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Low-mass stars appear to frequently host planetary systems. When these rocky planets develop high eccentricities as a result of secular torques or dynamical scatterings, they occasionally pass close to the host star. In these close passages, planets can be tidally disrupted, and sheared into bound and unbound debris tails. To suffer such a disruption the stellar density must by higher than the planetary density. This condition is met for the most common star and planet systems, M-dwarf stars hosting rocky planets. We describe the dynamics of a tidal disruption, and estimate the typical velocities of unbound ejecta. We simulate the gas dynamics of a planetary tidal disruption, and show that disruptions preserve the layered structure of a rocky body, with the outermost layers flung into interstellar space with the highest velocities. We compare these properties to that of the candidate interstellar meteoroid CNEOS-2014-01-08 (IM1). IM1's approximately 60~km~s$^{-1}$ excess speed relative to the local standard of rest is naturally reproduced by the unbound debris of the disruption of an Earth-like planet around an M-dwarf star. We suggest that such an encounter might explain the interstellar kinematics of IM1, and its unusual composition, especially if it originated in the fastest-expelled crust of a differentiated rocky planet. Finally, we estimate that the disruption of $\sim 10M_\oplus$ reservoirs of rocky planets per M-dwarf are needed to reproduce the inferred rate of IM1-like objects., Comment: Author's revised version, accepted for publication in A & A

We predict the X-ray background (XRB) expected from the population of quasars detected by the JWST spectroscopic surveys over the redshift range $z \sim 4-7$. We find that the measured UV emissivities, in combination with a best-fitting quasar SED template, imply a $\sim 10$ times higher unresolved X-ray background than constrained by current experiments. We illustrate the difficulty of simultaneously matching the faint-end of the quasar luminosity function and the X-ray background constraints. We discuss possible origins and consequences of this discrepancy., Comment: 6 pages, 4 figures; minor typos corrected, references updated. Matches version published in ApJL

We describe enhancements to the digest2 software, a short-arc orbit classifier for heliocentric orbits. Digest2 is primarily used by the Near-Earth Object (NEO) community to flag newly discovered objects for a immediate follow-up and has been a part of NEO discovery process for more than 15 years. We have updated the solar system population model used to weight the digest2 score according to the 2023 catalog of known solar system orbits and extended the list of mean uncertainties for 140 observatory codes. Moreover, we have added Astrometry Data Exchange Standard (ADES) input format support to digest2, which provides additional information for the astrometry, such as positional uncertainties for each detection. The digest2 code was also extended to read the roving observer astrometric format as well as the ability to compute a new parameter from the provided astrometric uncertainties ($RMS'$) that can serve as an indicator of in-tracklet curvature when compared with tracklet's great-circle fit RMS. Comparison with the previous version of digest2 confirmed the improvement in accuracy of NEO identification and found that using ADES XML input significantly reduces the computation time of the digest2., Comment: 14 pages, 8 tables, 6 figures, appendix

A recent study found dynamical evidence of a supermassive black hole of $\sim 3 \times 10^{6} \, \rm M_\odot$ at the center of Leo I, the most distant dwarf spheroidal galaxy of the Milky Way. This black hole, comparable in mass to the Milky Way's Sgr A*, places the system $>2$ orders of magnitude above the standard $M_\bullet-M_{\star}$ relation. We investigate the possibility, from a dynamical standpoint, that Leo I's stellar system was originally much more massive and, thus, closer to the relation. Extreme tidal disruption from one or two close passages within the Milky Way's virial radius could have removed most of its stellar mass. A simple analytical model suggests that the progenitor of Leo I could have experienced a mass loss in the range of $32\% - 57\%$ from a single pericenter passage, depending on the stellar velocity dispersion estimate. This mass loss percentage increases to the range $66\% - 78\%$ if the pericenter occurs at the minimum distance allowed by current orbital reconstructions. Detailed N-body simulations show that the mass loss could reach $\sim 90\%$ with up to two passages, again with pericenter distances compatible with the minimum value allowed by Gaia data. Despite very significant uncertainties in the properties of Leo I, we reproduce its current position and velocity dispersion, as well as the final stellar mass enclosed in $1$ kpc ($\sim 5\times 10^6 \, \rm M_\odot$) within a factor $< 2$. The most recent tidal stream is directed along our line of sight toward Leo I, making it difficult to detect. Evidence from this extreme tidal disruption event could be present in current Gaia data in the form of extended tidal streams., Comment: Accepted for publication in The Astrophysical Journal Letters. 9 pages, 4 figures. A video of the N-body simulation can be viewed here: https://www.fabiopacucci.com/resources/simulations/

