In ฮ Cold Dark Matter (ฮCDM) cosmology, galaxy clusters form via the hierarchical merging/accretion of formerly separate Dark Matter halo systems containing cold and collisionless DM. Due to the non-turbulent nature of CDM, we would expect the most massive and brightest cluster galaxy (BCG) to come to rest at the gravitational center of the clusterโs DM halo. To test this prediction, we looked...
Galaxy clusters are powerful probes used to constrain the cosmology of our universe. However, they are peppered with several systematic biases such as projection effects. Of them, the orientation of triaxial clusters with respect to the line-of-sight is expected to be one of the prime sources of scatter and potential bias in optical observables (i.e., richness and weak-lensing signal) of...
Galaxy cluster formation is driven by a variety of complicated physical processes that affect their growth and evolution through cosmic time. As a result, the matter distribution within the cluster, and therefore, its shape, can be a probe of these astrophysical processes and cosmology. Clusters grow through the accretion of new material, typically along two or three main filaments, giving...
We present a joint approach to studying galaxy clusters that combines X-ray data from the Chandra X-ray Observatory with millimeter data from both the South Pole Telescope (SPT) and the Planck satellite, leveraging the complementary capabilities of these three instruments. In particular, we exploited the high angular resolution of Chandra and SPT to map the innermost region of the cluster and...
Galaxy cluster mergers are rich sources of information to test both cluster astrophysics and cosmology. However, cluster mergers produce complex projected signals that are difficult to interpret from individual observational probes. Multi-probe constraints on both the gas and dark matter cluster components are necessary to infer merger parameters that are otherwise degenerate. We have...
Clusters of galaxies, formed at the latest stages of structure formation, are unique cosmological probes to study the formation and evolution of large-scale structures. With the advent of large CMB surveys like those from the Planck satellite, the ACT and SPT telescopes, we now have access to large catalogs of galaxy clusters detected at millimeter wavelength via the thermal Sunyaev-Zeldovich...
The multi-component matched filer (MCMF) cluster confirmation framework, designed to leverage the synergies between ICM-selected cluster surveys and optical imaging surveys, has been applied to some of the largest and high-quality surveys to date with a focus on high purity and well controlled cluster samples for cosmological purposes. MCMF confirmed cluster catalogs have subsequently been...
We present a catalog of 500 galaxy cluster candidates in the SPT-Deep field: a 100 square-degree field that combines data from the SPT-3G and SPTpol surveys to reach noise levels of 3.0, 2.2, and 9.0 uK-arcmin at 95, 150, and 220 GHz, respectively. This is comparable to noise levels expected for the wide field survey of CMB-S4, a next-generation CMB experiment. Candidates are selected via the...
Galaxy clusters are the largest gravitationally bound objects in the Universe, serving as powerful cosmological probes on the growth of structure on the largest physical scales. The thermal Sunyaev-Zeld'dovich (tSZ) effect is now a well-established technique for probing the intracluster medium (ICM) of galaxy clusters on these scales. Measuring the gas pressure serves as a robust tracer of...
In a self-similar paradigm of structure formation, the thermal pressure of the hot intra-cluster gas follows a universal distribution independent of the mass scale. Thus, this thermal pressure distribution is universal in every cluster once normalised to the proper mass and redshift dependencies. The reconstruction of such a universal pressure profile requires an individual estimate of the...
Mapping the distribution of baryonic mass in our Universe down to the group-sized halo masses it is essential to clarify how much baryonic matter is locked up in halos and in filaments. Non-gravitational processes affect the thermodynamical conditions of the hot gas and baryonic content of groups and clusters of galaxies, causing deviations from the theoretical self-similar expectations....
Optically identified galaxy clusters have the potential to provide some of the most precise cosmological constraints, as they enable the detection of lower-mass clusters. However, they are also highly susceptible to systematic effects, with projection effects being a major challenge. This misidentification of member galaxies introduces anisotropies in the observed distribution of optical...
We study the robustness of a simulation-based inference (SBI) method in the context of cosmological parameter estimation from galaxy cluster abundance in mock cluster datasets. I will describe an application where we train an SBI model, based on a mixture density network (MDN), to derive posteriors for cosmological parameters from a stacked cluster data vector constructed using an analytic...
Galaxy cluster abundance measurements serve as a powerful probe for constraining cosmological parameters such as the matter density ($\Omega_m$) and the amplitude of density fluctuations ($\sigma_8$). Wide-area surveys detect clusters using observables like the thermal Sunyaev-Zeldovich (SZ) effect, a spectral distortion in the Cosmic Microwave Background (CMB). Accurate cosmological...
Galaxy clusters serve as powerful cosmological probes through number count analysis. Beyond that, the gas distribution in cluster outskirts provides a model-independent method for deriving competitive cosmological constraints. By combining HIGHMzโa subsample of 32 of the most massive CHEX-MATE clustersโwith X-COP clusters, this study derives robust and precise constraints on the matter density...
