A new, much-improved model of the Galactic magnetic field (GMF) is presented. We use theWMAP7 Galactic synchrotron emission map and more than 40,000 extragalactic rotation measures to constrain the parameters of the GMF model, which is substantially generalized compared with earlier work to now include an out-of-plane component (as suggested by observations of external galaxies) and striated-random fields (motivated by theoretical considerations). The new model provides a greatly improved fit to observations. Consistent with our earlier analyses, the best-fit model has a disk field and an extended halo field. Our new analysis reveals the presence of a large, out-of-plane component of the GMF; as a result, the polarized synchrotron emission of our Galaxy seen by an edge-on observer is predicted to look intriguingly similar to what has been observed in external edge-on galaxies. We find evidence that the cosmic-ray electron density is significantly larger than given by GALPROP or else that there is a widespread striated component to the GMF.

We present astrophysical false positive probability calculations for everyKepler Object of Interest (KOI)—the first large-scale demonstration of a fully automated transiting planet validation procedure. Out of 7056 KOIs, we determine that 1935 have probabilities <1% of being astrophysical false positives, and thus may be considered validated planets. Of these, 1284 have not yet been validated or confirmed by other methods. In addition, we identify 428 KOIs that are likely to be false positives, but have not yet been identified as such, though some of these may be a result of unidentified transit timing variations. A side product of these calculations is full stellar property posterior samplings for every host star, modeled as single, binary, and triple systems. These calculations usevespa, a publicly available Python package that is able to be easily applied to any transiting exoplanet candidate.

We present initial results from theWide-field Infrared Survey Explorer (WISE), a four-band all-sky thermal infrared survey that produces data well suited for measuring the physical properties of asteroids, and the NEOWISE enhancement to theWISE mission allowing for detailed study of solar system objects. Using a NEATM thermal model fitting routine, we compute diameters for over 100,000 Main Belt asteroids from their IR thermal flux, with errors better than 10%. We then incorporate literature values of visible measurements (in the form of theH absolute magnitude) to determine albedos. Using these data we investigate the albedo and diameter distributions of the Main Belt. As observed previously, we find a change in the average albedo when comparing the inner, middle, and outer portions of the Main Belt. We also confirm that the albedo distribution of each region is strongly bimodal. We observe groupings of objects with similar albedos in regions of the Main Belt associated with dynamical breakup families. Asteroid families typically show a characteristic albedo for all members, but there are notable exceptions to this. This paper is the first look at the Main Belt asteroids in theWISE data, and only represents the preliminary, observed raw size, and albedo distributions for the populations considered. These distributions are subject to survey biases inherent to the NEOWISE data set and cannot yet be interpreted as describing the true populations; the debiased size and albedo distributions will be the subject of the next paper in this series.

Most star clusters dissolve into the Galaxy over tens to hundreds of millions of years after they form. While recent Gaia studies have honed our view of cluster dispersal, the exact chronology of which star formation events begat which star cluster remnants remains unclear. This problem is acute after 100 Myr, when cluster remnants have spread over hundreds of parsecs and most age estimates for main-sequence stars are too imprecise to link the stars to their birth events. Here we develop a Bayesian framework that combines TESS stellar rotation rates with Gaia kinematics to identify diffuse remnants of open clusters. We apply our method to the Pleiades, which previous studies have noted shows kinematic similarities to other nearby young stellar groups. We find that the Pleiades constitutes the bound core of a much larger, coeval structure that contains multiple known clusters distributed over 600 pc. We refer to this structure as the Greater Pleiades Complex. On the basis of uniform ages, coherent space velocities, detailed elemental abundances, and traceback histories, we conclude that most stars in this complex originated from the same giant molecular cloud. This work establishes a scalable approach for tracing the genealogies of nearby clusters and further cements the Pleiades as a cornerstone of stellar astrophysics. We aim to apply this methodology to other associations as part of the upcoming TESS All-Sky Rotation Survey.

