arXiv subjects

A. Dev

Publications and source records attributed to A. Dev.

14 recordsLinked to original sources

arXiv2026

What's Missing in AGN Feedback? Lessons learnt from Magneticum, IllustrisTNG and Simba

Accurately balancing gas reservoirs, star formation, and feedback across cosmic time remains a central challenge for galaxy formation models in modern hydrodynamical simulations. While different feedback prescriptions reproduce selected local galaxy properties with varying success, the most pronounced discrepancies emerge in predictions for the hot gas content of dark matter halos. We examine three state-of-the-art cosmological simulations: Magneticum, IllustrisTNG, and SIMBA, which struggle to simultaneously reproduce observed galaxy and halo gas properties in the local Universe. We confront their predictions with spatially resolved galaxy data from MaNGA and recent constraints on the hot gas mass fraction-halo mass (fgas-Mh) relation from eROSITA and Sunyaev-Zel'dovich (SZ) measurements. Reproducing the observed fgas-Mh relation requires strong active galactic nucleus (AGN) feedback. However, such feedback often leads to excessive quenching in simulated galaxy populations. Magneticum and SIMBA match the observed gas fraction relation but predict an overabundance of quenched galaxies. In contrast, IllustrisTNG implements weaker AGN feedback, yielding more realistic star-forming fractions but systematically overpredicting hot gas masses in massive groups and poor clusters. Overall, these tensions indicate current feedback models remain incomplete, not only in the total energy injected but also in the timing, location, and coupling of this energy to the surrounding gas. Our results therefore highlight the need to revisit subgrid feedback prescriptions and develop more self-consistent models capable of simultaneously regulating galaxy growth and the thermodynamic properties of halo gas. Motivated by this discrepancy, a companion study will explore whether the feedback strengths required to match halo gas constraints inevitably lead to overquenching and distorted galaxy demographics.

astro-ph.GA↗

arXiv2026

Spectral Data-cube Cleaning for CCAT Deep Spectroscopic Survey. I. Effect of correlated noise and filtering on the power spectrum

The Epoch of Reionization Spectrometer (EoR-Spec) on the Fred Young Submillimeter Telescope (FYST) will conduct the CCAT Deep Spectroscopic Survey (DSS) to perform line-intensity mapping of redshifted [C II] emission. Atmospheric $1/f$ noise and instrumental systematics affect power-spectrum recovery. We present realistic end-to-end simulations to quantify these effects and evaluate a Filter-and-Bin (F&B) pipeline. The simulated observations include instrument response, astrophysical emission, atmospheric noise, and observing strategy. The pipeline suppresses atmospheric $1/f$ noise by about four orders of magnitude at low temporal frequencies while leaving only minor residual correlated noise. For a single EoR-Spec module operating at 50% observing efficiency, the DSS is expected to detect the combined [C II] + CO power spectrum on shot-noise-dominated scales ($k > 0.1\,\mathrm{Mpc}^{-1}$). With two modules operating at full efficiency, detections are achievable over all targeted spatial scales. The transfer function exceeds 80% at $k \gtrsim 0.5\,\mathrm{Mpc}^{-1}$ but falls below 20% at $k \lesssim 0.1\,\mathrm{Mpc}^{-1}$, indicating significant suppression of large-scale modes. These results demonstrate that the F&B pipeline is effective for recovering the shot-noise regime, while improved map-making techniques will be required for accurate large-scale clustering measurements.

astro-ph.GA↗

arXiv2026

Testing masking effectiveness using multi-line image cubes based on COSMOS2020 for [CII] line intensity mapping at $z_{[CII]} > 3.5$

