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Michaela Hirschmann

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Related publications (87)

Page 3 of 5

The Physical Conditions of Emission-line Galaxies at Cosmic Dawn from JWST/NIRSpec Spectroscopy in the SMACS 0723 Early Release Observations

Michaela Hirschmann

We present rest-frame optical emission-line flux ratio measurements for five z > 5 galaxies observed by the James Webb Space Telescope Near-Infared Spectrograph (NIRSpec) in the SMACS 0723 Early Release Observations. We add several quality-control and post ...

IOP Publishing Ltd2023

Here There Be (dusty) Monsters: High-redshift Active Galactic Nuclei Are Dustier Than Their Hosts

Michaela Hirschmann

JWST spectroscopy has discovered a population of z greater than or similar to 3.5 galaxies with broad Balmer emission lines and narrow forbidden lines that are consistent with hosting active galactic nuclei (AGN). Many of these systems, now known as "littl ...

IOP Publishing Ltd2025

Efficient NIRCam Selection of Quiescent Galaxies at 3 < z < 6 in CEERS

Michaela Hirschmann

Substantial populations of massive quiescent galaxies at z ≥ 3 challenge our understanding of rapid galaxy growth and quenching over short timescales. In order to piece together this evolutionary puzzle, more statistical samples of these objects are requir ...

2024

Two Massive, Compact, and Dust-obscured Candidate z ≃ 8 Galaxies Discovered by JWST

Michaela Hirschmann

We present a search for extremely red, dust-obscured, z > 7 galaxies with JWST/NIRCam+MIRI imaging over the first 20 arcmin(2) of publicly available Cycle 1 data from the COSMOS-Web, CEERS, and PRIMER surveys. Based on their red color in F277W-F444W (simil ...

Iop Publishing Ltd2023

Near-infrared emission line diagnostics for AGN from the local Universe to z ∼ 3

Michaela Hirschmann

Optical rest-frame spectroscopic diagnostics are usually employed to distinguish between star formation and active galactic nucleus (AGN) powered emission. However, this method is biased against dusty sources, hampering a complete census of the AGN populat ...

Edp Sciences S A2023

The First Quenched Galaxies: When and How?

Michaela Hirschmann

Many quiescent galaxies discovered in the early Universe by JWST raise fundamental questions on when and how these galaxies became and stayed quenched. Making use of the latest version of the semianalytic model GAEA that provides good agreement with the ob ...

Iop Publishing Ltd2024

Crimson Behemoth: A massive clumpy structure hosting a dusty AGN at z =4.91

Michaela Hirschmann

The current paradigm for the co-evolution of galaxies and their supermassive black holes postulates that dust-obscured active galactic nuclei (AGNs) represent a transitional phase towards a more luminous and unobscured state. However, our understanding of ...

OXFORD UNIV PRESS2024

Evolution of the UV slope of galaxies at cosmic morning (z > 4): The properties of extremely blue galaxies

Michaela Hirschmann

We present an analysis of the UV continuum slope, β, using a sample of 726 galaxies with z > 4, selected from a mixture of JWST ERS, GTO, and GO observational programs. We considered only spectroscopic data obtained with the low-resolution (R ∼ 30−300) PRI ...

2025

Evidence for a Shallow Evolution in the Volume Densities of Massive Galaxies at z = 4-8 from CEERS

Michaela Hirschmann

We analyze the evolution of massive (log10[M ⋆/M ⊙] > 10) galaxies at z ∼ 4-8 selected from JWST Cosmic Evolution Early Release Survey (CEERS). We infer the physical properties of all galaxies in the CEERS NIRCam imaging through spectral energy distributio ...

2024

RUBIES: Evolved Stellar Populations with Extended Formation Histories at z ∼ 7–8 in Candidate Massive Galaxies Identified with JWST/NIRSpec

Michaela Hirschmann

The identification of red, apparently massive galaxies at z > 7 in early James Webb Space Telescope (JWST) photometry suggests a strongly accelerated time line compared to standard models of galaxy growth. A major uncertainty in the interpretation is wheth ...

