High-mass Regime Research Articles

Evidence for a steeper SMBH–Bulge mass relationship extended to low masses using TDE host galaxies

Abstract Tidal disruption events (TDEs) are excellent tools for probing low mass supermassive black holes (SMBHs) that may otherwise remain undetected. Here, we present an extended SMBH–Bulge mass scaling relationship using these lower mass TDE black holes and their host galaxies. Bulge masses are derived using Prospector fits to UV-MIR spectral energy distributions for the hosts of 40 TDEs that have a detected late-time UV/optical plateau emission, from which a SMBH mass is derived. Overall, we find that TDE plateaus are a successful method for probing BH scaling relations. We combine the observed TDE sample with a higher mass SMBH sample and extend the known relationship, recovering a steeper slope (m = 1.34 ± 0.03) than current literature estimates, which focus on the high mass regime. For the TDE only sample, we measure an equally significant but shallower relationship with a power-law slope of m = 1.17 ± 0.10 and significance <0.001. Forward modelling is used to determine whether known selection effects can explain both the comparatively flatter TDE only relation and the overall steepening across the full SMBH mass range. We find that the flattening at TDE masses can be accounted for, however the steepening can not. It appears that if a single slope extends for the whole BH mass range, it must be steeper to include the TDE population.

Future collider sensitivities to νSMEFT interactions

Abstract The discovery of neutrino oscillations and masses provides strong motivation to extend the Standard Model by including right-handed neutrinos, which lead to heavy neutrino states that could exist at the electroweak scale. These states may also be influenced by new high-scale, weakly interacting physics. Incorporating right-handed neutrinos into an effective field theory framework -the νSMEFT- offers a systematic approach to study the phenomenology of heavy neutrinos in current and upcoming experiments. In this work, we present the first prospective 95% exclusion plots achievable at a future lepton collider operating at a center-of-mass energy of s = 0.5 TeV for what we term the agnostic νSMEFT scenario. This study focuses on the high-mass regime where the heavy neutrino N decays promptly into leptons and jets. Specifically, we analyse the processes e + e − → νN → νμ − μ + ν and e + e − → νN → νμ −jj, deriving the exclusion regions in the α Λ 2 versus m N parameter space. When compared to prospective limits for the LHeC, we find that the semi-leptonic process with final jets in a lepton collider offers the greatest sensitivity, even with a straightforward cut-based analysis. The expected bounds are as stringent as those considered in recent studies for the low-mass regime where the N may be long-lived and detectable via displaced decay searches, both at the LHC and future colliders.

Long-lived quasinormal modes around regular black holes and wormholes in Covariant Effective Quantum Gravity

We study quasinormal modes of massive scalar and massless Dirac fields in the background of regular black holes and traversable wormholes arising in Covariant Effective Quantum Gravity. Using both the Jeffreys-Wentzel-Kramers-Brillouin approximation and time-domain integration, we analyze the impact of quantum corrections on the quasinormal spectra and late-time behavior of perturbations. Our results reveal the existence of slowly decaying, oscillatory tails and quasi-resonant modes in the scalar sector, particularly in the high-mass regime. In the fermionic case, the damping rate increases with the quantum correction parameter ξ, while the oscillation frequency decreases. We also observe pronounced echo-like structures in the time-domain profiles near the black hole-wormhole threshold. These findings provide insight into the dynamics of perturbations in quantum-corrected spacetimes and offer potential signatures for distinguishing black holes from wormholes in future gravitational wave observations.

Star Formation from Low to High Mass: A Comparative View

Star formation has often been studied by separating the low- and high-mass regimes with an approximate boundary at 8 M⊙. Although some of the outcomes of the star-formation process are different between the two regimes, it is less clear whether the physical processes leading to these outcomes are that different at all. Here, we systematically compare low- and high-mass star formation by reviewing the most important processes and quantities from an observational and theoretical point of view. We identify three regimes in which processes are either similar, quantitatively, or qualitatively different between low- and high-mass star formation. ▪ Similar characteristics can be identified for the turbulent gas properties and density structures of the star-forming regions. Many of the observational characteristics also do not depend that strongly on the environment. ▪ Quantitative differences can be found for outflow, infall, and accretion rates as well as mean column and volume densities. Also, the multiplicity significantly rises from low- to high-mass stars. The importance of the magnetic field for the formation processes appears still less well constrained. ▪ Qualitative differences between low- and high-mass star formation relate mainly to the radiative and ionizing feedback that occurs almost exclusively in regions forming high-mass stars. Nevertheless, accretion apparently can continue via disk structures in ionized accretion flows. Finally, we discuss to what extent a unified picture of star formation over all masses is possible and which issues need to be addressed in the future.

