arXiv subjects

Romeel Davé

Publications and source records attributed to Romeel Davé.

At least 55 records · Page 3Linked to original sources

arXiv2024

Large-scale geometry and topology of gas fields: Effects of AGN and stellar feedback

Feedback from stars and active galactic nuclei (AGNs) primarily affects the formation and evolution of galaxies and the circumgalactic medium, leaving some kind of imprint on larger scales. Based on the {\sc Simba} hydrodynamical simulation suite and using the full set of Minkowski functionals (MFs), this study systematically analyses the time evolution of the global geometry and topology of the gas temperature, pressure, density (total, HI, and H$_2$), and the metallicity fields between redshifts $z=5$ and $z=0$. The MFs show that small-scale astrophysical processes are persistent and manifest on larger, up to tens of Mpc scales, highlighting the specific morphological signatures of the relevant feedback mechanisms on these scales in the last $\sim12$~Gyr. In qualitative terms, we were able establish a ranking that varies according to the field considered: stellar feedback mostly determines the morphology of the pressure and density fields and AGN jets are the primary origin of the morphology of the temperature and metallicity fields, while X-ray heating and AGN winds play the second most important role in shaping the geometry and topology of all the gaseous fields, except metallicity. Hence, the cosmic evolution of the geometry and topology of fields characterising the thermodynamical and chemical properties of the cosmic web offers complementary, larger scale constraints to galaxy formation models.

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arXiv2024

\texttt{Simba}-\texttt{C}: the evolution of the thermal and chemical properties in the intragroup medium

The newly updated \texttt{GIZMO} and \texttt{Simba} based simulation, \texttt{Simba-C}, with its new stellar feedback, chemical enrichment, and recalibrated AGN feedback, allows for a detailed study of the intragroup medium X-ray properties. We discuss the impact of various physical mechanisms, e.g. stellar and AGN feedback, and chemical enrichment, on the composition and the global scaling relations of nearby galaxy groups. We also study the evolution ($z=2$ to $0$) of the global properties for the $1\,\mathrm{keV}$ temperature groups. \texttt{Simba-C} shows improved consistent matching with the observations of all X-ray scaling relations compared to \texttt{Simba}. It is well known that AGN feedback has a significant influence on $L_{X,0.5-2.0}-T_{spec,corr}$, $S_{500/2500}-T_{spec,corr}$, and gas mass fractions, with our \texttt{Simba-C} results consistent with it. Our recalibrated AGN feedback strength also showed an additional improvement in gas entropy, which now aligns with CLoGS observations. The updated stellar feedback and chemical enrichment model is shown to play an important role in our understanding of the chemical abundance ratios and their evolution within galaxy groups. In particular, we find that \texttt{Simba-C} produces an increase in the amount of heavier elements (specifically Si and Fe) relative to O, compared to \texttt{Simba}.

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arXiv2024

The UV luminosity function at 0.6 < z < 1 from UVCANDELS

UVCANDELS is a HST Cycle-26 Treasury Program awarded 164 orbits of primary ultraviolet (UV) F275W imaging and coordinated parallel optical F435W imaging in four CANDELS fields: GOODS-N, GOODS-S, EGS, and COSMOS, covering a total area of $\sim426$ arcmin$^2$. This is $\sim2.7$ times larger than the area covered by previous deep-field space UV data combined, reaching a depth of about 27 and 28 ABmag ($5σ$ in $0.2"$ apertures) for F275W and F435W, respectively. Along with the new photometric catalogs, we present an analysis of the rest-frame UV luminosity function (LF), relying on our UV-optimized aperture photometry method yielding a factor of $1.5\times$ increase than the H-isophot aperture photometry in the signal-to-noise ratios of galaxies in our F275W imaging. Using well tested photometric redshift measurements we identify 5810 galaxies at redshifts $0.6<z<1$, down to an absolute magnitude of $M_\text{UV} = -14.2$. In order to minimize the effect of uncertainties in estimating the completeness function, especially at the faint-end, we restrict our analysis to sources above $30\%$ completeness, which provides a final sample of 4726 galaxies at $-21.5<M_\text{UV}<-15.5$. We performed a maximum likelihood estimate to derive the best-fit parameters of the UV LF. We report a best-fit faint-end slope of $α= -1.359^{+0.041}_{-0.041}$ at $z \sim 0.8$. Creating sub-samples at $z\sim0.7$ and $z\sim0.9$, we observe a possible evolution of $α$ with redshift. The unobscured UV luminosity density at $M_\text{UV}<-10$ is derived as $ρ_\text{UV}=1.339^{+0.027}_{-0.030}\ (\times10^{26} \text{ergs/s/Hz/Mpc}^3)$ using our best-fit LF parameters. The new F275W and F435 photometric catalogs from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes (MAST).

