@inproceedings{17328,
abstract = {We study selfish mining attacks in longest-chain blockchains like Bitcoin, but where the proof of work is replaced with efficient proof systems - like proofs of stake or proofs of space - and consider the problem of computing an optimal selfish mining attack which maximizes expected relative revenue of the adversary, thus minimizing the chain quality. To this end, we propose a novel selfish mining attack that aims to maximize this objective and formally model the attack as a Markov decision process (MDP). We then present a formal analysis procedure which computes an ϵ-tight lower bound on the optimal expected relative revenue in the MDP and a strategy that achieves this ϵ-tight lower bound, where ϵ > 0 may be any specified precision. Our analysis is fully automated and provides formal guarantees on the correctness. We evaluate our selfish mining attack and observe that it achieves superior expected relative revenue compared to two considered baselines.
In concurrent work [Sarenche FC'24] does an automated analysis on selfish mining in predictable longest-chain blockchains based on efficient proof systems. Predictable means the randomness for the challenges is fixed for many blocks (as used e.g., in Ouroboros), while we consider unpredictable (Bitcoin-like) chains where the challenge is derived from the previous block.},
author = {Chatterjee, Krishnendu and Ebrahimzadeh, Amirali and Karrabi, Mehrdad and Pietrzak, Krzysztof Z and Yeo, Michelle X and Zikelic, Dorde},
booktitle = {Proceedings of the 43rd Annual ACM Symposium on Principles of Distributed Computing},
isbn = {9798400706684},
location = {Nantes, France},
pages = {268--278},
publisher = {Association for Computing Machinery},
title = {{Fully automated selfish mining analysis in efficient proof systems blockchains}},
doi = {10.1145/3662158.3662769},
year = {2024},
}
@article{18530,
abstract = {We explore the notion of history-determinism in the context of timed automata (TA) over infinite timed words. History-deterministic (HD) automata are those in which nondeterminism can be resolved on the fly, based on the run constructed thus far. History-determinism is a robust property that admits different game-based characterisations, and HD specifications allow for game-based verification without an expensive determinization step. We show that the class of timed ω
-languages recognized by HD timed automata strictly extends that of deterministic ones, and is strictly included in those recognised by fully non-deterministic TA. For non-deterministic timed automata it is known that universality is already undecidable for safety/reachability TA. For history-deterministic TA with arbitrary parity acceptance, we show that timed universality, inclusion, and synthesis all remain decidable and are EXPTIME-complete. For the subclass of TA with safety or reachability acceptance, one can decide (in EXPTIME) whether such an automaton is history-deterministic. If so, it can effectively determinized without introducing new automaton states.},
author = {Bose, Sougata and Henzinger, Thomas A and Lehtinen, Karoliina and Schewe, Sven and Totzke, Patrick},
issn = {1860-5974},
journal = {Logical Methods in Computer Science},
number = {4},
pages = {1--28},
publisher = {EPI Sciences},
title = {{History-deterministic timed automata}},
doi = {10.46298/lmcs-20(4:1)2024},
volume = {20},
year = {2024},
}
@phdthesis{18667,
abstract = {Many chemical and physical properties of materials are determined by the material’s shape,
for example the size of its pores and the width of its tunnels. This makes materials science
a prime application area for geometrical and topological methods. Nevertheless many
methods in topological data analysis have not been satisfyingly extended to the needs of
materials science. This thesis provides new methods and new mathematical theorems
targeted at those specific needs by answering four different research questions. While the
motivation for each of the research questions arises from materials science, the methods
are versatile and can be applied in different areas as well.
The first research question is concerned with image data, for example a three-dimensional
computed tomography (CT) scan of a material, like sand or stone. There are two commonly
used topologies for digital images and depending on the application either of them might be
required. However, software for computing the topological data analysis method persistence
homology, usually supports only one of the two topologies. We answer the question how to
compute persistent homology of an image with respect to one of the two topologies using
software that is intended for the other topology.
The second research question is concerned with image data as well, and asks how much
of the topological information of an image is lost when the resolution is coarsened. As
computer tomography scanners are more expensive the higher the resolution, it is an
important question in materials science to know which resolution is enough to get satisfying
persistent homology. We give theoretical bounds on the information loss based on different
geometrical properties of the object to be scanned. In addition, we conduct experiments on
sand and stone CT image data.
The third research question is motivated by comparing crystalline materials efficiently. As
the atoms within a crystal repeat periodically, crystalline materials are either modeled by
unmanageable infinite periodic point sets, or by one of their fundamental domains, which is
unstable under perturbation. Therefore a fingerprint of crystalline materials is needed, with
appropriate properties such that comparing the crystals can be eased by comparing the
fingerprints instead. We define the density fingerprint and prove the necessary properties.
