[
{
"id": "authors:13r4z-gwv02",
"collection": "authors",
"collection_id": "13r4z-gwv02",
"cite_using_url": "https://authors.library.caltech.edu/records/13r4z-gwv02",
"type": "article",
"title": "X-Ray Emission Signatures of Galactic Feedback in the Hot Circumgalactic Medium: Predictions from Cosmological Hydrodynamical Simulations",
"author": [
{
"family_name": "Silich",
"given_name": "Emily M.",
"orcid": "0000-0002-1616-5649",
"clpid": "Silich-Emily-M"
},
{
"family_name": "ZuHone",
"given_name": "John",
"orcid": "0000-0003-3175-2347"
},
{
"family_name": "Bellomi",
"given_name": "Elena",
"orcid": "0000-0001-6411-3686"
},
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Oppenheimer",
"given_name": "Benjamin",
"orcid": "0000-0002-3391-2116"
},
{
"family_name": "Hopkins",
"given_name": "Philip F.",
"orcid": "0000-0003-3729-1684",
"clpid": "Hopkins-P-F"
},
{
"family_name": "Lochhaas",
"given_name": "Cassandra",
"orcid": "0000-0003-1785-8022"
},
{
"family_name": "Ponnada",
"given_name": "Sam B.",
"orcid": "0000-0002-7484-2695",
"clpid": "Ponnada-Sam-B"
},
{
"family_name": "Vikhlinin",
"given_name": "Alexey",
"orcid": "0000-0001-8121-0234"
}
],
"abstract": "\n
Little is currently known about the physical properties of the hot circumgalactic medium (CGM) surrounding massive galaxies. Next-generation X-ray observatories will enable detailed studies of the hot CGM in emission. To support these future efforts, we make predictions of the X-ray emission from the hot CGM using a sample of 28 ∼Milky Way-mass disk galaxies at z = 0 from seven cosmological hydrodynamical simulation suites incorporating a wide range of galactic feedback prescriptions. The X-ray surface brightness (XSB) morphology of the hot CGM varies significantly across simulations. XSB-enhanced outflows and bubble-like structures are predicted in many galaxies simulated with active galactic nuclei (AGN) feedback and in some stellar-feedback-only galaxies, while other galaxies exhibit more isotropic XSB distributions at varying brightnesses. Galaxies simulated without cosmic-ray physics exhibit radial XSB profiles with similar shapes (∝r−3 within 20–200 kpc), with scatter about this slope likely due to underlying feedback physics. The hot CGM kinematics also differ substantially: velocity maps reveal signatures of bulk CGM rotation and high-velocity biconical outflows, particularly in simulations incorporating AGN feedback. Some stellar-feedback-only models also generate similar AGN-like outflows, which we postulate is due to centrally concentrated star formation. Simulations featuring AGN feedback frequently produce extended temperature enhancements in large-scale galactic outflows, while simulations incorporating cosmic-ray physics predict the coolest CGM due to pressure support being provided by cosmic rays rather than hot CGM. Individually resolved X-ray emission lines further distinguish hot CGM phases, with lower-energy lines (e.g., O VII) largely tracing volume-filling gas, and higher-energy lines (e.g., Fe XVII) highlighting high-velocity feedback-driven outflows.
\n
We develop and present the Descriptive Parametric Model (DPM), a tool for generating profiles of gaseous halos (pressure, electron density, and metallicity) as functions of radius, halo mass, and redshift. The model assumes single-phase, spherically symmetric, volume-filling warm/hot gas. The DPM framework enables mock observations of the circumgalactic medium (CGM), group halos, and clusters across a number of wavebands including X-ray, sub-millimeter/millimeter, radio, and ultraviolet (UV). We introduce three model families calibrated to reproduce cluster profiles while having different extrapolations to the CGM – (i) self-similar halos, (ii) a reduced gas model for lower halo masses, and (iii) a model with shallower radial slopes at lower masses. We demonstrate how our z = 0.0 − 0.6 models perform when applied to stacked and individual X-ray emission profiles, measurements of the thermal and kinetic Sunyaev-Zel'dovich Effect, electron dispersion measures from fast radio bursts, O VI absorption, and UV-derived pressures. Our investigation supports models that remove baryons from halos more effectively and have shallower profiles at lower halo mass. We discuss biases and systematics when modelling observables using consistent hot gaseous halo models for all wavebands explored. We release the DPMhalo code to encourage the use of our framework and new formulations in future investigations. Included with the DPMhalo distribution is a set of recent observations that allow the reproduction of most plots in this paper.
