arXiv subjects

Celine Boehm

Publications and source records attributed to Celine Boehm.

At least 19 recordsLinked to original sources

arXiv2026

Caustic Skeleton and the Local Cosmic Web: the Coma Cluster node and the Pisces-Perseus ridge

We apply caustic skeleton theory to the Manticore-Local simulations, which are Bayesian constrained reconstructions of the Local Universe from the 2M++ galaxy catalogue, and extract the three-dimensional multi-scale caustic skeleton of two canonical weblike structures in our Local Universe, namely the Coma Cluster and the Pisces-Perseus ridge as they represent the most prominent cluster node and filamentary artery in the nearby Universe. We show that the Caustic Skeleton network of caustic singularities accurately reproduces the observed large-scale organisation of galaxies in redshift space for one of the Manticore realisations. The hierarchy of caustic features allows us to establish a multi-scale classification of the large-scale environment in which observed 2M++ galaxies reside. One of the most interesting aspects of the theory is that it predicts two topologically distinct classes of filaments (A_4 swallowtail and D_4 umbilic caustics) that form through fundamentally different folding histories yet appear morphologically similar enough, on the surface, to be overlooked by conventional structure identifiers. We find that the influence of D_4 filaments only becomes increasingly relevant towards smaller scales, and the Pisces-Perseus Supercluster in particular is revealed to be a distinctly D_4-dominated structure compared to the extended Stickman structure around the Coma Cluster. In other words, caustic skeleton theory enables a novel topological characterisation of one of the most studied filamentary complexes in the nearby Universe. [Shortened]

astro-ph.CO↗

arXiv2026

SAGUI: SED-based Segmentation of Multi-band Galaxy Images -- Application to JADES in GOODS-South

We present sagui, a modular framework for the analysis of multi-band imaging data in spatially resolved galaxies, with synergies to integral-field spectroscopy (IFS). Building on the spectro-spatial paradigm introduced by capivara for IFS data, sagui extends this approach to imaging datasets, enabling a coherent, pixel-level treatment of spatial and spectral information across multiple bands. The method follows a two-stage strategy: a starlet-based decomposition is first used to identify and mask spatial structures across multiple scales while suppressing noise, and a spectral-similarity analysis then partitions the image into coherent pixel groups that preserve spectral consistency. In addition to compact and high-contrast structures, the framework incorporates a dedicated statistical treatment, based on a copula transform, to identify and recover faint, diffuse low-surface-brightness components. We demonstrate the method across a diverse range of galaxy morphologies, highlighting its ability to characterize complex spatial structures, including clumps, bars, interacting systems, and low-surface-brightness features. As a case study, we apply it to eleven morphologically diverse galaxies from the James Webb Space Telescope Advanced Deep Extragalactic Survey in the GOODS--South field. sagui is released under an MIT license and is available at https://rafaelsdesouza.github.io/sagui/.

astro-ph.IM↗

arXiv2025

AT2022zod: An Unusual Tidal Disruption Event in an Elliptical Galaxy at Redshift 0.11

Tidal Disruption Events (TDEs) have long been hypothesized as valuable indicators of black holes, offering insight into their demographics and behaviour out to high redshift. TDEs have also enabled the discovery of a few Massive Black Holes (MBHs) with inferred masses of $10^4$--$10^6\,M_\odot$, often associated with the nuclei of dwarf galaxies or ultra-compact dwarf galaxies (UCDs). Here we present AT2022zod, an extreme and short-lived optical flare in an elliptical galaxy at z=0.11, residing within 3kpc of the galaxy's centre. Its luminosity and ~30-day duration make it unlikely to have originated from the host galaxy's central supermassive black hole (SMBH), which estimate to have a mass around $10^8\,M_\odot$. Assuming that the emission mechanism is consistent with known observed TDEs, we find that such a rapidly evolving transient could either be produced by a MBH in the intermediate-mass range or, alternatively, result from the tidal disruption of a star on a non-parabolic orbit around the central SMBH. We suggest that the most plausible origin for AT2022zod is the tidal disruption of a star by a MBH embedded in a UCD. As the Vera C. Rubin Observatory's Legacy Survey of Space and Time comes online, we propose that AT2022zod serves as an important event for refining search strategies and characterization techniques for intermediate-mass black holes.