American Astronomical Society2024

An Atlas of Color-selected Quiescent Galaxies at z > 3 in Public JWST Fields

Michaela Hirschmann, Minju Lee

We present the results of a systematic search for candidate quiescent galaxies in the distant universe in 11 JWST fields with publicly available observations collected during the first 3 months of operations and covering an effective sky area of similar to ...

IOP Publishing Ltd2023

Tracing the quenching journey across cosmic time

Michaela Hirschmann

We present the latest version of the GAlaxy Evolution and Assembly (GAEA) theoretical model of galaxy formation. Our new model now combines (i) an updated treatment of feedback from active galactic nuclei, including an improved modelling of cold gas accret ...

EDP Sciences2024

CAPERS-LRD-z9: A Gas-enshrouded Little Red Dot Hosting a Broad-line Active Galactic Nucleus at z = 9.288

Michaela Hirschmann

We present CAPERS-LRD-z9, a little red dot (LRD) that we confirm to be a z = 9.288 broad-line active galactic nucleus (BLAGN). First identified as a high-redshift LRD candidate from PRIMER NIRCam photometry, follow-up NIRSpec/PRISM spectroscopy of CAPERS-L ...

2025

Euclid I. Overview of the Euclid mission

Jean-Paul Richard Kneib, Frédéric Courbin, Georges Meylan, Pascale Jablonka, Michaela Hirschmann, Yves Revaz, Austin Chandler Peel, Lucie Anemone Scharré, Bastien Clément

The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015–2025 programme of the ...

2025

The Ionizing Photon Production Efficiency of Star-forming Galaxies at z ∼ 4-10

Michaela Hirschmann

Context. Investigating the ionizing emission of star-forming galaxies and the escape fraction of ionizing photons is critical to understanding their contribution to reionization and their impact on the surrounding environment. The number of ionizing photon ...

EDP Sciences SA2025

A Merging Pair of Massive Quiescent Galaxies at z=3.44 in the Cosmic Vine

Michaela Hirschmann, Marion Nancy Amandine Farcy

We report the spectroscopic confirmation of a merging pair of massive quiescent galaxies at z = 3.44. Using JWST observations, we confirm that the two galaxies lie at a projected separation of 4.5 kpc with a velocity offset of similar to 680 km s(-1) (delt ...

EDP SCIENCES S A2025

The stellar mass function of quiescent galaxies in 2 < z < 2.5 protoclusters

Pascale Jablonka, Michaela Hirschmann, Yannick Michael Bahé

We present an analysis of the galaxy stellar mass function (SMF) of 14 known protoclusters between 2.0 < z < 2.5 in the COSMOS field, down to a mass limit of 10(9.5) M⊙. We use existing photometric redshifts with a statistical background subtraction, and c ...

Oxford Univ Press2023

SCUBADive. I. JWST plus ALMA Analysis of 289 Submillimeter Galaxies in COSMOS-web

Michaela Hirschmann

JWST has enabled detecting and spatially resolving the heavily dust-attenuated stellar populations of submillimeter galaxies, revealing detail that was previously inaccessible. In this work, we construct a sample of 289 submillimeter galaxies with joint At ...

IOP Publishing Ltd2025

Environmental effects on satellite galaxies from the perspective of cold gas

Michaela Hirschmann

Environment plays a pivotal role in shaping the evolution of satellite galaxies. Analysing the properties related to the cold gas phase of satellites provides insights into unravelling the complexity of environmental effects. We use the hydro-dynamical sim ...

2024

Not-so-little Red Dots: Two Massive and Dusty Starbursts at z ∼ 5-7 Pushing the Limits of Star Formation Discovered by JWST in the COSMOS-Web Survey

Michaela Hirschmann

We present the properties of two candidate massive (M ⋆ ∼ 1011 M ⊙) and dusty (A v > 2.5 mag) galaxies at z = 5-7 in the first 0.28 deg2 of the COSMOS-Web survey. One object is spectroscopically confirmed at z spec = 5.051, while the other has a robust z p ...

2024