The NEOWISE data set offers the opportunity to study the variations in albedo for asteroid classification schemes based on visible and near-infrared observations for a large sample of minor planets. We have determined the albedos for nearly 1900 asteroids classified by the Tholen, Bus, and Bus–DeMeo taxonomic classification schemes. We find that the S-complex spans a broad range of bright albedos, partially overlapping the low albedo C-complex at small sizes. As expected, the X-complex covers a wide range of albedos. The multiwavelength infrared coverage provided by NEOWISE allows determination of the reflectivity at 3.4 and 4.6 μm relative to the visible albedo. The direct computation of the reflectivity at 3.4 and 4.6 μm enables a new means of comparing the various taxonomic classes. Although C, B, D, and T asteroids all have similarly low visible albedos, the D and T types can be distinguished from the C and B types by examining their relative reflectance at 3.4 and 4.6 μm. All of the albedo distributions are strongly affected by selection biases against small, low albedo objects, as all objects selected for taxonomic classification were chosen according to their visible light brightness. Due to these strong selection biases, we are unable to determine whether or not there are correlations between size, albedo, and space weathering. We argue that the current set of classified asteroids makes any such correlations difficult to verify. A sample of taxonomically classified asteroids drawn without significant albedo bias is needed in order to perform such an analysis.

TheKepler mission has discovered more than 2500 exoplanet candidates in the first two years of spacecraft data, with approximately 40% of those in candidate multi-planet systems. The high rate of multiplicity combined with the low rate of identified false positives indicates that the multiplanet systems contain very few false positive signals due to other systems not gravitationally bound to the target star. False positives in the multi-planet systems are identified and removed, leaving behind a residual population of candidate multi-planet transiting systems expected to have a false positive rate less than 1%. We present a sample of 340 planetary systems that contain 851 planets that are validated to substantially better than the 99% confidence level; the vast majority of these have not been previously verified as planets. We expect ∼two unidentified false positives making our sample of planet very reliable. We present fundamental planetary properties of our sample based on a comprehensive analysis ofKepler light curves, ground-based spectroscopy, and high-resolution imaging. Since we do not require spectroscopy or high-resolution imaging for validation, some of our derived parameters for a planetary system may be systematically incorrect due to dilution from light due to additional stars in the photometric aperture. Nonetheless, our result nearly doubles the number verified exoplanets.

We present revised near-infrared albedo fits of 2835 main-belt asteroids observed byWISE/NEOWISE over the course of its fully cryogenic survey in 2010. These fits are derived from reflected-light near-infrared images taken simultaneously with thermal emission measurements, allowing for more accurate measurements of the near-infrared albedos than is possible for visible albedo measurements. Because our sample requires reflected light measurements, it undersamples small, low-albedo asteroids, as well as those with blue spectral slopes across the wavelengths investigated. We find that the main belt separates into three distinct groups of 6%, 16%, and 40% reflectance at 3.4 μm. Conversely, the 4.6 μm albedo distribution spans the full range of possible values with no clear grouping. Asteroid families show a narrow distribution of 3.4 μm albedos within each family that map to one of the three observed groupings, with the (221) Eos family being the sole family associated with the 16% reflectance 3.4 μm albedo group. We show that near-infrared albedos derived from simultaneous thermal emission and reflected light measurements are important indicators of asteroid taxonomy and can identify interesting targets for spectroscopic follow-up.

T Pyxidis (T Pyx) is the prototypical recurrent nova (RN), with five eruptions from 1890 to 1967 and a mysterious nova shell. We report new observations of the nova shell with theHubble Space Telescope (HST) in the year 2007, which provides a long time baseline to compare withHST images from 1994 and 1995. We find that the knots in the nova shell are expanding with velocities ranging from roughly 500 km s⁻¹ to 715 km s⁻¹, assuming a distance of 3500 pc. The fractional expansion of the knots is constant, which implies no significant deceleration of the knots, which must have been ejected by an eruption close to the year 1866. We see knots that have turned on after 1995; this shows that the knots are powered by shocks from the collision of the “1866” ejecta with fast ejecta from later RN eruptions. We derive that the “1866” ejecta has a total mass of ∼10^−4.5 M_☉, which with the low ejection velocity shows that the “1866” event was an ordinary nova eruption, not an RN eruption. This also implies that the accretion rate before the ordinary nova event must have been low (around the 4 × 10⁻¹¹ M_☉ yr⁻¹ expected for gravitational radiation alone), and that the matter accumulated on the surface of the white dwarf for ∼750,000 years. The current accretion rate (>10⁻⁸ M_☉ yr⁻¹) is ∼1000× higher than expected for a system below the period gap, with the plausible reason being that the “1866” event started a continuing supersoft source that drives the accretion. The accretion rate has been declining since before the 1890 eruption, with the current rate being only 3% of its earlier value. The decline in the observed accretion rate shows that the supersoft source is not self-sustaining; we calculate that the accretion in T Pyx will effectively stop in upcoming decades. With this, T Pyx will enter a state of hibernation lasting for an estimated 2,600,000 years before gravitational radiation brings the system into contact again. Thus, T Pyx has an evolutionary cycle going from an ordinary CV state (lasting 750,000 years), to its current RN state (lasting little longer than a century), to a future hibernation state (lasting 2,600,000 years), and then repeating this cycle.

