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1. The Comprehensive Archive of Substellar and Planetary Accretion Rates

   https://doi.org/10.3847/1538-3881/ad06b8  

   Betti, S K; Follette, K B; Ward-Duong, K; Peck, A E; Aoyama, Y; Bary, J; Dacus, B; Edwards, S; Marleau, G-D; Mohamed, K; et al (November 2023, The Astronomical Journal)

   Abstract Accretion rates ( $\dot{M}$) of young stars show a strong correlation with object mass (M); however, extension of the $\dot{M}–M$relation into the substellar regime is less certain. Here, we present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest compilation to date of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the $\dot{M}–M$relation and compare brown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original 1σscatter in the $\log \dot{M}–\log M$relation by ∼17%, suggesting that it makes only a small contribution to the dispersion. The CASPAR rederived values are best fit by $\dot{M}\propto M^{2.02\pm 0.06}$from 10M_Jto 2M_⊙, confirming previous results. However, we argue that the brown-dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we derive separate age-dependent $\dot{M}–M$relations for these regions and find a steepening in the brown-dwarf $\dot{M}–M$slope with age. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of ∼44%. This result highlights the significant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster than stars, potentially as a result of different accretion mechanisms. 

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2. Equilibrium States of Galactic Atmospheres. I. The Flip Side of Mass Loading

   https://doi.org/10.3847/1538-4357/ad81d6  

   Voit, G_Mark; Pandya, Viraj; Fielding, Drummond_B; Bryan, Greg_L; Carr, Christopher; Donahue, Megan; Oppenheimer, Benjamin_D; Somerville, Rachel_S (November 2024, The Astrophysical Journal)

   Abstract This paper presents a new framework for understanding the relationship between a galaxy and its circumgalactic medium (CGM). It focuses on howimbalancesbetween heating and cooling cause either expansion or contraction of the CGM. It does this by trackingallof the mass and energy associated with a halo’s baryons, including their gravitational potential energy, even if feedback has pushed some of those baryons beyond the halo’s virial radius. We show how a star-forming galaxy’s equilibrium state can be algebraically derived within the context of this framework, and we analyze how the equilibrium star formation rate depends on supernova feedback. We consider the consequences of varying the mass loading parameter ${\eta }_M\equiv {\dot{M}}_{\mathrm{wind}}/{\dot{M}}_{*}$relating a galaxy’s gas mass outflow rate ( ${\dot{M}}_{\mathrm{wind}}$) to its star formation rate ( ${\dot{M}}_{*}$) and obtain results that challenge common assumptions. In particular, we find that equilibrium star formation rates in low-mass galaxies are generally insensitive to mass loading, and when mass loading does matter, increasing it actually results inmorestar formation because more supernova energy is needed to resist atmospheric contraction. 

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3. Analytical Model of Disk Evaporation and State Transitions in Accreting Black Holes

   https://doi.org/10.3847/1538-4357/ac6d5c  

   Cho 조, Hyerin 혜린; Narayan, Ramesh (June 2022, The Astrophysical Journal)

   Abstract State transitions in black hole X-ray binaries are likely caused by gas evaporation from a thin accretion disk into a hot corona. We present a height-integrated version of this process, which is suitable for analytical and numerical studies. With radiusrscaled to Schwarzschild units and coronal mass accretion rate ${\dot{m}}_c$to Eddington units, the results of the model are independent of black hole mass. State transitions should thus be similar in X-ray binaries and an active galactic nucleus. The corona solution consists of two power-law segments separated at a break radiusr_b∼ 10³(α/0.3)⁻², whereαis the viscosity parameter. Gas evaporates from the disk to the corona forr>r_b, and condenses back forr<r_b. Atr_b, ${\dot{m}}_c$reaches its maximum, ${\dot{m}}_{c,\max }\approx 0.02{\left(\alpha /0.3\right)}^3$. If atr≫r_bthe thin disk accretes with ${\dot{m}}_d<{\dot{m}}_{c,\max }$, then the disk evaporates fully before reachingr_b, giving the hard state. Otherwise, the disk survives at all radii, giving the thermal state. While the basic model considers only bremsstrahlung cooling and viscous heating, we also discuss a more realistic model that includes Compton cooling and direct coronal heating by energy transport from the disk. Solutions are again independent of black hole mass, andr_bremains unchanged. This model predicts strong coronal winds forr>r_b, and aT∼ 5 × 10⁸K Compton-cooled corona forr<r_b. Two-temperature effects are ignored, but may be important at small radii. 