Sensitivity of WIMP bounds on the velocity distribution in the limit of a massless mediator

We discuss the sensitivity of the bounds on the spin-independent (SI) and spin-dependent (SD) WIMP-proton and WIMP-neutron interaction couplings α SI,SD p,n on the WIMP velocity distribution for a massless mediator. We update the bounds in the Standard Halo Model (SHM) for direct detection and the neutrino signal from WIMP annihilation in the Sun (fixing the annihilation channel to bb̅), and set a halo-independent bound for the first time using the single-stream method. In the case of a massless mediator the SHM capture rate in the Sun diverges and is regularized by removing the contribution of WIMPs locked into orbits that extend beyond the Sun-Jupiter distance. We discuss the dependence of the SHM bounds on the Jupiter cut showing that it can be sizeable for α SD p and a WIMP mass mχ exceeding 1 TeV. Our updated SHM bounds show an improvement between about two and three orders of magnitude compared to the previous ones in the literature. Our halo-independent analysis shows that, with the exception of α SD p at large mχ , the relaxation of the bounds compared to the SHM is of the same order of that for contact interactions, i.e. relatively moderate in the low and high WIMP mass regimes and as large as ∼ 102 for mχ ≃ 20 GeV. On the other hand, the exact determination of the relaxation of the bound becomes not reliable for α SD p and mχ ≳ 1 TeV due to the sensitivity of the SHM capture rate in the Sun to the details of the Maxwellian velocity distribution at low incoming WIMP speeds. In contrast, the halo-independent bounds are robust against the details of the velocity distribution including the Jupiter cut and the local escape speed, as expected.

The SOFIA Massive (SOMA) Star Formation Q-band follow-up

Context. Evidence that the chemical characteristics around low- and high-mass protostars are similar has been found: notably, a variety of carbon-chain species and complex organic molecules (COMs) form around both types. On the other hand, the chemical compositions around intermediate-mass (IM) protostars (2 M⊙ < m* < 8 M⊙) have not been studied with large samples. In particular, it is unclear the extent to which carbon-chain species form around them. Aims. We aim to obtain the chemical compositions of a sample of IM protostars, focusing particularly on carbon-chain species. We also aim to derive the rotational temperatures of HC5N to confirm whether carbon-chain species are formed in the warm gas around these stars. Methods. We conducted Q-band (31.5–50 GHz) line survey observations toward 11 mainly IM protostars with the Yebes 40 m radio telescope. The target protostars were selected from a subsample of the source list of the SOFIA Massive Star Formation project. Assuming local thermodynamic equilibrium, we derived the column densities of the detected molecules and the rotational temperatures of HC5N and CH3 OH. Results. Nine carbon-chain species (HC3N, HC5N, C3H, C4H linear-H2CCC, cyclic-C3H2, CCS, C3S, and CH3CCH), three COMs (CH3OH, CH3CHO, and CH3CN), H2CCO, HNCO, and four simple sulfur-bearing species (13CS, C34S, HCS+, and H2CS) are detected. The rotational temperatures of HC5N are derived to be ~20–30 K in three IM protostars (Cepheus E, HH288, and IRAS 20293+3952). The rotational temperatures of CH3OH are derived in five IM sources and found to be similar to those of HC5N. Conclusions. The rotational temperatures of HC5N around the three IM protostars are very similar to those around low- and high-mass protostars. These results indicate that carbon-chain molecules are formed in lukewarm gas (~20–30 K) around IM protostars via the warm carbon-chain chemistry process. Thus, carbon-chain formation occurs ubiquitously in the warm gas around protostars across a wide range of stellar masses. Carbon-chain molecules and COMs coexist around most of the target IM protostars, which is similar to the situation for low- and high-mass protostars. In summary, the chemical characteristics around protostars are the same in the low-, intermediate- and high-mass regimes.