We created line intensity mapping intensity cubes for CO and [CII] emission lines using the COSMOS2020 galaxy catalogue, forming predictions based on empirical data, for observations from Prime-Cam mounted on the Fred Young Submm Telescope. We also included simulated noise including white and correlated components, and tested masking techniques to recover [CII] signal at $3.5<z<8.2$. We applied line luminosity models to the COSMOS2020 galaxy catalogue, spanning 1.44deg$^2$, to estimate the [CII] and CO J=1-0 emission, with other CO transitions derived using Spectral Line Energy Distribution templates. From these we made cubes for four 40 GHz bands in the EoR-Spec frequency range (205-420GHz), as well as a potential future upgrade to EoR-Spec including bands at 150 and 90GHz. Given the incompleteness of the empirical catalogue, these predictions are conservative lower limits, which we subsequently extrapolated from. We applied masks to recover the [CII] power spectra, using bright galaxies of COSMOS2020 as a foreground catalogue to target CO at low z (targeted masking), and matching bright voxels across frequency bands to eliminate those associated with CO emission (blind masking). Our CO intensity cube predictions are consistent with ALMA, VLA and NOEMA observations, indicating that this method gives realistic CO estimates for E-COSMOS. In ideal conditions, masking can recover [CII] above 300GHz, with targeted masking requiring a complete foreground catalogue of bright CO sources to prevent them from contributing to contaminant emission, and blind masking needing additional lower frequency ranges to be effective. However, noise will hinder [CII] recovery above 300 GHz until near the end of the currently planned 2000 hour observing period, as $S/N<5$ without extra observing time. Whilst CO can be recovered below 300GHz, [CII] will be unavailable without cross correlation techniques.

astro-ph.GA↗

arXiv2025

The eROSITA view on the halo mass-temperature relation: From low-mass groups to massive clusters

Galaxy groups and clusters are among the best probes of structure formation and growth in a cosmological context. Most of their baryonic component is dominated by the intracluster medium (ICM), whose thermodynamical properties serve as indicators of the halo's dynamical state and can be used for the halo mass determination in the self-similar scenario. However, baryonic processes, such as AGN feedback and gas cooling, may affect the global properties of the ICM, especially in the group regime. These effects might lead to deviations from self-similar predictions in galaxy groups' scaling relations, while they remain in place for massive galaxy clusters. Additionally, the low-mass end of the scaling relations, ranging from $10^{13}$ to $10^{14} M_\odot$, remains unclear and poorly populated, as current X-ray surveys detect only the brightest groups. Here, we present the Mass-Temperature relation across the full mass range, from massive clusters to low-mass groups ($10^{13}M_\odot$), as observed by eROSITA. Using spectral stacking from eROSITA eRASS1 data for optically selected galaxy groups, we find that, in the lower mass range, galaxy groups follow the power-law relation known for galaxy clusters. We further validate these results by conducting the same stacking procedure on mock eRASS:4 data using the Magneticum hydrodynamical simulation. This indicates that AGN feedback is more likely to affect the distribution of baryons in the intragroup medium rather than the overall halo gas temperature. No significant changes in the Mass-Temperature relation slope suggest that temperature can serve as a reliable mass proxy across the entire mass range. This validates the use of temperature-derived masses, particularly in cosmological studies, significantly broadening the mass range and enabling applications such as improving the cluster mass function studies and cosmological parameter estimate.

astro-ph.GA↗

arXiv2025

The impact of assembly history on the X-ray detectability of halos. From galaxy groups to galaxy clusters

Galaxy groups represent a significant fraction of the halo population, playing a crucial role in galaxy formation and evolution. However, their detection in X-rays remains challenging, raising questions about the physical mechanisms driving their detectability in current surveys. Using the Magneticum simulations, we construct a mock X-ray lightcone of the local Universe ($z<0.2$) to investigate the selection function of galaxy groups and clusters. We find that AGN activity is a key driver of baryon depletion, but late-time mergers boost X-ray brightness by replenishing the gas reservoir in the halos, highlighting the interplay between feedback processes and the environment. Our analysis shows that X-ray bright groups experience sustained late-time mass accretion, maintaining higher gas fractions and fueling the central supermassive black holes (SMBH), further increasing the X-ray emissivity in the core. In contrast, X-ray faint groups form earlier and lose most of their gas over time, resembling fossil groups. Magneticum predicts strong anti-correlations between gas fraction (or X-ray luminosity) and SMBH mass, stellar mass (both in the central galaxy and intracluster light), and group richness at fixed halo mass. We derive predictions on the hot gas fraction at fixed halos mass (e.g. a group of total mass $M_{500}=10^{13} M_{\odot}$ can have hot gas fractions in the range $f_\mathrm{gas}=0.02-0.06$ and a central SMBH with a median mass of $M_\mathrm{BH}=10^9 M_{\odot}$ and a scatter of $0.5$ dex) compatible with the most recent measurements of the baryonic fraction. These findings will aid the interpretation of future X-ray surveys, demonstrating the power of simulation-based inference.