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4. Mapping the Growth of Supermassive Black Holes as a Function of Galaxy Stellar Mass and Redshift

   https://doi.org/10.3847/1538-4357/ad27cc  

   Zou, Fan; Yu, Zhibo; Brandt, W N; Tak, Hyungsuk; Yang, Guang; Ni, Qingling (March 2024, The Astrophysical Journal)

   Abstract The growth of supermassive black holes is strongly linked to their galaxies. It has been shown that the population mean black hole accretion rate ( $\overline{\mathrm{BHAR}}$) primarily correlates with the galaxy stellar mass (M_⋆) and redshift for the general galaxy population. This work aims to provide the best measurements of $\overline{\mathrm{BHAR}}$as a function ofM_⋆and redshift over ranges of 10^9.5<M_⋆< 10¹²M_⊙andz< 4. We compile an unprecedentedly large sample with 8000 active galactic nuclei (AGNs) and 1.3 million normal galaxies from nine high-quality survey fields following a wedding cake design. We further develop a semiparametric Bayesian method that can reasonably estimate $\overline{\mathrm{BHAR}}$and the corresponding uncertainties, even for sparsely populated regions in the parameter space. $\overline{\mathrm{BHAR}}$is constrained by X-ray surveys sampling the AGN accretion power and UV-to-infrared multiwavelength surveys sampling the galaxy population. Our results can independently predict the X-ray luminosity function (XLF) from the galaxy stellar mass function (SMF), and the prediction is consistent with the observed XLF. We also try adding external constraints from the observed SMF and XLF. We further measure $\overline{\mathrm{BHAR}}$for star-forming and quiescent galaxies and show that star-forming $\overline{\mathrm{BHAR}}$is generally larger than or at least comparable to the quiescent $\overline{\mathrm{BHAR}}$. 

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5. Magnetogram-matching Biot–Savart Law and Decomposition of Vector Magnetograms

   https://doi.org/10.3847/1538-4357/add895  

   Titov, Viacheslav S; Downs, Cooper; Török, Tibor; Linker, Jon A; Prazak, Michael; Qiu, Jiong A (July 2025, The Astrophysical Journal)

   Abstract We generalize a magnetogram-matching Biot–Savart law (BSl) from planar to spherical geometry. For a given coronal current densityJ, this law determines the magnetic field $\tilde{\mathit{B}}$whose radial component vanishes at the surface. The superposition of $\tilde{\mathit{B}}$with a potential field defined by a given surface radial field,B_r, provides the entire configuration whereB_rremains unchanged by the currents. Using this approach, we (1) upgrade our regularized BSls for constructing coronal magnetic flux ropes (MFRs) and (2) propose a new method for decomposing a measured photospheric magnetic field as $\mathit{B}={\mathit{B}}_{\mathrm{pot}}+{\mathit{B}}_T+{\mathit{B}}_{\tilde{S}}$, where the potential,B_pot, toroidal,B_T, and poloidal, ${\mathit{B}}_{\tilde{S}}$, fields are determined byB_r,J_r, and the surface divergence ofB–B_pot, respectively, all derived from magnetic data. OurB_Tis identical to the one in the alternative Gaussian decomposition by P. W. Schuck et al., whileB_potand ${\mathit{B}}_{\tilde{S}}$are different from their poloidal fields ${\mathit{B}}_{\mathrm{P}}^{<}$and ${\mathit{B}}_{\mathrm{P}}^{>}$, which arepotentialin the infinitesimal proximity to the upper and lower side of the surface, respectively. In contrast, our ${\mathit{B}}_{\tilde{S}}$has no such constraints and, asB_potandB_T, refers to thesameupper side of the surface. In spite of these differences, for a continuousJdistribution across the surface,B_potand ${\mathit{B}}_{\tilde{S}}$are linear combinations of ${\mathit{B}}_{\mathrm{P}}^{<}$and ${\mathit{B}}_{\mathrm{P}}^{>}$. We demonstrate that, similar to the Gaussian method, our decomposition allows one to identify the footprints and projected surface-location of MFRs in the solar corona, as well as the direction and connectivity of their currents. 

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