General Relativity (GR) intrinsically predicts its own breakdown at the Big Bang singularity. The Borde-Guth-Vilenkin (BGV) theorem rigorously demonstrates that any spacetime with an average expansion rate greater than zero must be geodesically incomplete to the past. To understand this failure, we must deeply analyze the Raychaudhuri equation, which governs the kinematics of geodesic congruences.
The American Astronomical Society (AAS), established in 1899 and based in Washington, DC, is the major organization of professional astronomers in North America. Its membership of about 7,000 individuals also includes physicists, mathematicians, geologists, engineers, and others whose research and educational interests lie within the broad spectrum of subjects comprising contemporary astronomy. The mission of the AAS is to enhance and share humanity's scientific understanding of the universe.
ISSN: 1538-4357
OPEN ACCESS
The Astrophysical Journal is an open access journal devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Publications in ApJ constitute significant new research that is directly relevant to astrophysical applications, whether based on observational results or on theoretical insights or modeling.
Impact factor5.7
-
The following article is Open accessFrom Infinite Dimensions to Black Hole Universes: Refuting the Big Bang Theory
Debjit Adhikari et al 2026 ApJ 1005 13
- Necroplanetology: Simulating the Tidal Disruption of Differentiated Planetary Material Orbiting WD 1145+017
Girish M. Duvvuri et al 2020 ApJ 893 166
View article, Necroplanetology: Simulating the Tidal Disruption of Differentiated Planetary Material Orbiting WD 1145+017PDF, Necroplanetology: Simulating the Tidal Disruption of Differentiated Planetary Material Orbiting WD 1145+017Download ePub, Necroplanetology: Simulating the Tidal Disruption of Differentiated Planetary Material Orbiting WD 1145+017The WD 1145+017 system shows irregular transit features that are consistent with the tidal disruption of differentiated asteroids with bulk densities
and bulk masses . We use the open-source N-body code REBOUND to simulate this disruption with different internal structures: varying the core volume fraction, mantle/core density ratio, and the presence/absence of a thin low-density crust. We allow the rubble pile to partially disrupt and capture lightcurves at a specific point during the disruption at cadences comparable to those from ground-based photometry. As a proof-of-concept we show that varying these structural parameters have observationally distinguishable effects on the transit lightcurve as the asteroid is disrupted and compare the simulation-generated lightcurves to data from Gary et al. With the caveat that our simulations do not model the sublimation in detail or account for its effects on orbital evolution, we find that a low core fraction and low mantle/core density ratio asteroid is most consistent with the stable transit feature present for multiple weeks circa 2016 April (referred to as G6121 in Gary et al. and A1 in Hallakoun et al.). Connecting tidal disruption simulations to photometry suggests characteristics for the interior structure and composition of an exoplanetary body, information that is only possible because we are observing the death of the planetary system in action. All-sky survey missions such as TESS and LSST will be able to detect other systems like WD 1145+017, creating a sample of subjects for a new subfield of planetary science: necroplanetology. - Catalog of Nearby Exoplanets
R. P. Butler et al 2006 ApJ 646 505
We present a catalog of nearby exoplanets. It contains the 172 known low-mass companions with orbits established through radial velocity and transit measurements around stars within 200 pc. We include five previously unpublished exoplanets orbiting the stars HD 11964, HD 66428, HD 99109, HD 107148, and HD 164922. We update orbits for 83 additional exoplanets, including many whose orbits have not been revised since their announcement, and include radial velocity time series from the Lick, Keck, and Anglo-Australian Observatory planet searches. Both these new and previously published velocities are more precise here due to improvements in our data reduction pipeline, which we applied to archival spectra. We present a brief summary of the global properties of the known exoplanets, including their distributions of orbital semimajor axis, minimum mass, and orbital eccentricity.
