Lyman α absorption beyond the disc of simulated spiral galaxies

Röttgers, Bernhard; Naab, Thorsten; Černetič, Miha; Davé, Romeel; Kauffmann, Guinevere; Borthakur, Sanchayeeta; Foidl, Horst

doi:10.1093/mnras/staa1490

Cited by 30 publications

(18 citation statements)

References 70 publications

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“…Our results are also consistent with the N(H i)-b relationship for dwarf galaxies from the NIHAO simulation suite Gutcke et al (2017). The distribution of strong H i absorbers (with N(H i) 10 15 cm −2 ) appears to be less extended compared to more massive, star-forming galaxies in previous numerical works (e.g., Gutcke et al 2017;Röttgers et al 2020). In addition, several recent studies have found that the spacial distribution and covering fractions of the strong H i absorbing systems can be sensitive to instability processes occurring at smaller scales, and thus sensitive to the CGM-resolution cosmological simulations (e.g., Hummels et al 2019;Suresh et al 2019;van de Voort et al 2019).…”

Section: The Circumgalactic Mediumsupporting

confidence: 89%

The baryon cycle of Seven Dwarfs with superbubble feedback

Mina

Shen

Keller

et al. 2021

A&A

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We present results from a high-resolution, cosmological, ΛCDM simulation of a group of field dwarf galaxies with the “superbubble” model for clustered SN feedback, accounting for thermal conduction and cold gas evaporation. We compared our results to a previous simulation which has the same initial condition and galaxy formation physics (other than SN feedback), but adopts a delayed-cooling model for supernova. The simulated luminous galaxies have blue colors, low star formation efficiencies and metallicities, and high cold gas content, reproducing the observed scaling relations of dwarf galaxies in the Local Volume. Bursty star formation histories and superbubble-driven outflows lead to the formation of kpc-size dark matter (DM) cores when stellar masses reaches M* > 106 M⊙, similar to previous findings. However, the superbubble model appears more effective in destroying DM cusps than the delayed-cooling model in the previous study, reflecting a higher coupling efficiency of SN energy with the ISM. On larger scale, superbubble-driven outflows have a more moderate impact: galaxies have higher gas content, more extended stellar discs, and a smaller metal-enriched region in the circumgalactic medium (CGM). The two halos with Mvir ∼ 109 M⊙, which formed ultra-faint dwarf galaxies with the delayed-cooling mode, remain dark due to the different impact of metal-enriched galactic winds from two nearby luminous galaxies, indicating that the formation of faint dwarfs is highly dependent on feedback and environmental effects. The column density distributions of H I, Si II, C IV and O VI as a function of the scaled impact parameter (b/Rvir) are in good agreement with recent observations of CGM around isolated dwarf galaxies. While H I is ubiquitous with a covering fraction of unity within the CGM, low and intermediate ions like Si II and C IV are less extended (typically confined within 0.2 − 0.3 Rvir), and non-detections are common. O VI is more extended with column density N(O VI) ≳ 1013.5 cm−2 within Rvir, but its mass is only 11% of the total CGM oxygen budget, as the diffuse CGM is highly ionised by the UV background. Superbubble feedback produces C IV and O VI column densities that are an order of magnitude higher than those in the previous study using delayed-cooling feedback. Thus, the CGM and DM cores are most sensitive probes of feedback mechanisms.

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Section: The Circumgalactic Mediumsupporting

confidence: 89%

The baryon cycle of Seven Dwarfs with superbubble feedback

Mina

Shen

Keller

et al. 2021

A&A

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“…Mock absorption spectra are generated through the simulation volume using the spectrum generation tools in the Pygad 2 analysis package (Röttgers et al 2020). The spectra are computed from gas particles who smoothing lengths intersect with the LOS, so spectrum generation is not dependent on our halo-finding procedure.…”

Section: Spectral Generationmentioning

confidence: 99%

“…The resulting ion column densities for each pixel are converted into an optical depth using the oscillator strength of each species. See Röttgers et al (2020) for further details on Pygad.…”