astro-ph.HE↗

arXiv2025

LHAASO Galactic Plane $\gamma$-rays Strongly Constrain Heavy Dark Matter

LHAASO, a ground-based observatory, is unveiling new frontiers in our understanding of high-energy $\gamma-$rays and cosmic rays. It has recently observed high energy diffuse $\gamma-$rays from the Galactic plane in the TeV-PeV range. For the first time, we analyze this data to search for signatures of heavy decaying and annihilating dark matter in the mass range $10^{5}-10^{11}$ GeV. We compute the expected photon flux from both Galactic and extragalactic dark matter, incorporating attenuation due to photon pair production. For the Galactic contribution, we include both prompt photons and secondary photons produced via inverse Compton scattering, accounting for electron/positron propagation. For the extragalactic component, in addition to the prompt and inverse Compton contributions, we also include cascade photons arising from inverse Compton scattering of pair-produced electrons and positrons. By combining all these contributions, we derive constraints on the dark matter parameter space. Our bounds for various two body Standard Model final states are strongest to date. This underscore LHAASO's capability to discover the nature of heavy dark matter.

hep-ph↗

arXiv2024

Using dust to constrain dark matter models

In this paper, we use hydrodynamic zoom-in simulations of Milky Way-type haloes to explore using dust as an observational tracer to discriminate between cold and warm dark matter (WDM) universes. Comparing a cold and 3.5 keV WDM particle model, we tune the efficiency of galaxy formation in our simulations using a variable supernova rate to create Milky Way systems with similar satellite galaxy populations while keeping all other simulation parameters the same. Cold dark matter (CDM), having more substructure, requires a higher supernova efficiency than WDM to achieve the same satellite galaxy number. These different supernova efficiencies create different dust distributions around their host galaxies, which we generate by post-processing the simulation output with the \powderday{} codebase. Analysing the resulting dust in each simulation, we find $\sim$4.5 times more dust in our CDM Milky Way haloes compared with WDM. The distribution of dust out to $R_{200\text{c}}$ is then explored, revealing that the WDM simulations are noticeably less concentrated than their CDM counterparts, although differences in substructure complicate the comparison. Our results indicate that dust is a possible unique probe to test theories of dark matter.

astro-ph.GA↗

arXiv2024

First constraint on the weak mixing angle using direct detection experiments

Current ton-scale dark matter direct detection experiments have reached an important milestone with the detection of solar neutrinos. In this paper, we show that these data can be used to determine a critical parameter of the Standard Model in particle physics, across an energy regime that has never been probed before. In particular, we show that the value of the weak mixing angle ($\theta_W$) which relates the mass of the $W$ and $Z$ bosons can be derived from 1) the recent measurements of coherent neutrino-nucleus scattering by PandaX-4T and XENONnT in the sub-GeV energy range -- a regime which is usually only probed by low energy neutrino experiments -- and from 2) XENONnT electron recoil data through neutrino-electron scattering at energy scale $\simeq 0.1 ~ \rm{ MeV}$, corresponding to a momentum transfer region over an order of magnitude smaller than that explored by atomic parity violation experiments. Now that an indicative measurement of the weak mixing angle exists at these lowest energy frontier, the challenge for the next generation of such experiments will be to provide a more precise measurement in the keV-MeV energy range.

hep-ph↗

arXiv2023

JASMINE: Near-Infrared Astrometry and Time Series Photometry Science

Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, the Japan Aerospace Exploration Agency. JASMINE has two main science goals. One is the Galactic archaeology with Galactic Center Survey, which aims to reveal the Milky Way's central core structure and formation history from Gaia-level (~25 $\mu$as) astrometry in the Near-Infrared (NIR) Hw-band (1.0-1.6 $\mu$m). The other is the Exoplanet Survey, which aims to discover transiting Earth-like exoplanets in the habitable zone from NIR time-series photometry of M dwarfs when the Galactic center is not accessible. We introduce the mission, review many science objectives, and present the instrument concept. JASMINE will be the first dedicated NIR astrometry space mission and provide precise astrometric information of the stars in the Galactic center, taking advantage of the significantly lower extinction in the NIR. The precise astrometry is obtained by taking many short-exposure images. Hence, the JASMINE Galactic center survey data will be valuable for studies of exoplanet transits, asteroseismology, variable stars and microlensing studies, including discovery of (intermediate mass) black holes. We highlight a swath of such potential science, and also describe synergies with other missions.