The COVID-19 pandemic's impact on preschool children's school readiness skills remains understudied. This research investigates Head Start preschool children's early numeracy, literacy, and executive function outcomes during a pandemic-affected school year, using a novel virtual assessment methodology. Study children (N = 336; mean age = 51 months; 46% Hispanic; 36% Black Non-Hispanic; 52% female) in a network of Head Start centers in four states (Nevada, New Jersey, Pennsylvania, and Wisconsin) experienced low in-person preschool exposure compared to national pre-pandemic norms. However, study children experienced fall to spring score gains during the pandemic-affected year of 0.05 SD in executive function, 0.27 SD in print knowledge, and 0.45-0.71 SD in early numeracy skills, growth not outside the general range of that observed in pre-pandemic research studies. For two of the three early numeracy domains measured, spring test score outcomes were stronger among children who attended more in-person preschool. We discuss implications for future research and policy.

This study synthesizes existing research on the implementation of tutoring programs which we define as one-to-one or small-group instruction in which a human tutor supports students grades K-12 in an academic subject area. Tutoring has emerged as an especially promising strategy for supporting students' academic success with strong causal evidence finding large, positive effects on students' math and reading test scores across grade levels. Prior studies have reviewed this causal evidence of effects, but none have summarized the evidence on implementation. We iteratively developed search and selection criteria to identify studies addressing key research questions and synthesized these 40 studies which employ a range of research methodologies to describe how tutoring is implemented and experienced. We find that existing research provides rich descriptions of tutoring implementation within specific programs of focus, with most studies describing after-school tutoring and small-scale programs run by university professors. While few elements of implementation are studied in depth across multiple studies, common patterns emerge. Tutoring program launch is often facilitated by strategic relationships between schools and external tutoring providers and strengthened by transparent assessments of program quality and effectiveness. Successful tutoring implementation often hinges on the support of key school leaders with the power to direct the use of school funding, space, and time. Tutoring setting and schedule, tutor recruitment and training, and curriculum identification influence whether students are able to access tutoring services and the quality of the instruction provided. Ultimately, the evidence points to strong tutoring being driven by positive student-tutor relationships through which tutors provide instruction strategically targeted for students' strengths and needs driving towards a long-term academic goal.

We have conducted an extensive towed-magnetic-sled survey during the period 14-28 June, 2023, over the seafloor centered around the calculated path of the bolide CNEOS 2014-01-08 (IM1) about 85 km north of Manus Island, Papua New Guinea. We found about 700 spherules of diameter 0.05-1.3 millimeters in our samples, of which 57 were analyzed so far. The spherules were significantly concentrated along the expected meteor path. Mass spectrometry of 47 spherules near the high-yield regions along IM1's path reveals a distinct extra-solar abundance pattern for 5 of them, while background spherules have abundances consistent with a solar system origin. The unique spherules show an excess of Be, La and U, by up to three orders of magnitude relative to the solar system standard of CI chondrites. These "BeLaU"-type spherules, never seen before, also have very low refractory siderophile elements such as Re. Volatile elements, such as Mn, Zn, Pb, are depleted as expected from evaporation losses during a meteor's airburst. In addition, the mass-dependent variations in $^{57}$Fe/$^{54}$Fe and $^{56}$Fe/$^{54}$Fe are also consistent with evaporative loss of the light isotopes during the spherules' travel in the atmosphere. The "BeLaU" abundance pattern is not found in control regions outside of IM1's path and does not match commonly manufactured alloys or natural meteorites in the solar system. This evidence points towards an association of "BeLaU"-type spherules with IM1, supporting its interstellar origin independently of the high velocity and unusual material strength implied from the CNEOS data. We suggest that the "BeLaU" abundance pattern could have originated from a highly differentiated magma ocean of a planet with an iron core outside the solar system or from more exotic sources., Comment: Submitted for publication in a peer-reviewed journal

We provide an $\Omega(n\log n) $ lower bound and an $O(n^2)$ upper bound for the smallest size of rooted binary trees (a.k.a. phylogenetic tree shapes), which are universal for rooted binary trees with $n$ leaves, i.e., contain all of them as induced binary subtrees. We explicitly compute the smallest universal trees for $n\leq 11$. We also provide an $\Omega(n^2) $ lower bound and an $O(n^4)$ upper bound for the smallest size of tanglegrams, which are universal for size $n$ tanglegrams, i.e., which contain all of them as induced subtanglegrams. Some of our results generalize to rooted $d$-ary trees and to $d$-ary tanglegrams., Comment: 18 pages, 14 figures