The fourth research question is motivated by studying the hole-structure or connectedness,
i.e. persistent homology or merge trees, of crystalline materials. A common way to deal
with periodicity is to take a fundamental domain and identify opposite boundaries to form a
torus. However, computing persistent homology or merge trees on that torus loses some
of the information materials scientists are interested in and is additionally not stable under
certain noise. We therefore decorate the merge tree stemming from the torus with additional
information describing the density and growth rate of the periodic copies of a component
within a growing spherical window. We prove all desired properties, like stability and efficient
computability.},
author = {Heiss, Teresa},
isbn = {978-3-99078-052-7},
issn = {2663-337X},
keywords = {persistent homology, topological data analysis, periodic, crystalline materials, images, fingerprint},
pages = {111},
publisher = {Institute of Science and Technology Austria},
title = {{New methods for applying topological data analysis to materials science}},
doi = {10.15479/at:ista:18667},
year = {2024},
}
@article{15119,
abstract = {In this paper we consider an SPDE where the leading term is a second order operator with periodic boundary conditions, coefficients which are measurable in (t,ω) , and Hölder continuous in space. Assuming stochastic parabolicity conditions, we prove Lp((0,T)×Ω,tκdt;Hσ,q(Td)) -estimates. The main novelty is that we do not require p=q . Moreover, we allow arbitrary σ∈R and weights in time. Such mixed regularity estimates play a crucial role in applications to nonlinear SPDEs which is clear from our previous work. To prove our main results we develop a general perturbation theory for SPDEs. Moreover, we prove a new result on pointwise multiplication in spaces with fractional smoothness.},
author = {Agresti, Antonio and Veraar, Mark},
issn = {0246-0203},
journal = {Annales de l'Institut Henri Poincaré, Probabilités et Statistiques},
number = {1},
pages = {413--430},
publisher = {Institute of Mathematical Statistics},
title = {{Stochastic maximal Lp(Lq)-regularity for second order systems with periodic boundary conditions}},
doi = {10.1214/22-AIHP1333},
volume = {60},
year = {2024},
}
@article{18492,
abstract = {Surveys in the Milky Way and Large Magellanic Cloud have revealed that the majority of massive stars will interact with companions during their lives. However, knowledge of the binary properties of massive stars at low metallicity, and therefore in conditions approaching those of the Early Universe, remain sparse. We present the Binarity at LOw Metallicity (BLOeM) campaign, an ESO large programme designed to obtain 25 epochs of spectroscopy for 929 massive stars in the Small Magellanic Cloud, allowing us to probe multiplicity in the lowest-metallicity conditions to date (Z = 0.2 Z⊙). BLOeM will provide (i) the binary fraction, (ii) the orbital configurations of systems with periods of P ≲ 3 yr, (iii) dormant black-hole binary candidates (OB+BH), and (iv) a legacy database of physical parameters of massive stars at low metallicity. Main sequence (OB-type) and evolved (OBAF-type) massive stars are observed with the LR02 setup of the GIRAFFE instrument of the Very Large Telescope (3960–4570 Å resolving power R = 6200; typical signal-to-noise ratio(S/N) ≈70–100). This paper utilises the first nine epochs obtained over a three-month time period. We describe the survey and data reduction, perform a spectral classification of the stacked spectra, and construct a Hertzsprung-Russell diagram of the sample via spectral-type and photometric calibrations. Our detailed classification reveals that the sample covers spectral types from O4 to F5, spanning the effective temperature and luminosity ranges 6.5 ≲ Teff/kK ≲ 45 and 3.7 < log L/L⊙ < 6.1 and initial masses of 8 ≲ Mini ≲ 80 M⊙. The sample comprises 159 O-type stars, 331 early B-type (B0–3) dwarfs and giants (luminosity classes V–III), 303 early B-type supergiants (II–I), and 136 late-type BAF supergiants. At least 82 stars are OBe stars: 20 O-type and 62 B-type (13% and 11% of the respective samples). In addition, the sample includes 4 high-mass X-ray binaries, 3 stars resembling luminous blue variables, 2 bloated stripped-star candidates, 2 candidate magnetic stars, and 74 eclipsing binaries.},
author = {Shenar, T. and Bodensteiner, J. and Sana, H. and Crowther, P. A. and Lennon, D. J. and Abdul-Masih, M. and Almeida, L. A. and Backs, F. and Berlanas, S. R. and Bernini-Peron, M. and Bestenlehner, J. M. and Bowman, D. M. and Bronner, V. A. and Britavskiy, N. and De Koter, A. and De Mink, S. E. and Deshmukh, K. and Evans, C. J. and Fabry, M. and Gieles, M. and Gilkis, A. and González-Torà, G. and Gräfener, G. and Götberg, Ylva Louise Linsdotter and Hawcroft, C. and Hénault-Brunet, V. and Herrero, A. and Holgado, G. and Janssens, S. and Johnston, C. and Josiek, J. and Justham, S. and Kalari, V. M. and Katabi, Z. Z. and Keszthelyi, Z. and Klencki, J. and Kubát, J. and Kubátová, B. and Langer, N. and Lefever, R. R. and Ludwig, B. and Mackey, J. and Mahy, L. and Maíz Apellániz, J. and Mandel, I. and Maravelias, G. and Marchant, P. and Menon, A. and Najarro, F. and Oskinova, L. M. and O'Grady, A. J.G. and Ovadia, R. and Patrick, L. R. and Pauli, D. and Pawlak, M. and Ramachandran, V. and Renzo, M. and Rocha, D. F. and Sander, A. A.C. and Sayada, T. and Schneider, F. R.N. and Schootemeijer, A. and Schösser, E. C. and Schürmann, C. and Sen, K. and Shahaf, S. and Simón-Díaz, S. and Stoop, M. and Toonen, S. and Tramper, F. and Van Loon, J. Th and Valli, R. and Van Son, L. A.C. and Vigna-Gómez, A. and Villaseñor, J. I. and Vink, J. S. and Wang, C. and Willcox, R.},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{Binarity at LOw Metallicity (BLOeM): A spectroscopic VLT monitoring survey of massive stars in the SMC}},
doi = {10.1051/0004-6361/202451586},
volume = {690},
year = {2024},
}
@article{18448,
abstract = {Aims. This paper utilises the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) to extend the observational studies of dust and polycyclic aromatic hydrocarbon (PAH) emission to a new mass and star formation rate (SFR) parameter space beyond our local Universe. The combination of fully sampled spectral energy distributions (SEDs) with multiple mid-infrared (mid-IR) bands and the unprecedented sensitivity of MIRI allows us to investigate dust obscuration and PAH behaviour from z = 0.7 up to z = 2 in typical main-sequence galaxies. Our focus is on constraining the evolution of PAH strength and the dust-obscured luminosity fraction before and during cosmic noon, the epoch of peak star formation activity in the Universe.