The 136 yr long optical light curve of OJ 287 is explained by a binary black hole model where the secondary is in a 12 yr orbit around the primary. Impacts of the secondary on the accretion disk of the primary generate a series of optical flares that follow a quasi-Keplerian relativistic mathematical model. The orientation of the binary in space is determined from the behavior of the primary jet. Here, we ask how the jet of the secondary black hole projects onto the sky plane. Assuming that the jet is initially perpendicular to the disk, and that it is ballistic, we follow its evolution after the Lorentz transformation to the observer’s frame. Since the orbital speed of the secondary is of the order of one-tenth of the speed of light, the result is a change in the jet direction by more than a radian during an orbital cycle. We match the theoretical jet line with the recent 12μas resolution RadioAstron map of OJ 287 and determine the only free parameter of the problem, the apparent speed of the jet relative to speed of light. It turns out that the Doppler factor of the jet,δ ∼ 5, is much lower than in the primary jet. Besides following a unique shape of the jet path, the secondary jet is also distinguished by a different spectral shape than in the primary jet. The present result on the spectral shape agrees with the huge optical flare of 2021 November 12, also arising from the secondary jet.

We report the detection of 13 heavy elements (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, and Sr) in the photosphere of LSPM J0207+3331, a ∼3 Gyr old hydrogen-rich white dwarf with an effective temperature comparable to that of the Sun. Upper limits on carbon, obtained through the absence of molecular CH, suggest accretion from a carbon-volatile-depleted source. The accreted parent body exhibits slight deficits of Mg and Si relative to Fe but otherwise bulk Earth-like abundance patterns; a reasonable interpretation is that LSPM J0207+3331 is accreting a massive differentiated rocky body that had a core mass fraction higher than the Earth’s. The high level of pollution indicates that substantial accretion events can still occur even after 3 Gyr of cooling. We also detect weak Caii H & K line core emission, making this only the second known isolated polluted white dwarf to exhibit this phenomenon and suggesting the presence of additional physical processes in or above the upper atmosphere. Our analysis also highlights the critical importance of including heavy elements in the model atmosphere structure calculations for highly polluted hydrogen-rich white dwarfs. Neglecting their contribution significantly impacts the inferred thermodynamic structure, leading to inaccuracies in derived stellar parameters. Finally, we show that the observed 11.6μm infrared excess can be explained by a single silicate dust disk rather than a two-ring disk model.

Some electromagnetically observed ultracompact binaries will be strong gravitational wave sources for space-based detectors like the Laser Interferometer Space Antenna (LISA). These sources have historically been referred to as “verification binaries” under the assumption that they will be exploited to assess mission performance. This paper quantitatively interrogates that scenario by considering targeted analyses of known galactic sources in the context of a full simulation of the galactic gravitational wave foreground. We find that the analysis of the best currently known LISA binaries, even making maximal use of the available information about the sources, is susceptible to ambiguity or biases when not simultaneously fitting to the rest of the galactic population. While galactic binaries discovered electromagnetically in advance of, or during, the LISA survey are highly valuable multimessenger systems, the need for a global treatment of the galactic gravitational wave foreground calls into question whether or not they are the best sources for data characterization.