",
"doi": "10.1093/mnras/staf1581",
"issn": "0035-8711",
"publisher": "Royal Astronomical Society",
"publication": "Monthly Notices of the Royal Astronomical Society",
"publication_date": "2025-11",
"series_number": "3",
"volume": "543",
"issue": "3",
"pages": "2649-2669"
},
{
"id": "authors:9n6kw-63590",
"collection": "authors",
"collection_id": "9n6kw-63590",
"cite_using_url": "https://authors.library.caltech.edu/records/9n6kw-63590",
"type": "article",
"title": "Turbulence-dominated CGM: the origin of UV absorbers with equivalent widths of \u223c1\u2009\u00c5",
"author": [
{
"family_name": "Kakoly",
"given_name": "Aharon",
"orcid": "0009-0001-9850-8827"
},
{
"family_name": "Stern",
"given_name": "Jonathan",
"orcid": "0000-0002-7541-9565"
},
{
"family_name": "Faucher-Gigu\u00e8re",
"given_name": "Claude-Andr\u00e9",
"orcid": "0000-0002-4900-6628"
},
{
"family_name": "Fielding",
"given_name": "Drummond B",
"orcid": "0000-0003-3806-8548"
},
{
"family_name": "Goldner",
"given_name": "Roy"
},
{
"family_name": "Sun",
"given_name": "Guochao",
"orcid": "0000-0003-4070-497X"
},
{
"family_name": "Hummels",
"given_name": "Cameron B",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
}
],
"abstract": "Theoretical arguments and observations suggest that in massive haloes (\u2060\u2060>10¹²M\u2299), the circumgalactic medium (CGM) is dominated by a ‘hot’ phase with gas temperature near the virial temperature (T≈T_(vir)\u2060\u2060) and a quasi-hydrostatic pressure profile. Lower-mass haloes are however unlikely to be filled with a similar quasi-static hot phase, due to rapid radiative cooling. Using the FIRE (Feedback In Realistic Environment) cosmological zoom simulations, we demonstrate that the hot phase is indeed subdominant at inner radii (\u227e0.3R_(vir)) of \u227e10¹²M\u2299 haloes, and the inner CGM is instead filled with T \u226a T_(vir) gas originating in outflows and inflows, with a turbulent velocity comparable to the halo virial velocity. The turbulent velocity thus exceeds the mass-weighted sound speed in the inner CGM, and the turbulence is supersonic. UV absorption features from such CGM trace the wide lognormal density distributions of the predominantly cool and turbulent volume-filling phase, in contrast with tracing localized cool ‘clouds’ embedded in a hot medium. We predict equivalent widths of Wλ ~ 2λv_c/c~1Å for a broad range of strong UV and EUV transitions (Mg ii, C ii, C iv, Si ii–iv, O iii–v) in sightlines through inner CGM dominated by turbulent pressure of \u227eL\u2605 galaxies at redshifts \u20600 ≤ z \u227e2, where λ is the transition wavelength, v_c is the circular velocity, and c is the speed of light. Comparison of our predictions with observational constraints suggests that star forming \u227eL\u2605 and dwarf galaxies are generally dominated by turbulent pressure in their inner CGM, rather than by thermal pressure. The inner CGM surrounding these galaxies is thus qualitatively distinct from that around quenched galaxies and massive discs such as the Milky-Way and M31, in which thermal pressure likely dominates.
",
"doi": "10.1093/mnras/staf1516",
"issn": "0035-8711",
"publisher": "Royal Astronomical Society",
"publication": "Monthly Notices of the Royal Astronomical Society",
"publication_date": "2025-11",
"series_number": "4",
"volume": "543",
"issue": "4",
"pages": "3345-3366"
},
{
"id": "authors:8ws7z-a2d56",
"collection": "authors",
"collection_id": "8ws7z-a2d56",
"cite_using_url": "https://authors.library.caltech.edu/records/8ws7z-a2d56",
"type": "article",
"title": "A Practical Guide to Hosting a Virtual Conference",
"author": [
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Oppenheimer",
"given_name": "Benjamin",
"orcid": "0000-0002-3391-2116"
},
{
"family_name": "Voit",
"given_name": "G. Mark",
"orcid": "0000-0002-3514-0383"
},
{
"family_name": "Werk",
"given_name": "Jessica",
"orcid": "0000-0002-0355-0134"
}
],
"abstract": "Virtual meetings have long been the outcast of scientific interaction. For many of us, the COVID-19 pandemic has only strengthened that sentiment as countless Zoom meetings have left us bored and exhausted. But remote conferences do not have to be negative experiences. If well designed, they have some distinct advantages over conventional in-person meetings, including universal access, longevity of content, as well as minimal costs and carbon footprint. This article details our experiences as organizers of a successful fully virtual scientific conference, the KITP program “Fundamentals of Gaseous Halos” hosted over 8 weeks in winter 2021. Herein, we provide detailed recommendations on planning and optimization of remote meetings, with application to traditional in-person events as well. We hope these suggestions will assist organizers of future virtual conferences and workshops.