Methods. In this study, we utilise MIRI multi-band imaging data from the SMILES survey (5 to 25 μm), complemented with NIRCam photometry from the JADES survey (1 to 5 μm), available HST photometry (0.4 to 0.9 μm), and spectroscopic redshifts from the FRESCO and JADES surveys in GOODS-S for 443 star-forming (without dominant active galactic nucleus (AGN)) galaxies at z = 0.7 − 2.0. This redshift range was chosen to ensure that the MIRI data cover mid-IR dust emission. Our methodology involved employing ultraviolet (UV) to IR energy balance SED fitting to robustly constrain the fraction of dust mass in PAHs and dust-obscured luminosity. Additionally, we inferred dust sizes from MIRI 15 μm imaging data, enhancing our understanding of the physical characteristics of dust within these galaxies.
Results. We find a strong correlation between the fraction of dust in PAHs (PAH fraction, qPAH) with stellar mass. Moreover, the sub-sample with robust qPAH measurements (N = 216) shows a similar behaviour between qPAH and gas-phase metallicity to that at z ∼ 0, suggesting a universal relation: qPAH is constant (∼3.4%) above a metallicity of Z ∼ 0.5 Z⊙ and decreases to < 1% at metallicities ≲0.3 Z⊙. This indicates that metallicity is a good indicator of the interstellar medium properties that affect the balance between the formation and destruction of PAHs. The lack of a redshift evolution from z ∼ 0 − 2 also implies that above Z ∼ 0.5 Z⊙ the PAH emission effectively traces obscured luminosity and the previous locally calibrated PAH-SFR calibrations remain applicable in this metallicity regime. We observe a strong correlation between the obscured UV luminosity fraction (ratio of obscured to total luminosity) and stellar mass. Above the stellar mass of M* > 5 × 109 M⊙, on average, more than half of the emitted luminosity is obscured, while there exists a non-negligible population of lower-mass galaxies with > 50% obscured fractions. At a fixed mass, the obscured fraction correlates with SFR surface density. This is a result of higher dust covering fractions in galaxies with more compact star-forming regions. Similarly, galaxies with high IRX (IR to UV luminosity) at a given mass or UV continuum slope (β) tend to have higher ΣSFR and shallower attenuation curves, owing to their higher effective dust optical depths and more compact star-forming regions.},
author = {Shivaei, Irene and Alberts, Stacey and Florian, Michael and Rieke, George and Wuyts, Stijn and Bodansky, Sarah and Bunker, Andrew J. and Cameron, Alex J. and Curti, Mirko and Da'Eugenio, Francesco and Dudzevičiūte, Ugne and Ji, Zhiyuan and Johnson, Benjamin D. and Kramarenko, Ivan and Lyu, Jianwei and Matthee, Jorryt J and Morrison, Jane and Naidu, Rohan and Pérez-González, Pablo G. and Reddy, Naveen and Robertson, Brant and Sun, Yang and Tacchella, Sandro and Whitaker, Katherine and Williams, Christina C. and Willmer, Christopher N.A. and Witstok, Joris and Xiao, Mengyuan and Zhu, Yongda},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{A new census of dust and polycyclic aromatic hydrocarbons at z = 0.7-2 with JWST MIRI}},
doi = {10.1051/0004-6361/202449579},
volume = {690},
year = {2024},
}
@article{17889,
abstract = {The increasingly neutral intergalactic gas at z > 6 impacts the Lyman-α (Lyα) flux observed from galaxies. One luminous galaxy, COLA1, stands out because of its unique double-peaked Lyα line at z = 6.6, unseen in any simulation of reionization. Here, we present JWST/NIRCam wide-field slitless spectroscopy in a 21 arcmin2 field centered on COLA1. We find 141 galaxies spectroscopically selected through the [O III] doublet at 5.35 < z < 6.95, with 40 of these sources showing Hβ. For COLA1, we additionally detect [O III]4363 as well as Hγ. We measure a systemic redshift of z = 6.5917 for COLA1, confirming the classical double-peak nature of the Lyα profile. This implies that it resides in a highly ionized bubble and that it is leaking ionizing photons with a high escape fraction of fesc(LyC) = 20–50%, making it a prime laboratory to study Lyman continuum escape in the Epoch of Reionization. COLA1 shows all the signs of a prolific ionizer with a Lyα escape fraction of 81 ± 5%, Balmer decrement indicating no dust, a steep UV slope (βUV = −3.2 ± 0.4), and a star-formation surface density ≳10× that of typical galaxies at similar redshift. We detect five galaxies in COLA1’s close environment (Δz < 0.02). Exploiting the high spectroscopic completeness inherent to grism surveys, and using mock simulations that fully mimic the selection function, we show that the number of detected companions is very typical for a normal similarly UV-bright (MUV ∼ −21.3) galaxy – that is, the ionized bubble around COLA1 is unlikely to be due to an excessively large over-density. Instead, the measured ionizing properties suggest that COLA1 by itself might be powering the bubble required to explain its double-peaked Lyα profile (Rion ≈ 0.7 pMpc), with only minor contributions from detected neighbors (−19.5 ≲ MUV ≲ −17.5).},