Time evolution of o-H2D+, N2D+, and N2H+ during the high-mass star formation process

Context. Deuterium fractionation is a well-established evolutionary tracer in low-mass star formation, but its applicability to the high-mass regime remains an open question. In this context, the abundances and ratios of different deuterated species have often been proposed as reliable evolutionary indicators for different stages of the high-mass star formation process. Aims. In this study, we investigate the role of N2H+ and key deuterated molecules (o-H2D+ and N2D+) as tracers of the different stages of the high-mass star formation process. We assess whether their abundance ratios can serve as reliable evolutionary indicators. Methods. We conducted APEX observations of o-H2D+ (110–111), N2H+ (4−3), and N2D+ (3−2) in a sample of 40 high-mass clumps at different evolutionary stages, selected from the ATLASGAL survey. Molecular column densities and abundances relative to H2, X, were derived through spectral line modelling, both under local thermodynamic equilibrium (LTE) and non-LTE conditions. Results. The o-H2D+ column densities show the smallest deviation from LTE conditions when derived under non-LTE assumptions. In contrast, N2H+ shows the largest discrepancy between the column densities derived from LTE and non-LTE. In all the cases discussed, we found that X(o-H2D+) decreases more significantly with each respective evolutionary stage than in the case of X(N2D+); whereas X(N2H+) increases slightly. Therefore, the validity of the X(o-H2D+)/X(N2D+) ratio as a reliable evolutionary indicator, recently proposed as a promising tracer of the different evolutionary stages, was not observed for this sample. While the deuteration fraction derived from N2D+ and N2H+ clearly decreases with clump evolution, the interpretation of this trend is complex, given the different distribution of the two tracers. Conclusions. Our results suggest that a careful consideration of the observational biases and beam-dilution effects are crucial for an accurate interpretation of the evolution of the deuteration process during the high-mass star formation process.

Big Galaxies and Big Black Holes: The Massive Ends of the Local Stellar and Black Hole Mass Functions and the Implications for Nanohertz Gravitational Waves

We construct the z = 0 galaxy stellar mass function (GSMF) by combining the GSMF at stellar masses M * ≲ 1011.3 M ⊙ from the census study of Leja et al. and the GSMF of massive galaxies at M * ≳ 1011.5 M ⊙ from the volume-limited MASSIVE galaxy survey. To obtain a robust estimate of M * for local massive galaxies, we use MASSIVE galaxies with M * measured from detailed dynamical modeling or stellar population synthesis modeling (incorporating a bottom-heavy initial mass function) with high-quality spatially resolved spectroscopy. These two independent sets of M * agree to within ∼7%. Our new z = 0 GSMF has a higher amplitude at M * ≳ 1011.5 M ⊙ than previous studies, alleviating prior concerns of a lack of mass growth in massive galaxies between z ∼ 1 and 0. We derive a local black hole mass function (BHMF) from this GSMF and the scaling relation of supermassive black holes (SMBHs) and galaxy masses. The inferred abundance of local SMBHs above ∼1010 M ⊙ is consistent with the number of currently known systems. The predicted amplitude of the nanohertz stochastic gravitational-wave background is also consistent with the levels reported by Pulsar Timing Array teams. Our z = 0 GSMF therefore leads to concordant results in the high-mass regime of the local galaxy and SMBH populations and the gravitational-wave amplitude from merging SMBHs. An exception is that our BHMF yields a z = 0 SMBH mass density that is notably higher than the value estimated from quasars at higher redshifts.

