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  • American Astronomical Society  (7)
  • Physics  (7)
  • 1
    Online Resource
    Online Resource
    The AGORA High-resolution Galaxy Simulations Comparison Project. VI. Similarities and Differences in the Circumgalactic Medium
    American Astronomical Society ; 2024
    In:  The Astrophysical Journal Vol. 962, No. 1 ( 2024-02-01), p. 29-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 962, No. 1 ( 2024-02-01), p. 29-
    Abstract: We analyze the circumgalactic medium (CGM) for eight commonly-used cosmological codes in the AGORA collaboration. The codes are calibrated to use identical initial conditions, cosmology, heating and cooling, and star formation thresholds, but each evolves with its own unique code architecture and stellar feedback implementation. Here, we analyze the results of these simulations in terms of the structure, composition, and phase dynamics of the CGM. We show properties such as metal distribution, ionization levels, and kinematics are effective tracers of the effects of the different code feedback and implementation methods, and as such they can be highly divergent between simulations. This is merely a fiducial set of models, against which we will in the future compare multiple feedback recipes for each code. Nevertheless, we find that the large parameter space these simulations establish can help disentangle the different variables that affect observable quantities in the CGM, e.g., showing that abundances for ions with higher ionization energy are more strongly determined by the simulation’s metallicity, while abundances for ions with lower ionization energy are more strongly determined by the gas density and temperature.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/ad12cb
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2024
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    How Metals Are Transported in and out of a Galactic Disk: Dependence on the Hydrodynamic Schemes in Numerical Simulations
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Vol. 917, No. 1 ( 2021-08-01), p. 12-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 917, No. 1 ( 2021-08-01), p. 12-
    Abstract: Metallicity is a fundamental probe for understanding the baryon physics in a galaxy. Since metals are intricately associated with radiative cooling, star formation, and stellar feedback, reproducing the observed metal distribution through numerical experiments will provide a prominent way to examine our understanding of galactic baryon physics. In this study, we analyze the dependence of the galactic metal distribution on numerical schemes and quantify the differences in metal mixing among modern galaxy simulation codes (the mesh-based code Enzo and the particle-based codes Gadget-2 and Gizmo-PSPH ). In particular, we examine different stellar feedback strengths and an explicit metal diffusion scheme in particle-based codes, as a way to alleviate the well-known discrepancy in metal transport between mesh-based and particle-based simulations. We demonstrate that a sufficient number of gas particles are needed in the gas halo to properly investigate the metal distribution therein. Including an explicit metal diffusion scheme does not significantly affect the metal distribution in the galactic disk but does change the amount of low-metallicity gas in a hot diffuse halo. We also find that the spatial distribution of metals depends strongly on how the stellar feedback is modeled. We demonstrate that the previously reported discrepancy in metals between mesh-based and particle-based simulations can be mitigated with our proposed prescription, enabling these simulations to be reliably utilized in the study of metals in galactic halos and the circumgalactic medium.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/abffd0
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    The AGORA High-resolution Galaxy Simulations Comparison Project. V. Satellite Galaxy Populations in a Cosmological Zoom-in Simulation of a Milky Way–Mass Halo
    American Astronomical Society ; 2024
    In:  The Astrophysical Journal Vol. 964, No. 2 ( 2024-04-01), p. 123-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 964, No. 2 ( 2024-04-01), p. 123-
    Abstract: We analyze and compare the satellite halo populations at z ∼ 2 in the high-resolution cosmological zoom-in simulations of a 10 12 M ⊙ target halo ( z = 0 mass) carried out on eight widely used astrophysical simulation codes ( Art-I , Enzo , Ramses , Changa , Gadget-3 , Gear , Arepo-t , and Gizmo ) for the AGORA High-resolution Galaxy Simulations Comparison Project. We use slightly different redshift epochs near z = 2 for each code (hereafter “ z ∼ 2”) at which the eight simulations are in the same stage in the target halo’s merger history. After identifying the matched pairs of halos between the CosmoRun simulations and the DMO simulations, we discover that each CosmoRun halo tends to be less massive than its DMO counterpart. When we consider only the halos containing stellar particles at z ∼ 2, the number of satellite galaxies is significantly fewer than that of dark matter halos in all participating AGORA simulations and is comparable to the number of present-day satellites near the Milky Way or M31. The so-called “missing satellite problem” is fully resolved across all participating codes simply by implementing the common baryonic physics adopted in AGORA and the stellar feedback prescription commonly used in each code, with sufficient numerical resolution (≲100 proper pc at z = 2). We also compare other properties such as the stellar mass–halo mass relation and the mass–metallicity relation. Our work highlights the value of comparison studies such as AGORA, where outstanding problems in galaxy formation theory are studied simultaneously on multiple numerical platforms.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/ad245b
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2024
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Merger-tree-based Galaxy Matching: A Comparative Study across Different Resolutions
    American Astronomical Society ; 2024
    In:  The Astrophysical Journal Vol. 965, No. 2 ( 2024-04-01), p. 156-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 965, No. 2 ( 2024-04-01), p. 156-