- The following article is Open accessNo Stream Left Unscathed: The Imprint of a Host Galaxy
Arpit Arora et al 2026 ApJ 1008 91
View article, No Stream Left Unscathed: The Imprint of a Host GalaxyPDF, No Stream Left Unscathed: The Imprint of a Host GalaxyDownload ePub, No Stream Left Unscathed: The Imprint of a Host GalaxyStellar streams from disrupted globular clusters are excellent probes of dark matter (DM) subhalos. Observed Milky Way streams display a remarkable diversity of features: spurs, gaps, kinks, cocoons, and density variations, many attributed to subhalo encounters. But how much of this diversity arises from the host itself? We simulate ∼15,000 globular cluster streams across four Milky Way–mass halos from the FIRE-2 cosmological simulations, evolved in basis-function expansion potentials capturing the evolving disk, halo, and large-scale structure while excluding small-scale perturbers such as DM subhalos and giant molecular clouds. We find that roughly three-quarters of streams develop complex features from the host potential, such as spurs, kinks, and cocoon-like envelopes. Even the smoothest streams exhibit 10%–25% width variation along their track and host overdensities and gaps at scales of ∼2°, squarely in the 1°–5° range predicted for subhalo-induced gaps. Pericentric distance is the primary predictor of stream morphology, with ∼15 kpc separating smooth from disturbed streams and circular orbits beyond ∼20 kpc producing the smoothest streams. Only ∼70 out of ∼15,000 streams are free of detectable wiggles in the track at any scale. Analogs to observed features, such as the GD-1 spur and the ATLAS–Aliqa Uma kink, emerge even without the presence of subhalos. As next-generation surveys (LSST, Euclid, and the Nancy Grace Roman Space Telescope) resolve stream structure across hundreds of streams, the baseline established here, i.e., streams evolved without small-scale perturbers, becomes essential for extracting DM substructure constraints.
- GRAVITATIONAL WAVES FROM MASSIVE MAGNETARS FORMED IN BINARY NEUTRON STAR MERGERS
Simone Dall'Osso et al 2015 ApJ 798 25
View article, GRAVITATIONAL WAVES FROM MASSIVE MAGNETARS FORMED IN BINARY NEUTRON STAR MERGERSPDF, GRAVITATIONAL WAVES FROM MASSIVE MAGNETARS FORMED IN BINARY NEUTRON STAR MERGERSBinary neutron star (NS) mergers are among the most promising sources of gravitational waves (GWs), as well as candidate progenitors for short gamma-ray bursts (SGRBs). Depending on the total initial mass of the system and the NS equation of state (EOS), the post-merger phase can be characterized by a prompt collapse to a black hole or by the formation of a supramassive NS, or even a stable NS. In the latter cases of post-merger NS (PMNS) formation, magnetic field amplification during the merger will produce a magnetar and induce a mass quadrupole moment in the newly formed NS. If the timescale for orthogonalization of the magnetic symmetry axis with the spin axis is smaller than the spindown time, the NS will radiate its spin down energy primarily via GWs. Here we study this scenario for the various outcomes of NS formation: we generalize the set of equilibrium states for a twisted torus magnetic configuration to include solutions that, for the same external dipolar field, carry a larger magnetic energy reservoir; we hence compute the magnetic ellipticity for such configurations, and the corresponding strength of the expected GW signal as a function of the relative magnitude of the dipolar and toroidal field components. The relative number of GW detections from PMNSs and from binary NSs is a very strong function of the NS EOS, being higher (∼1%) for the stiffest EOSs and negligibly small for the softest ones. For intermediate-stiffness EOSs, such as the n = 4/7 polytrope recently used by Giacomazzo and Perna or the GM1 used by Lasky et al., the relative fraction is ∼0.3%; correspondingly, we estimate a GW detection rate from stable PMNSs of ∼0.1–1 yr−1 with advanced detectors, and of ∼100–1000 yr−1 with detectors of third generation such as the Einstein Telescope. Measurement of such GW signals would provide constraints on the NS EOS and, in connection with an SGRB, on the nature of the binary progenitors giving rise to these events.
- The following article is Open accessInferring 3D Coronal Magnetic Fields through Seismology-assisted Inversions of IQU-only Spectropolarimetric Observations
Alin Răzvan Paraschiv 2026 ApJ 1008 29
View article, Inferring 3D Coronal Magnetic Fields through Seismology-assisted Inversions of IQU-only Spectropolarimetric ObservationsPDF, Inferring 3D Coronal Magnetic Fields through Seismology-assisted Inversions of IQU-only Spectropolarimetric ObservationsDownload ePub, Inferring 3D Coronal Magnetic Fields through Seismology-assisted Inversions of IQU-only Spectropolarimetric ObservationsThe routine measurement of the Stokes IQUV signals of emission lines in the solar corona is still a challenging endeavor, particularly for observations using small-aperture instruments. Therefore, recent studies have explored the use of coronal seismology and propagating Alfvénic waves as alternative diagnostics of the coronal magnetic field. In particular, Z. Yang et al. showed that plane-of-sky (POS) phase-speed measurements provide a direct and consistent diagnostic of the POS magnetic-field component (BPOS). Building on recent theoretical advances in solar coronal polarization, we devise a novel inversion scheme and extended the CLEDB software package to exploit Stokes IQU observations of two coronal emission lines combined with coronal seismology-derived BPOS estimations. Using this framework, we perform a comprehensive statistical analysis demonstrating that this combination of diagnostics allows us to infer both magnetic-field orientation and strength with an accuracy comparable to that of Stokes IQUV spectropolarimetry. This type of diagnostics is particularly suited for the Fe xiii 1074.7 and 1079.8 nm line pair routinely observed by new-generation instruments such as DKIST Cryo-NIRSP, DL-NIRSP, MLSO CoMP/UCoMP, and targeted by the future COSMO and CORSAIR efforts.