We study the recent Physical Review Letter [1] which presents a new mechanism for black hole evaporation through a spatially dependent temperature. This new temperature is comparable to the Hawking result near the black hole, but is very small far away, and therefore could be a small correction. Here we apply the proposed reasoning to the case of de Sitter space, finding that it over predicts the de Sitter temperature of a minimally coupled scalar by factor of $\approx 4.3$ and therefore cannot be ignored in any limit. This indicates an inconsistency in the proposed formalism., Comment: 2 pages, 1 figure, in double column format

We consider a cross-silo federated learning (FL) setting where a machine learning model with a fully connected first layer is trained between different clients and a central server using FedAvg, and where the aggregation step can be performed with secure aggregation (SA). We present SRATTA an attack relying only on aggregated models which, under realistic assumptions, (i) recovers data samples from the different clients, and (ii) groups data samples coming from the same client together. While sample recovery has already been explored in an FL setting, the ability to group samples per client, despite the use of SA, is novel. This poses a significant unforeseen security threat to FL and effectively breaks SA. We show that SRATTA is both theoretically grounded and can be used in practice on realistic models and datasets. We also propose counter-measures, and claim that clients should play an active role to guarantee their privacy during training., Comment: Accepted to ICML2023

We infer the evolution of the UV luminosities of galaxies in haloes of masses $10^{10} - 10^{11} M_{\odot}$ in the redshift range of $z \sim 9-16$ from the recent JWST data. Within the standard $\Lambda$CDM cosmological model, it is found that the average luminosities in this halo mass range show an exponential evolution with redshift, in excess of that expected from astrophysical considerations including the evolution of UV luminosity from Population III galaxies. We find that an enhancement of power on scales $k \sim 1$ Mpc$^{-1}$, as captured by a cosmological transfer function modified from the $\Lambda$CDM form, is able to alleviate this effect and allow for a non-evolving UV luminosity as a function of redshift at $z > 10$, consistently with the corresponding findings for lower redshifts. We discuss the possible astrophysical and cosmological reasons for such an enhancement., Comment: 7 pages, 6 figures; accepted for publication in ApJL

(Abridged) Unidentified Aerial Phenomena (UAP) have resisted explanation and have received little formal scientific attention for 75 years. A primary objective of the Galileo Project is to build an integrated software and instrumentation system designed to conduct a multimodal census of aerial phenomena and to recognize anomalies. Here we present key motivations for the study of UAP and address historical objections to this research. We describe an approach for highlighting outlier events in the high-dimensional parameter space of our census measurements. We provide a detailed roadmap for deciding measurement requirements, as well as a science traceability matrix (STM) for connecting sought-after physical parameters to observables and instrument requirements. We also discuss potential strategies for deciding where to locate instruments for development, testing, and final deployment. Our instrument package is multimodal and multispectral, consisting of (1) wide-field cameras in multiple bands for targeting and tracking of aerial objects and deriving their positions and kinematics using triangulation; (2) narrow-field instruments including cameras for characterizing morphology, spectra, polarimetry, and photometry; (3) passive multistatic arrays of antennas and receivers for radar-derived range and kinematics; (4) radio spectrum analyzers to measure radio and microwave emissions; (5) microphones for sampling acoustic emissions in the infrasonic through ultrasonic frequency bands; and (6) environmental sensors for characterizing ambient conditions (temperature, pressure, humidity, and wind velocity), as well as quasistatic electric and magnetic fields, and energetic particles. The use of multispectral instruments and multiple sensor modalities will help to ensure that artifacts are recognized and that true detections are corroborated and verifiable., Comment: This paper is published in the Journal of Astronomical Instrumentation, 12(1), 2340006 (2023) https://doi.org/10.1142/S2251171723400068