author = {Torralba-Torregrosa, Alberto and Matthee, Jorryt J and Naidu, Rohan P. and Mackenzie, Ruari and Pezzulli, Gabriele and Hutter, Anne and Arnalte-Mur, Pablo and Gurung-López, Siddhartha and Tacchella, Sandro and Oesch, Pascal and Kashino, Daichi and Conroy, Charlie and Sobral, David},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{Anatomy of an ionized bubble: NIRCam grism spectroscopy of the z = 6.6 double-peaked Lyman- α emitter COLA1 and its environment}},
doi = {10.1051/0004-6361/202450318},
volume = {689},
year = {2024},
}
@article{18904,
abstract = {The Planetary Transits and Oscillations of stars mission (PLATO) will allow us to measure surface rotation and monitor photometric activity of tens of thousands of main sequence solar-type and subgiant stars. This paper is the first of a series dedicated to the preparation of the analysis of stellar surface rotation and photospheric activity with the near-future PLATO data. We describe in this work the strategy that will be implemented in the PLATO pipeline to measure stellar surface rotation, photometric activity, and long-term modulations. The algorithms are applied on both noise-free and noisy simulations of solar-type stars, which include activity cycles, latitudinal differential rotation, and spot evolution. PLATO simulated systematics are included in the noisy light curves. We show that surface rotation periods can be recovered with confidence for most of the stars with only six months of observations and that the recovery rate of the analysis significantly improves as additional observations are collected. This means that the first PLATO data release will already provide a substantial set of measurements for this quantity, with a significant refinement on their quality as the instrument obtains longer light curves. Measuring the Schwabe-like magnetic activity cycle during the mission will require that the same field be observed over a significant timescale (more than four years). Nevertheless, PLATO will provide a vast and robust sample of solar-type stars with constraints on the activity-cycle length. Such a sample is lacking from previous missions dedicated to space photometry.},
author = {Breton, S. N. and Lanza, A. F. and Messina, S. and Pagano, I. and Bugnet, Lisa Annabelle and Corsaro, E. and García, R. A. and Mathur, S. and Santos, A. R. G. and Aigrain, S. and Amard, L. and Brun, A. S. and Degott, L. and Noraz, Q. and Palakkatharappil, D. B. and Panetier, E. and Strugarek, A. and Belkacem, K. and Goupil, M.-J and Ouazzani, R. M. and Philidet, J. and Renié, C. and Roth, O.},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{Measuring stellar surface rotation and activity with the PLATO mission. I. Strategy and application to simulated light curves}},
doi = {10.1051/0004-6361/202449893},
volume = {689},
year = {2024},
}
@article{18447,
abstract = {We present the first results on the spatial distribution of star formation in 454 star-forming galaxies just after the epoch of reionisation (4.8 < z < 6.5) using Hα emission-line maps and F444W imaging that traces the stellar continuum from the JWST FRESCO NIRCam Slitless Spectroscopy Survey. The Hα equivalent width profiles of star-forming galaxies across the main sequence at z ∼ 5.3 with stellar masses 6.8≤ log(M*/M⊙) < 11.1 increase with radius, which provides direct evidence for the inside-out growth of star-forming galaxies just after the epoch of reionisation. GALFIT was used to calculate half-light radii, Reff, and central surface densities within 1 kiloparsec, Σ1kpc of Hα and the continuum. At a fixed stellar mass of Log(M*/M⊙) = 9.5, Σ1kpc, Hα is 1.04 ± 0.05 times higher than Σ1kpc, C, Reff, Hα is 1.18 ± 0.03 times larger than Reff, C and both Reff measurements are smaller than 1 kiloparsec. These measurements suggest the rapid build-up of compact bulges via star formation just after the epoch of reionisation. By comparison to analogous work done at lower redshifts with Hubble Space Telescope WFC3 slitless spectroscopy as part of the 3D-HST (z ∼ 1) and CLEAR (z ∼ 0.5) surveys, we find that Reff(z) evolves at the same pace for Hα and the continuum, but Σ1kpc(z) evolves faster for Hα than the stellar continuum. As a function of the Hubble parameter, Reff, Hα/Reff,C = 1.1h(z) and Σ1 kpc, Hα/Σ1 kpc,C = h(z)1.3. These parametrisations suggest that the inside-out growth of the disk starts to dominate the inside-out growth of the bulge towards lower redshifts. This is supported by the redshift evolution in the EW(Hα) profiles from FRESCO, 3D-HST, and CLEAR at fixed stellar mass and when star-forming progenitors are traced, in which in EW(Hα) rapidly increases with radius within the half-light radius at z ∼ 5.3, but EW(Hα) increases only significantly with radius in the outer disk at z ∼ 0.5.},