astro-ph.IM↗

arXiv2023

The spin axes of globular clusters and correlations with gamma-ray emission

A growing number of Milky Way globular clusters have been identified to possess a noticeable degree of solid-body rotation. For several clusters, the combination of stellar proper motions and radial velocities allows for 3-dimensional spin axes to be extracted. In this paper we consider the orientations of these spin axes, and ask whether they are correlated with any other properties of the clusters -- either global properties to do with their orbits and origin, or internal properties related to the cluster composition. We discuss the possibility of alignments between the spin axes of globular clusters, chemodynamical groupings, and their orbital poles. We also point out a previously unidentified negative correlation between the measured gamma-ray emissivities and the inclination of the globular cluster spins with respect to the line of sight. Given that this correlation is not present in other wavelengths, we cannot conclusively attribute it solely to sampling bias. If the correlation holds up to scrutiny with more data, it may be indicative of sources of anisotropic gamma-ray emission in globular clusters. We discuss the plausibility of such an anisotropy arising from a population of dynamically formed millisecond pulsars with some degree of spin-orbit alignment.

astro-ph.GA↗

arXiv2022

Gravitational-wave event rates as a new probe for dark matter microphysics

We show that gravitational waves have the potential to unravel the microphysical properties of dark matter due to the dependence of the binary black hole merger rate on cosmic structure formation, which is itself highly dependent on the dark matter scenario. In particular, we demonstrate that suppression of small-scale structure -- such as that caused by interacting, warm, or fuzzy dark matter -- leads to a significant reduction in the rate of binary black hole mergers at redshifts $z\gtrsim5$. This shows that future gravitational-wave observations will provide a new probe of physics beyond the $\Lambda$CDM model.

astro-ph.CO↗

arXiv2022

Can radial motions in the stellar halo constrain the rate of change of mass in the Galaxy?

A change in the mass of the Galaxy with time will leave its imprint on the motions of the stars, with stars having radially outward (mass loss) or inward (mass accretion) bulk motions. Here we test the feasibility of using the mean radial motion of stars in the stellar halo to constrain the rate of change of mass in the Galaxy, for example, due to decay of dark matter into invisible dark sector particles or more conservatively from the settling of baryons. In the current $\Lambda$CDM paradigm of structure formation, the stellar halo is formed by accretion of satellites onto the host galaxy. Over time, as the satellites disrupt and phase mix, the mean radial motion $\langle V_{R} \rangle$ of the stellar halo is eventually expected to be close to zero. But most halos have substructures due to incomplete mixing of specific accretion events and this can lead to nonzero $\langle V_{R} \rangle$ in them. Using simulations, we measure the mean radial motion, $\langle V_{R} \rangle$, of stars in 13 $\Lambda$CDM stellar halos lying in a spherical shell of radius 30 kpc. We find that for most halos, the shell motion is quite small, with 75\% of halos having $\langle V_{R}\rangle \lesssim 1.2 \ {\rm km}s^{-1}$. When substructures are removed by using a clustering algorithm, $\langle V_{R}\rangle$ is reduced even further, with 75\% of halos having $\langle V_{R}\rangle \lesssim 0.6 \ {\rm km}s^{-1}$. A value of $\langle V_{R}\rangle \approx 0.6 \ {\rm km}s^{-1}$ can be attained corresponding to a galactic mass loss rate of 2\% per Gyr. We show that this can place constraints on dark matter decay parameters such as the decay lifetime and the kick velocity that is imparted to the daughter particle. The advent of all-sky stellar surveys involving millions to billions of stars is encouraging for detecting signatures of dark matter decay.