",
"doi": "10.3847/25c2cfeb.f3f3a3d8",
"issn": "0002-7537",
"publisher": "American Astronomical Society",
"publication": "Bulletin of the AAS",
"publication_date": "2025-04-03",
"series_number": "1",
"volume": "57",
"issue": "1",
"pages": "2025i007"
},
{
"id": "authors:mbr2z-4bh84",
"collection": "authors",
"collection_id": "mbr2z-4bh84",
"cite_using_url": "https://authors.library.caltech.edu/records/mbr2z-4bh84",
"type": "article",
"title": "Hooks, Lines, and Sinkers: How Active Galactic Nucleus Feedback and Cosmic-Ray Transport Shape the Far-infrared\u2013Radio Correlation of Galaxies",
"author": [
{
"family_name": "Ponnada",
"given_name": "Sam B.",
"orcid": "0000-0002-7484-2695",
"clpid": "Ponnada-Sam-B"
},
{
"family_name": "Cochrane",
"given_name": "Rachel K.",
"orcid": "0000-0001-8855-6107"
},
{
"family_name": "Hopkins",
"given_name": "Philip F.",
"orcid": "0000-0003-3729-1684",
"clpid": "Hopkins-P-F"
},
{
"family_name": "Butsky",
"given_name": "Iryna S.",
"orcid": "0000-0003-1257-5007"
},
{
"family_name": "Wellons",
"given_name": "Sarah",
"orcid": "0000-0002-3977-2724"
},
{
"family_name": "Sanchez",
"given_name": "N. Nicole",
"orcid": "0000-0001-7589-6188",
"clpid": "Sanchez-N-Nicole"
},
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Lu",
"given_name": "Yue Samuel"
},
{
"family_name": "Kere\u0161",
"given_name": "Du\u0161an",
"orcid": "0000-0002-1666-7067"
},
{
"family_name": "Hayward",
"given_name": "Christopher C.",
"orcid": "0000-0003-4073-3236"
}
],
"abstract": "\n
The far-infrared–radio correlation (FRC) is one of the most promising empirical constraints on the role of cosmic rays (CRs) and magnetic fields in galaxy formation and evolution. While many theories have been proposed in order to explain the emergence and maintenance of the FRC across a gamut of galaxy properties and redshift, the nonlinear physics at play remain unexplored in full complexity and within a cosmological context. We present the first reproduction of the z ∼ 0 FRC using detailed synthetic observations of state-of-the-art cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE-3) suite with explicitly evolved CR proton and electron (CRe) spectra, for three models for CR transport and multichannel active galactic nucleus (AGN) feedback. In doing so, we generally verify the predictions of \"calorimeter\" theories at high FIR luminosities (L60 μm \u2273 109.5 L\u2299) and at low FIR luminosities (L60 μm \u2272 109.5 L\u2299), the so-called \"conspiracy\" of increasing UV radiation escape in tandem with increasing CRe escape, and find that the global FRC is insensitive to orders-of-magnitude locally variable CR transport coefficients. Importantly, the indirect effect of AGN feedback on emergent observables highlights novel interpretations of outliers in the FRC. In particular, we find that in many cases \"radio-excess\" objects can be better understood as \"IR-dim\" objects with longer-lived radio contributions at low z from Type Ia supernovae and intermittent black hole accretion in quenching galaxies, though this is sensitive to the interplay of CR transport and AGN feedback physics. This creates characteristic evolutionary tracks leading to the z = 0 FRC, which shape the subsequent late-time behavior of each model.