Self-similarity of the magnetic field at different scales: The case of G31.41+0.31

Context. Dust polarization observations of the massive protocluster G31.41+0.31 carried out at ~1″ (~3750 au) resolution with the SMA at 870 µm have revealed one of the clearest examples to date of an hourglass-shaped magnetic field morphology in the high-mass regime. Additionally, ~O.″24 (~900 au) resolution observations with ALMA at 1.3 mm have confirmed these results. The next step is to investigate whether the magnetic field maintains its hourglass-shaped morphology down to circumstellar scales. Aims. To study the magnetic field morphology toward the four (proto)stars A, B, C, and D contained in G31.41+0.31 and examine whether the self-similarity observed at core scales (1″ and 0.″ 24 resolution) still holds at circumstellar scales, we carried out ALMA observations of the polarized dust continuum emission at 1.3 mm and 3.1 mm at an angular resolution of ~0.″068 (~250 au), sufficient to resolve the envelope emission of the embedded protostars. Methods. We used ALMA to perform full polarization observations at 233 GHz (Band 6) and 97.5 GHz (Band 3) with a synthesized beam of 0.″072 × 0.″064. We carried out polarization observations at two different wavelengths to confirm that the polarization traces magnetically aligned dust grains and is not due to dust self-scattering. Results. The polarized emission and the direction of the magnetic field obtained at the two wavelengths are basically the same, except for an area between the embedded sources C and B. In such an area, the emission at 1.3 mm could be optically thick and affected by dichroic extinction. In the rest of the core, the similarity of the emission at the two wavelengths suggests that the polarized emission is due to magnetically aligned grains. The polarized emission has been successfully modeled with a poloidal field with a small toroidal component on the order of 10% of the poloidal component, with a position angle ϕ = −63°, an inclination i = 50°, and a mass-to-flux ratio λ = 2.66. The magnetic field axis is oriented perpendicular to the NE-SW velocity gradient detected in the core. The strength of the plane-of-the-sky component of the mean magnetic field, estimated using both the Davis-Chandrasekhar-Fermi and the polarization-intensity gradient methods, is in the range ~10−80 mG, for a density range 1.4 × 107−5 × 108 cm−3. The mass-to-flux ratio is in the range λ~1.9−3.0, which suggests that the core is “supercritical”. The polarization-intensity gradient method indicates that the magnetic field cannot prevent gravitational collapse inside the massive core. The collapse in the external part of the core is (slightly) sub-Alfvénic and becomes super-Alfvénic close to the center. Conclusions. Dust polarization measurements from large core scales to small circumstellar scales, in the hot molecular core G31.41+0.31 have confirmed the presence of a strong magnetic field with an hourglass-shaped morphology. This result suggests that the magnetic field could have a relevant role in regulating the star-forming process of massive stars at all scales, although it cannot prevent the collapse. However, it cannot be ruled out that the large opacity of the central region of the core may hinder the study of the magnetic field at circumstellar scales. Therefore, high-angular resolution observations at longer wavelengths, tracing optically thinner emission, are needed to confirm this self-similarity.

Morphology of Galaxies in JWST Fields: Initial Distribution and Evolution of Galaxy Morphology

Abstract A recent study from the Horizon Run 5 (HR5) cosmological simulation has predicted that galaxies with log M * / M ⊙ ≲ 10 in the cosmic morning (10 ≳ z ≳ 4) dominantly have disk-like morphology in the ΛCDM universe, which is driven by the tidal torque in the initial fluctuations of matter. For a direct comparison with observation we identify a total of about 19,000 James Webb Space Telescope (JWST) galaxies with log M * / M ⊙ > 9 at z = 0.6–8.0 utilizing deep JWST/NIRCam images of publicly released fields, including North Ecliptic Pole Time-Domain Fields, Next Generation Deep Extragalactic Exploratory Public survey, Cosmic Evolution Early Release Science Survey, Cosmic Evolution Survey, UltraDeep Survey, and SMACS J0723-7327. We estimate their stellar masses and photometric redshifts with the redshift dispersion of σ NMAD = 0.009 and an outlier fraction of only about 6%. We classify galaxies into three morphological types, disks, spheroids, and irregulars, applying the same criteria used in the HR5 study. The morphological distribution of the JWST galaxies shows that disk galaxies account for 60%–70% at all redshift ranges. However, in the high-mass regime ( log M * / M ⊙ ≳ 11 ), spheroidal morphology becomes the dominant type. This implies that the mass growth of galaxies is accompanied by a morphological transition from disks to spheroids. The fraction of irregulars is about 20% or less at all masses and redshifts. All the trends in the morphology distribution are consistently found in the six JWST fields. These results are in close agreement with the results from the HR5 simulation, particularly confirming the prevalence of disk galaxies at small masses in the cosmic morning and noon.