(Abridged) Quantitative three-dimensional (3D) position and velocity estimates obtained by passive radar will assist the Galileo Project in the detection and classification of aerial objects by providing critical measurements of range, location, and kinematics. These parameters will be combined with those derived from the Project{\textquoteright}s suite of electromagnetic sensors and used to separate known aerial objects from those exhibiting anomalous kinematics. SkyWatch, a passive multistatic radar system based on commercial broadcast FM radio transmitters of opportunity, is a network of receivers spaced at geographical scales that enables estimation of the 3D position and velocity time series of objects at altitudes up to 80km, horizontal distances up to 150km, and at velocities to {\textpm}2{\textpm}2km/s ({\textpm}6{\textpm}6Mach). The receivers are designed to collect useful data in a variety of environments varying by terrain, transmitter power, relative transmitter distance, adjacent channel strength, etc. In some cases, the direct signal from the transmitter may be large enough to be used as the reference with which the echoes are correlated. In other cases, the direct signal may be weak or absent, in which case a reference is communicated to the receiver from another network node via the internet for echo correlation. Various techniques are discussed specific to the two modes of operation and a hybrid mode. Delay and Doppler data are sent via internet to a central server where triangulation is used to deduce time series of 3D positions and velocities. A multiple receiver (multistatic) radar experiment is undergoing Phase 1 testing, with several receivers placed at various distances around the Harvard{\textendash}Smithsonian Center for Astrophysics (CfA), to validate full 3D position and velocity recovery., Comment: This paper is published in the Journal of Astronomical Instrumentation, 12(1) (2023) 10.1142/S2251171723400044 The abstract has been updated

The derived graph of a voltage graph consisting of a single vertex and two loops of different voltages is a circulant graph with two generators. We characterize the automorphism groups of connected, two-generator circulant graphs, and give their determining and distinguishing number, and when relevant, their cost of 2-distinguishing. We do the same for the subdivisions of connected, two-generator circulant graphs obtained by replacing one loop in the voltage graph with a directed cycle.

Betelgeuse, the nearest red supergiant, dimmed to an unprecedented level in early 2020. The star emerged from this Great Dimming episode with its typical, roughly 400-day pulsation cycle halved, and a new dominant period of around 200 days. The dimming event has been attributed to a surface mass ejection, in which rising material drove shocks through the stellar atmosphere and expelled some material, partially obscuring the star as it formed molecules and dust. In this paper, we use hydrodynamic simulations to reveal the connections between Betelgeuse's vigorously convective envelope, the surface mass ejection, and the pulsation mode switching that ensued. An anomalously hot convective plume, generated rarely but naturally in the star's turbulent envelope, can rise and break free from the surface, powering an upwelling that becomes the surface mass ejection. The rising plume also breaks the phase coherence of the star's pulsation, causing the surface to keep expanding even as the deeper layers contract. This drives a switch from the 400-day fundamental mode of pulsation, in which the whole star expands and contracts synchronously, to the 200-day first overtone, where a radial node separates the interior and exterior of the envelope moving in opposite phase. We predict that the star's convective motions will damp the overtone oscillation and Betelgeuse will return to its previous, 400-day fundamental mode pulsation in the next 5-10 years. With its resolved surface and unprecedentedly detailed characterization, Betelgeuse opens a window to episodic surface mass ejection in the late-stage evolution of massive stars., Comment: Submitted to AAS Journals, we welcome comments!

Neutron stars are born out of core-collapse supernovae, and they are imparted natal kicks at birth as a consequence of asymmetric ejection of matter and possibly neutrinos. Unless the force resulting from the kicks is exerted exactly at their center, it will also cause the neutron star to rotate. In this paper, we discuss the possibility that neutron stars may receive off-center natal kicks at birth, which imprint a natal rotation. In this scenario, the observed pulsar spin and transverse velocity in the Galaxy are expected to correlate. We develop a model of the natal rotation imparted to neutron stars and constrain it by the observed population of pulsars in our Galaxy. When considering a single-kick position parameter, we find that the location of the off-center kick is $R_{\rm kick}=2.03^{+3.74}_{-1.69}$\,km at $90\%$ confidence, and is robust when considering pulsars with different observed periods, transverse velocities, and ages. Nonetheless, the model encounters challenges in effectively fitting the data, particularly at small transverse velocities, prompting the exploration of alternative models that include more complex physics. Our framework could be used as a guide for core-collapse simulations of massive stars., Comment: 7 pages, 2 figures, 1 table, accepted by ApJ

Recent observations and detections of interstellar objects (ISOs) passing through the solar system have sparked a wave of interest into these objects. Although rare, these ISOs can be captured into bound orbits around the Sun. In this study, we investigate the novel idea of capture of ISOs into near-Earth orbits and find that a steady population of ISOs exists among the current population of Near Earth Objects (NEOs). Using numerical simulations, we find that the capture of ISOs into near-Earth orbits is dominated by Jupiter which is $10^4\times$ more efficient in capturing ISOs compared to Earth. Captured ISOs are more likely to be in orbits with high eccentricities and low inclinations. We also investigate the stability of captured ISOs and find that they are generally unstable and have an average survival life time of $\sim 1$ Myr, consistent with lifetime of NEOs originating from outer asteroid belt, and are ejected from the solar system due to interactions with other planets or the Sun. Our results have important implications for understanding the population of ISOs in the solar system and possible future detection. We find that about one to a few $50-70$ m sized captured ISOs among NEOs would be detectable by LSST over its lifetime. By detecting and studying captured interstellar objects, we can learn about the properties and origins of such objects, and the formation and evolution of exoplanetary systems and even our solar system., Comment: 14 pages. 12 figures. New version with updated analysis. Accepted in MNRAS