Section: Spectral Generationmentioning

confidence: 99%

“…We focus on the EWs here, since in many cases the Doppler parameter cannot be directly determined from the spectra, and the PyIGM column densities therefore assume a Doppler parameter that may not be correct (Röttgers et al 2020). The EW in PyIGM were measured in ±600 km s −1 windows around the galaxy redshift, after continuum fitting.…”

Section: Absorption Statisticsmentioning

confidence: 99%

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The low-redshift circumgalactic medium in simba

Appleby

Davé

Sorini

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We examine the properties of the low-redshift circumgalactic medium (CGM) around star-forming and quenched galaxies in the Simba cosmological hydrodynamic simulations, focusing on comparing H i and metal line absorption to observations from the COS-Halos and COS-Dwarfs surveys. Halo baryon fractions are generally $\lesssim 50{{\ \rm per\ cent}}$ of the cosmic fraction due to stellar feedback at low masses, and jet-mode AGN feedback at high masses. Baryons and metals in the CGM of quenched galaxies are $\gtrsim 90{{\ \rm per\ cent}}$ hot gas, while the CGM of star-forming galaxies is more multi-phase. Hot CGM gas has low metallicity, while warm and cool CGM gas have metallicity close to that of galactic gas. Equivalent widths, covering fractions and total path absorption of H i and selected metal lines (Mg ii, Si iii, C iv and O vi) around a matched sample of Simba star-forming galaxies are mostly consistent with COS-Halos and COS-Dwarfs observations to $\lesssim 0.4$ dex, depending on ion and assumed ionising background. Around matched quenched galaxies, absorption in all ions is lower, with H i absorption significantly under-predicted. Metal-line absorption is sensitive to choice of photo-ionising background; assuming recent backgrounds, Simba matches O vi but under-predicts low ions, while an older background matches low ions but under-predicts O vi. Simba reproduces the observed dichotomy of O vi absorption around star forming and quenched galaxies. CGM metals primarily come from stellar feedback, while jet-mode AGN feedback reduces absorption particularly for lower ions.

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“…Software: Astropy (https://www.astropy.org/; Astropy Collaboration et al 2018), gizmo (http://www.tapir. caltech.edu/ ∼ phopkins/Site/GIZMO.html; Hopkins 2015; Springel 2005), Matplotlib (https://matplotlib.org/), Plotly (https://plotly.com/), pygad (https://bitbucket.org/broett/pygad/src/master/; Röttgers et al 2020)…”

mentioning

confidence: 99%

The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds

Lucchini,

D'Onghia,

Fox

2021

Preprint

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We present new simulations of the formation of the Magellanic Stream based on an updated firstpassage interaction history for the Magellanic Clouds, including both the Galactic and Magellanic Coronae and a live dark matter halo for the Milky Way. This new interaction history is needed because previously successful orbits need updating to account for the Magellanic Corona and the loosely bound nature of the Magellanic Group. These orbits involve two tidal interactions over the last 3.5 Gyrs and reproduce the Stream's position and appearance on the sky, mass distribution, and velocity profile. Most importantly, our simulated Stream is only ∼20 kpc away from the Sun at its closest point, whereas previous first-infall models predicted a distance of 100 − 200 kpc. This dramatic paradigm shift in the Stream's 3D position would have several important implications. First, estimates of the observed neutral and ionized masses would be reduced by a factor of ∼5. Second, the stellar component of the Stream is also predicted to be <20 kpc away. Third, the enhanced interactions with the MW's hot corona at this small distance would substantially shorten the Stream's lifetime. Finally, the MW's UV radiation field would be much stronger, potentially explaining the Hα emission observed along most of the Stream. Our prediction of a 20 kpc Stream could be tested by searching for UV absorption lines towards distant MW halo stars projected onto the Stream.

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Lyman α absorption beyond the disc of simulated spiral galaxies

Cited by 30 publications

References 70 publications

The baryon cycle of Seven Dwarfs with superbubble feedback

The baryon cycle of Seven Dwarfs with superbubble feedback

The low-redshift circumgalactic medium in simba

The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds

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