\n
\n
We make an in-depth analysis of different active galactic nuclei (AGN) jet models’ signatures, inducing quiescence in galaxies with a halo mass of 1012M\u2299. Three jet models, including cosmic-ray-dominant, hot thermal, and precessing kinetic jets, are studied at two energy flux levels each, compared to a jet-free, stellar feedback-only simulation. Each of our simulations is idealized isolated galaxy simulations with AGN jet powers that are constant in time and generated using GIZMO and with FIRE stellar feedback. We examine the distribution of Mg ii, O vi, and O viii ions, alongside gas temperature and density profiles. Low-energy ions, like Mg ii, concentrate in the interstellar medium (ISM), while higher energy ions, e.g., O viii, prevail at the AGN jet cocoon’s edge. High-energy flux jets display an isotropic ion distribution with lower overall density. High-energy thermal or cosmic-ray jets pressurize at smaller radii, significantly suppressing core density. The cosmic-ray jet provides extra pressure support, extending cool and warm gas distribution. A break in the ion-to-mass ratio slope in O vi and O viii is demonstrated in the ISM-to-circumgalactic medium (CGM) transition (between 10 and 30 kpc), growing smoothly toward the CGM at greater distances.
\n
We present CloudFlex, an open-source tool for predicting absorption-line signatures of cool gas in galaxy halos with small-scale structure. Motivated by analyses of ∼104 K material in hydrodynamical simulations of turbulent, multiphase media, we model cool gas structures as complexes of cloudlets sampled from a power-law distribution of mass ∝ m_(cl)−α with velocities drawn from a turbulent velocity field. The user may specify α, the lower limit of the cloudlet mass distribution (m_(cl,min)), and several other parameters that set the mass, size, and velocity distribution of the complex. This permits investigation of the relation between these parameters and absorption-line observables. As a proof-of-concept, we calculate the Mg iiλ2796 absorption induced by the cloudlets in background quasi-stellar object (QSO) spectra. We demonstrate that, at fixed metallicity, the covering fraction of sight lines with equivalent widths W2796 < 0.3 Å increases significantly with decreasing m_(cl,min), cloudlet number density (ncl), and complex size. We then use this framework to predict the halo-scale W2796 distribution around ∼L* galaxies. We show that the observed incidences of W2796 > 0.3 Å sight lines with impact parameters 10 kpc < R⊥ < 50 kpc in projected QSO–galaxy studies are consistent with our model over much of parameter space. However, they are underpredicted by models with m_(cl,min) ≥ 100 M\u2299 and ncl ≥ 0.03 cm−3, in keeping with a picture in which the inner cool circumgalactic medium (CGM) is dominated by numerous low-mass cloudlets (mcl \u2272 100M\u2299) with a volume filling factor \u22721%. When used to model absorption-line data sets built from multi-sight line and/or spatially extended background probes, CloudFlex enables detailed constraints on the size and velocity distributions of structures comprising the photoionized CGM.
",
"doi": "10.3847/1538-4357/ad5965",
"issn": "0004-637X",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal",
"publication_date": "2024-09-10",
"series_number": "2",
"volume": "972",
"issue": "2",
"pages": "148"
},
{
"id": "authors:bfv5d-32w55",
"collection": "authors",
"collection_id": "bfv5d-32w55",
"cite_using_url": "https://authors.library.caltech.edu/records/bfv5d-32w55",
"type": "article",
"title": "Objects May Be Closer than They Appear: Significant Host Galaxy Dispersion Measures of Fast Radio Bursts in Zoom-in Simulations",
"author": [
{
"family_name": "Orr",
"given_name": "Matthew E.",
"orcid": "0000-0003-1053-3081"
},
{
"family_name": "Burkhart",
"given_name": "Blakesley",
"orcid": "0000-0001-5817-5944"
},
{
"family_name": "Lu",
"given_name": "Wenbin",
"orcid": "0000-0002-1568-7461"
},
{
"family_name": "Ponnada",
"given_name": "Sam B.",
"orcid": "0000-0002-7484-2695",
"clpid": "Ponnada-Sam-B"
},
{
"family_name": "Hummels",
"given_name": "Cameron B.",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
}
],
"abstract": "\n
We investigate the contribution of host galaxies to the overall dispersion measures (DMs) for fast radio bursts (FRBs) using the Feedback in Realistic Environments (FIRE-2) cosmological zoom-in simulation suite. We calculate DMs from every star particle in the simulated L* galaxies by ray-tracing through their multiphase interstellar medium, summing the line-of-sight free thermal electron column for all gas elements within ±20 kpc of the galactic midplane. At z = 0, we find average (median) host-galaxy DMs of 74 (43) and 210 (94) pc cm−3 for older (\u227310 Myr) and younger (\u227210 Myr) stellar populations, respectively. Inclination raises the median DM measured for older populations (\u227310 Myr) in the simulations by a factor of ∼2 but generally does not affect the younger stars deeply embedded in H ii regions except in extreme edge-on cases (inclination \u227385°). In kinematically disturbed snapshots (z = 1 in FIRE), the average (median) host-galaxy DMs are higher: 80 (107) and 266 (795) pc cm−3 for older (\u227310 Myr) and younger (\u227210 Myr) stellar populations, respectively. FIRE galaxies tend to have higher DM values than cosmological simulations such as IllustrisTNG, with larger tails in their distributions to high DMs. As a result, FRB host galaxies may be closer (lower redshift) than previously inferred. Furthermore, constraining host-galaxy DM distributions may help significantly constrain FRB progenitor models.