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arXiv2024

The Next Generation Deep Extragalactic Exploratory Public Near-Infrared Slitless Survey Epoch 1 (NGDEEP-NISS1): Extra-Galactic Star-formation and Active Galactic Nuclei at 0.5 < z < 3.6

The Next Generation Deep Extragalactic Exploratory Public (NGDEEP) survey program was designed specifically to include Near Infrared Slitless Spectroscopic observations (NGDEEP-NISS) to detect multiple emission lines in as many galaxies as possible and across a wide redshift range using the Near Infrared Imager and Slitless Spectrograph (NIRISS). We present early results obtained from the the first set of observations (Epoch 1, 50$\%$ of the allocated orbits) of this program (NGDEEP-NISS1). Using a set of independently developed calibration files designed to deal with a complex combination of overlapping spectra, multiple position angles, and multiple cross filters and grisms, in conjunction with a robust and proven algorithm for quantifying contamination from overlapping dispersed spectra, NGDEEP-NISS1 has achieved a 3$σ$ sensitivity limit of 2 $\times$ 10$^{-18}$ erg/s/cm$^2$. We demonstrate the power of deep wide field slitless spectroscopy (WFSS) to characterize the star-formation rates, and metallicity ([OIII]/H$β$), and dust content, of galaxies at $1<z<3.5$. The latter showing intriguing initial results on the applicability and assumptions made regarding the use of Case B recombination. Further, we identify the presence of active galactic nuclei (AGN) and infer the mass of their supermassive black holes (SMBHs) using broadened restframe MgII and H$β$ emission lines. The spectroscopic results are then compared with the physical properties of galaxies extrapolated from fitting spectral energy distribution (SED) models to photometry alone. The results clearly demonstrate the unique power and efficiency of WFSS at near-infrared wavelengths over other methods to determine the properties of galaxies across a broad range of redshifts.

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arXiv2024

The Effects of Stellar and AGN Feedback on the Cosmic Star Formation History in the Simba Simulations

Using several variants of the cosmological Simba simulations, we investigate the impact of different feedback prescriptions on the cosmic star formation history. Adopting a global-to-local approach, we link signatures seen in global observables, such as the star formation rate density (SFRD) and the galaxy stellar mass function (GSMF), to feedback effects in individual galaxies. We find a consistent picture: stellar feedback mainly suppresses star formation below halo masses of $M_{\rm H} = 10^{12} \rm \, M_{\odot}$ and before $z = 2$, whereas AGN feedback quenches the more massive systems after $z = 2$. Among Simba's AGN feedback modes, AGN jets are the dominant quenching mechanism and set the shape of the SFRD and the GSMF at late times. AGN-powered winds only suppress the star formation rate in intermediate-mass galaxies ($M_{\rm \star} = 10^{9.5 - 10} \rm \, M_{\odot}$), without affecting the overall stellar mass-assembly significantly. At late times, the AGN X-ray feedback mode mainly quenches residual star formation in massive galaxies. Our analysis reveals that this mode is also necessary to produce the first fully quenched galaxies before $z=2$, where the jets alone are inefficient. These initially highly star-forming galaxies contain relatively large black holes, likely strengthening the X-ray-powered heating and ejection of gas from the dense, central region of galaxies. Such extra heating source quenches the local star formation and produces a more variable accretion rate. More generally, this effect also causes the break down of correlations between the specific star formation rate, the accretion rate and the black hole mass.