Observations of high-order multiplicity in a high-mass stellar protocluster

The dominant mechanism forming multiple stellar systems in the high-mass regime (M* ≳ 8 M⊙) remained unknown because direct imaging of multiple protostellar systems at early phases of high-mass star formation is very challenging. High-mass stars are expected to form in clustered environments containing binaries and higher-order multiplicity systems. So far only a few high-mass protobinary systems, and no definitive higher-order multiples, have been detected. Here we report the discovery of one quintuple, one quadruple, one triple and four binary protostellar systems simultaneously forming in a single high-mass protocluster, G333.23–0.06, using Atacama Large Millimeter/submillimeter Array high-resolution observations. We present a new example of a group of gravitationally bound binary and higher-order multiples during their early formation phases in a protocluster. This provides the clearest direct measurement of the initial configuration of primordial high-order multiple systems, with implications for the in situ multiplicity and its origin. We find that the binary and higher-order multiple systems, and their parent cores, show no obvious sign of disk-like kinematic structure. We conclude that the observed fragmentation into binary and higher-order multiple systems can be explained by core fragmentation, indicating its crucial role in establishing the multiplicity during high-mass star cluster formation.

Finite temperature considerations in the structure of quadratic GUP-modified white dwarfs

In quantum gravity phenomenology, the effect of the generalized uncertainty principle (GUP) on white dwarf structure has been given much attention in recent literature. However, these studies assume a zero temperature equation of state (EoS), excluding young white dwarfs whose initial temperatures are substantially high. To that cause, this paper calculates the Chandrasekhar EoS and resulting mass-radius relations of finite temperature white dwarfs modified by the quadratic GUP, an approach that extends Heisenberg’s uncertainty principle by a quadratic term in momenta. The EoS was first approximated by treating the quadratic GUP parameter as perturbative, causing the EoS to exhibit expected thermal deviations at low pressures, and conflicting behaviors at high pressures, depending on the order of approximation. We then proceeded with a full numerical simulation of the modified EoS, and showed that in general, finite temperatures cause the EoS at low pressures to soften, while the quadratic GUP stiffens the EoS at high pressures. This modified EoS was then applied to the Tolman–Oppenheimer–Volkoff equations and its classical approximation to obtain the modified mass-radius relations for general relativistic and Newtonian white dwarfs. The relations for both cases were found to exhibit the expected thermal deviations at small masses, where low-mass white dwarfs are shifted to the high-mass regime at large radii, while high-mass white dwarfs acquire larger masses, beyond the Chandrasekhar limit. Additionally, we find that for sufficiently large values of the GUP parameter and temperature, we obtain mass-radius relations that are completely removed from the ideal case, as high-mass deviations due to GUP and low-mass deviations due to temperature are no longer mutually exclusive.

Halo-independent bounds on the non-relativistic effective theory of WIMP-nucleon scattering from direct detection and neutrino observations

We combine experimental constraints from direct detection searches and from neutrino telescopes looking for WIMP annihilations in the Sun to derive halo-independent bounds on each of the 28 WIMP-proton and WIMP-neutron couplings of the effective non-relativistic Hamiltonian that drives the scattering process off nuclei of a WIMP of spin 1/2. The method assumes that the velocity distribution is normalized to one and homogeneous at the the solar system scale, as well as equilibrium between WIMP capture and annihilation in the Sun, and requires to fix the WIMP annihilation channels (we assume bb̅). We consider a single non-vanishing coupling at a time, and find that for most of the couplings the degree of relaxation of the halo-independent bounds compared to those obtained by assuming the Standard Halo Model is with few exceptions relatively moderate in the low and high WIMP mass regimes, where it can be as small as a factor of ≃ 2, while in the intermediate mass range between 10 GeV and 200 GeV it can be as large as ∼ 103. An exception to this general pattern, with more moderate values of the bound relaxation, is observed in the case of spin-dependent WIMP-proton couplings with no or a comparatively small momentum suppression, for which WIMP capture is strongly enhanced because it is driven by scattering events off 1H , which is the most abundant target in the Sun. Within this class of operators the relaxation is particularly small for interactions that are driven by only the velocity-dependent term, for which the solar capture signal is enhanced compared to the direct detection one, thanks to the highest speed of scattering WIMPs within the Sun due to the larger gravitational acceleration.