- The following article is Open accessConnecting Current and Future Dual Active Galactic Nucleus Searches to LISA and Pulsar Timing Array Gravitational-wave Detections
Nianyi Chen et al 2026 ApJ 1008 89
View article, Connecting Current and Future Dual Active Galactic Nucleus Searches to LISA and Pulsar Timing Array Gravitational-wave DetectionsPDF, Connecting Current and Future Dual Active Galactic Nucleus Searches to LISA and Pulsar Timing Array Gravitational-wave DetectionsDownload ePub, Connecting Current and Future Dual Active Galactic Nucleus Searches to LISA and Pulsar Timing Array Gravitational-wave DetectionsDual active galactic nuclei (DAGN) mark the observable stage of massive black hole (MBH) pairing during galaxy mergers and are the progenitors of the MBH binaries that generate low-frequency gravitational waves. Using the large-volume ASTRID cosmological simulation, we construct mock DAGN catalogs tailored to the selection functions of current (COSMOS-Web and DESI) and forthcoming (Nancy Grace Roman Space Telescope (Roman) and Lynx X-ray Observatory (Lynx)) surveys, enabling direct comparisons between simulations and observations. With realistic observational selections, ASTRID reproduces the observed dual fractions, projected separations, and host-galaxy properties across redshifts. We predict a substantial population of small-separation (<5 kpc) duals that remain inaccessible to current surveys, demonstrating that the apparent paucity of subkiloparsec systems in COSMOS-Web is primarily a consequence of observational selection rather than an intrinsic absence. Following each simulated dual to coalescence, we show that DAGN are effective tracers of MBH mergers: ∼30%–70% merge within ≲1 Gyr, and 20%–60% of these mergers produce gravitational-wave signals detectable by the Laser Interferometer Space Antenna (LISA). Duals observable with Roman and Lynx are the progenitors of ∼10%–50% of low-redshift LISA sources and contribute ∼30% of the PTA-band stochastic gravitational-wave background. We further identify massive green-valley galaxies hosting moderate-luminosity active galactic nuclei (AGN), together with massive star-forming galaxies containing bright quasars at z > 1, as the environments most likely to host imminent MBH binaries. These results establish a unified cosmological framework connecting DAGN demographics, MBH binary evolution, and gravitational-wave sources, while identifying high-priority targets for coordinated electromagnetic and multimessenger observations in the coming decade.
- The following article is Open accessThe Milky Way Atlas for Linear Filaments. III. Giant Filaments and Magnetic Fields as Evidence of a Bubbly Galactic Disk
Naval K. Bhadari et al 2026 ApJ 1008 98
View article, The Milky Way Atlas for Linear Filaments. III. Giant Filaments and Magnetic Fields as Evidence of a Bubbly Galactic DiskPDF, The Milky Way Atlas for Linear Filaments. III. Giant Filaments and Magnetic Fields as Evidence of a Bubbly Galactic DiskDownload ePub, The Milky Way Atlas for Linear Filaments. III. Giant Filaments and Magnetic Fields as Evidence of a Bubbly Galactic DiskLinear filamentary structures are fundamental constituents of the interstellar medium and play a central role in star formation. Their relative orientation with respect to the ambient magnetic field (B-field) provides key constraints on filament formation mechanisms. We investigate the relative orientation between Milky Way linear filaments (MWLFs) and the plane-of-sky B-field using polarization observations from the Atacama Cosmology Telescope DR6, complemented by Planck data. Filament orientations are compared with the local B-field and the Galactic plane, while projection effects and statistical significance are quantified using Monte Carlo simulations of vector pairs in three dimensions. We find no strong preferential alignment between MWLFs and the ambient B-field. Although the B-field is preferentially aligned with the Galactic plane with relative angles θBG ∼ 0°–25°, filament orientations exhibit a bimodal distribution, being either parallel or perpendicular to the plane (θFG ∼ 0°–15° and ∼75°–90°). Filaments located far from the Galactic midplane (∣z∣ > 90 pc) preferentially show perpendicular alignment with both the plane and the B-field, whereas those near the midplane exhibit a bimodal orientation. These results indicate that large-scale B-fields do not dominate the formation of MWLFs and instead favor a super-Alfvénic regime in which magnetic forces are dynamically subdominant, as expected for filaments associated with supernova-driven shells. Overall, our findings suggest that a face-on view of the Milky Way would resemble nearby disk galaxies such as M74, as observed in JWST images, with its disk structured by a network of supernova-driven bubbles (i.e., a bubbly disk).
