Objective:The main aim of this post is to explore how feedback processes and closure radius affect the baryon distribution within dark matter halos and their outskirts.
Background:
- Baryons: Baryons, or ordinary matter, are everything we see in the universe, including stars, planets, and interstellar gas. And what we don't see is dark matter. The distribution of baryons in the universe is affected by physical feedback, and the baryon distribution is not uniform.
- The cumulative baryon fraction: The ratio between baryonic matter and total matter within a sphere of radius (𝑹𝒔) centered at the halo center.
- (Halo) Baryon fraction: ratio of the mass of baryonic matter to the total mass within a halo.
- Closure Radius: The closure radius (𝑹𝒄 ) is the radius within which the baryon fraction reaches a specified fraction of the cosmic average baryon fraction and substantially impact big name formation in galaxies. halos evolve through accretion and mergers galaxies; the closure radius isn't always static but change with time and also varying with redshifts.
- The cosmic value: overall baryon fraction observed in the universe on large scales.
- Halo mass: Total mass (dark matter and baryonic matter) present within the halo boundary.
- Haloes: There is a spherical region around the galaxy called halo which contains all the matter (dark matter and baryonic matter). All the matter present inside this halo is balanced by the force of gravity.
- Astronomical Feedback: Astronomical feedback mechanisms contain energy and momentum from stars and AGN affecting their environment, shaping celebrity formation, fuel dynamics, and galaxy increase.
- Stellar Feedback: Stars impact their environment, like supernova explosions, in which loss of life massive stars eject enormous quantities of materials into environment, and stellar winds, that are continuous streams of particles blown off by means of stars in the course of their lives.
- AGN Feedback: AGN feedback is powered by supermassive black holes and is an extremely active phenomenon. AGN feedback ejects baryonic particles in the form of jets into and out of the halo and emits high-power radiation.
- TNG: To help the studying the Galaxy formation and evolution at different scales and resolutions.
- EAGLE: To help the studying the Galaxy formation and evolution due to feedback process.
- SIMBA: To help the studying the Galaxy formation and evolution due to AGN feedback process and baryonic distribution.
Results
Feedback mechanics and Baryonic distributions in halo:
- Low-Mass Haloes: In haloes with masses less than the Milky Way, stellar feedback is a dominant process. Supernovae and stellar winds are pushing gas out into the CGM and even beyond. lower baryon fractions.
- Intermediate-Mass Haloes: Stellar feedback maintains to play a position but is complemented by means of different techniques like AGN remarks in greater large systems.
- Massive Haloes: AGN comments will become massive. Energy released from accreting black holes heats the fuel, preventing it from cooling and falling back into the halo, or ejecting it to larger distances. This warm gas stays inside the outskirts.
Feedback Effects and Baryonic distributions on Halo Outskirts:
- Stellar and AGN feedback mechanisms affect the distribution of baryonic matter when they expel energetic gas from the inner regions of haloes into the IGM and CGM. Feedback processes lower central baryon fractions by driving gas outward, impacting star formation rates, gas density, temperature, and composition.
- Density and Temperature Changes: Feedback mechanisms, such as stellar winds and supernova explosions, cause significant changes in the density and temperature profiles of gas in halo outskirts.
- 1. Dwarfs: The value of cumulative baryon fraction increases as we move away from the centre of the halo because of the smaller mass of these galaxies and hence the gravitational potential of these galaxies is less. Therefore, the cumulative baryon fraction can only reach 10 to 20% of the cosmic charge even at Rc.
- 2. Milky Way-like Haloes: This halo is larger than the halo of a dwarf galaxy and smaller than a galaxy cluster. In these, the value of baryons at Rc itself reaches 30 to 60% of the cosmic value. their mass is more than that of a dwarf galaxy, due to it has a high-power gravitational potential. Due to which baryons get trapped in this halo.
- 3. Galaxy Clusters: These halos are considered to be the largest halos in the universe. They have the largest mass, due to which their gravitational potential is the highest, so the baryons get trapped inside, due to which at Rc, the cumulative baryon fraction reaches 100% of the cosmic value.
Comparison of Simulations:
- The closure radii obtained from the TNG, EAGLE, and SIMBA feedback models have different values due to the variations in the feedback models. SIMBA shows much larger Rୡ values as compared to TNG and EAGLE's Rୡ because the AGN feedback is very strong in it.
Relation between Halo Mass, Closure radius and Feedback Effects:
- Dwarf Galaxies (low-mass haloes): Smaller closure radii due to weaker stellar feedback.
- Milky Way-like Haloes: The closure radius is intermediate as compared to dwarf galaxies and large clusters. These holes have affected from both stellar and AGN feedback.
- Massive Clusters (galaxy clusters): Have large closure radii as strong AGN remarks turns into dominant, heating the gasoline and expelling it to more distances.
- Mathematical Formulation: ,
Conclusion:
- To understand galaxy formation and cosmic evolution, we need to understand the closure radius and feedback mechanism because these feedback mechanics and closure radius affect the baryon distribution inside and outside the halo. And closure radius also depends on halo mass, halo size, closure radius, and is also affected by the gravity of dark matter.