    Abstract: We introduce a novel halo/galaxy matching technique between two cosmological simulations with different resolutions, which utilizes the positions and masses of halos along their subhalo merger tree. With this tool, we conduct a study of resolution biases through the galaxy-by-galaxy inspection of a pair of simulations that have the same simulation configuration but different mass resolutions, utilizing a suite of IllustrisTNG simulations to assess the impact on galaxy properties. We find that, with the subgrid physics model calibrated for TNG100-1, subhalos in TNG100-1 (high resolution) have ≲0.5 dex higher stellar masses than their counterparts in the TNG100-2 (low resolution). It is also discovered that the subhalos with M gas ∼ 10 8.5 M ⊙ in TNG100-1 have ∼0.5 dex higher gas mass than those in TNG100-2. The mass profiles of the subhalos reveal that the dark matter masses of subhalos in TNG100-2 converge well with those from TNG100-1, except within 4 kpc of the resolution limit. The differences in stellar mass and hot gas mass are most pronounced in the central region. We exploit machine learning to build a correction mapping for the physical quantities of subhalos from low- to high-resolution simulations (TNG300-1 and TNG100-1), which enables us to find an efficient way to compile a high-resolution galaxy catalog even from a low-resolution simulation. Our tools can easily be applied to other large cosmological simulations, testing and mitigating the resolution biases of their numerical codes and subgrid physics models.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/ad34d1
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2024
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Dark Matter Deficient Galaxies Produced via High-velocity Galaxy Collisions in High-resolution Numerical Simulations
    American Astronomical Society ; 2020
    In:  The Astrophysical Journal Vol. 899, No. 1 ( 2020-08-01), p. 25-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 899, No. 1 ( 2020-08-01), p. 25-
    Abstract: The recent discovery of diffuse dwarf galaxies that are deficient in dark matter appears to challenge the current paradigm of structure formation in our universe. We describe numerical experiments to determine if so-called dark matter deficient galaxies (DMDGs) could be produced when two gas-rich, dwarf-sized galaxies collide with a high relative velocity of ∼300 km s −1 . Using idealized high-resolution simulations with both mesh-based and particle-based gravito-hydrodynamics codes, we find that DMDGs can form as high-velocity galaxy collisions and separate dark matter from the warm disk gas, which subsequently is compressed by shock and tidal interaction to form stars. Then using the large simulated universe Il lustris TNG, we discover a number of high-velocity galaxy collision events in which DMDGs are expected to form. However, we did not find evidence that these types of collisions actually produced DMDGs in the TNG100-1 run. We argue that the resolution of the numerical experiment is critical to realizing the “collision-induced” DMDG formation scenario. Our results demonstrate one of many routes in which galaxies could form with unconventional dark matter fractions.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/aba434
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2020
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    Growth of a Massive Black Hole in a Dense Star Cluster Via Tidal Disruption Accretion
    American Astronomical Society ; 2023
    In:  The Astrophysical Journal Vol. 943, No. 2 ( 2023-02-01), p. 77-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 943, No. 2 ( 2023-02-01), p. 77-
    Abstract: Stars that are tidally disrupted by a massive black hole (MBH) may contribute significantly to the growth of the MBH, especially in dense nuclear star clusters. Yet, this tidal disruption accretion (TDA) of stars onto the MBH has largely been overlooked compared to the gas accretion (GA) channel in most numerical experiments until now. In this work, we implement a black hole growth channel via TDA in the high-resolution adaptive mesh refinement code Enzo to investigate its influence on an MBH seed’s early evolution. We find that an MBH seed grows rapidly from 10 3 to ≳10 6 M ⊙ in 200 Myr in some of the tested simulations. Compared to an MBH seed that grows only via GA, TDA can enhance the MBH’s growth rate by more than 1 order of magnitude. However, as predicted, TDA mainly helps the early growth of the MBH (from 10 3–4 to ≲10 5 M ⊙ ) while the later evolution is generally dominated by GA. We also observe that the star formation near the MBH is suppressed when TDA is the most active, sometimes with a visible cavity in gas (of size ∼ a few pc) created in the vicinity of the MBH. It is because the MBH may grow expeditiously with both GA and TDA, and the massive MBH could consume its neighboring gas faster than being replenished by gas inflows. Our study demonstrates the need to consider different channels of black hole accretion that may provide clues for the existence of supermassive black holes at high redshifts.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/aca75d
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 7
    Online Resource
    Online Resource
    The AGORA High-resolution Galaxy Simulations Comparison Project. IV. Halo and Galaxy Mass Assembly in a Cosmological Zoom-in Simulation at z ≤ 2
    American Astronomical Society ; 2024
    In:  The Astrophysical Journal Vol. 968, No. 2 ( 2024-06-01), p. 125-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 968, No. 2 ( 2024-06-01), p. 125-
    Abstract: In this fourth paper from the AGORA Collaboration, we study the evolution down to redshift z = 2 and below of a set of cosmological zoom-in simulations of a Milky Way mass galaxy by eight of the leading hydrodynamic simulation codes. We also compare this CosmoRun suite of simulations with dark matter-only simulations by the same eight codes. We analyze general properties of the halo and galaxy at z = 4 and 3, and before the last major merger, focusing on the formation of well-defined rotationally supported disks, the mass–metallicity relation, the specific star formation rate, the gas metallicity gradients, and the nonaxisymmetric structures in the stellar disks. Codes generally converge well to the stellar-to-halo mass ratios predicted by semianalytic models at z ∼ 2. We see that almost all the hydro codes develop rotationally supported structures at low redshifts. Most agree within 0.5 dex with the observed mass–metallicity relation at high and intermediate redshifts, and reproduce the gas metallicity gradients obtained from analytical models and low-redshift observations. We confirm that the intercode differences in the halo assembly history reported in the first paper of the collaboration also exist in CosmoRun , making the code-to-code comparison more difficult. We show that such differences are mainly due to variations in code-dependent parameters that control the time stepping strategy of the gravity solver. We find that variations in the early stellar feedback can also result in differences in the timing of the low-redshift mergers. All the simulation data down to z = 2 and the auxiliary data will be made publicly available.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/ad43de
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2024
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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