author = {Matharu, Jasleen and Nelson, Erica J. and Brammer, Gabriel and Oesch, Pascal A. and Allen, Natalie and Shivaei, Irene and Naidu, Rohan P. and Chisholm, John and Covelo-Paz, Alba and Fudamoto, Yoshinobu and Giovinazzo, Emma and Herard-Demanche, Thomas and Kerutt, Josephine and Kramarenko, Ivan and Marchesini, Danilo and Meyer, Romain A. and Prieto-Lyon, Gonzalo and Reddy, Naveen and Shuntov, Marko and Weibel, Andrea and Wuyts, Stijn and Xiao, Mengyuan},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{A first look at spatially resolved star formation at 4.8 < z < 6.5 with JWST FRESCO NIRCam slitless spectroscopy}},
doi = {10.1051/0004-6361/202450522},
volume = {690},
year = {2024},
}
@article{18493,
abstract = {Context. The escape of Lyman-α photons at redshifts greater than two is an ongoing subject of study and an important quantity to further understanding of Lyman-α emitters (LAEs), the transmission of Lyman-α photons through the interstellar medium and intergalactic medium, and the impact these LAEs have on cosmic reionisation.
Aims. This study aims to assess the Lyman-α escape fraction, fesc, Lyα, over the redshift range 2.9 < z < 6.7, focusing on Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT/MUSE) selected, gravitationally lensed, intrinsically faint LAEs. These galaxies are of particular interest as the potential drivers of cosmic reionisation.
Methods. We assessed fesc, Lyα in two ways: through an individual study of 96 LAEs behind the A2744 lensing cluster, with James Webb Space Telescope/Near-Infrared Camera (JWST/NIRCam) and HST data, and through a study of the global evolution of fesc, Lyα using the state-of-the-art luminosity functions for LAEs and the UV-selected ‘parent’ population (dust-corrected). We compared these studies to those in the literature based on brighter samples.
Results. We find a negligible redshift evolution of fesc, Lyα for our individual galaxies; it is likely that it was washed out by significant intrinsic scatter. We observed a more significant evolution towards higher escape fractions with decreasing UV magnitude and fit this relation. When comparing the two luminosity functions to derive fesc, Lyα in a global sense, we saw agreement with previous literature when integrating the luminosity functions to a bright limit. However, when integrating using a faint limit equivalent to the observational limits of our samples, we observed enhanced values of fesc, Lyα, particularly around z ∼ 6, where fesc, Lyα becomes consistent with 100% escape. This indicates for the faint regimes we sampled that galaxies towards reionisation tend to allow very large fractions of Lyman-α photons to escape. We interpret this as evidence of a lack of any significant dust in these populations; our sample is likely dominated by young, highly star-forming chemically unevolved galaxies. Finally, we assessed the contribution of the LAE population to reionisation using our latest values for fesc, Lyα and the LAE luminosity density. The dependence on the escape fraction of Lyman continuum photons is strong, but for values similar to those observed recently in z ∼ 3 LAEs and high-redshift analogues, LAEs could provide all the ionising emissivity necessary for reionisation.},
author = {Goovaerts, I. and Thai, T. T. and Pello, R. and Tuan-Anh, P. and Laporte, N. and Matthee, Jorryt J and Nanayakkara, T. and Pharo, J.},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{Charting the Lyman-α escape fraction in the range 2.9 < z < 6.7 and consequences for the LAE reionisation contribution}},
doi = {10.1051/0004-6361/202451432},
volume = {690},
year = {2024},
}
@article{18528,
abstract = {The recent measurement of magnetic field strength inside the radiative interior of red giant stars has opened the way toward full 3D characterization of the geometry of stable large-scale magnetic fields. However, current measurements, which are limited to dipolar (ℓ = 1) mixed modes, do not properly constrain the topology of magnetic fields due to degeneracies on the observed magnetic field signature on such ℓ = 1 mode frequencies. Efforts focused toward unambiguous detections of magnetic field configurations are now key to better understand angular momentum transport in stars. We investigated the detectability of complex magnetic field topologies (such as the ones observed at the surface of stars with a radiative envelope with spectropolarimetry) inside the radiative interior of red giants. We focused on a field composed of a combination of a dipole and a quadrupole (quadrudipole) and on an offset field. We explored the potential of probing such magnetic field topologies from a combined measurement of magnetic signatures on ℓ = 1 and quadrupolar (ℓ = 2) mixed mode oscillation frequencies. We first derived the asymptotic theoretical formalism for computing the asymmetric signature in the frequency pattern for ℓ = 2 modes due to a quadrudipole magnetic field. To access asymmetry parameters for more complex magnetic field topologies, we numerically performed a grid search over the parameter space to map the degeneracy of the signatures of given topologies. We demonstrate the crucial role played by ℓ = 2 mixed modes in accessing internal magnetic fields with a