\n
Cosmic rays (CRs) may drive outflows and alter the phase structure of the circumgalactic medium, with potentially important implications on galaxy formation. However, these effects ultimately depend on the dominant mode of transport of CRs within and around galaxies, which remains highly uncertain. To explore potential observable constraints on CR transport, we investigate a set of cosmological fire-2 CR-magnetohydrodynamic simulations of L* galaxies which evolve CRs with transport models motivated by self-confinement (SC) and extrinsic turbulence (ET) paradigms. To first order, the synchrotron properties diverge between SC and ET models due to a CR physics-driven hysteresis. SC models show a higher tendency to undergo 'ejective' feedback events due to a runaway buildup of CR pressure in dense gas due to the behaviour of SC transport scalings at extremal CR energy densities. The corresponding CR wind-driven hysteresis results in brighter, smoother, and more extended synchrotron emission in SC runs relative to ET and constant diffusion runs. The differences in synchrotron arise from different morphology, interstellar medium gas, and B properties, potentially ruling out SC as the dominant mode of CR transport in typical star-forming L* galaxies, and indicating the prospect for non-thermal radio continuum observations to constrain CR transport physics.
",
"doi": "10.1093/mnrasl/slae017",
"issn": "1745-3925",
"publisher": "Royal Astronomical Society",
"publication": "Monthly Notices of the Royal Astronomical Society: Letters",
"publication_date": "2024-05",
"series_number": "1",
"volume": "530",
"issue": "1",
"pages": "L1-L6"
},
{
"id": "authors:x49d5-fr865",
"collection": "authors",
"collection_id": "x49d5-fr865",
"cite_using_url": "https://authors.library.caltech.edu/records/x49d5-fr865",
"type": "article",
"title": "The dispersion measure contributions of the cosmic web",
"author": [
{
"family_name": "Walker",
"given_name": "Charles R. H.",
"orcid": "0000-0002-1943-1324"
},
{
"family_name": "Spitler",
"given_name": "Laura G.",
"orcid": "0000-0002-3775-8291"
},
{
"family_name": "Ma",
"given_name": "Yin-Zhe",
"orcid": "0000-0001-8108-0986"
},
{
"family_name": "Cheng",
"given_name": "Cheng"
},
{
"family_name": "Artale",
"given_name": "Maria Celeste",
"orcid": "0000-0003-0570-785X"
},
{
"family_name": "Hummels",
"given_name": "Cameron B.",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
}
],
"abstract": "Context. The large-scale distribution of baryons, commonly referred to as the cosmic web, is sensitive to gravitational collapse, mergers, and galactic feedback processes, and its large-scale structure (LSS) can be classified as halos, filaments, and voids. Fast radio bursts (FRBs) are extragalactic transient radio sources that undergo dispersion along their propagation paths. These systems provide insight into ionised matter along their sightlines by virtue of their dispersion measures (DMs), and have been investigated as probes of the LSS baryon fraction, the diffuse baryon distribution, and of cosmological parameters. Such efforts are highly complementary to the study of intergalactic medium (IGM) through X-ray observations, the Sunyaev-Zeldovich effect, and galaxy populations.
\nAims. We use the cosmological simulation IllustrisTNG to study FRB DMs accumulated while traversing different types of LSS.
\nMethods. We combined methods for deriving electron density, classifying LSS, and tracing FRB sightlines through TNG300-1. We identified halos, filaments, voids, and collapsed structures along randomly selected sightlines, and calculated their DM contributions.