Multiple scales of view for outflow driven by a high-mass young stellar object, G25.82–W1

Abstract We are investigating the extended outflow from G25.82–W1, which is one of the members of the high-mass protocluster G25.82–0.17. The aim is to study the star-forming environment of G25.82–W1. To identify the outflow, we obtained CO 2-1 data using the Atacama Large Millimeter/submillimeter Array.We have identified several spatial and spectral outflows, including: 1) an extended N1–S1 CO outflow, driven by a high-mass young stellar object (HM-YSO) named G25.82–W1; 2) an elongated SE–NW outflow powered by G25.82–W2; 3) a compact and curved N2–S2 CO outflow originating from G25.82–E; and 4) a pair of knotty lobes centered on G25.82–W.Furthermore, the innermost region of the N1–S1 CO outflow, traced by the 22 GHz H2O maser, reveals a complex spatial and velocity structure within a 2” from its launching point.To accurately calculate the properties of the N1–S1 CO outflow, we have utilized an accurate distance measurement of d=4.5 kpc, derived from the annual parallax of the H2O masers. The outflow rate and force are comparable to those observed in outflows from other HM-YSOs. The physical properties of the N1–S1 CO outflow follow a trend connecting the low and high-mass regimes, supporting the idea that the star-forming mode in G25.82–W1 is likely a scaled-up version of low-mass star formation.

From 3D hydrodynamic simulations of common-envelope interaction to gravitational-wave mergers

Modelling the evolution of progenitors of gravitational-wave merger events in binary stars faces two major uncertainties: the common-envelope phase and supernova kicks. These two processes are critical for the final orbital configuration of double compact-object systems with neutron stars and black holes. Predictive one-dimensional models of common-envelope interaction are lacking and multidimensional simulations are challenged by the vast range of relevant spatial and temporal scales. Here, we present three-dimensional, magnetohydrodynamic simulations of the common-envelope interaction of an initially 10 M⊙ red supergiant primary star with a black-hole and a neutron-star companion. Employing the moving-mesh code AREPO and replacing the core of the primary star and the companion with point masses, we show that the high-mass regime is accessible to full ab initio simulations. About half of the common envelope is dynamically ejected at the end of our simulations and the ejecta mass fraction keeps growing. Almost complete envelope ejection seems possible if all ionised gas left over at the end of our simulation eventually recombines and the released energy continues to help unbind the envelope. We find that the dynamical plunge-in of both companions terminates at orbital separations that are too wide for gravitational waves to merge the systems in a Hubble time. However, the orbital separations at the end of our simulations are still decreasing such that the true final value at the end of the common-envelope phase remains uncertain. We discuss the further evolution of the system based on analytical estimates. A subsequent mass-transfer episode from the remaining 3 M⊙ core of the supergiant to the compact companion does not shrink the orbit sufficiently either. A neutron-star–neutron-star and neutron-star–black-hole merger is still expected for a fraction of the systems if the supernova kick aligns favourably with the orbital motion. For double neutron star (neutron-star–black-hole) systems we estimate mergers in about 9% (1%) of cases while about 77% (94%) of binaries are disrupted; that is, supernova kicks actually enable gravitational-wave mergers in the binary systems studied here. Assuming orbits smaller by one-third after the common-envelope phase enhances the merger rates by about a factor of two. However, the large post-common-envelope orbital separations found in our simulations mean that a reduction in predicted gravitational-wave merger events appears possible.

