EDGE – Dark matter or astrophysics? Breaking dark matter heating degeneracies with H i rotation in faint dwarf galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2024)

Authors:

Martin P Rey, Matthew DA Orkney, Justin I Read, Payel Das, Oscar Agertz, Andrew Pontzen, Anastasia A Ponomareva, Stacy Y Kim, William McClymont

Abstract:

Abstract Low-mass dwarf galaxies are expected to reside within dark matter halos that have a pristine, ‘cuspy’ density profile within their stellar half-light radii. This is because they form too few stars to significantly drive dark matter heating through supernova-driven outflows. Here, we study such simulated faint systems (104 ≤ M⋆ ≤ 2 × 106 M⊙) drawn from high-resolution (3 pc) cosmological simulations from the ‘Engineering Dwarf Galaxies at the Edge of galaxy formation’ (EDGE) project. We confirm that these objects have steep and rising inner dark matter density profiles at z = 0, little affected by galaxy formation effects. But five dwarf galaxies from the suite also showcase a detectable H i reservoir ($M_{\mathrm{H\, \small {I} }}\approx 10^{5}-10^{6} \, \mbox{M}_\mathrm{\odot }$), analogous to the observed population of faint, H i-bearing dwarf galaxies. These reservoirs exhibit episodes of ordered rotation, opening windows for rotation curve analysis. Within actively star-forming dwarfs, stellar feedback easily disrupts the tenuous H i discs (vφ, g ≈ 10 km s−1), making rotation short-lived (≪150 Myr) and more challenging to interpret for dark matter inferences. In contrast, we highlight a long-lived (≥500 Myr) and easy-to-interpret H i rotation curve extending to ≈2 r1/2, 3D in a quiescent dwarf, that has not formed new stars since z = 4. This stable gas disc is supported by an oblate dark matter halo shape that drives high angular momentum gas flows. Our results strongly motivate further searches for H i in rotation curves in the observed population of H i-bearing low-mass dwarfs, that provide a key regime to disentangle the respective roles of dark matter microphysics and galaxy formation effects in driving dark matter heating.

MIGHTEE-H i: H i galaxy properties in the large scale structure environment at z ∼ 0.37 from a stacking experiment

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2024)

Authors:

Francesco Sinigaglia, Giulia Rodighiero, Ed Elson, Alessandro Bianchetti, Mattia Vaccari, Natasha Maddox, Anastasia A Ponomareva, Bradley S Frank, Matt J Jarvis, Barbara Catinella, Luca Cortese, Sambit Roychowdhury, Maarten Baes, Jordan D Collier, Olivier Ilbert, Ali A Khostovan, Sushma Kurapati, Hengxing Pan, Isabella Prandoni, Sambatriniaina HA Rajohnson, Mara Salvato, Srikrishna Sekhar, Gauri Sharma

Abstract:

<jats:title>Abstract</jats:title> <jats:p>We present the first measurement of HI mass of star-forming galaxies in different large scale structure environments from a blind survey at z ∼ 0.37. In particular, we carry out a spectral line stacking analysis considering 2875 spectra of colour-selected star-forming galaxies undetected in HI at 0.23 &amp;lt; z &amp;lt; 0.49 in the COSMOS field, extracted from the MIGHTEE-HI Early Science datacubes, acquired with the MeerKAT radio telescope. We stack galaxies belonging to different subsamples depending on three different definitions of large scale structure environment: local galaxy overdensity, position inside the host dark matter halo (central, satellite, or isolated), and cosmic web type (field, filament, or knot). We first stack the full star-forming galaxy sample and find a robust HI detection yielding an average galaxy HI mass of MHI = (8.12 ± 0.75) × 109 M⊙ at ∼11.8σ. Next, we investigate the different subsamples finding a negligible difference in MHI as a function of the galaxy overdensity. We report an HI excess compared to the full sample in satellite galaxies (MHI = (11.31 ± 1.22) × 109, at ∼10.2σ) and in filaments (MHI = (11.62 ± 0.90) × 109. Conversely, we report non-detections for the central and knot galaxies subsamples, which appear to be HI-deficient. We find the same qualitative results also when stacking in units of HI fraction (fHI). We conclude that the HI amount in star-forming galaxies at the studied redshifts correlates with the large scale structure environment.</jats:p>