quadrupolar component. The degeneracy of the quadrudipole compared to pure dipolar fields is lifted when considering magnetic asymmetries in both ℓ = 1 and ℓ = 2 mode frequencies. In addition to the analytical derivation for the quadrudipole, we present the prospect for complex magnetic field inversions using magnetic sensitivity kernels from standard perturbation analysis for forward modeling. Using this method, we explored the detectability of offset magnetic fields from ℓ = 1 and ℓ = 2 frequencies and demonstrate that offset fields may be mistaken for weak and centered magnetic fields, resulting in underestimating the magnetic field strength in stellar cores. We emphasize the need to characterize ℓ = 2 mixed-mode frequencies, (along with the currently characterized ℓ = 1 mixed modes), to unveil the higher-order components of the geometry of buried magnetic fields and to better constrain angular momentum transport inside stars.},
author = {Das, Srijan B and Einramhof, Lukas and Bugnet, Lisa Annabelle},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{Unveiling complex magnetic field configurations in red giant stars}},
doi = {10.1051/0004-6361/202450918},
volume = {690},
year = {2024},
}
@article{15336,
abstract = {Submillimeter surveys toward overdense regions in the early Universe are essential for uncovering the obscured star formation and the cold gas content of assembling galaxies within massive dark matter halos. In this work, we present deep ALMA mosaic observations covering an area of ∼2′×2′ around MUSE Quasar Nebula 01 (MQN01), one of the largest and brightest Ly-α emitting nebulae discovered thus far; it surrounds a radio-quiet quasar at z ≃ 3.25. Our observations target the 1.2 and the 3 mm dust continuum as well as the carbon monoxide CO(4–3) transition in galaxies in the vicinity of the quasar. We identify a robust sample of 11 CO-line-emitting galaxies (including a closely separated quasar companion) that lie within ±4000 km s−1 of the quasar systemic redshift. A fraction of these objects were missed in previous deep rest-frame optical/UV surveys, which highlights the critical role of (sub)millimeter imaging. We also detect a total of 11 sources revealed in the dust continuum at 1.2 mm; six of them have either high-fidelity spectroscopic redshift information from rest-frame UV metal absorptions or the CO(4–3) line that places them in the same narrow redshift range. A comparison of the CO luminosity function and 1.2 mm number count density with those of the general fields points to a galaxy overdensity of δ > 10. We find evidence of a systematic flattening at the bright end of the CO luminosity function with respect to the trend measured in blank fields. Our findings reveal that galaxies in dense regions at z ∼ 3 are more massive and significantly richer in molecular gas than galaxies in fields, which enables a faster and accelerated assembly. This is the first in a series of studies aimed at characterizing one of the densest regions of the Universe found so far at z > 3.},
author = {Pensabene, A. and Cantalupo, S. and Cicone, C. and Decarli, R. and Galbiati, M. and Ginolfi, M. and De Beer, S. and Fossati, M. and Fumagalli, M. and Lazeyras, T. and Pezzulli, G. and Travascio, A. and Wang, W. and Matthee, Jorryt J and Maseda, M. V.},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{ALMA survey of a massive node of the Cosmic Web at z ∼ 3: I. Discovery of a large overdensity of CO emitters}},
doi = {10.1051/0004-6361/202348659},
volume = {684},
year = {2024},
}
@article{18527,
abstract = {Context. Galaxies evolve through a dynamic exchange of material with their immediate surrounding environment, the so-called circumgalactic medium (CGM). Understanding the physics of gas flows and the nature of the CGM is fundamental to studying galaxy evolution, especially at 4 ≤ z ≤ 6 (i.e., after the Epoch of Reionization) when galaxies rapidly assembled their masses and reached their chemical maturity. Galactic outflows are predicted to enrich the CGM with metals, although it has also been suggested that gas stripping in systems undergoing a major merger may play a role.
Aims. In this work, we explore the metal enrichment of the medium around merging galaxies at z ∼ 4.5, observed by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE). To do so, we study the nature of the [CII] 158 μm emission in the CGM around these systems, using simulations to help disentangle the mechanisms contributing to the CGM metal pollution.
Methods. By adopting an updated classification of major merger systems in the ALPINE survey, we selected and analyzed merging galaxies whose components can be spatially and/or spectrally resolved in a robust way. This makes it possible to distinguish between the [CII] emission coming from the single components of the system and that coming from the system as a whole. We also made use of the dustyGadget cosmological simulation to select synthetic analogs of observed galaxies and guide the interpretation of the observational results.