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arXiv2024

ELUCID VIII: Simulating the Coma Galaxy Cluster to Calibrate Model and Understand Feedback

We conducted an investigation of the Coma cluster of galaxies by running a series of constrained hydrodynamic simulations with GIZMO-SIMBA and GADGET-3, based on initial conditions reconstructed from the SDSS survey volume in the ELUCID project. We compared simulation predictions and observations for galaxies, ICM and IGM in and around the Coma cluster to constrain galaxy formation physics. Our results demonstrate that this type of constrained investigation allows us to probe in more detail the implemented physical processes, because the comparison between simulations and observations is free of cosmic variance and hence can be conducted in a ''one-to-one'' manner. We found that an increase in the earlier star formation rate and the supernova feedback of the original GIZMO-SIMBA model is needed to match observational data on stellar, ISM and ICM metallicity. The simulations without AGN feedback can well reproduce the observational ICM electron density, temperature, and entropy profiles, ICM substructures, and the IGM temperature-density relation, while the ones with AGN feedback usually fail. However, one requires something like AGN feedback to reproduce a sufficiently large population of quiescent galaxies, particularly in low-density regions. The constrained simulations of the Coma cluster thus provide a test bed to understand processes that drive galaxy formation and evolution.

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arXiv2024

Star formation efficiency across large-scale galactic environments

Environmental effects on the evolution of galaxies have been one of the leading questions in galaxy studies for decades. In this work, we investigate the relationship between the star formation activity of galaxies and their environmental matter density using the cosmological hydrodynamic simulation Simba. The star formation activity indicators we explore include the star formation efficiency (SFE), specific star formation rate (sSFR) and molecular hydrogen mass fraction ($f^*_{H_2}$) and the environment is considered as the large-scale environmental matter density, calculated based on the stellar mass of nearby galaxies on a 1 Mpc/h grid using the cloud in cell (CIC) method. Our sample includes galaxies with $9<\log(M_*/M_{\odot})$ at $0 1.5$). We present a scaling relation for the depletion time of molecular hydrogen (${t_{depl}}=1/SFE$) as a function of galaxy parameters including environmental density. Our findings provide a framework for quantifying the environmental effects on the star formation activities of galaxies as a function of stellar mass and redshift. The most significant environmental dependence is seen at later cosmic times ($z<1.5$) and towards lower stellar masses ($9<\log(M_*/M_{\odot})<10$). Future large galaxy surveys can use this framework to look for the environmental dependence of the star formation activity and examine our predictions.

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arXiv2024

The Cosmic Baryon Partition between the IGM and CGM in the SIMBA Simulations

We use the Simba suite of cosmological hydrodynamical simulations to investigate the importance of various stellar and AGN feedback mechanisms in partitioning the cosmic baryons between the intergalactic (IGM) and circumgalactic (CGM) media in the $z\leq 1$ Universe. We identify the AGN jets as the most prominent mechanism for the redistribution of baryons between the IGM and CGM. In contrast to the full feedback models, deactivating AGN jets results in $\approx20$ per cent drop in fraction of baryons residing in the IGM and a consequent increase of CGM baryon fraction by $\approx 50$ per cent. We find that stellar feedback modifies the partition of baryons on a $10$ per cent level. We further examine the physical properties of simulated haloes in different mass bins, and their response to various feedback models. On average, a sixfold decrease in the CGM mass fraction due to the inclusion of feedback from AGN jets is detected in $10^{12}M_{\odot} \leq M_{\rm 200} \leq 10^{14}M_{\odot}$ haloes. Examination of the average radial gas density profiles of $M_{200} > 10^{12}M_{\odot}$ haloes reveals up to an order of magnitude decrease in gas densities due to the AGN jet feedback. We compare gas density profiles from Simba simulations to the predictions of the modified NFW model, and show that the latter provides a reasonable approximation within the virial radii of the full range of halo masses, but only when rescaled by the appropriate mass-dependent CGM fraction of the halo. The relative partitioning of cosmic baryons and, subsequently, the feedback models can be constrained observationally with fast radio bursts (FRBs) in upcoming surveys.

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arXiv2023

An Exploration of AGN and Stellar Feedback Effects in the Intergalactic Medium via the Low Redshift Lyman-$α$ Forest

We explore the role of galactic feedback on the low redshift Lyman-$α$ (Ly$α$)~forest ($z \lesssim 2$) 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 sub-grid models. We find that both AGN and stellar feedback in Simba play a role in setting the Ly$α$ forest 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 the $b$-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 Ly$α$ forest, but varying the stellar feedback model does produce subtle changes. Our results imply that the low-$z$ Ly$α$ forest can be sensitive to changes in the ultraviolet background (UVB), 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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arXiv2023

Feedback-driven anisotropy in the circumgalactic medium for quenching galaxies in the SIMBA simulations