\nResults. We present a comprehensive analysis of the redshift-evolving cosmological DM components of the cosmic web. We find that the filamentary contribution to DM dominates, increasing from ∼71% to ∼80% on average for FRBs originating at z\u2004=\u20040.1 versus z\u2004=\u20045, while the halo contribution falls, and the void contribution remains consistent to within ∼1%. The majority of DM variance between sightlines originates from halo and filamentary environments, potentially making void-only sightlines more precise probes of cosmological parameters. We find that, on average, an FRB originating at z\u2004=\u20041 will intersect ∼1.8 foreground collapsed structures of any mass, with this value increasing to ∼12.4 structures for an FRB originating at z\u2004=\u20045. The measured impact parameters between our sightlines and TNG structures of any mass appear consistent with those reported for likely galaxy-intersecting FRBs. However, we measure lower average accumulated DMs from these structures than the ∼90\u2006pc\u2006cm−3 DM excesses reported for these literature FRBs, indicating that some of this DM may arise from beyond the structures themselves.
",
"doi": "10.1051/0004-6361/202347139",
"issn": "0004-6361",
"publisher": "EDP Sciences",
"publication": "Astronomy & Astrophysics",
"publication_date": "2024-03",
"volume": "683",
"pages": "A71"
},
{
"id": "authors:4250q-jav63",
"collection": "authors",
"collection_id": "4250q-jav63",
"cite_using_url": "https://authors.library.caltech.edu/records/4250q-jav63",
"type": "article",
"title": "The AGORA High-resolution Galaxy Simulations Comparison Project. VI. Similarities and Differences in the Circumgalactic Medium",
"author": [
{
"family_name": "Strawn",
"given_name": "Clayton",
"orcid": "0000-0001-9695-4017"
},
{
"family_name": "Roca-F\u00e0brega",
"given_name": "Santi",
"orcid": "0000-0002-6299-152X"
},
{
"family_name": "Primack",
"given_name": "Joel R.",
"orcid": "0000-0001-5091-5098"
},
{
"family_name": "Kim",
"given_name": "Ji-hoon",
"orcid": "0000-0003-4464-1160"
},
{
"family_name": "Genina",
"given_name": "Anna",
"orcid": "0000-0003-0073-3012"
},
{
"family_name": "Hausammann",
"given_name": "Loic",
"orcid": "0000-0002-4687-4948"
},
{
"family_name": "Kim",
"given_name": "Hyeonyong",
"orcid": "0000-0002-7820-2281"
},
{
"family_name": "Lupi",
"given_name": "Alessandro",
"orcid": "0000-0001-6106-7821"
},
{
"family_name": "Nagamine",
"given_name": "Kentaro",
"orcid": "0000-0001-7457-8487"
},
{
"family_name": "Powell",
"given_name": "Johnny W.",
"orcid": "0000-0002-3764-2395"
},
{
"family_name": "Revaz",
"given_name": "Yves",
"orcid": "0000-0002-6227-0108"
},
{
"family_name": "Shimizu",
"given_name": "Ikkoh",
"orcid": "0000-0001-5686-8368"
},
{
"family_name": "Vel\u00e1zquez",
"given_name": "H\u00e9ctor",
"orcid": "0000-0002-5181-4528"
},
{
"family_name": "Abel",
"given_name": "Tom",
"orcid": "0000-0002-5969-1251"
},
{
"family_name": "Ceverino",
"given_name": "Daniel",
"orcid": "0000-0002-8680-248X"
},
{
"family_name": "Dong",
"given_name": "Bili"
},
{
"family_name": "Jung",
"given_name": "Minyong",
"orcid": "0000-0002-9144-1383"
},
{
"family_name": "Quinn",
"given_name": "Thomas R.",
"orcid": "0000-0001-5510-2803"
},
{
"family_name": "Shin",
"given_name": "Eun-jin",
"orcid": "0000-0002-4639-5285"
},
{
"family_name": "Barrow",
"given_name": "Kirk S. S.",
"orcid": "0000-0002-8638-1697"
},
{
"family_name": "Dekel",
"given_name": "Avishai",
"orcid": "0000-0003-4174-0374"
},
{
"family_name": "Oh",
"given_name": "Boon Kiat",
"orcid": "0000-0003-4597-6739"
},
{
"family_name": "Mandelker",
"given_name": "Nir",
"orcid": "0000-0001-8057-5880"
},
{
"family_name": "Teyssier",
"given_name": "Romain",
"orcid": "0000-0001-7689-0933"
},
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Maji",
"given_name": "Soumily"
},
{
"family_name": "Man",
"given_name": "Antonio"
},
{
"family_name": "Mayerhofer",
"given_name": "Paul"
},
{
"literal": "the AGORA Collaboration"
}
],
"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.