Independent constraints on the Hubble constant ($H_0$) from local distance ladders and early Universe CMB data can be derived from cluster sizes by combining X-ray and millimetre observations of the intracluster medium. Using XMM-Newton and Planck data, we present the inference on $H_0$ by studying systematic mismatches, $\eta_T$, between X-ray and millimetre temperature (or pressure)...
Modern multi-platform, multi-band millimeter-wavelength surveys of the sky with arcminute resolution are designed to explore the origin and evolution of the universe. The next generation of CMB experiments, including the Simons Observatory (SO), will address a wide range of pressing scientific questions with unprecedented sensitivity. Among these, one of the primary targets is the faint...
MISTRAL is a new facility instrument open to the scientific community that will help investigate the โmissing baryonโ problem, as well as many other scientific cases from extragalactic astrophysics to solar system science. The MIllimeter Sardinia radio Telescope Receiver based on Array of Lumped elements KIDs (MISTRAL) is a cryogenic W-band LEKID camera which has been mounted at the Gregorian...
The TolTEC camera is a trichroic polarimeter deployed on the 50-meter Large Millimeter Telescope (LMT) on Sierra Negra in Mexico. It observes in three photometric bands 150, 220, and 280 GHz with respective angular resolutions of 10, 6, and 5 arcseconds. TolTEC achieved first light in 2022 and commenced commissioning in December of that year. Issues with the LMT and TolTEC prevented...
OLIMPO is a concept for a balloon-borne instrument to map the thermal and kinematic SZE at high signal-to-noise in a sample of nearby galaxy clusters and connecting bridges. In combination with X-ray data primarily from eROSITA and radio observations from SKA Pathfinders, OLIMPO will provide precise constraints on the turbulent and coherent velocities within the ICM due to structure growth...
The Next-generation Extended Wavelength-MUltiband Sub/millimeter Inductance Camera (NEW-MUSIC) on the Leighton Chajnantor Telescope (LCT) will be a first-of-its-kind, six-band, trans-mil-li-me-ter-wave (``trans-mm'') polarimeter covering 2.4 octaves of spectral bandwidth to open a new window on the trans-mm time-domain frontier, in particular new frontiers in energy, density, time, and...
In Sunyaev-Zeldovich (SZ) cluster cosmology, accurately determining cluster masses is crucial for constraining cosmological parameters through cluster number counts.
As the mass is not an observable, a scaling relation is needed to link cluster masses to the integrated Compton parameter Y, i.e., the SZ observable, to exploit data from large millimeter surveys. Current cosmological results use...
Understanding the scaling relations between galaxy cluster properties (such as mass, luminosity, richness, and luminosity) is crucial for unraveling the physical processes shaping them. However, these relations are highly sensitive to uncertainties in sample selection functions, requiring assumptions about the abundance and properties of unobserved populations. The potential impact of...
We present our analysis of the factors that impact the reconstruction of density profiles in galaxy clusters, which are a fundamental tool for studying the properties of the intra-cluster medium and a key ingredient for measuring the total mass radial profiles under the assumption of hydrostatic equilibrium.
We used a sample of 105 galaxy clusters drawn from cosmological simulations...
Galaxy clusters form through the accretion of smaller structures, with mergers of subclumps and the sloshing of cold gas in higher-entropy environments affecting their intracluster medium (ICM) distribution. These processes leave observable imprints, such as edges, shocks, cold fronts, and discontinuities in surface brightness, as well as variations in integrated quantities.
In this study,...
In this talk, I will introduce the Resolved Cluster Evolution Sunyaev-Zeldovich Survey (ReCESS): a 200-hour-plus observing campaign aimed at resolving the intracluster medium (ICM) through the thermal Sunyaev-Zeldovich (tSZ) effect in 25 ACT-selected galaxy clusters within a redshift range of $1.2 < z < 2$ using MUSTANG-2 on the GBT and ALMA. I will present the first results on the average...
I will talk about reconstructing the non-linear matter power spectrum $P(k)$ using a joint analysis of gravitational lensing of the cosmic microwave background (CMB) and lensing of galaxies. This reconstruction is motivated by the $S_8$ tension between early-universe CMB predictions and late-time observables. We use CMB lensing data from the Atacama Cosmology Telescope DR6 and cosmic shear...
Precision measurements of the cosmic microwave backgroundโs gravitational lensing provide a uniquely powerful window into the distribution of dark matter, offering insights into neutrinos, dark energy, and enabling powerful consistency tests of the standard cosmological model.
In this talk, I will describe ongoing efforts in producing state-of-the-art CMB lensing maps from the final...
The weak gravitational lensing of the cosmic microwave background photons due to the line-of-sight matter distribution is a powerfully precise probe of cosmology. One of the key insights that this phenomenon known as CMB lensing unveils is an unbiased mapping of dark matter and its characteristics, allowing us to trace the formation and growth of large-scale structure over vast cosmic epochs....