We use the SIMBA galaxy formation simulation suite to explore anisotropies in the properties of circumgalactic gas that result from accretion and feedback processes. We particularly focus on the impact of bipolar active galactic nuclei (AGN) jet feedback as implemented in SIMBA, which quenches galaxies and has a dramatic effect on large-scale gas properties. We show that jet feedback at low redshifts is most common in the stellar mass range $(1-5)\times 10^{10}M_\odot$, so we focus on galaxies with active jets in this mass range. In comparison to runs without jet feedback, jets cause lower densities and higher temperatures along the galaxy minor axis (SIMBA jet direction) at radii >=$0.5r_{200c}-4r_{200c}$ and beyond. This effect is less apparent at higher or lower stellar masses, and is strongest within green valley galaxies. The metallicity also shows strong anisotropy out to large scales, driven by star formation feedback. We find substantially stronger anisotropy at <=$0.5r_{200c}$, but this also exists in runs with no explicit feedback, suggesting that it is due to anisotropic accretion. Finally, we explore anisotropy in the bulk radial motion of the gas, finding that both star formation and AGN wind feedback contribute to pushing the gas outwards along the minor axis at <=1 Mpc, but AGN jet feedback further causes bulk outflow along the minor axis out to several Mpc, which drives quenching via gas starvation. These results provide observational signatures for the operation of AGN feedback in galaxy quenching.

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arXiv2023

Halo Scaling Relations and Hydrostatic Mass Bias in the Simba Simulation From Realistic Mock X-ray Catalogues

We present a new end-to-end pipeline for Mock Observations of X-ray Halos and Analysis (MOXHA) for hydrodynamic simulations of massive halos, and use it to investigate X-ray scaling relations and hydrostatic mass bias in the Simba cosmological hydrodynamic simulation for halos with $M_{500}\sim 10^{13-15}M_\odot$. MOXHA ties together existing yT-based software packages and adds new functionality to provide an end-to-end pipeline for generating mock X-ray halo data from large-scale or zoom simulation boxes. We compare MOXHA-derived halo properties in Simba to their emission-weighted counterparts, and forecast the systematic mass bias in mock Athena observations. Overall, we find inferred hydrostatic masses are biased low compared to true Simba values. For simple mass-weighting, we find $b_\text{MW} = 0.15^{+0.15}_{-0.14}$ ($16-84\%$ range), while emission-weighting increases this to $b_\text{LW}=0.30^{+0.19}_{-0.10}$. The larger bias versus mass-weighted values we attribute to the spectroscopic and emission-weighted temperatures being biased systematically lower than mass-weighted temperatures. The full MOXHA pipeline recovers the emission-weighted hydrostatic masses at $R_{500}$ reasonably well, yielding $b_\text{X}=0.33^{+0.28}_{-0.34}$. MOXHA-derived halo X-ray scalings are in very good agreement with observed scaling relations, with the inclusion of lower-mass groups significantly steepening the $L_\text{X}-M_{500}$, $M_{500}-T_\text{X}$, and $L_\text{X}-T_\text{X}$ relations. This indicates the strong effect the Simba feedback model has on low-mass halos, which strongly evacuates poor groups but still retains enough gas to reproduce observations. We find similar trends for analogous scaling relations measured at $R_{500}$, as expected for halo-wide gas evacuation.

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arXiv2023

Distinguishing AGN Feedback Models with the Thermal Sunyaev-Zel'dovich Effect

Current models of galaxy formation require strong feedback from active galactic nuclei (AGN) to explain the observed lack of star formation in massive galaxies since z~2 but direct evidence of this energy input is limited. We use the SIMBA cosmological galaxy formation simulations to assess the ability of thermal Sunyaev-Zel'dovich (tSZ) measurements to provide such evidence, by mapping the pressure structure of the circumgalactic medium around massive z~0.2-1.5 galaxies. We undertake a stacking approach to calculate the total tSZ signal and its radial profile in simulations with varying assumptions of AGN feedback, and we assess its observability with current and future telescopes. By convolving our predictions with the 2.1' beam of the Atacama Cosmology Telescope (ACT), we show that current observations at z~1 are consistent with SIMBA's fiducial treatment of AGN feedback, and inconsistent with SIMBA models without feedback. At z~0.5, observational signals lie between SIMBA run with and without AGN feedback, suggesting AGN in SIMBA may inject too much energy at late times. By convolving our data with a 9.5'' beam corresponding to the TolTEC camera on the Large Millimeter Telescope Alfonso Serrano (LMT), we predict a unique profile for AGN feedback that can be distinguished with future higher-resolution measurements. Finally, we explore a novel approach to quantify the non-spherically symmetric features surrounding our galaxies by plotting radial profiles representing the component of the stack with m-fold symmetry.