Results. We find a large diffuse [CII] envelope (≳20 kpc) embedding all the merging systems, with at least 25% of the total [CII] emission coming from the medium between the galaxies. Using predictions from dustyGadget, we suggest that this emission has a multi-fold nature, with dynamical interactions between galaxies playing a major role in stripping the gas and enriching the medium with heavy elements.},
author = {Di Cesare, Claudia and Ginolfi, M. and Graziani, L. and Schneider, R. and Romano, M. and Popping, G.},
issn = {1432-0746},
journal = {Astronomy & Astrophysics},
publisher = {EDP Sciences},
title = {{Carbon envelopes around merging galaxies at z ~ 4.5}},
doi = {10.1051/0004-6361/202449164},
volume = {690},
year = {2024},
}
@article{22154,
abstract = {The inertia bound and ratio bound (also known as the Cvetković bound and Hoffman bound) are two fundamental inequalities in spectral graph theory, giving upper bounds on the independence number a(G) of a graph G in terms of spectral information about a weighted adjacency matrix of G. For both inequalities, given a graph G, one needs to make a judicious choice of weighted adjacency matrix to obtain as strong a bound as possible. While there is a well‐established theory surrounding the ratio bound, the inertia bound is much more mysterious, and its limits are rather unclear. In fact, only recently did Sinkovic find the first example of a graph for which the inertia bound is not tight (for any weighted adjacency matrix), answering a longstanding question of Godsil. We show that the inertia bound can be extremely far from tight, and in fact can significantly underperform the ratio bound: for example, one of our results is that for infinitely many n, there is an n‐vertex graph for which even the unweighted ratio bound can prove a(G)<4n^3/4, but the inertia bound is always at least n/4. In particular, these results address questions of Rooney, Sinkovic, and Wocjan–Elphick–Abiad.},
author = {Kwan, Matthew and Wigderson, Yuval},
issn = {1469-2120},
journal = {Bulletin of the London Mathematical Society},
number = {10},
pages = {3196--3208},
publisher = {Wiley},
title = {{The inertia bound is far from tight}},
doi = {10.1112/blms.13127},
volume = {56},
year = {2024},
}
@article{14980,
abstract = {Precision sensing and manipulation of milligram-scale mechanical oscillators has attracted growing interest in the fields of table-top explorations of gravity and tests of quantum mechanics at macroscopic scales. Torsional oscillators present an opportunity in this regard due to their remarked isolation from environmental noise. For torsional motion, an effective employment of optical cavities to enhance optomechanical interactions—as already established for linear oscillators—so far faced certain challenges. Here, we propose a concept for sensing and manipulating torsional motion, where exclusively the torsional rotations of a pendulum are mapped onto the path length of a single two-mirror optical cavity. The concept inherently alleviates many limitations of previous approaches. A proof-of-principle experiment is conducted with a rigidly controlled pendulum to explore the sensing aspects of the concept and to identify practical limitations in a potential state-of-the art setup. Based on this study, we anticipate development of precision torque sensors utilizing torsional pendulums that can support sensitivities below 10−19Nm/√Hz, while the motion of the pendulums are dominated by quantum radiation pressure noise at sub-microwatts of incoming laser power. These developments will provide horizons for experiments at the interface of quantum mechanics and gravity.},
author = {Agafonova, Sofya and Mishra, Umang and Diorico, Fritz R and Hosten, Onur},
issn = {2643-1564},
journal = {Physical Review Research},
number = {1},
publisher = {American Physical Society},
title = {{Zigzag optical cavity for sensing and controlling torsional motion}},
doi = {10.1103/physrevresearch.6.013141},
volume = {6},
year = {2024},
}
@article{14802,
abstract = {Frequency-stable lasers form the back bone of precision measurements in science and technology. Such lasers typically attain their stability through frequency locking to reference cavities. State-of-the-art locking performances to date had been achieved using frequency modulation based methods, complemented with active drift cancellation systems. We demonstrate an all passive, modulation-free laser-cavity locking technique (squash locking) that utilizes changes in spatial beam ellipticity for error signal generation, and a coherent polarization post-selection for noise resilience. By comparing two identically built proof-of-principle systems, we show a frequency locking instability of 5×10−7 relative to the cavity linewidth at 10 s averaging. The results surpass the demonstrated performances of methods engineered over the last five decades, potentially enabling an advancement in the precision control of lasers, while creating avenues for bridging the performance gaps between industrial grade lasers with scientific ones due to the afforded simplicity and scalability.},
author = {Diorico, Fritz R and Zhutov, Artem and Hosten, Onur},
issn = {2334-2536},
journal = {Optica},
keywords = {Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials},
number = {1},
pages = {26--31},
publisher = {Optica Publishing Group},
title = {{Laser-cavity locking utilizing beam ellipticity: accessing the 10−7 instability scale relative to cavity linewidth}},
doi = {10.1364/optica.507451},
volume = {11},
year = {2024},
}
@phdthesis{17225,
abstract = {This thesis describes the development of an atom interferometer designed to exploit the
advantages of utilizing quantum entanglement for enhanced precision measurements beyond
the standard quantum limit. While the project remains ongoing, significant progress has been
made.
A key contribution of this work is the development of Quantrol, an experimental control
system leveraging the ARTIQ framework. This software enables precise timing and control
without requiring prior knowledge of ARTIQ’s implementation details or coding experience.
The interface offers user friendly visual comprehension of the experimental sequence and
extended capabilities, allowing researchers to scan variables with a simple click of a mouse.