Star formation in galaxies is regulated by the interplay of a range of processes that shape the multiphase gas in the interstellar and circumgalactic media. Using the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) suite of cosmological simulations, we study the effects of varying feedback and cosmology on the average star formation histories (SFHs) of galaxies atz ∼ 0 across the IllustrisTNG, SIMBA, and ASTRID galaxy formation models. We find that galaxy SFHs in all three models are sensitive to changes in stellar feedback, which affect the efficiency of baryon cycling and the rates at which central black holes grow, whereas the effects of varying active galactic nucleus (AGN) feedback depend on model-specific implementations of black hole seeding, accretion, and feedback. We also find strong interaction terms that couple stellar and AGN feedback, usually by regulating the amount of gas available for the central black hole to accrete. Using a double power law to describe the average SFHs, we derive a general set of equations relating the shape of the SFHs to physical quantities like baryon fraction and black hole mass across all three models. We find that a single set of equations (albeit with different coefficients) can describe the SFHs across all three CAMELS models, with cosmology dominating the SFH at early times, followed by halo accretion, and feedback and baryon cycling at late times. Galaxy SFHs provide a novel, complementary probe to constrain cosmology and feedback, and can connect the observational constraints from current and upcoming galaxy surveys with the physical mechanisms responsible for regulating galaxy growth and quenching.

The development and implementation of self-consistent spectrotemporal models of X-ray reverberation off of the inner accretion disk have produced several recent X-ray-reverberation-based black hole (BH) mass measurements. We analyze the 2016 simultaneous NuSTAR + Swift observation of the Seyfert 1.5 galaxy 4U 1344−60, presenting the first temporal evidence of X-ray reverberation from the inner disk in this source by using Gaussian process regression to interpolate over gaps in the light curves. We find no such temporal signature in the 2011 Suzaku data, consistent with a previous analysis of that flux spectrum. By performing a joint spectrotemporal fit to the flux and lag spectra of the 2016 data, we show that the lag spectrum requires a boosted reverberation signal and prefers an enhanced coronal height compared to the flux spectrum. These inconsistencies may point toward a coronal and/or inner disk geometry significantly different than the assumed lamppost and razor-thin ones. The best model description prefers radial gradients in disk density and ionization, yielding a BH mass of, which is comparable to the range of BH mass estimates in the literature (i.e.,). The lack of inner disk reverberation during the 2011 epoch and its emergence during the 2016 epoch may be due to a reduction in the beaming of a vertically extended X-ray corona or the inward migration of the inner disk radius if the disk is “slim” instead of razor-thin.

We present new stellar population models,α-MC, self-consistently taking into account nonsolar [α/Fe] abundances for both isochrones and stellar spectra. Theα-MC models are based onα-enhanced MIST isochrones and C3K spectral libraries, which are publicly available in FSPS. Our new models cover a wide range of ages (), metallicities ([Fe/H] = [−2.5, +0.5] in steps of 0.25, [α/Fe] = −0.2, +0.0, +0.2, +0.4, +0.6), and wavelengths (0.1–2.5μm). We investigate the separate and combined effects ofα-enhanced isochrones and stellar spectral libraries on simple stellar populations, including their broadband colors, spectral indices, and full spectra. We find that the primary effect ofα-enhancement in isochrones is to lower the overall continuum levels and redden the continuum shapes, whileα-enhancement in stellar spectra mainly affects individual spectral lines. At constant [Fe/H],α-enhancement has significant impacts on the broadband colors by ∼0.1–0.4 mag across all ages (0.01–10 Gyr). The effects ofα-enhancement on colors at fixed [Z/H] are smaller, by ∼0.1–0.2 mag. The spectral indices involvingα-elements, Ca4227 and Mgb, increase with [α/Fe] (both at fixed [Fe/H] and fixed [Z/H]) due to enhancedα-abundances. At constant [Fe/H],α-enhancement weakens most Fe-sensitive and hydrogen Balmer lines. Our new self-consistentα-enhanced models will be essential in deriving accurate physical properties of high-redshift galaxies, whereα-enhancement is expected to be common.