",
"doi": "10.3847/1538-4357/ad12cb",
"issn": "0004-637X",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal",
"publication_date": "2024-02-10",
"series_number": "1",
"volume": "962",
"issue": "1",
"pages": "29"
},
{
"id": "authors:v2k9r-yz896",
"collection": "authors",
"collection_id": "v2k9r-yz896",
"cite_using_url": "https://authors.library.caltech.edu/records/v2k9r-yz896",
"type": "article",
"title": "Synchrotron emission on FIRE: equipartition estimators of magnetic fields in simulated galaxies with spectrally resolved cosmic rays",
"author": [
{
"family_name": "Ponnada",
"given_name": "Sam B",
"orcid": "0000-0002-7484-2695",
"clpid": "Ponnada-Sam-B"
},
{
"family_name": "Panopoulou",
"given_name": "Georgia V",
"orcid": "0000-0001-7482-5759"
},
{
"family_name": "Butsky",
"given_name": "Iryna S",
"orcid": "0000-0003-1257-5007",
"clpid": "Butsky-Iryna-S"
},
{
"family_name": "Hopkins",
"given_name": "Philip F",
"orcid": "0000-0003-3729-1684",
"clpid": "Hopkins-P-F"
},
{
"family_name": "Skalidis",
"given_name": "Raphael",
"orcid": "0000-0003-2337-0277",
"clpid": "Skalidis-Raphael"
},
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Quataert",
"given_name": "Eliot",
"orcid": "0000-0001-9185-5044"
},
{
"family_name": "Kere\u0161",
"given_name": "Du\u0161an",
"orcid": "0000-0002-1666-7067"
},
{
"family_name": "Faucher-Gigu\u00e8re",
"given_name": "Claude-Andr\u00e9",
"orcid": "0000-0002-4900-6628"
},
{
"family_name": "Su",
"given_name": "Kung-Yi",
"orcid": "0000-0003-1598-0083"
}
],
"abstract": "Synchrotron emission is one of few observable tracers of galactic magnetic fields (B) and cosmic rays (CRs). Much of our understanding of B in galaxies comes from utilizing synchrotron observations in conjunction with several simplifying assumptions of equipartition models, however, it remains unclear how well these assumptions hold, and what B these estimates physically represent. Using Feedback in Realistic Environments project simulations which self-consistently evolve CR proton, electron, and positron spectra from MeV to TeV energies, we present the first synthetic synchrotron emission predictions from simulated L* galaxies with ‘live’ spectrally resolved CR-magnetohydrodynamic. We find that synchrotron emission can be dominated by relatively cool and dense gas, resulting in equipartition estimates of B with fiducial assumptions underestimating the ‘true’ B in the gas that contributes the most emission by factors of 2–3 due to small volume-filling factors. Motivated by our results, we present an analytical framework that expands upon equipartition models for estimating B in a multiphase medium. Comparing our spectrally resolved synchrotron predictions to simpler spectral assumptions used in galaxy simulations with CRs, we find that spectral evolution can be crucial for accurate synchrotron calculations towards galactic centres, where loss terms are large.
",
"doi": "10.1093/mnras/stad3978",
"issn": "0035-8711",
"publisher": "Royal Astronomical Society",
"publication": "Monthly Notices of the Royal Astronomical Society",
"publication_date": "2024-02",
"series_number": "4",
"volume": "527",
"issue": "4",
"pages": "11707-11718"
},
{
"id": "authors:aa3xr-0aj89",
"collection": "authors",
"collection_id": "aa3xr-0aj89",
"cite_using_url": "https://authors.library.caltech.edu/records/aa3xr-0aj89",
"type": "article",
"title": "The Halo21 absorption modelling challenge: lessons from 'observing' synthetic circumgalactic absorption spectra",
"author": [
{
"family_name": "Hafen",
"given_name": "Zachary",
"orcid": "0000-0001-7326-1736"
},
{
"family_name": "Sameer",
"orcid": "0000-0001-9966-6790"
},
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Charlton",
"given_name": "Jane",
"orcid": "0000-0003-4877-9116"
},
{
"family_name": "Mandelker",
"given_name": "Nir",
"orcid": "0000-0001-8057-5880"
},
{
"family_name": "Wijers",
"given_name": "Nastasha",
"orcid": "0000-0001-6374-7185"
},
{
"family_name": "Bullock",
"given_name": "James",
"orcid": "0000-0003-4298-5082"
},
{
"family_name": "Faerman",
"given_name": "Yakov",
"orcid": "0000-0003-3520-6503"
},
{
"family_name": "Lehner",
"given_name": "Nicolas",
"orcid": "0000-0001-9158-0829"
},
{
"family_name": "Stern",
"given_name": "Jonathan",
"orcid": "0000-0002-7541-9565"
}
],
"abstract": "In the Halo21 absorption modelling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, and density (Z, T, and nH) of the underlying gas using observational methods. We iteratively generated and analysed three increasingly complex data samples: ion column densities of isolated uniform clouds, mock spectra of 1–3 uniform clouds, and mock spectra of high-resolution turbulent mixing zones. We found that the observational estimates were accurate for both uniform cloud samples, with Z, T, and nH retrieved within 0.1 dex of the source value for $\\gtrsim 90~{{\\ \\rm per\\ cent}}$ of absorption systems. In the turbulent-mixing scenario, the mass, temperature, and metallicity of the strongest absorption components were also retrieved with high accuracy. However, the underlying properties of the subdominant components were poorly constrained because the corresponding simulated gas contributed only weakly to the H i absorption profiles. On the other hand, including additional components beyond the dominant ones did improve the fit, consistent with the true existence of complex cloud structures in the source data.
