Kavli Institute for Particle Astrophysics and Cosmology

The Simons Observatory (SO) is a new suite of cosmic microwave background telescopes in the Chilean Atacama Desert with an extensive science program spanning cosmology, Galactic and extragalactic astrophysics, and particle physics. SO will survey the millimeter-wave sky over a wide range of angular scales using six spectral bands across three types of dichroic, polarization-sensitive transition-edge sensor (TES) detector modules: Low-Frequency (LF) modules with bandpasses centered near 30 and 40 GHz, Mid-Frequency (MF) modules near 90 and 150 GHz, and Ultra-High-Frequency (UHF) modules near 220 and 280 GHz. Twenty-five UHF detector modules, each containing 1720 optically-coupled TESs connected to microwave SQUID multiplexing readout, have now been produced. This work summarizes the pre-deployment characterization of these detector modules in laboratory cryostats. Across all UHF modules, we find an average operable TES yield of 83%, equating to over 36,000 devices tested. The distributions of (220, 280) GHz saturation powers have medians of (24, 26) pW, near the centers of their target ranges. For both bands, the median optical efficiency is 0.6, the median effective time constant is 0.4 ms, and the median dark noise-equivalent power (NEP) is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula>40 aW<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$/\sqrt{\mathbf {Hz}}$</tex-math></inline-formula>. The expected photon NEPs at (220, 280) GHz are (64, 99) aW<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$/\sqrt{\mathbf {Hz}}$</tex-math></inline-formula>, indicating these detectors will achieve background-limited performance on the sky. Thirty-nine UHF and MF detector modules are currently operating in fielded SO instruments, which are transitioning from the commissioning stage to full science observations.

Abstract With the goal of extracting as much information as possible from Chandra and XMM-Newton observations of faint, diffuse sources such as galaxy clusters, as well as those of future X-ray telescopes, we present a strategy for forward modeling all of the foreground and background signals present in these data. This work leverages widespread efforts to understand the soft X-ray emission from the Galaxy, as well as the cosmic X-ray background and instrument-specific, particle-induced backgrounds. Statistically, a forward model of the foregrounds and backgrounds is preferable to alternatives because it requires no binning of the data, and allows for straightforward marginalization over systematic uncertainties. We apply these methods to several galaxy clusters at intermediate-to-high redshifts, spanning a range of masses and morphologies, using Chandra and/or XMM-Newton data. Our results suggest a modest improvement even for relatively bright clusters at these redshifts, and more substantial advantages in the high-redshift, low-surface-brightness regime. We also discuss and provide a simple correction for a time-dependent miscalibration of the Chandra advanced CCD imaging spectrometer detectors identified in archival galaxy cluster data.

A bstract The vertex detector is crucial for precision measurements of the Higgs boson at the electron-positron Higgs factory. Benchmarked with $$ H\to c\overline{c} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mover> <mml:mi>c</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> and $$ H\to s\overline{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>s</mml:mi> <mml:mover> <mml:mi>s</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> measurements in the $$ \nu \overline{\nu}H $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ν</mml:mi> <mml:mover> <mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>H</mml:mi> </mml:math> channel, we perform an optimisation study on the inner radius and spatial resolution of the vertex detector using the Jet Origin Identification (JOI) framework, which determines the parton flavour of jets using advanced Artificial Intelligence (AI) algorithm. We observe that, compared to the reference detector configuration, halving the inner radius and spatial resolution improves the transverse and longitudinal impact parameter resolution approximately by a factor of two, while increasing the accuracy and significance of the $$ H\to c\overline{c}/s\overline{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mover> <mml:mi>c</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>/</mml:mo> <mml:mi>s</mml:mi> <mml:mover> <mml:mi>s</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> measurement by 4% and 8%, respectively. Conversely, doubling these parameters results in comparable degradation, with variations in the inner radius being the dominant factor. Our results provide guidance for detector design and highlight promising prospects for identifying the $$ H\to s\overline{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>s</mml:mi> <mml:mover> <mml:mi>s</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> decay mode at future Higgs factories.