Solar flares are explosive releases of magnetic energy stored in the solar corona, driven by magnetic reconnection. These events accelerate electrons, generating hard X-ray emissions, and often display quasi-periodic pulsations (QPPs) across the energy spectra. However, the energy transfer process remains poorly constrained, with competing theories proposing different acceleration mechanisms. We investigate electron acceleration and transport in a flaring coronal loop by solving a time-dependent Fokker–Planck equation. Our model incorporates transient turbulent acceleration, simulating the effects of impulsive energy input to emulate the dynamics of time-dependent reconnection processes. We compute the density-weighted electron flux, a diagnostic directly comparable to observed X-ray emissions, across the energy and spatial domains from the corona to the chromosphere. We investigate different time-dependent functional forms of the turbulent acceleration, finding that the functional form of the acceleration source maintains its signature across energy bands (1–100 keV) with a response time that is energy dependent (with higher-energy bands displaying longer response times). In addition, we find that (a) for a square pulse the switch on and off response time is different; (b) for a sinusoidal input the periodicity is preserved; and (c) for a damped sinusoidal the decay rate increases with density and higher-energy bands lose energy faster. This work presents a novel methodology for analyzing electron acceleration and transport in flares driven by time-dependent sources.

The Astropy Project supports and fosters the development of open-source and openly developedPython packages that provide commonly needed functionality to the astronomical community. A key element of the Astropy Project is the core packageastropy, which serves as the foundation for more specialized projects and packages. In this article, we summarize key features in the core package as of the recent major release, version 5.0, and provide major updates on the Project. We then discuss supporting a broader ecosystem of interoperable packages, including connections with several astronomical observatories and missions. We also revisit the future outlook of the Astropy Project and the current status of Learn Astropy. We conclude by raising and discussing the current and future challenges facing the Project.

We report measurements of the mass density, Ω_M, and cosmological-constant energy density, Ω_Λ, of the universe based on the analysis of 42 type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fitted jointly with a set of supernovae from the Calán/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. All supernova peak magnitudes are standardized using a SN Ia light-curve width-luminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation 0.8Ω_M-0.6Ω_Λ≈-0.2±0.1 in the region of interest (Ω_M≲1.5). For a flat (Ω_M+Ω_Λ=1) cosmology we find Ω_M^flat=0.28^+0.09_-0.08 (1 σ statistical)^+0.05_-0.04 (identified systematics). The data are strongly inconsistent with a Λ=0 flat cosmology, the simplest inflationary universe model. An open, Λ=0 cosmology also does not fit the data well: the data indicate that the cosmological constant is nonzero and positive, with a confidence ofP(Λ>0)=99%, including the identified systematic uncertainties. The best-fit age of the universe relative to the Hubble time ist₀^flat=14.9^+1.4_-1.1(0.63/h) Gyr for a flat cosmology. The size of our sample allows us to perform a variety of statistical tests to check for possible systematic errors and biases. We find no significant differences in either the host reddening distribution or Malmquist bias between the low-redshift Calán/Tololo sample and our high-redshift sample. Excluding those few supernovae that are outliers in color excess or fit residual does not significantly change the results. The conclusions are also robust whether or not a width-luminosity relation is used to standardize the supernova peak magnitudes. We discuss and constrain, where possible, hypothetical alternatives to a cosmological constant.

We present measurements of dust reddening using the colors of stars with spectra in the Sloan Digital Sky Survey. We measure reddening as the difference between the measured and predicted colors of a star, as derived from stellar parameters from the Sloan Extension for Galactic Understanding and Exploration Stellar Parameter Pipeline. We achieve uncertainties of 56, 34, 25, and 29 mmag in the colorsu −g,g −r,r −i, andi −z, per star, though the uncertainty varies depending on the stellar type and the magnitude of the star. The spectrum-based reddening measurements confirm our earlier “blue tip” reddening measurements, finding reddening coefficients different by −3%, 1%, 1%, and 2% inu −g,g −r,r −i, andi −z from those found by the blue tip method, after removing a 4% normalization difference. These results prefer anR_V = 3.1 Fitzpatrick reddening law to O'Donnell or Cardelli et al. reddening laws. We provide a table of conversion coefficients from the Schlegel et al. (SFD) maps ofE(B −V) to extinction in 88 bandpasses for four values ofR_V, using this reddening law and the 14% recalibration of SFD first reported by Schlafly et al. and confirmed in this work.