The previous decade saw the discovery of the first four known interstellar objects due to advances in astronomical viewing equipment. Future sky surveys with greater sensitivity will allow for more frequent detections of such objects, including increasingly small objects. We consider the capabilities of the Legacy Survey of Space and Time (LSST) of the Vera C. Rubin Observatory to detect interstellar objects of small sizes during its period of operation over the next decade. We use LSST's detection capabilities and simulate populations of interstellar objects in the range of 1-50m in diameter to calculate the expected number of small interstellar objects that will be detected. We use previous detections of interstellar objects to calibrate our object density estimates. We also consider the impact of the population's albedo on detection rates by considering populations with two separate albedo distributions: a constant albedo of 0.06 and an albedo distribution that resembles near earth asteroids. We find that the number of detections increases with the diameter over the range of diameters we consider. We estimate a detection rate of up to a small ISO every two years of LSST's operation with an increase by a factor of ten for future surveys that extend a magnitude deeper., Comment: 17 pages, 7 figures

The first interstellar object observed in our solar system, 1I/`Oumuamua, exhibited several peculiar properties, including extreme elongation and non-gravitational acceleration. Bergner and Seligman (hereafter BS23) proposed that evaporation of trapped H$_2$ created by cosmic rays (CRs) can explain the non-gravitational acceleration. However, their modeling of the thermal structure of 1I/`Oumuamua ignored the crucial cooling effect of evaporating H$_2$. By taking into account the cooling by H$_2$ evaporation, we show that the surface temperature of H$_2$-water ice is a factor of 9 lower than the case without evaporative cooling. As a result, the thermal speed of outgassing H$_2$ is decreased by a factor of 3. Our one-dimensional thermal modeling that takes into account evaporative cooling for two chosen values of thermal conductivity of $\kappa=0.01$ and $0.1$ WK$^{-1}$m$^{-1}$ shows that the water ice volume available for H$_2$ sublimation at $T>30$ K would be reduced by a factor of 9 and 5 compared to the results of BS23, not enabling enough hydrogen to propel 1I/`Oumuamua., Comment: 6 pages, 2 figure; Accepted for publication, Astrophysical Journal Letters

The first meter-scale interstellar meteor (IM1) was detected by US government sensors in 2014, identified as an interstellar object candidate in 2019, and confirmed by the Department of Defense (DoD) in 2022. We use data from a nearby seismometer to localize the fireball to a $\sim 16 \mathrm{\; km^2}$ region within the $\sim 120 \mathrm{\; km^2}$ zone allowed by the precision of the DoD-provided coordinates. The improved localization is of great importance for a forthcoming expedition to retrieve the meteor fragments., Comment: 4 pages, 4 figures; submitted for publication

We use the ASTRID cosmological hydrodynamic simulation to investigate the properties and evolution of triple and quadruple Massive Black Hole (MBH) systems at $z = 2-3$. Only a handful of MBH tuple systems have been detected to date. In ASTRID, we find $4\%$ of the $M_{\rm BH}>10^7\,M_\odot$ are in tuples with $\Delta r_{\rm max} < 200\,{\rm kpc}$. The tuple systems span a range of separations with the majority of the observable AGN systems at $\Delta r \sim 50-100$ kpc. They include some of the most massive BHs (up to $10^{10} \,M_\odot$) but with at least one of the components of $M_{\rm BH} \sim 10^7 \,M_\odot$. Tuples' host galaxies are typically massive with $M_* \sim 10^{10-11} \,M_\odot$. We find that $>10\%$ massive halos with $M_{\rm halo} > 10^{13} M_\odot$ host MBH tuples. Following the subsequent interactions between MBHs in tuples, we found that in $\sim 5\%$ of the triplets all three MBHs merge within a Gyr, and $15\%$ go through one merger. As a by-product of the complex multi-galaxy interaction of these systems, we also find that up to $\sim 5\%$ of tuples lead to runaway MBHs. In ASTRID, virtually all of the ultramassive black holes ($>10^{10} \,M_\odot $) have undergone a triple quasar phase while for BHs with $M_{\rm BH} \sim 10^9 \,M_\odot$ this fraction drops to $50\%$., Comment: 10 pages, 9 figures; comments welcome