The galaxy-wide stellar initial mass function in the presence of cluster-to-cluster IMF variations

We calculate the stellar integrated galactic initial mass function (IGIMF) in the presence of cluster-to-cluster variations of the IMF. Variations of the IMF for a population of coeval clusters that populate the initial cluster mass function (ICLMF) are taken into account in the form of Gaussian distribution functions of the IMF parameters. For the tapered power-law function used in this work, these are the slope at the high-mass end, Γ, the slope at the low-mass end, γ, and the characteristic mass Mch. The level of variations is modeled by varying the width of the Gaussian distributions. The reference values are the standard deviations of the parameters observed for the population of young clusters in the present-day Milky Way, which are σΓ = 0.6, σγ = 0.25, and σMch = 0.27 M⊙. We find that increasing the levels of dispersion for γ and Γ tends to moderately flatten the IGIMF at the low and high-mass end, respectively. The characteristic mass of the IGIMF is, however, strongly impacted by variations in Mch. Increasing the value of σMch shifts the peak of the IGIMF to lower masses, rendering the IGIMF more bottom heavy. This can provide a simple explanation for the bottom-heavy stellar mass function that is inferred for early-type galaxies since these are likely the result of a merger of disk galaxies where the physical conditions of the star-forming gas may vary significantly both in time and space in the merging system. The effect of IMF variations on the IGIMF is compared to the effects of other processes and sources of systematic variations such as those due to variations in the shape of ICLMF, the gas-phase metallicity, and the galactic star formation rate (SFR) which can potentially affect the maximum mass of stellar clusters in a galaxy and set the mean value of the characteristic mass in clusters. For the various dependencies we have explored, we found that the effect of IMF variations is a dominant factor that always affects the characteristic mass of the IGIMF. For the regimes at low metallicity where the IGIMF resembles a single power law, an increased level of IMF variations renders the IGIMF steeper and more bottom heavy, especially at low SFRs. On the other hand, variations in the IMF in the high mass regime can be easily dominated by variations in the slope of the ICLMF. We compare our results of the metallicity and SFR-dependent IGIMF to a sample of Milky Way ultra-faint dwarf (UFD) satellite galaxies that have available metallicity measurements. The present-day stellar mass function of these galaxies is a good analog to the IGIMF at the time their overall population of stars formed. We show that the slope of the stellar mass function of the UFD galaxies measured for stars in the mass range [0.4, 0.8] M⊙ can only be reproduced when IMF variations of the same order as those measured in the present-day Milky Way are included. Our results suggest that the inclusion of IMF variations in models of galaxy formation and evolution is of vital importance in order to improve our understanding of star formation and star formation feedback effects on galactic scales.

Combining Planck and SPT Cluster Catalogs: Cosmological Analysis and Impact on the Planck Scaling Relation Calibration

We provide the first combined cosmological analysis of the South Pole Telescope (SPT) and Planck cluster catalogs. The aim is to provide an independent calibration for Planck scaling relations, exploiting the cosmological constraining power of the SPT-SZ cluster catalog and its dedicated weak lensing (WL) and X-ray follow-up observations. We build a new version of the Planck cluster likelihood. In the νΛ CDM scenario, focusing on the mass slope and mass bias of Planck scaling relations, we find and , respectively. The results for the mass slope show a ∼4 σ departure from the self-similar evolution, α SZ ∼ 1.8. This shift is mainly driven by the matter density value preferred by SPT data, Ω m = 0.30 ± 0.03, lower than the one obtained by Planck data alone, . The mass bias constraints are consistent both with outcomes of hydrodynamical simulations and external WL calibrations, (1 − b) ∼ 0.8, and with results required by the Planck cosmic microwave background cosmology, (1 − b) ∼ 0.6. From this analysis, we obtain a new catalog of Planck cluster masses M 500. We estimate the ratio between the published Planck M SZ masses and our derived masses M 500, as a “measured mass bias,” . We analyze the mass, redshift, and detection noise dependence of , finding an increasing trend toward high redshift and low mass. These results mimic the effect of departure from self-similarity in cluster evolution, showing different dependencies for the low-mass, high-mass, low-z, and high-z regimes.