We present cosmological parameter measurements from the Deep Lens Survey (DLS) using galaxy–mass and galaxy–galaxy power spectra in the multipole rangeℓ = 250–2000. We measure galaxy–galaxy power spectra from two lens bins centered atz ∼ 0.27 and 0.54 and galaxy–mass power spectra by cross-correlating the positions of galaxies in these two lens bins with galaxy shapes in two source bins centered atz ∼ 0.64 and 1.1. We marginalize over a baryonic feedback process using a single-parameter representation and a sum of neutrino masses, as well as photometric redshift and shear calibration systematic uncertainties. For a flat ΛCDM cosmology, we determine, in good agreement with our previous DLS cosmic shear and thePlanck cosmic microwave background (CMB) measurements. Without the baryonic feedback marginalization,S₈ decreases by because the dark-matter-only power spectrum lacks the suppression at the highestℓ values owing to active galactic nucleus (AGN) feedback. Together with thePlanck CMB measurements, we constrain the baryonic feedback parameter to, which suggests an interesting possibility that the actual AGN feedback might be stronger than the recipe used in the OverWhelmingly Large cosmological hydrodynamical Simulations. The interpretation is limited by the validity of the baryonic feedback simulation and the one-parameter representation of the effect.

We present a full-sky 100 μm map that is a reprocessed composite of theCOBE/DIRBE andIRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from theIRAS scan pattern. Using the DIRBE 100 and 240 μm data, we have constructed a map of the dust temperature so that the 100 μm map may be converted to a map proportional to dust column density. The dust temperature varies from 17 to 21 K, which is modest but does modify the estimate of the dust column by a factor of 5. The result of these manipulations is a map with DIRBE quality calibration andIRAS resolution. A wealth of filamentary detail is apparent on many different scales at all Galactic latitudes. In high-latitude regions, the dust map correlates well with maps of H I emission, but deviations are coherent in the sky and are especially conspicuous in regions of saturation of H I emission toward denser clouds and of formation of H₂ in molecular clouds. In contrast, high-velocity H I clouds are deficient in dust emission, as expected.

To generate the full-sky dust maps, we must first remove zodiacal light contamination, as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 μm DIRBE map against the Leiden-Dwingeloo map of H I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 μm flux. This procedure removes virtually all traces of the zodiacal foreground. For the 100 μm map no significant CIB is detected. At longer wavelengths, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 ± 13 nW m^-2 sr^-1 at 140 μm and of 17 ± 4 nW m^-2 sr^-1 at 240 μm (95% confidence). This integrated flux ~2 times that extrapolated from optical galaxies in the Hubble Deep Field.

The primary use of these maps is likely to be as a new estimator of Galactic extinction. To calibrate our maps, we assume a standard reddening law and use the colors of elliptical galaxies to measure the reddening per unit flux density of 100 μm emission. We find consistent calibration using theB-R color distribution of a sample of the 106 brightest cluster ellipticals, as well as a sample of 384 ellipticals withB-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsicB-V versus Mg₂ index to tighten the power of the test greatly. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates cosmic microwave background radiation experiments and for estimating soft X-ray absorption. We describe how to access our maps readily for general use.

HEALPix—the Hierarchical Equal Area isoLatitude Pixelization—is a versatile structure for the pixelization of data on the sphere. An associated library of computational algorithms and visualization software supports fast scientific applications executable directly on discretized spherical maps generated from very large volumes of astronomical data. Originally developed to address the data processing and analysis needs of the present generation of cosmic microwave background experiments (e.g., BOOMERANG,WMAP), HEALPix can be expanded to meet many of the profound challenges that will arise in confrontation with the observational output of future missions and experiments, including, e.g.,Planck,Herschel,SAFIR, and the Beyond Einstein inflation probe. In this paper we consider the requirements and implementation constraints on a framework that simultaneously enables an efficient discretization with associated hierarchical indexation and fast analysis/synthesis of functions defined on the sphere. We demonstrate how these are explicitly satisfied by HEALPix.

We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves of 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift fromz = 0.001 to 2.26. This work features an increased sample size from the addition of multiple cross-calibrated photometric systems of SNe covering an increased redshift span, and improved treatments of systematic uncertainties in comparison to the original Pantheon analysis, which together result in a factor of 2 improvement in cosmological constraining power. For a flat ΛCDM model, we find Ω_M = 0.334 ± 0.018 from SNe Ia alone. For a flatw₀CDM model, we measurew₀ = −0.90 ± 0.14 from SNe Ia alone,H₀ = 73.5 ± 1.1 km s⁻¹ Mpc⁻¹ when including the Cepheid host distances and covariance (SH0ES), andw₀ = when combining the SN likelihood with Planck constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); bothw₀ values are consistent with a cosmological constant. We also present the most precise measurements to date on the evolution of dark energy in a flatw₀w_aCDM universe, and measurew_a = from Pantheon+ SNe Ia alone,H₀ = 73.3 ± 1.1 km s⁻¹ Mpc⁻¹ when including SH0ES Cepheid distances, andw_a = when combining Pantheon+ SNe Ia with CMB and BAO data. Finally, we find that systematic uncertainties in the use of SNe Ia along the distance ladder comprise less than one-third of the total uncertainty in the measurement ofH₀ and cannot explain the present “Hubble tension” between local measurements and early universe predictions from the cosmological model.