Abstract We present imaging and spectroscopic analyses of Chandra and XMM-Newton observations of ACT-CL J0123.5−0428, one of the most massive, highest-redshift galaxy clusters detected within the survey fields of the Atacama Cosmology Telescope. The Chandra data are sufficient to characterize the morphology of this cluster and constrain the geometrically deprojected temperature in two spatial bins out to r 2500 , revealing a dynamically relaxed system whose temperature drops to kT = 1.8 ± 0.6 keV in the inner ∼40 kpc. Within this same inner radius, the surface brightness and density of the intracluster medium are sharply peaked, and the cooling time falls to t cool = 28 0 − 120 + 150 Myr. A novel forward-modeling analysis of the XMM data extends imaging and spectroscopic measurements of this system out to r 500 , constraining the redshift to z = 1.50 ± 0.03, with a mean temperature of kT = 7.3 ± 1.1 keV and an emission-weighted mean metallicity of Z / Z ⊙ = 0.4 3 − 0.25 + 0.46 . We also utilize the limited optical–IR photometric coverage of the cluster to characterize the properties of the brightest cluster galaxy (BCG), which is coincident with the X-ray peak. Despite the high redshift and strong cool core, the BCG exhibits no signs of recent or ongoing star formation, suggesting active galactic nucleus feedback has been acting persistently to stem star formation since z ∼ 2.5. These measurements identify ACT-CL J0123.5−0428 as the highest-redshift, dynamically relaxed, cool core galaxy cluster discovered to date, making it a premier target for future astrophysical and cosmological studies.

Abstract In this draft, we investigate constant redshift function Morris–Thorne-like traversable wormhole (WH) models which described as a relativistic static fluid distribution in Schwarzschild-type coordinates with a topological global monopole charge under the influence of D -dimensional Einstein gravity. In this scenario we consider three distinct shape functions, while matter sector is supported by anisotropic fluid configuration. We show some basic criteria for the viability of all three shape function models, the radial null energy condition is generally violated while tangential components are satisfied in the vicinity of the throat for appropriately chosen parameter values. We examine that the active gravitational mass becomes negative near the throat which indicates the existence of exotic matter (EM) and positive anisotropy parameter helps in maintaining the throat stability, while the adiabatic indices lie above the relativistic threshold supporting the stability of the WH configurations. We also employ the complexity factor as a diagnostic tool for anisotropy and density inhomogeneity which reveals that the WH geometries evolve toward minimal complexity at large radial distances. We analyze the influence of monopole parameter on the WH’s throat and curvature through 2 D and 3 D embedding diagrams, however, the total amount of EM is estimated by utilizing volume integral quantifier (VIQ) approach in our considered gravity theory.

Abstract The X-ray source around supermassive black holes in active galactic nuclei (AGN) has been dubbed the corona by analogy to the solar (and stellar) corona. Both stellar and AGN coronae are orders of magnitude hotter than their counterpart optical source; the stellar photosphere and accretion disk respectively. Both coronae vary on short time scales down to seconds. The coronal activity in the Sun is well imaged and its activity has been shown to be driven by magnetic energy converted into heat through the process of magnetic reconnection. While it has been theorized that AGN corona are also magnetically driven, the driving mechanism of AGN coronal activity has not been directly observed. A smoking gun of magnetic reconnection is when a coronal flare’s temporal evolution in hard and soft X-rays follows the Neupert Effect. These flares result in both a solar coronal mass ejection, and energetic particles streaming down along magnetic field lines to the photosphere. Here, we report the detection of the Neupert Effect in an AGN corona, providing the first direct evidence for magnetic reconnection in AGN. Our measurements indicate a magnetic field loop height of up to 30 gravitational radii, and a distance of about 400 gravitational radii between the corona and the UV emitting accretion disk. The present findings thus enable the application of solar coronal physics to the less accessible AGN corona.