astro-ph.GA↗

arXiv2024

Average X-ray properties of galaxy groups. From Milky Way-like halos to massive clusters

This study examines the average X-ray properties of massive halos at z< 0.2, covering the largest halo mass range to date, from Milky Way-like halos to massive clusters. The analysis is based on stacking in the eFEDS area of the GAMA galaxy group sample, validated with synthetic data that mimic observed eROSITA X-ray and GAMA optical data using Magneticum lightcones. Stacking was conducted in halo mass bins and tested for AGN and X-ray binary contamination, systematics in the halo mass proxy, and uncertainties in optical group centers. The study provides average X-ray surface brightness profiles in six mass bins, spanning Milky Way-like systems to poor clusters. The scatter in the X-ray luminosity-mass (LX-M) relation is attributed to gas concentration: low X-ray luminosity systems at fixed halo mass exhibit lower central gas concentrations than high-luminosity systems, consistent with Magneticum predictions. However, discrepancies in dark matter concentration arise, with Magneticum predicting undetected groups as older and more relaxed, while observations suggest the opposite. New LX-M relations are presented covering three decades of halo mass. These relations fit a single power law, aligning with previous studies. Magneticum matches observed gas distributions across all masses, whereas IllustrisTNG, EAGLE, Simba, and FLAMINGO exhibit significant discrepancies at various mass scales. Simulations calibrated on local galaxy properties accurately reproduce central galaxies but fail to capture gas properties. Conversely, simulations like Magneticum excel in gas predictions but produce overly massive central galaxies. Further exploration of gas and dark matter distributions and their effects on galaxy properties is critical to comprehending the role of gravitational forces and feedback in shaping large-scale structure and galaxy evolution.

astro-ph.GA↗

arXiv2024

The perils of stacking optically selected groups in eROSITA data. The Magneticum perspective

Hydrodynamical simulation predictions are often compared with observational data without fully accounting for systematics and biases specific to observational techniques. Using the magnetohydrodynamical simulation Magneticum, we generate mock eROSITA eRASS:4 data, combined with GAMA-like spectroscopic surveys and optically selected galaxy catalogs from the same light-cone, to analyze hot gas properties in galaxy groups via a stacking technique. This study aims to (i) incorporate observational systematics into predictions and (ii) evaluate the reliability of stacking techniques for determining average X-ray properties of galaxy groups. Our analysis provides X-ray emission predictions from Magneticum, including contributions from AGN, X-ray binaries (XRBs), and the Intra-Group Medium (IGM) as a function of halo mass, covering Milky Way (MW)-like groups to poor clusters. We find that AGN and XRBs dominate the X-ray surface brightness profiles of low-mass halos. The reliability of stacking techniques is tested by reproducing input X-ray surface brightness and electron density profiles, accounting for completeness and contamination of prior samples, miscentering of optical group centers, uncertainties in X-ray emissivity due to gas temperature and metallicity assumption, and systematics in halo mass proxies. The halo mass proxy emerges as the primary source of systematics, affecting X-ray surface brightness and scaling relations. We show that stacked X-ray luminosity-mass relations are flatter than input relations but consistent with observations. Additionally, the retrieved hot gas fraction-mass relation aligns well with observational data. These results highlight the need to account for systematic errors when comparing stacking techniques to other methods using different prior catalogs or predictions.

astro-ph.GA↗

arXiv2024

The hot gas mass fraction in halos. From Milky Way-like groups to massive clusters