On the Significance of the Thick Disks of Disk Galaxies

The Astrophysical Journal Supplement Series American Astronomical Society 271:1 (2024) 1

Authors:

Sukyoung K Yi, JK Jang, Julien Devriendt, Yohan Dubois, San Han, Taysun Kimm, Katarina Kraljic, Minjung Park, Sebastien Peirani, Christophe Pichon, Jinsu Rhee

The Cosmos in Its Infancy: JADES Galaxy Candidates at z > 8 in GOODS-S and GOODS-N

The Astrophysical Journal American Astronomical Society 964:1 (2024) 71

Authors:

Kevin N Hainline, Benjamin D Johnson, Brant Robertson, Sandro Tacchella, Jakob M Helton, Fengwu Sun, Daniel J Eisenstein, Charlotte Simmonds, Michael W Topping, Lily Whitler, Christopher NA Willmer, Marcia Rieke, Katherine A Suess, Raphael E Hviding, Alex J Cameron, Stacey Alberts, William M Baker, Stefi Baum, Rachana Bhatawdekar, Nina Bonaventura, Kristan Boyett, Andrew J Bunker, Stefano Carniani, Stephane Charlot, Jacopo Chevallard, Zuyi Chen, Mirko Curti, Emma Curtis-Lake, Francesco D’Eugenio, Eiichi Egami, Ryan Endsley, Ryan Hausen, Zhiyuan Ji, Tobias J Looser, Jianwei Lyu, Roberto Maiolino, Erica Nelson, Dávid Puskás, Tim Rawle, Lester Sandles, Aayush Saxena, Renske Smit, Daniel P Stark, Christina C Williams, Chris Willott, Joris Witstok

A recently quenched galaxy 700 million years after the Big Bang.

Nature (2024)

Authors:

Tobias J Looser, Francesco D'Eugenio, Roberto Maiolino, Joris Witstok, Lester Sandles, Emma Curtis-Lake, Jacopo Chevallard, Sandro Tacchella, Benjamin D Johnson, William M Baker, Katherine A Suess, Stefano Carniani, Pierre Ferruit, Santiago Arribas, Nina Bonaventura, Andrew J Bunker, Alex J Cameron, Stephane Charlot, Mirko Curti, Anna de Graaff, Michael V Maseda, Tim Rawle, Hans-Walter Rix, Bruno Rodríguez Del Pino, Renske Smit, Hannah Übler, Chris Willott, Stacey Alberts, Eiichi Egami, Daniel J Eisenstein, Ryan Endsley, Ryan Hausen, Marcia Rieke, Brant Robertson, Irene Shivaei, Christina C Williams, Kristan Boyett, Zuyi Chen, Zhiyuan Ji, Gareth C Jones, Nimisha Kumari, Erica Nelson, Michele Perna, Aayush Saxena, Jan Scholtz

Abstract:

Local and low-redshift (z<3) galaxies are known to broadly follow a bimodal distribution: actively star forming galaxies with relatively stable star-formation rates, and passive systems. These two populations are connected by galaxies in relatively slow transition. In contrast, theory predicts that star formation was stochastic at early cosmic times and in low-mass systems 1-4: these galaxies transitioned rapidly between starburst episodes and phases of suppressed star formation, potentially even causing temporary quiescence -so-called mini-quenching events 5,6. However, the regime of star-formation burstiness is observationally highly unconstrained. Directly observing mini-quenched galaxies in the primordial Universe is therefore of utmost importance to constrain models of galaxy formation and transformation 7,8. Early quenched galaxies have been identified out to redshift z < 5 [e.g. 9-12], and these are all found to be massive (M > 1010 M) and relatively old. Here we report a (mini-)quenched galaxy at z=7.3, when the Universe was only 700 Myr old. The JWST/NIRSpec spectrum is very blue (UV =0.16 ± 0.03 mag), but exhibits a Balmer break and no nebular emission lines. The galaxy experienced a short starburst followed by rapid quenching; its stellar mass (4-6×108 M) falls in a range that is sensitive to various feedback mechanisms, which can result in perhaps only temporary quenching.