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Abstract We explore the role of galactic feedback on the low-redshift Lyα(Lyα) forest (z≲ 2) statistics and its potential to alter the thermal state of the intergalactic medium. Using the Cosmology and Astrophysics with Machine Learning Simulations (CAMELS) suite, we explore variations of the AGN and stellar feedback models in the IllustrisTNG and Simba subgrid models. We find that both AGN and stellar feedback in Simba play a role in setting the Lyαforest column density distribution function (CDD) and the Doppler width (b-value) distribution. The Simba AGN jet feedback mode is able to efficiently transport energy out to the diffuse IGM, causing changes in the shape and normalization of the CDD and a broadening of theb-value distribution. We find that stellar feedback plays a prominent role in regulating supermassive black hole growth and feedback, highlighting the importance of constraining stellar and AGN feedback simultaneously. In IllustrisTNG, the AGN feedback variations explored in CAMELS do not affect the Lyαforest, but varying the stellar feedback model does produce subtle changes. Our results imply that the low-zLyαforest can be sensitive to changes in the ultraviolet background, stellar and black hole feedback, and that AGN jet feedback in particular can have a strong effect on the thermal state of the IGM.
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Efficient Long-range Active Galactic Nuclei (AGNs) Feedback Affects the Low-redshift Lyα Forest
Abstract Active galactic nuclei (AGNs) feedback models are generally calibrated to reproduce galaxy observables such as the stellar mass function and the bimodality in galaxy colors. We use variations of the AGN feedback implementations in the IllustrisTNG (TNG) and Simba cosmological hydrodynamic simulations to show that the low-redshift Ly α forest can provide constraints on the impact of AGN feedback. We show that TNG overpredicts the number density of absorbers at column densities N HI < 10 14 cm −2 compared to data from the Cosmic Origins Spectrograph (in agreement with previous work), and we demonstrate explicitly that its kinetic feedback mode, which is primarily responsible for galaxy quenching, has a negligible impact on the column density distribution (CDD) of absorbers. In contrast, we show that the fiducial Simba model, which includes AGN jet feedback, is the preferred fit to the observed CDD of the z = 0.1 Ly α forest across 5 orders of magnitude in column density. We show that the Simba results with jets produce a quantitatively better fit to the observational data than the Simba results without jets, even when the ultraviolet background is left as a free parameter. AGN jets in Simba are high speed, collimated, weakly interacting with the interstellar medium (via brief hydrodynamic decoupling), and heated to the halo virial temperature. Collectively these properties result in stronger long-range impacts on the intergalactic medium when compared to TNG’s kinetic feedback mode, which drives isotropic winds with lower velocities at the galactic radius. Our results suggest that the low-redshift Ly α forest provides plausible evidence for long-range AGN jet feedback.
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- PAR ID:
- 10458999
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 945
- Issue:
- 1
- ISSN:
- 2041-8205
- Page Range / eLocation ID:
- L17
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.3847/2041-8213/acb7f1