The main proposed project is to implement atom interferometric sequence with squeezed input
states inside of a dipole trap generated by a high finesse cavity. The presence of the dipole
trap allows one dimensional atomic cloud split while maintaining relatively strong confinement
in other directions.
We are currently able to trap and cool 87Rb atoms to few micro kelvin temperatures, load
them into the dipole trap and state prepare them to be used for squeezing and interferometric
sequence.},
author = {Li, Vyacheslav},
issn = {2663-337X},
pages = {79},
publisher = {Institute of Science and Technology Austria},
title = {{Towards a quantum entanglement enhanced atom interferomter}},
doi = {10.15479/at:ista:17225},
year = {2024},
}
@article{15169,
abstract = {Interpretation of extracellular recordings can be challenging due to the long range of electric field. This challenge can be mitigated by estimating the current source density (CSD). Here we introduce kCSD-python, an open Python package implementing Kernel Current Source Density (kCSD) method and related tools to facilitate CSD analysis of experimental data and the interpretation of results. We show how to counter the limitations imposed by noise and assumptions in the method itself. kCSD-python allows CSD estimation for an arbitrary distribution of electrodes in 1D, 2D, and 3D, assuming distributions of sources in tissue, a slice, or in a single cell, and includes a range of diagnostic aids. We demonstrate its features in a Jupyter Notebook tutorial which illustrates a typical analytical workflow and main functionalities useful in validating analysis results.},
author = {Chintaluri, Chaitanya and Bejtka, Marta and Sredniawa, Wladyslaw and Czerwinski, Michal and Dzik, Jakub M. and Jedrzejewska-Szmek, Joanna and Wojciki, Daniel K.},
issn = {1553-7358},
journal = {PLoS Computational Biology},
number = {3},
publisher = {Public Library of Science},
title = {{kCSD-python, reliable current source density estimation with quality control}},
doi = {10.1371/journal.pcbi.1011941},
volume = {20},
year = {2024},
}
@inproceedings{17147,
abstract = {Efficient utilization of large-scale biobank data is crucial for inferring the genetic basis of disease and predicting health outcomes from the DNA. Yet we lack efficient, accurate methods that scale to data where electronic health records are linked to whole genome sequence information. To address this issue, our paper develops a new algorithmic paradigm based on Approximate Message Passing (AMP), which is specifically tailored for genomic prediction and association testing. Our method yields comparable out-of-sample prediction accuracy to the state of the art on UK Biobank traits, whilst dramatically improving computational complexity, with a 8x-speed up in the run time. In addition, AMP theory provides a joint association testing framework, which outperforms the currently used REGENIE method, in roughly a third of the compute time. This first, truly large-scale application of the AMP framework lays the foundations for a far wider range of statistical analyses for hundreds of millions of variables measured on millions of people.},
author = {Depope, Al and Mondelli, Marco and Robinson, Matthew Richard},
booktitle = {2024 IEEE International Conference on Acoustics, Speech, and Signal Processing},
isbn = {9798350344851},
issn = {1520-6149},
location = {Seoul, Korea},
pages = {13151--13155},
publisher = {IEEE},
title = {{Inference of genetic effects via approximate message passing}},
doi = {10.1109/ICASSP48485.2024.10447198},
year = {2024},
}
@article{22179,
abstract = {Burr and Erd˝os in 1975 conjectured, and Chv´atal, R¨odl, Szemer´edi and
Trotter later proved, that the Ramsey number of any bounded degree
graph is linear in the number of vertices. In this paper, we disprove
the natural directed analogue of the Burr–Erd˝os conjecture, answering a
question of Buci´c, Letzter, and Sudakov. If H is an acyclic digraph, the
oriented Ramsey number of H, denoted −→r1(H), is the least N such that
every tournament on N vertices contains a copy of H. We show that for
any Δ ≥ 2 and any sufficiently large n, there exists an acyclic digraph H
with n vertices and maximum degree Δ such that
−→r1(H) ≥ nΩ(Δ2/3/ log5/3 Δ).
This proves that −→r1(H) is not always linear in the number of vertices for
bounded-degree H. On the other hand, we show that −→r1(H) is nearly linear
in the number of vertices for typical bounded-degree acyclic digraphs H,
and obtain linear or nearly linear bounds for several natural families of
bounded-degree acyclic digraphs.
For multiple colors, we prove a quasi-polynomial upper bound −→rk(H)=
2(log n)Ok(1) for all bounded-degree acyclic digraphs H on n vertices, where −→rk(H) is the least N such that every k-edge-colored tournament on N
vertices contains a monochromatic copy of H. For k ≥ 2 and n ≥ 4, we
exhibit an acyclic digraph H with n vertices and maximum degree 3 such
that −→rk(H) ≥ nΩ(log n/ log log n), showing that these Ramsey numbers can
grow faster than any polynomial in the number of vertices.},
author = {Fox, Jacob and He, Xiaoyu and Wigderson, Yuval},
issn = {1565-8511},
journal = {Israel Journal of Mathematics},
number = {1},
pages = {1--48},
publisher = {Springer Nature},
title = {{Ramsey numbers of sparse digraphs}},
doi = {10.1007/s11856-024-2624-y},
volume = {263},
year = {2024},
}