. He has recently submitted a publication along this line in which he study the influence of the star formation history of a galaxy on its colors (Chaves-Montero et al. 2019). He finds that galaxy colors depend primarily on the fraction of stellar mass formed by a galaxy over its last billion years; this simplification will be crucial for the implementation of surrogate models.
  • Cross-correlation of LSS and CMB. Jonás is a co-author of a recent publication that introduces a new cosmological observable, Angular Redshift Fluctuations (ARF). ARF are angular fluctuations in maps of galaxy redshifts and they encode precise cosmological information (Hernández-Monteagudo C.; Chaves-Montero, J.; Angulo, R.; 2019, submitted). Taking advantage of the strong correlation between ARF and CMB anisotropies induced by the kinematic Sunyaev-Zel’dovich effect, he has conducted the first tomographic census of baryons in the Universe (Chaves-Montero et al. 2019, submitted). Interestingly, he detects practically all baryons in the intergalactic medium using this novel methodology, solving the “missing baryon problem”.
  • Precise estimation of photometric redshifts. The estimation of photometric redshifts consists in the mapping of galaxy colors into redshift, which is very complicated due to the limited information encoded in a few colors. He has studied the impact of uncertainties arising from this noisy mapping on cosmological observables (Chaves-Montero et al. 2018), and has worked on new techniques to identify quasars in multi-band surveys (Chaves-Montero et al. 2017). He is now working on using Bayesian neural networks and Gaussian mixture models to improve the estimation of photometric redshifts.

Jonás graduated in Physics from the University of Salamanca in 2012, finished a M.Sc. in Astrophysics at the Autonomous University of Madrid in 2013 (thesis: “Velocity fields around voids”), and carried out Ph.D. studies at Centro de Estudios de Física del Cosmos de Aragón (CEFCA) from 2013 to 2017 (thesis: “New techniques for an optimal cosmological exploitation of galaxy surveys”). Since 2017, he is a postdoctoral appointee in the Cosmological Physics and Advanced Computing (CPAC) group at Argonne National Laboratory.

In this movie, we fly through the distribution of galaxies that future mission SPHEREx will observe. As the movie advances, we get farther and farther away from Earth, observing galaxies that populated the distant universe; indeed, the inset shows the path of the observer through the lightcone. Galaxies are biased tracers of the underlying distribution of dark matter, which is indicated using blue colors. The visualization is based on the trillion-particle Outer Rim simulation carried out with HACC.

Recent Publications

  1. Angular Redshift Fluctuations: a New Cosmological Observable
    Hernández-Monteagudo, Carlos; Chaves-Montero, Jonás; Angulo, Raúl
    Submitted to PRL, arXiv: 1911.12056
  2. Tomographic detection of the kinematic Sunyaev-Zel’dovich effect using angular redshift fluctuation
    Chaves-Montero, Jonás; Hernández-Monteagudo, Carlos; Angulo, Raúl E; Emberson, J. D.
    Submitted to MNRAS, arXiv: 1911.10690
  3. Surrogate modelling the Baryonic Universe I: The colour of star formation
    Chaves-Montero, Jonás; Hearin, Andrew
    Submitted to MNRAS, arXiv: 1910.11883
  4. The effect of photometric redshift uncertainties on galaxy clustering and baryonic acoustic oscillations
    Chaves-Montero, Jonás; Angulo, Raúl E; and Hernández-Monteagudo, Carlos
    Monthly Notices of the Royal Astronomical Society, Volume 477, Issue 3, 2018, Pages 3892–3909.
  5. Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey II: Report of a Community Workshop on the Scientific Synergies Between the SPHEREx Survey and Other Astronomy Observatories
    Doré, Olivier; Werner, Michael W; Ashby, Matthew LN; Bleem, Lindsey E; Bock, Jamie; Burt, Jennifer; Capak, Peter; Chang, Tzu-Ching; Chaves-Montero, Jonás; Charbonneau, David; and others
    arXiv preprint, 2018. arXiv:1805.05489.
  6. ELDAR, a new method to identify AGN in multi-filter surveys: the ALHAMBRA test case
    Chaves-Montero, Jonás; Bonoli, Silvia; Salvato, Mara; Greisel, Natascha; Díaz-García, Luis A; López-Sanjuan, Carlos; Viironen, Kerttu; Fernández-Soto, Alberto; Pović, Mirjana; Ascaso, Begoña; and others
    Monthly Notices of the Royal Astronomical Society, Volume 472, Issue 2, 2017, Pages 2085-2106.
  7. Subhalo abundance matching and assembly bias in the EAGLE simulation
    Chaves-Montero, Jonás; Angulo, Raúl E; Schaye, Joop; Schaller, Matthieu; Crain, Robert A; Furlong, Michelle; and Theuns, Tom
    Monthly Notices of the Royal Astronomical Society, Volume 460, Issue 3, 2016, Pages 3100-3118.