By using eROSITA data in the eFEDS area, we provide a measure of the hot gas fraction vs. halo mass relation over the largest halo mass range, from Milky Way-sized halos to massive clusters, and to the largest radii ever probed so far in local systems. To cope with the incompleteness and selection biases of the X-ray selection, we apply the stacking technique in eROSITA data of a highly complete and tested sample of optically selected groups. The method has been extensively tested on mock observations. In massive clusters, the hot gas alone provides a baryon budget within $R_{200}$ consistent with the cosmic value. At the same time, at the group mass scale, it accounts only for 20-40% of it. The hot gas fraction vs. halo mass relation is well-fitted by a power law, with a consistent shape and a normalization varying at maximum by a factor of 2 from $r_{500}$ to $r_{200}$. Such a relation is consistent with other works in the literature that consider X-ray survey data at the same depth as eFEDS. However, it provides a lower average gas fraction in the group regime than works based on X-ray bright group samples. The comparison of the observed relation with the predictions of several hydrodynamical simulations (BAHAMAS, FLAMINGO, SIMBA, Illustris, IllustrisTNG, MillenniumTNG, and Magneticum) shows that all simulations but Magneticum and SIMBA overpredict the gas fraction, with the largest discrepancy (up to a factor of 3) in the massive group-poor cluster halo mass range. We emphasize the need for mechanisms that can effectively expel gas to larger radii in galaxy groups without excessively quenching star formation in their member galaxies. Current hydrodynamical simulations face a significant challenge in balancing their subgrid physics: none can sufficiently evacuate gas from the halo virial region without negatively impacting the properties of the resident galaxy population.

astro-ph.GA↗

arXiv2024

[CII] line intensity mapping the epoch of reionization with the Prime-Cam on FYST II. CO foreground masking based on an external catalog

Context. The Fred Young Submillimeter Telescope (FYST) line intensity mapping (LIM) survey will measure the power spectrum (PS) of the singly ionized carbon 158 $\rm \mu$m fine-structure line, [CII], to trace the appearance of the first galaxies that emerged during and right after the epoch of reionization (EoR, $6<z<9$). Aims. We aim to quantify the contamination of the (post-)EoR [CII] LIM signal by foreground carbon monoxide (CO) line emission ($3 < J_{ \rm up} < 12$) and assess the efficiency to retrieve this [CII] LIM signal by the targeted masking of bright CO emitters. Methods. Using the IllustrisTNG300 simulation, we produced mock CO intensity tomographies based on empirical star formation rate-to-CO luminosity relations. Combining these predictions with the [CII] PS predictions of the first paper of this series, we evaluated a masking technique where the interlopers are identified and masked using an external catalog whose properties are equivalent to those of a deep Euclid survey. Results. Prior to masking, our [CII] PS forecast is an order of magnitude lower than the predicted CO contamination in the 225 GHz ([CII] emitted at $z=6.8-8.3$) band of the FYST LIM survey, at the same level in its 280 GHz ([CII] emitted at $z=5.3-6.3$) and 350 GHz ([CII] emitted at $z=4.1-4.8$) bands, and an order of magnitude higher in its 410 GHz ([CII] emitted at $z=3.4-3.9$) band. For our fiducial model, the optimal masking depth is reached when less than 10\% of the survey volume is masked at 350 and 410 GHz but around 40\% at 280 GHz and 60 \% at 225 GHz. At these masking depths we anticipate a detection of the [CII] PS at 350 and 410 GHz, a tentative detection at 280 GHz, whereas at 225 GHz the CO signal still dominates our model. In the last case, alternative decontamination techniques will be needed.

astro-ph.GA↗

arXiv2024

Detecting Galaxy Groups and AGNs populating the local Universe in the eROSITA era

The eROSITA will deliver an unprecedented volume of X-ray survey observations, 20-30 times more sensitive than ROSAT in the soft band (0.5-2 keV) and for the first time imaging in the hard band (2-10 keV) including galaxy clusters and groups along with obscured and unobscured AGNs. This calls for a powerful theoretical effort to control the systematics and biases that may affect the data analysis. We investigate the detection technique and selection effects in the galaxy group and AGN populations of a mock eROSITA survey at the depth of eRASS:4. We create a $30\times 30$ deg$^{2}$ mock observation based on the cosmological hydrodynamical simulation Magneticum Pathfinder within z=0-0.2. We combine a physical background extracted from the real eFEDS background analysis with realistic simulations of X-ray emission for the hot gas, AGNs and X-ray binaries. We apply a detection procedure equivalent to the reduction done on eRASS data and evaluate the completeness and contamination to reconstruct the luminosity functions of the extended and point sources in the catalogue. We assess the completeness of extended detections as a function of the input X-ray flux and halo. We achieve full recovery of the brightest (most massive) clusters and AGNs. However, a significant fraction of galaxy groups remains undetected. Examining the gas properties between the detected and undetected galaxy groups at fixed halo mass, we observe that the detected population exhibits, on average, higher X-ray brightness compared to the undetected ones. Moreover, we find that X-ray luminosity primarily correlates with the hot gas fraction, rather than temperature or metallicity. Our simulation suggests the presence of a systematic selection effect in current surveys, resulting in X-ray survey catalogues predominantly composed of the lowest-entropy, gas-richest, and highest surface brightness halos on galaxy group scales.