astro-ph.GA↗

arXiv2022

Probing dark matter interactions with 21cm observations

Similarly to warm dark matter which features a cut-off in the matter power spectrum due to free-streaming, many interacting dark matter models predict a suppression of the matter power spectrum on small length scales through collisional damping. Forecasts for 21cm line intensity mapping have shown that an instrument like the SKA will be able to probe a suppression of power in warm dark matter scenarios in a statistically significant way. Here we investigate the implications of these findings on interacting dark matter scenarios, particularly dark matter-neutrino interactions, which we use as an example. Using a suite of cosmological $N$-body simulations, we demonstrate that interacting scenarios show a suppression of the non-linear power spectrum similar to warm dark matter models. This implies that 21cm line intensity mapping will be able to set the strongest limits yet on dark matter-neutrino scattering, improving the constraints by two orders of magnitude over current Lyman-$\alpha$ bounds, and by four orders of magnitude over cosmic microwave background and baryon acoustic oscillations limits. However, to distinguish between warm dark matter and interacting scenarios, our simulations show that percent-level precision measurements of the matter power spectrum at redshifts $z\gtrsim15$ are necessary, as the key features of interacting scenarios are washed out by non-linear evolution at later times.

astro-ph.CO↗

arXiv2022

Radio sky reveals primordial electron-proton interactions

For several decades, astronomers have measured the electromagnetic emission in the universe from the lowest to the highest energies with incredible precision. The lowest end of the spectrum, corresponding to radio waves, is fairly well studied and understood. Yet there is a long standing discrepancy between measurements and predictions, which has prompted the construction of many new models of radio emitters. Here we show that remnant electron-proton interactions, leading to photon production in the early universe, also referred to as cosmic free-free emission, solves the discrepancy between theory and observations. While the possibility of cosmic free-free emission has been postulated for several decades, this is the first time that the amplitude and shape of the signal has been computed and its existence demonstrated. Using current measurements we estimate this emission to become important from around a redshift of $z \simeq 2150$. This contribution from fundamental particles and interactions represents the lowest energy test from the early universe of one of the pillars of modern physics, Quantum Electrodynamics. The next generation of deep radio surveys will be able to measure primordial signals from this cosmic era with greater precision and further solidify our understanding of the radio sky.

astro-ph.CO↗

arXiv2022

Snowmass2021 Cosmic Frontier White Paper: Dark Matter Physics from Halo Measurements

The non-linear process of cosmic structure formation produces gravitationally bound overdensities of dark matter known as halos. The abundances, density profiles, ellipticities, and spins of these halos can be tied to the underlying fundamental particle physics that governs dark matter at microscopic scales. Thus, macroscopic measurements of dark matter halos offer a unique opportunity to determine the underlying properties of dark matter across the vast landscape of dark matter theories. This white paper summarizes the ongoing rapid development of theoretical and experimental methods, as well as new opportunities, to use dark matter halo measurements as a pillar of dark matter physics.

hep-ph↗

arXiv2021

Reticulum II: Particle Dark Matter and Primordial Black Holes Limits

Reticulum II (Ret II) is a satellite galaxy of the Milky Way and presents a prime target to investigate the nature of dark matter (DM) because of its high mass-to-light ratio. We evaluate a dedicated INTEGRAL observation campaign data set to obtain $\gamma$-ray fluxes from Ret II and compare those with expectations from DM. Ret II is not detected in the $\gamma$-ray band 25--8000 keV, and we derive a flux limit of $\lesssim 10^{-8}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$. The previously reported 511 keV line is not seen, and we find a flux limit of $\lesssim 1.7 \times 10^{-4}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$. We construct spectral models for primordial black hole (PBH) evaporation and annihilation/decay of particle DM, and subsequent annihilation of positrons produced in these processes. We exclude that the totality of DM in Ret II is made of a monochromatic distribution of PBHs of masses $\lesssim 8 \times 10^{15}\,\mathrm{g}$. Our limits on the velocity-averaged DM annihilation cross section into $e^+e^-$ are $\langle \sigma v \rangle \lesssim 5 \times 10^{-28} \left(m_{\rm DM} / \mathrm{MeV} \right)^{2.5}\,\mathrm{cm^3\,s^{-1}}$. We conclude that analysing isolated targets in the MeV $\gamma$-ray band can set strong bounds on DM properties without multi-year data sets of the entire Milky Way, and encourage follow-up observations of Ret II and other dwarf galaxies.