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arXiv2023

SIMBA-C: An updated chemical enrichment model for galactic chemical evolution in the SIMBA simulation

We introduce a new chemical enrichment and stellar feedback model into GIZMO, using the SIMBA sub-grid models as a base. Based on the state-of-the-art chemical evolution model of Kobayashi et al., SIMBA-C tracks 34 elements from H$\rightarrow$Ge and removes SIMBA's instantaneous recycling approximation. Furthermore, we make some minor improvements to SIMBA's base feedback models. SIMBA-C provides significant improvements on key diagnostics such as the knee of the $z=0$ galaxy stellar mass function, the faint end of the main sequence, and the ability to track black holes in dwarf galaxies. SIMBA-C also matches better with recent observations of the mass-metallicity relation at $z=0,2$. By not assuming instantaneous recycling, SIMBA-C provides a much better match to galactic abundance ratio measures such as [O/Fe] and [N/O]. SIMBA-C thus opens up new avenues to constrain feedback models using detailed chemical abundance measures across cosmic time.

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arXiv2023

MIGHTEE-HI: The HI mass-stellar mass relation over the last billion years

We study the $M_{\rm HI}-M_{\star}$ relation over the last billion years using the MIGHTEE-HI sample. We first model the upper envelope of the $M_{\rm HI}-M_{\star}$ relation with a Bayesian technique applied to a total number of 249 HI-selected galaxies, without binning the datasets, while taking account of the intrinsic scatter. We fit the envelope with both linear and non-linear models, and find that the non-linear model is preferred over the linear one with a measured transition stellar mass of $\log_{10}(M_\star$/$M_{\odot})$ = $9.15\pm0.87$, beyond which the slope flattens. This finding supports the view that the lack of HI gas is ultimately responsible for the decreasing star formation rate observed in the massive main-sequence galaxies. For spirals alone, which are biased towards the massive galaxies in our sample, the slope beyond the transition mass is shallower than for the full sample, indicative of distinct gas processes ongoing for the spirals/high-mass galaxies from other types with lower stellar masses. We then create mock catalogues for the MIGHTEE-HI detections and non-detections with two main galaxy populations of late- and early-type galaxies to measure the underlying $M_{\rm HI}-M_{\star}$ relation. We find that the turnover in this relation persists whether considering the two galaxy populations as a whole or separately. We note that an underlying linear relation could mimic this turnover in the observed scaling relation, but a model with a turnover is strongly preferred. Measurements on the logarithmic average of HI masses against the stellar mass are provided as a benchmark for future studies.

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arXiv2023

Mapping Circumgalactic Medium Observations to Theory Using Machine Learning

We present a random forest framework for predicting circumgalactic medium (CGM) physical conditions from quasar absorption line observables, trained on a sample of Voigt profile-fit synthetic absorbers from the Simba cosmological simulation. Traditionally, extracting physical conditions from CGM absorber observations involves simplifying assumptions such as uniform single-phase clouds, but by using a cosmological simulation we bypass such assumptions to better capture the complex relationship between CGM observables and underlying gas conditions. We train random forest models on synthetic spectra for HI and selected metal lines around galaxies across a range of star formation rates, stellar masses, and impact parameters, to predict absorber overdensities, temperatures, and metallicities. The models reproduce the true values from Simba well, with normalised transverse standard deviations of $0.50-0.54$ dex in overdensity, $0.32-0.54$ dex in temperature, and $0.49-0.53$ dex in metallicity predicted from metal lines (not HI), across all ions. Examining the feature importance, the random forest indicates that the overdensity is most informed by the absorber column density, the temperature is driven by the line width, and the metallicity is most sensitive to the specific star formation rate. Alternatively examining feature importance by removing one observable at a time, the overdensity and metallicity appear to be more driven by the impact parameter. We introduce a normalising flow approach in order to ensure the scatter in the true physical conditions is accurately spanned by the network. The trained models are available online.