",
"doi": "10.1093/mnras/stad3889",
"issn": "0035-8711",
"publisher": "Royal Astronomical Society",
"publication": "Monthly Notices of the Royal Astronomical Society",
"publication_date": "2024-02",
"series_number": "1",
"volume": "528",
"issue": "1",
"pages": "39-60"
},
{
"id": "authors:h938b-hjm59",
"collection": "authors",
"collection_id": "h938b-hjm59",
"cite_using_url": "https://authors.library.caltech.edu/records/h938b-hjm59",
"type": "article",
"title": "The Large Magellanic Cloud's \u223c30 kpc Bow Shock and Its Impact on the Circumgalactic Medium",
"author": [
{
"family_name": "Setton",
"given_name": "David J.",
"orcid": "0000-0003-4075-7393",
"clpid": "Setton-David-J"
},
{
"family_name": "Besla",
"given_name": "Gurtina",
"orcid": "0000-0003-0715-2173",
"clpid": "Besla-Gurtina"
},
{
"family_name": "Patel",
"given_name": "Ekta",
"orcid": "0000-0002-9820-1219",
"clpid": "Patel-Ekta"
},
{
"family_name": "Hummels",
"given_name": "Cameron",
"orcid": "0000-0002-3817-8133",
"clpid": "Hummels-Cameron"
},
{
"family_name": "Zheng",
"given_name": "Yong",
"orcid": "0000-0003-4158-5116",
"clpid": "Zheng-Yong"
},
{
"family_name": "Schneider",
"given_name": "Evan",
"orcid": "0000-0001-9735-7484",
"clpid": "Schneider-Evan"
},
{
"family_name": "Salem",
"given_name": "Munier",
"orcid": "0000-0002-0197-526X",
"clpid": "Salem-Munier"
}
],
"abstract": "The interaction between the supersonic motion of the Large Magellanic Cloud (LMC) and the circumgalactic medium (CGM) is expected to result in a bow shock that leads the LMC's gaseous disk. In this letter, we use hydrodynamic simulations of the LMC's recent infall to predict the extent of this shock and its effect on the Milky Way's (MW) CGM. The simulations clearly predict the existence of an asymmetric shock with a present-day standoff radius of \u223c6.7 kpc and a transverse diameter of \u223c30 kpc. Over the past 500 Myr, \u223c8% of the MW's CGM in the southern hemisphere should have interacted with the shock front. This interaction may have had the effect of smoothing over inhomogeneities and increasing mixing in the MW CGM. We find observational evidence of the existence of the bow shock in recent H\u03b1 maps of the LMC, providing a potential explanation for the envelope of ionized gas surrounding the LMC. Furthermore, the interaction of the bow shock with the MW CGM may also explain the observations of ionized gas surrounding the Magellanic Stream. Using recent orbital histories of MW satellites, we find that many satellites have likely interacted with the LMC shock. Additionally, the dwarf galaxy Ret2 is currently sitting inside the shock, which may impact the interpretation of the reported gamma-ray excess in Ret2. This work highlights how bow shocks associated with infalling satellites are an underexplored yet potentially very important dynamical mixing process in the circumgalactic and intracluster media.
",
"doi": "10.3847/2041-8213/ad0da6",
"issn": "2041-8205",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal Letters",
"publication_date": "2023-12-10",
"series_number": "1",
"volume": "959",
"issue": "1",
"pages": "L11"
}
]