- The following article is Open accessStrong Lens Discoveries in DESI Legacy Imaging Surveys DR10 with Two Deep Learning Architectures
Jose Carlos Inchausti et al 2026 ApJ 1008 102
View article, Strong Lens Discoveries in DESI Legacy Imaging Surveys DR10 with Two Deep Learning ArchitecturesPDF, Strong Lens Discoveries in DESI Legacy Imaging Surveys DR10 with Two Deep Learning ArchitecturesDownload ePub, Strong Lens Discoveries in DESI Legacy Imaging Surveys DR10 with Two Deep Learning ArchitecturesWe have conducted a search for strong gravitational lensing systems in the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 10 (DR10). This paper is the fourth in a series of searches. This is the first catalog of lens candidates covering nearly the entirety of the extragalactic sky south of declination δ ≈ +32∘, all observed by DECam, covering ∼14,000 deg2. We impose a z-band magnitude cut of <20 in AB magnitude. We deploy a residual neural network and EfficientNet as an ensemble trained on a compilation of known lensing systems and high-grade candidates as well as nonlenses in the same footprint. The predictions from these two base models are aggregated using a meta-learner. After applying our ensemble to the survey data, we exclude known candidates and systems, and use our own visual inspection portal to rank images in the top 0.01 percentile of all neural network recommendations. We have found 811 lens candidates, five of which are confirmed through Euclid Quick Data Release (Q1). These include 484 new candidates in the Legacy Surveys DR9 footprint, all parts of which have been searched for strong lenses at least once before, either by our group or others. Combining the discoveries from this work with those from the first three papers in this series (335, 1210, and 1512), we have discovered a total of 3868 new candidates in the DESI Legacy Surveys.
- The Relation between Quasar and Merging Galaxy Luminosity Functions and the Merger-driven Star Formation History of the Universe
Philip F. Hopkins et al 2006 ApJ 652 864
View article, The Relation between Quasar and Merging Galaxy Luminosity Functions and the Merger-driven Star Formation History of the UniversePDF, The Relation between Quasar and Merging Galaxy Luminosity Functions and the Merger-driven Star Formation History of the UniverseUsing a model for the self-regulated growth of supermassive BHs in mergers involving gas-rich galaxies, we study the relationship between quasars and the population of merging galaxies and predict the merger-driven SFR density of the universe. Mergers drive gas inflows, fueling starbursts and ``buried'' quasars until feedback disperses the gas, allowing the quasar to be briefly visible as a bright optical source. By simulating the evolution of such events, we demonstrate that the observed statistics of merger rates/fractions, luminosity and mass functions, SFR distributions, quasar (and quasar host) luminosity functions, and elliptical/red galaxy luminosity and mass functions are self-consistent. We use our simulations to deconvolve quasar and merger luminosity functions and determine the birthrate of BHs and merger rates as a function of mass. From this, we predict the merging galaxy luminosity function in various observed wavebands, color-magnitude relations, mass functions, SFR distributions and density, and quasar host galaxy luminosity function, as a function of redshift from z = 0 to 6. We invert this to predict quasar luminosity functions from observed merger luminosity functions or SFR distributions. Our results show good agreement with observations, but idealized models of quasar light curves give inaccurate estimates and are ruled out at >99.9% confidence, provided that quasars are triggered in mergers. Using only quasar observations, we estimate the contribution of mergers to the SFR density of the universe to high redshifts, z ~ 4, and constrain the evolution in the characteristic initial gas fractions of quasar and spheroid-producing mergers.