astro-ph.CO↗

arXiv2024

[CII] luminosity models and large-scale image cubes based on COSMOS 2020 and ALPINE-ALMA [CII] data back to the epoch of reionisation

We have implemented a novel method to create simulated [CII] emission line intensity mapping (LIM) data cubes using COSMOS 2020 galaxy catalogue data. It allows us to provide solid lower limits for previous simulation-based model predictions and the expected signal strength of upcoming surveys. We applied [CII]158$\mu$m luminosity models to COSMOS 2020 to create LIM cubes covering a 1.2$\times$1.2 deg$^2$ sky area. These models were derived using galaxy bulk property data from the ALPINE-ALMA survey over the redshift range $4.4 1 when using FYST parameters. However, our high-redshift results remain inconclusive because of the poor completeness of COSMOS 2020 at $z$>6.3. These predictions will be improved on the basis of future JWST data.

astro-ph.GA↗

arXiv2021

CCAT-prime Collaboration: Science Goals and Forecasts with Prime-Cam on the Fred Young Submillimeter Telescope

We present a detailed overview of the science goals and predictions for the Prime-Cam direct detection camera/spectrometer being constructed by the CCAT-prime collaboration for dedicated use on the Fred Young Submillimeter Telescope (FYST). The FYST is a wide-field, 6-m aperture submillimeter telescope being built (first light in mid-2024) by an international consortium of institutions led by Cornell University and sited at more than 5600 meters on Cerro Chajnantor in northern Chile. Prime-Cam is one of two instruments planned for FYST and will provide unprecedented spectroscopic and broadband measurement capabilities to address important astrophysical questions ranging from Big Bang cosmology through reionization and the formation of the first galaxies to star formation within our own Milky Way galaxy. Prime-Cam on the FYST will have a mapping speed that is over ten times greater than existing and near-term facilities for high-redshift science and broadband polarimetric imaging at frequencies above 300 GHz. We describe details of the science program enabled by this system and our preliminary survey strategies.

astro-ph.CO↗

arXiv2009

Constraining dark matter-dark energy interaction with gas mass fraction in galaxy clusters

The recent observational evidence for the current cosmic acceleration have stimulated renewed interest in alternative cosmologies, such as scenarios with interaction in the dark sector (dark matter and dark energy). In general, such models contain an unknown negative-pressure dark component coupled with the pressureless dark matter and/or with the baryons that results in an evolution for the Universe rather different from the one predicted by the standard $Λ$CDM model. In this work we test the observational viability of such scenarios by using the most recent galaxy cluster gas mass fraction versus redshift data (42 X-ray luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.063 < z < 1.063) (Allen et al. 2008) to place bounds on the parameter $ε$ that characterizes the dark matter/dark energy coupling. The resulting are consistent with, and typically as constraining as, those derived from other cosmological data. Although a time-independent cosmological constant ($Λ$CDM model) is a good fit to these galaxy cluster data, an interacting dark energy component cannot yet be ruled out.

astro-ph.CO↗

arXiv2002

Brane World Cosmologies and Statistical Properties of Gravitational Lenses

Brane world cosmologies seem to provide an alternative explanation for the present accelerated stage of the Universe with no need to invoke either a cosmological constant or an exotic \emph{quintessence} component. In this paper we investigate statistical properties of gravitational lenses for some particular scenarios based on this large scale modification of gravity. We show that a large class of such models are compatible with the current lensing data for values of the matter density parameter $Ω_{\rm{m}} \leq 0.94$ ($1σ$). If one fixes $Ω_{\rm{m}}$ to be $\simeq 0.3$, as suggested by most of the dynamical estimates of the quantity of matter in the Universe, the predicted number of lensed quasars requires a slightly open universe with a crossover distance between the 4 and 5-dimensional gravities of the order of $1.76 H_o^{-1}$.

astro-ph↗