This is the first of a series of papers presenting the Modules for Experiments in Stellar Astrophysics (MESA) Isochrones and Stellar Tracks (MIST) project, a new comprehensive set of stellar evolutionary tracks and isochrones computed using MESA, a state-of-the-art open-source 1D stellar evolution package. In this work, we present models with solar-scaled abundance ratios covering a wide range of ages (), masses (), and metallicities (). The models are self-consistently and continuously evolved from the pre-main sequence (PMS) to the end of hydrogen burning, the white dwarf cooling sequence, or the end of carbon burning, depending on the initial mass. We also provide a grid of models evolved from the PMS to the end of core helium burning for. We showcase extensive comparisons with observational constraints as well as with some of the most widely used existing models in the literature. The evolutionary tracks and isochrones can be downloaded from the project website athttp://waps.cfa.harvard.edu/MIST/.

We present the large-scale correlation function measured from a spectroscopic sample of 46,748 luminous red galaxies from the Sloan Digital Sky Survey. The survey region covers 0.72h^-3 Gpc³ over 3816 deg² and 0.16 <z < 0.47, making it the best sample yet for the study of large-scale structure. We find a well-detected peak in the correlation function at 100h^-1 Mpc separation that is an excellent match to the predicted shape and location of the imprint of the recombination-epoch acoustic oscillations on the low-redshift clustering of matter. This detection demonstrates the linear growth of structure by gravitational instability betweenz ≈ 1000 and the present and confirms a firm prediction of the standard cosmological theory. The acoustic peak provides a standard ruler by which we can measure the ratio of the distances toz = 0.35 andz = 1089 to 4% fractional accuracy and the absolute distance toz = 0.35 to 5% accuracy. From the overall shape of the correlation function, we measure the matter density Ω_mh² to 8% and find agreement with the value from cosmic microwave background (CMB) anisotropies. Independent of the constraints provided by the CMB acoustic scale, we find Ω_m = 0.273 ± 0.025 + 0.123(1 +w₀) + 0.137Ω_K. Including the CMB acoustic scale, we find that the spatial curvature is Ω_K = -0.010 ± 0.009 if the dark energy is a cosmological constant. More generally, our results provide a measurement of cosmological distance, and hence an argument for dark energy, based on a geometric method with the same simple physics as the microwave background anisotropies. The standard cosmological model convincingly passes these new and robust tests of its fundamental properties.

We present optical light curves, redshifts, and classifications for spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. We detail improvements to the PS1 SN photometry, astrometry, and calibration that reduce the systematic uncertainties in the PS1 SN Ia distances. We combine the subset of PS1 SNe Ia (0.03 < z < 0.68) with useful distance estimates of SNe Ia from the Sloan Digital Sky Survey (SDSS), SNLS, and various low-z andHubble Space Telescope samples to form the largest combined sample of SNe Ia, consisting of a total of SNe Ia in the range of 0.01 < z < 2.3, which we call the “Pantheon Sample.” When combiningPlanck 2015 cosmic microwave background (CMB) measurements with the Pantheon SN sample, we find and for thewCDM model. When the SN and CMB constraints are combined with constraints from BAO and localH₀ measurements, the analysis yields the most precise measurement of dark energy to date: and for theCDM model. Tension with a cosmological constant previously seen in an analysis of PS1 and low-z SNe has diminished after an increase of 2× in the statistics of the PS1 sample, improved calibration and photometry, and stricter light-curve quality cuts. We find that the systematic uncertainties in our measurements of dark energy are almost as large as the statistical uncertainties, primarily due to limitations of modeling the low-redshift sample. This must be addressed for future progress in using SNe Ia to measure dark energy.