- The following article is Open accessMachine Learning Acceleration of Neutron Star Pulse Profile Modeling
Preston G. Waldrop et al 2026 ApJ 1008 109
View article, Machine Learning Acceleration of Neutron Star Pulse Profile ModelingPDF, Machine Learning Acceleration of Neutron Star Pulse Profile ModelingDownload ePub, Machine Learning Acceleration of Neutron Star Pulse Profile ModelingRay-tracing algorithms that compute pulse profiles from rotating neutron stars are essential tools for constraining neutron star properties with data from missions such as Neutron star Interior Composition Explorer. However, the high computational cost of these simulations presents a significant bottleneck for inference algorithms that require millions of evaluations, such as Markov Chain Monte Carlo methods. In this work, we develop a neural network model that accelerates this calculation by predicting the observed flux from the surface of a spinning neutron star as a function of its physical parameters and rotational phase. Leveraging GPU-parallelized evaluation, we demonstrate that our model achieves many orders of magnitude speedup compared to traditional ray tracing while maintaining high accuracy. We also show that the trained network can efficiently accommodate complex emission geometries, including noncircular and multiple hotspots, by integrating over localized flux patches.
- The following article is Open accessFrom Infinite Dimensions to Black Hole Universes: Refuting the Big Bang Theory
Debjit Adhikari et al 2026 ApJ 1005 13
View article, From Infinite Dimensions to Black Hole Universes: Refuting the Big Bang TheoryPDF, From Infinite Dimensions to Black Hole Universes: Refuting the Big Bang TheoryDownload ePub, From Infinite Dimensions to Black Hole Universes: Refuting the Big Bang TheoryWe present a unified framework reconciling quantum gravity, loop quantum cosmology, and higher-dimensional topology to demonstrate that black hole interiors give rise to causally disconnected universes. By refuting the standard Big Bang singularity paradigm, we show that infinite-dimensional Hilbert spaces underpin the structure of emerging spacetimes, providing observational signatures detectable via gravitational wave astronomy and the cosmic microwave background.
- The following article is Open accessRapid Orbital Decay of Supersoft X-Ray Source WX Cen: A Surrounding Circumbinary Disk
Zhi-Qiang Liu et al 2026 ApJ 1009 66
View article, Rapid Orbital Decay of Supersoft X-Ray Source WX Cen: A Surrounding Circumbinary DiskPDF, Rapid Orbital Decay of Supersoft X-Ray Source WX Cen: A Surrounding Circumbinary DiskDownload ePub, Rapid Orbital Decay of Supersoft X-Ray Source WX Cen: A Surrounding Circumbinary DiskWX Cen is most likely a candidate of compact binary supersoft X-ray sources (SSSs), which consists of a white dwarf (WD) and a donor star that fills the Roche lobe. Recently, this source was detected to be experiencing a rapid orbital decay at a rate of
. According to the mass function and optical eclipses, the donor-star mass can be constrained to be 0.41−0.44, 0.47−0.50, and 0.55−0.59 M⊙ when the WD mass is 0.7, 0.9, and 1.2 M⊙, respectively. The observed orbital period derivative cannot be produced by the angular momentum loss (AML) due to mass loss during the accretion of the WD and magnetic braking (MB) mechanisms, including standard MB, convection and rotation-enhanced MB, and anomalous MB prescriptions. We propose that the rapid orbital decay of WX Cen is caused by the tidal torque that originates from the resonant interaction between the binary and a surrounding circumbinary (CB) disk. Detailed stellar evolution models indicate that a WD binary with a 2.5 × 10−7M⊙ CB disk can evolve toward a WX Cen-like system, which has an orbital period derivative of and a relatively high mass-transfer rate of 5.3 × 10−7M⊙ yr−1 that can trigger a stable hydrogen burning process on the surface of the WD. - The following article is Open accessGeneralized Predictions for the Electromagnetic Signatures of Mirror Stars
Franco Cabral et al 2026 ApJ 1009 65
View article, Generalized Predictions for the Electromagnetic Signatures of Mirror StarsPDF, Generalized Predictions for the Electromagnetic Signatures of Mirror StarsDownload ePub, Generalized Predictions for the Electromagnetic Signatures of Mirror StarsMirror stars are a generic prediction of dissipative dark matter (DM) models, including minimal atomic DM and twin baryons in the mirror twin Higgs. Mirror stars capture regular atoms from the interstellar medium through highly suppressed kinetic mixing interactions between the regular and the dark photon. This results in the accumulation of a “nugget,” which draws heat from the mirror star core and emits distinctive X-ray and optical signals. In this work, we solve the stellar structure equations of optically thick nuggets across a wide range of the effective mirror star parameter space, and characterize their emission spectra using stellar atmosphere models. This complements an earlier analysis of lower-mass optically thin nuggets. We find that optically thick mirror star nuggets occupy distinct regions of the (stellar surface temperature, luminosity, surface gravity) space, and can be distinguished from regular stars in both Hertzsprung–Russell diagrams and temperature–surface gravity diagrams using astrometric and spectroscopic stellar catalogues. Our detailed predictions, which are publicly available, now give for the first time a general picture of mirror star signals in the optical and IR to enable realistic mirror star searches using existing catalogues and new telescope observations.