We investigated the physics of black hole accretion flows, particularly focusing on phenomena like magnetic reconnection and plasmoid formation, which are believed to be responsible for energetic events such as flares observed from astrophysical black holes. We aim to understand the influence of radiative cooling on plasmoid formation within black hole accretion flows that are threaded by multi-loop magnetic field configurations. We conducted 2D and 3D two-temperature general relativistic magnetohydrodynamic simulations. By varying the magnetic loop sizes and the mass accretion rate, we explored how radiative cooling alters the accretion dynamics, disk structure, and properties of reconnection-driven plasmoid chains. Our results demonstrate that radiative cooling suppresses the transition to the magnetically arrested disk state by reducing magnetic flux accumulation near the horizon. It significantly modifies the disk morphology by lowering the electron temperature and compressing the disk, which leads to increased density at the equatorial plane and decreased magnetization. Within the current sheets, radiative cooling triggers layer compression and the collapse of plasmoids, shortening their lifetime and reducing their size, while the frequency of plasmoid events increases. Moreover, we observe enhanced negative energy-at-infinity density in plasmoids near the ergosphere, with its peaks corresponding to plasmoid formation events. Radiative cooling plays a critical role in shaping both macroscopic accretion flow properties and microscopic reconnection phenomena near black holes. This suggests that radiative cooling modulates black hole energy extraction through reconnection-driven Penrose processes, highlighting its importance in models of astrophysical black holes.

ABSTRACT We present the first joint analysis of the kinetic Sunyaev–Zeldovich (kSZ) effect with galaxy–galaxy lensing (GGL) for CMASS galaxies in the Baryon Oscillation Spectroscopic Survey. We show these complementary probes can disentangle baryons from dark matter in the outskirts of galactic haloes by alleviating model degeneracies that are present when fitting to kSZ or GGL measurements alone. In our joint kSZ + GGL analysis we show that the baryon density profile is well constrained on scales from 0.3 to 50 Mpc$\,h^{-1}$. With our well-constrained profile of the baryon density, we provide direct comparisons to simulations. For our model we find an outer slope of the baryon distribution that is shallower than predicted by some hydrodynamical simulations, consistent with enhanced baryonic feedback. We also show that not including baryons in a model for GGL can shift halo mass estimates by $\sim 20~{{\ \rm per\ cent}}$ compared to a model that includes baryons and is jointly fit to kSZ + GGL measurements. Our modelling code GGL and kSZ (glasz) is publicly available at https://github.com/James11222/glasz.

Abstract Many state-of-the-art galaxy simulations featuring traditional feedback modes have significant challenges producing enough extended soft X-ray (∼0.5−2 keV) emission at R ∼ 0.5 R vir −1 R vir observed around galaxies with stellar masses M * ≲ 10 11 M ⊙ , without violating galaxy mass function constraints. Moreover, thermal Sunyaev–Zel’dovich (tSZ) measurements probing the thermal pressure of similar galaxies indicate that it is orders of magnitude lower than predictions from simple halo hydrodynamics and many hydrodynamical simulations. We demonstrate that these constraints can be met congruously with a large nonthermal pressure contribution in the form of cosmic rays (CRs) from supernovae and/or active galactic nuclei (AGN), which lowers the tSZ signal, while CR leptons produce plentiful soft X-rays via inverse Compton scattering of the cosmic microwave background. The combination of these two observations is far more constraining on the pressure budget of galactic halos than either alone—if these novel tSZ and X-ray observations are borne out by future studies, then taken together they reveal the strongest evidence for CR support in halos to date . Conversely, it is very difficult to produce the extended X-rays via traditional thermal emission without increasing the overall thermal pressure and thus tSZ signal in tandem, making these tensions even worse. Finally, tSZ and X-rays together unlock a novel observational method to constrain halo CR pressure relative to thermal pressure, with implications for CR transport parameters and AGN feedback energetics across various galaxy mass scales. Taking the currently observed constraints at M halo ∼ 10 12 M ⊙ imply that the halo CR pressure must at least be equal to the gas thermal pressure.