Delivery of Gas onto the Circumplanetary Disk of Giant Planets: Planetary-mass Dependence of the Source Region of Accreting Gas and Mass Accretion Rate

Gas accretion onto the circumplanetary disks and the source region of accreting gas are important to reveal dust accretion that leads to satellite formation around giant planets. We performed local three-dimensional high-resolution hydrodynamic simulations of an isothermal and inviscid gas flow around a planet to investigate the planetary-mass dependence of the gas accretion bandwidth and gas accretion rate onto circumplanetary disks. We examined cases with various planetary masses corresponding to M p = 0.05–1M Jup at 5.2 au, where M Jup is the current Jovian mass. We found that the radial width of the gas accretion band is proportional to for the low-mass regime with M p ≲ 0.2M Jup while it is proportional to M p for the high-mass regime with M p ≳ 0.2M Jup. We found that the ratio of the mass accretion rate onto the circumplanetary disk to that into the Hill sphere is about 0.4 regardless of the planetary mass for the cases we examined. Combining our results with the gap model obtained from global hydrodynamic simulations, we derive a semi-analytical formula of mass accretion rate onto circumplanetary disks. We found that the mass dependence of our three-dimensional accretion rates is the same as the previously obtained two-dimensional case, although the qualitative behavior of accretion flow onto the circumplanetary disk is quite different between the two cases.

The bulge masses of TDE host galaxies and their scaling with black hole mass

ABSTRACT Tidal disruption events (TDEs) provide a means to probe the low end of the supermassive black hole (SMBH) mass distribution, as they are only observable below the Hills mass (≲ 108 M⊙). Here, we attempt to calibrate the scaling of SMBH mass with host galaxy bulge mass, enabling SMBH masses to be estimated for large TDE samples without the need for follow-up observations or extrapolations of relations based on high-mass samples. We derive host galaxy masses using prospector fits to the UV-MIR spectral energy distributions for the hosts of 29 well-observed TDEs with BH mass estimates from mosfit. We then conduct detailed bulge/disc decomposition using SDSS and PanSTARRS imaging, and provide a catalogue of bulge masses. We measure a positive correlation between SMBH and bulge mass for the TDE sample, with a power-law slope of 0.28 and significance p = 0.06 (Spearmans) and p = 0.05 (Pearsons), and an intrinsic scatter of 0.2 dex. Applying MC resampling and bootstrapping, we find a more conservative estimate of the slope is 0.18 ± 0.11, dominated by the systematic errors from prospector and mosfit. This is shallower than the slope at high SMBH mass, which may be due to a bias in the TDE sample towards lower mass BHs that can more easily disrupt low-mass stars outside of the event horizon. When combining the TDE sample with that of the high-mass regime, we find that TDEs are successful in extending the SMBH – stellar mass relationship further down the mass spectrum and provide a relationship across the full range of SMBH masses.

The Sejong Open Cluster Survey (SOS). VII. A Photometric Study of the Young Open Cluster IC 1590

Abstract Young open clusters are ideal laboratories to understand the star formation process. We present deep UBVI and Hα photometry for the young open cluster IC 1590 in the center of the H ii region NGC 281. Early-type members are selected from UBV photometric diagrams, and low-mass pre-main-sequence (PMS) members are identified by using Hα photometry. In addition, the published X-ray source list and Gaia astrometric data are also used to isolate probable members. A total of 408 stars are selected as members. The mean reddening obtained from early-type members is 〈E(B − V)〉 = 0.40 ± 0.06 (s.d.). We confirm the abnormal extinction law for the intracluster medium. The distance modulus to the cluster determined from the zero-age main-sequence fitting method is 12.3 ± 0.2 mag (d = 2.88 ± 0.28 kpc), which is consistent with the distance d = 2.70 − 0.20 + 0.24 kpc from the recent Gaia parallaxes. We also estimate the ages and masses of individual members by means of stellar evolutionary models. The mode of the age of PMS stars is about 0.8 Myr. The initial mass function of IC 1590 is derived. It appears to be a steeper shape (Γ = −1.49 ± 0.14) than that of the Salpeter/Kroupa initial mass function for the high-mass regime (m > 1 M ⊙). The signature of mass segregation is detected from the difference in the slopes of the initial mass functions for the inner ( r < 2 .′ 5 ) and outer regions of this cluster. We finally discuss the star formation history in NGC 281.