- The following article is Open accessAT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGN
Yael Dgany et al 2026 ApJ 1009 71
View article, AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGNPDF, AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGNDownload ePub, AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGNThe emission mechanism and host galaxy preference of optical/UV tidal disruption events (TDEs) are still not entirely understood. We present observations of the TDE AT 2022csn, which is one of the most distant (dL ∼ 726 Mpc) and luminous (
) optical/UV TDEs observed to date. Although it is a spectroscopically normal H + He TDE, it shows some photometric peculiarities, exhibiting a pronounced double-peaked light curve (with peaks separated by 18.30 ± 2.84 days in the g band) and lying in the low-temperature and large-radius end of the optical/UV TDE population. The host galaxy of AT 2022csn shows evidence for a significant starburst within the last gigayear, consistent with hosts of other optical/UV TDEs, as well as narrow emission lines, consistent with hosts of Type II AGN. Interaction between the TDE and a preexisting AGN accretion disk might explain the peculiar photometric properties. However, it is puzzling that a TDE would be visible in a Type II AGN, where according to the AGN unification picture the central region around the supermassive black hole is obscured. We suggest a few scenarios to reconcile this. AT 2022csn together with AT 2019ahk, which shows similar properties, may belong to a new subset of low-temperature, high-radius TDEs in galaxies with Type II AGN emission features. - The following article is Open accessX-Ray Variability and Photosphere Evolution during Accretion Disk Formation in Tidal Disruption Events
Xiaoshan Huang et al 2026 ApJ 1009 64
View article, X-Ray Variability and Photosphere Evolution during Accretion Disk Formation in Tidal Disruption EventsPDF, X-Ray Variability and Photosphere Evolution during Accretion Disk Formation in Tidal Disruption EventsDownload ePub, X-Ray Variability and Photosphere Evolution during Accretion Disk Formation in Tidal Disruption EventsThe early time emission in tidal disruption events (TDEs) originates from both accretion and shocks, producing photons that eventually emerge from an inhomogeneous photosphere. We model disk formation following debris stream self-intersection in a TDE using three-dimensional, frequency-integrated, and multigroup radiation hydrodynamics simulations. We find a more circularized disk forms about 24 days following the stream–stream collision, once the mass fallback rate passes its peak and the debris stream density decreases. Despite the absence of a circularized disk at early times, various shocks and the asymmetric photosphere are sufficient to drive a wide range of X-ray-to-optical ratios and soft X-ray variability. We find that with strong apsidal precession, the first light is from the stream–stream collision. It launches an optically thick outflow, but only produces modest prompt emission. The subsequent optical and UV light-curve rise is mainly powered by shocks in the turbulent accretion flow close to the black hole. The optical–UV luminosity peaks roughly when the disk forms and shock-driven outflows subside. Radiation pressure clears the polar region and creates optically thin channels. We obtain the broadband spectral energy distribution (SED) by postprocessing multigroup simulations with 16–20 frequency groups. The SED has a blackbody component that peaks in the extreme-UV. The soft X-ray component either resembles a thermal tail, or can be described by a power law associated with bulk Compton scattering. The blackbody parameters are broadly consistent with observed optical TDEs and vary weakly with viewing angle, but the soft X-ray emission is highly angle dependent.
