Josephine Baggen

Josephine Baggen

PhD candidate in Astronomy, Yale University

I study the formation of the first massive galaxies and black holes in the early Universe. My work focuses on little red dots: compact, red sources discovered by the James Webb Space Telescope in the first billion years, whose nature is still unknown. I combine JWST imaging, strong gravitational lensing and models of galaxy and black hole formation to find out what they are. I work with Prof. Pieter van Dokkum.

josephine.baggen@yale.edu · CV · Publications

Josephine Baggen

First-author papers

  1. (Re)solving the Complex Multiscale Morphology and V-shaped Spectral Energy Distribution of a Newly Discovered Strongly Lensed Little Red Dot in A383

    J. F. W. Baggen, P. van Dokkum, I. Labbé, G. Brammer

    ApJL 1006, L14 (2026)

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    Figure from “(Re)solving the Complex Multiscale Morphology and V-shaped Spectral Energy Distribution of a Newly Discovered Strongly Lensed Little Red Dot in A383”Figure from “(Re)solving the Complex Multiscale Morphology and V-shaped Spectral Energy Distribution of a Newly Discovered Strongly Lensed Little Red Dot in A383”

  2. Connecting the Dots: UV-bright Companions of Little Red Dots as Lyman–Werner Sources Enabling Direct-collapse Black Hole Formation

    J. F. W. Baggen, M. T. Scoggins, P. van Dokkum, Z. Haiman, A. Torralba, et al.

    ApJL 1002, L4 (2026)

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    Figure from “Connecting the Dots: UV-bright Companions of Little Red Dots as Lyman–Werner Sources Enabling Direct-collapse Black Hole Formation”

  3. The Impact of Baryonic Effects on the Dynamical Masses Inferred Using Satellite Kinematics

    J. F. W. Baggen, F. C. van den Bosch, K. Mitra

    The Open Journal of Astrophysics 9, 58198 (2026)

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    Figure from “The Impact of Baryonic Effects on the Dynamical Masses Inferred Using Satellite Kinematics”

  4. The Small Sizes and High Implied Densities of “Little Red Dots” with Balmer Breaks Could Explain Their Broad Emission Lines without an Active Galactic Nucleus

    J. F. W. Baggen, P. van Dokkum, G. Brammer, A. de Graaff, M. Franx, et al.

    ApJL 977, L13 (2024)

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    Figure from “The Small Sizes and High Implied Densities of “Little Red Dots” with Balmer Breaks Could Explain Their Broad Emission Lines without an Active Galactic Nucleus”

  5. Sizes and Mass Profiles of Candidate Massive Galaxies Discovered by JWST at 7 < z < 9: Evidence for Very Early Formation of the Central 100 pc of Present-day Ellipticals

    J. F. W. Baggen, P. van Dokkum, I. Labbé, G. Brammer, T. B. Miller, et al.

    ApJL 955, L12 (2023)

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    Figure from “Sizes and Mass Profiles of Candidate Massive Galaxies Discovered by JWST at 7 < z < 9: Evidence for Very Early Formation of the Central 100 pc of Present-day Ellipticals”

All publications →

Yale Club Tennis at the USTA Tennis on Campus National Championship

Beyond astronomy

Outside of research, I play tennis with the Yale Club Tennis team, with whom I competed at the USTA Tennis on Campus National Championship.