astro-ph.HE↗

arXiv2021

Comment on: Cosmological black holes are not described by the Thakurta metric

Recently, H\"utsi et al.[arXiv:2105.09328] critiqued our work that reconsidered the mathematical description of cosmological black holes. In this short comment, we highlight some of the conceptual issues with this criticism in relation to the interpretation of the quasi-local Misner-Sharp mass, and the fact that our description of cosmological black holes does not impose any assumptions about matter accretion.

astro-ph.CO↗

arXiv2021

Particle detection and tracking with DNA

We present the first proof-of-concept simulations of detectors using biomaterials to detect particle interactions. The essential idea behind a "DNA detector" involves the attachment of a forest of precisely-sequenced single or double-stranded nucleic acids from a thin holding layer made of a high-density material. Incoming particles break a series of strands along a roughly co-linear chain of interaction sites and the severed segments then fall to a collection area. Since the sequences of base pairs in nucleic acid molecules can be precisely amplified and measured using polymerase chain reaction (PCR), the original spatial position of each broken strand inside the detector can be reconstructed with nm precision. Motivated by the potential use as a low-energy directional particle tracker, we perform the first Monte Carlo simulations of particle interactions inside a DNA detector. We compare the track topology as a function of incoming direction, energy, and particle type for a range of ionising particles. While particle identification and energy reconstruction might be challenging without a significant scale-up, the excellent potential angular and spatial resolution ($\lesssim 25^\circ$ axial resolution for a keV-scale particles and nm-scale track segments) are clear advantages of this concept. We conclude that a DNA detector could be a cost-effective, portable, and powerful new particle detection technology. We outline the outstanding experimental challenges, and suggest directions for future laboratory tests.

physics.ins-det↗

arXiv2020

Optical reconstruction of dust in the region of SNR RX J1713.7-3946 from astrometric data

The origin of the radiation observed in the region of the supernova remnant RX J1713.7-3946, one of the brightest TeV emitters, has been debated since its discovery. The existence of atomic and molecular clouds in this object supports the idea that part of the GeV gamma rays in this region originate from proton-proton collisions. However, the observed column density of protons derived from gas observations cannot explain the whole emission. Yet there could be a fraction of protons contained in fainter structures that have note been detected so far. Here we search for faint objects in the line of sight of RX J1713.7-3946 using the principle of light extinction and the ESA/Gaia DR2 astrometric and photometric data. We reveal and locate with precision a number of dust clouds and note that only one appears to be in the vicinity of RX J1713.7-3946. We estimate the embedded mass to $M_{dust} = (7.0 \pm 0.6) \times 10^3 \, M_{\odot}$ which might be big enough to contain the missing protons. Finally, using the fact that the supernova remnant is expected to be located in a dusty environment and that there appears to be only one such structure in the vicinity of RX J1713.7-3946, we set a very precise constrain to the supernova remnant distance, at ($1.12 \pm 0.01$) kpc.

astro-ph.HE↗

arXiv2020

The full Boltzmann hierarchy for dark matter-massive neutrino interactions

The impact of dark matter-neutrino interactions on the measurement of the cosmological parameters has been investigated in the past in the context of massless neutrinos exclusively. Here we revisit the role of a neutrino-dark matter coupling in light of ongoing cosmological tensions by implementing the full Boltzmann hierarchy for three massive neutrinos. Our tightest 95% CL upper limit on the strength of the interactions, parameterized via $u_\chi =\frac{\sigma_0}{\sigma_{Th}}\left(\frac{m_\chi}{100 \text{GeV}}\right)^{-1}$, is $u_\chi\leq3.34 \cdot 10^{-4}$, arising from a combination of Planck TTTEEE data, Planck lensing data and SDSS BAO data. This upper bound is, as expected, slightly higher than previous results for interacting massless neutrinos, due to the correction factor associated with neutrino masses. We find that these interactions significantly relax the lower bounds on the value of $\sigma_8$ that is inferred in the context of $\Lambda$CDM from the Planck data, leading to agreement within 1-2$\sigma$ with weak lensing estimates of $\sigma_8$, as those from KiDS-1000. However, the presence of these interactions barely affects the value of the Hubble constant $H_0$.

astro-ph.CO↗