-
The following article is Open accessFrom Infinite Dimensions to Black Hole Universes: Refuting the Big Bang Theory
Debjit Adhikari et al 2026 ApJ 1005 13
View article, From Infinite Dimensions to Black Hole Universes: Refuting the Big Bang Theory PDF, From Infinite Dimensions to Black Hole Universes: Refuting the Big Bang TheoryGeneral Relativity (GR) intrinsically predicts its own breakdown at the Big Bang singularity. The Borde-Guth-Vilenkin (BGV) theorem rigorously demonstrates that any spacetime with an average expansion rate greater than zero must be geodesically incomplete to the past. To understand this failure, we must deeply analyze the Raychaudhuri equation, which governs the kinematics of geodesic congruences.
- Measurements of Ω and Λ from 42 High-Redshift Supernovae
S. Perlmutter et al 1999 ApJ 517 565
View article, Measurements of Ω and Λ from 42 High-Redshift SupernovaePDF, Measurements of Ω and Λ from 42 High-Redshift SupernovaeWe report measurements of the mass density, ΩM, and cosmological-constant energy density, ΩΛ, 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 0.8ΩM-0.6ΩΛ≈-0.2±0.1 in the region of interest (ΩM≲1.5). For a flat (ΩM+ΩΛ=1) cosmology we find ΩMflat=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 of P(Λ>0)=99%, including the identified systematic uncertainties. The best-fit age of the universe relative to the Hubble time is t0flat=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.
- MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD
Edward F. Schlafly and Douglas P. Finkbeiner 2011 ApJ 737 103
View article, MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFDPDF, MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFDWe 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 colors u − g, g − r, r − i, and i − 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% in u − g, g − r, r − i, and i − z from those found by the blue tip method, after removing a 4% normalization difference. These results prefer an RV = 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 of E(B − V) to extinction in 88 bandpasses for four values of RV, using this reddening law and the 14% recalibration of SFD first reported by Schlafly et al. and confirmed in this work.
- The following article is Open accessThe Pantheon+ Analysis: Cosmological Constraints
Dillon Brout et al 2022 ApJ 938 110
View article, The Pantheon+ Analysis: Cosmological ConstraintsPDF, The Pantheon+ Analysis: Cosmological ConstraintsDownload ePub, The Pantheon+ Analysis: Cosmological ConstraintsWe present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves of 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift from z = 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 ΩM = 0.334 ± 0.018 from SNe Ia alone. For a flat w0CDM model, we measure w0 = −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), and w0 =
when combining the SN likelihood with Planck constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); both w0 values are consistent with a cosmological constant. We also present the most precise measurements to date on the evolution of dark energy in a flat w0waCDM universe, and measure wa = from Pantheon+ SNe Ia alone, H0 = 73.3 ± 1.1 km s−1 Mpc−1 when including SH0ES Cepheid distances, and wa = 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 of H0 and cannot explain the present “Hubble tension” between local measurements and early universe predictions from the cosmological model. - The Dust Content and Opacity of Actively Star-forming Galaxies
Daniela Calzetti et al 2000 ApJ 533 682
View article, The Dust Content and Opacity of Actively Star-forming GalaxiesPDF, The Dust Content and Opacity of Actively Star-forming GalaxiesWe present far-infrared (FIR) photometry at 150 and 205 μm of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT. Five of the eight galaxies are detected in both wave bands, and these data are used, in conjunction with IRAS archival photometry, to model the dust emission at λ ≳ 40 μm. The FIR spectral energy distributions (SEDs) are best fitted by a combination of two modified Planck functions, with T ~ 40-55 K (warm dust) and T ~ 20-23 K (cool dust) and with a dust emissivity index
= 2. The cool dust can be a major contributor to the FIR emission of starburst galaxies, representing up to 60% of the total flux. This component is heated not only by the general interstellar radiation field, but also by the starburst itself. The cool dust mass is up to ~150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts in our sample close to Milky Way values, once rescaled for the appropriate metallicity. The ratio between the total dust FIR emission in the range 1-1000 μm and the IRAS FIR emission in the range 40-120 μm is ~1.75, with small variations from galaxy to galaxy. This ratio is about 40% larger than previously inferred from data at millimeter wavelengths. Although the galaxies in our sample are generally classified as "UV bright," for four of them the UV energy emerging shortward of 0.2 μm is less than 15% of the FIR energy. On average, about 30% of the bolometric flux is coming out in the UV-to-near-IR wavelength range; the rest is emitted in the FIR. Energy balance calculations show that the FIR emission predicted by the dust reddening of the UV-to-near-IR stellar emission is within a factor of ~2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If our sample of local starbursts is representative of high-redshift (z ≳ 1), UV-bright, star-forming galaxies, these galaxies' FIR emission will be generally undetected in submillimeter surveys, unless (1) their bolometric luminosity is comparable to or larger than that of ultraluminous FIR galaxies and (2) their FIR SED contains a cool dust component. - HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere
K. M. Górski et al 2005 ApJ 622 759
View article, HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the SpherePDF, HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the SphereHEALPix—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.
- MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS
Jieun Choi et al 2016 ApJ 823 102
View article, MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELSPDF, MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELSThis 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 at http://waps.cfa.harvard.edu/MIST/. - Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds
David J. Schlegel et al 1998 ApJ 500 525
View article, Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation ForegroundsPDF, Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation ForegroundsWe present a full-sky 100 μm map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS 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 and IRAS 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 the B-R color distribution of a sample of the 106 brightest cluster ellipticals, as well as a sample of 384 ellipticals with B-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsic B-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.
- The following article is Open accessThe Pantheon+ Analysis: The Full Data Set and Light-curve Release
Dan Scolnic et al 2022 ApJ 938 113
View article, The Pantheon+ Analysis: The Full Data Set and Light-curve ReleasePDF, The Pantheon+ Analysis: The Full Data Set and Light-curve ReleaseDownload ePub, The Pantheon+ Analysis: The Full Data Set and Light-curve ReleaseHere we present 1701 light curves of 1550 unique, spectroscopically confirmed Type Ia supernovae (SNe Ia) that will be used to infer cosmological parameters as part of the Pantheon+ SN analysis and the Supernovae and H0 for the Equation of State of dark energy distance-ladder analysis. This effort is one part of a series of works that perform an extensive review of redshifts, peculiar velocities, photometric calibration, and intrinsic-scatter models of SNe Ia. The total number of light curves, which are compiled across 18 different surveys, is a significant increase from the first Pantheon analysis (1048 SNe), particularly at low redshift (z). Furthermore, unlike in the Pantheon analysis, we include light curves for SNe with z < 0.01 such that SN systematic covariance can be included in a joint measurement of the Hubble constant (H0) and the dark energy equation-of-state parameter (w). We use the large sample to compare properties of 151 SNe Ia observed by multiple surveys and 12 pairs/triplets of “SN siblings”—SNe found in the same host galaxy. Distance measurements, application of bias corrections, and inference of cosmological parameters are discussed in the companion paper by Brout et al., and the determination of H0 is discussed by Riess et al. These analyses will measure w with ∼3% precision and H0 with ∼1 km s−1 Mpc−1 precision.
- Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies
Daniel J. Eisenstein et al 2005 ApJ 633 560
View article, Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red GalaxiesPDF, Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red GalaxiesWe 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 0.72 h-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 100 h-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 between z ≈ 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 to z = 0.35 and z = 1089 to 4% fractional accuracy and the absolute distance to z = 0.35 to 5% accuracy. From the overall shape of the correlation function, we measure the matter density Ωmh2 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 Ωm = 0.273 ± 0.025 + 0.123(1 + w0) + 0.137ΩK. Including the CMB acoustic scale, we find that the spatial curvature is ΩK = -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.
- The following article is Open accessLittle Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys
Jorryt Matthee et al 2024 ApJ 963 129
View article, Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST SurveysPDF, Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST SurveysDownload ePub, Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST SurveysCharacterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad Hα emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 Hα lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s−1, contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼107–8M⊙. In the UV luminosity range MUV,AGN+host = −21 to −18, we measure number densities of ≈10−5 cMpc−3. This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad Hα LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex Hα profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization.
![$5\leqslant \mathrm{log}(\mathrm{Age})\ [\mathrm{year}]\leqslant 10.3$](https://content.cld.iop.org/journals/0004-637X/823/2/102/revision1/apj523363ieqn1.gif)
![$-2.0\leqslant [{\rm{Z}}/{\rm{H}}]\leqslant 0.5$](https://content.cld.iop.org/journals/0004-637X/823/2/102/revision1/apj523363ieqn3.gif)
![$-4.0\leqslant [{\rm{Z}}/{\rm{H}}]\lt -2.0$](https://content.cld.iop.org/journals/0004-637X/823/2/102/revision1/apj523363ieqn4.gif)
Journal links
Journal information
- 1996-present
The Astrophysical Journal
doi: 10.1088/issn.0004-637X
Online ISSN: 1538-4357
Print ISSN: 0004-637X