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arXiv2023

Cosmological baryon spread and impact on matter clustering in CAMELS

We quantify the cosmological spread of baryons relative to their initial neighboring dark matter distribution using thousands of state-of-the-art simulations from the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project. We show that dark matter particles spread relative to their initial neighboring distribution owing to chaotic gravitational dynamics on spatial scales comparable to their host dark matter halo. In contrast, gas in hydrodynamic simulations spreads much further from the initial neighboring dark matter owing to feedback from supernovae (SNe) and Active Galactic Nuclei (AGN). We show that large-scale baryon spread is very sensitive to model implementation details, with the fiducial \textsc{SIMBA} model spreading $\sim$40\% of baryons $>$1\,Mpc away compared to $\sim$10\% for the IllustrisTNG and \textsc{ASTRID} models. Increasing the efficiency of AGN-driven outflows greatly increases baryon spread while increasing the strength of SNe-driven winds can decrease spreading due to non-linear coupling of stellar and AGN feedback. We compare total matter power spectra between hydrodynamic and paired $N$-body simulations and demonstrate that the baryonic spread metric broadly captures the global impact of feedback on matter clustering over variations of cosmological and astrophysical parameters, initial conditions, and galaxy formation models. Using symbolic regression, we find a function that reproduces the suppression of power by feedback as a function of wave number ($k$) and baryonic spread up to $k \sim 10\,h$\,Mpc$^{-1}$ while highlighting the challenge of developing models robust to variations in galaxy formation physics implementation.

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arXiv2023

Spectroscopic Confirmation of CEERS NIRCam-selected Galaxies at $\boldsymbol{z \simeq 8-10}$

We present JWST/NIRSpec prism spectroscopy of seven galaxies selected from the Cosmic Evolution Early Release Science Survey (CEERS) NIRCam imaging with photometric redshifts z_phot>8. We measure emission line redshifts of z=7.65 and 8.64 for two galaxies, and z=9.77(+0.37,-0.29) and 10.01(+0.14,-0.19) for two others via the detection of continuum breaks consistent with Lyman-alpha opacity from a mostly neutral intergalactic medium. The presence (absense) of strong breaks (strong emission lines) give high confidence that these two galaxies are at z>9.6, but the break-derived redshifts have large uncertainties given the low spectral resolution and relatively low signal-to-noise of the CEERS NIRSpec prism data. The two z~10 sources are relatively luminous (M_UV<-20), with blue continua (-2.3 8 candidates with CEERS NIRSpec spectroscopy do not have secure redshifts, but the absence of emission lines in their spectra is consistent with redshifts z>9.6. We find that z>8 photometric redshifts are generally in agreement (within uncertainties) with the spectroscopic values. However, the photometric redshifts tend to be slightly overestimated (average Delta(z)=0.50+/-0.12), suggesting that current templates do not fully describe the spectra of very high-z sources. Overall, our results solidifies photometric evidence for a high space density of bright galaxies at z>8 compared to theoretical model predictions, and further disfavors an accelerated decline in the integrated UV luminosity density at z>8.

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arXiv2023

Boundless baryons: how diffuse gas contributes to anisotropic tSZ signal around simulated Three Hundred clusters

Upcoming advances in galaxy surveys and cosmic microwave background data will enable measurements of the anisotropic distribution of diffuse gas in filaments and superclusters at redshift $z=1$ and beyond, observed through the thermal Sunyaev-Zel'dovich (tSZ) effect. These measurements will help distinguish between different astrophysical feedback models, account for baryons that appear to be 'missing' from the cosmic census, and present opportunities for using locally-anisotropic tSZ statistics as cosmological probes. This study seeks to guide such future measurements by analysing whether diffuse intergalactic gas is a major contributor to anisotropic tSZ signal in The Three Hundred Gizmo-Simba hydrodynamic simulations. We apply multiple different halo boundary and temperature criteria to divide concentrated from diffuse gas at $z=1$, then create mock Compton-$y$ maps for the separated components. The maps from 98 simulation snapshots are centred on massive galaxy clusters, oriented by the most prominent galaxy filament axis, and stacked. Results vary significantly depending on the definition used for diffuse gas, indicating that assumptions should be clearly defined when claiming observations of the warm-hot intergalactic medium. In all cases, the diffuse gas is important, contributing 25-60% of the tSZ signal in the far field ($>4 h^{-1}$ comoving Mpc) from the stacked clusters. The gas 1-2 virial radii from halo centres is especially key. Oriented stacking and environmental selections help to amplify the signal from the warm-hot intergalactic medium, which is aligned but less concentrated along the filament axis than the hot halo gas.

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