skip to main content

Title: Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XI. Accretion Disk Reverberation Mapping of Mrk 142
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Award ID(s):
1907290 1909199
Publication Date:
Journal Name:
The Astrophysical Journal
Page Range or eLocation-ID:
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    As part of our ongoing initiative to accurately calculate the accretion rate of planetesimals in the core-accretion model, we demonstrated in a recent article that when the calculations include the gravitational force of the Sun (the original core-accretion model did not include solar gravity), results change considerably (ApJ, 899:45). In this paper, we have advanced our previous study by including the effect of Saturn. To maintain focus on the effect of this planet, and in order to be consistent with previous studies, we did not include the effect of the nebular gas. Results demonstrate that, as expected, Saturn’s perturbation decreases the rate of accretion by scattering many planetesimals out of Jupiter’s accretion zone. It also increases the velocities with which planetesimals encounter the envelope, which in agreement with our previous findings enhances their breakup due to the ram pressure. Results also show that, because the effect of Saturn in scattering of planetesimals increases with its mass, this planet might not have played a significant role in the accretion of planetesimals by proto-Jupiter during the early stage of its growth. Finally, the late accretion of planetesimals, as obtained in our previous study, appears in our new results as well, implyingmore »that, combined with the rapid infall of the gas, it can result in the mixing of material in the outer regions of the envelope, which may explain the enhancement of the envelope’s high-Zmaterial.

    « less
  2. ABSTRACT Recent ALMA molecular line observations have revealed 3D gas velocity structure in protoplanetary discs, shedding light on mechanisms of disc accretion and structure formation. (1) By carrying out viscous simulations, we confirm that the disc’s velocity structure differs dramatically using vertical stress profiles from different accretion mechanisms. Thus, kinematic observations tracing flows at different disc heights can potentially distinguish different accretion mechanisms. On the other hand, the disc surface density evolution is mostly determined by the vertically integrated stress. The sharp disc outer edge constrained by recent kinematic observations can be caused by a radially varying α in the disc. (2) We also study kinematic signatures of a young planet by carrying out 3D planet–disc simulations. The relationship between the planet mass and the ‘kink’ velocity is derived, showing a linear relationship with little dependence on disc viscosity, but some dependence on disc height when the planet is massive (e.g. 10MJ). We predict the ‘kink’ velocities for the potential planets in DSHARP discs. At the gap edge, the azimuthally averaged velocities at different disc heights deviate from the Keplerian velocity at similar amplitudes, and its relationship with the planet mass is consistent with that in 2D simulations. After removingmore »the planet, the azimuthally averaged velocity barely changes within the viscous time-scale, and thus the azimuthally averaged velocity structure at the gap edge is due to the gap itself and not directly caused to the planet. Combining both axisymmetric kinematic observations and the residual ‘kink’ velocity is needed to probe young planets in protoplanetary discs.« less
  3. We studied the accretion disc structure in the doubly imaged lensed quasar SDSS J1339+1310 using r -band light curves and UV-visible to near-IR spectra from the first 11 observational seasons after its discovery. The 2009−2019 light curves displayed pronounced microlensing variations on different timescales, and this microlensing signal permitted us to constrain the half-light radius of the 1930 Å continuum-emitting region. Assuming an accretion disc with an axis inclined at 60° to the line of sight, we obtained log( r 1/2 /cm) = 15.4 −0.4 +0.93 . We also estimated the central black hole mass from spectroscopic data. The width of the C  IV , Mg  II , and H β emission lines, and the continuum luminosity at 1350, 3000, and 5100 Å, led to log( M BH / M ⊙ ) = 8.6 ± 0.4. Thus, hot gas responsible for the 1930 Å continuum emission is likely orbiting a 4.0 × 10 8   M ⊙ black hole at an r 1/2 of only a few tens of Schwarzschild radii.
  4. Abstract. A great challenge in climate modeling is how to parameterizesubgrid cloud processes, such as autoconversion and accretion in warm-rainformation. In this study, we use ground-based observations and retrievalsover the Azores to investigate the so-called enhancement factors,Eauto and Eaccr, which are often used in climate modelsto account for the influence of subgrid variance of cloud and precipitationwater on the autoconversion and accretion processes. Eauto andEaccr are computed for different equivalent model grid sizes. Thecalculated Eauto values increase from 1.96 (30 km) to 3.2(180 km), and the calculated Eaccr values increase from 1.53(30 km) to 1.76 (180 km). Comparing the prescribed enhancement factors inMorrison and Gettleman (2008, MG08) to the observed ones, we found that ahigher Eauto (3.2) at small grids and lower Eaccr (1.07)are used in MG08, which might explain why most of the general circulation models (GCMs) producetoo-frequent precipitation events but with too-light precipitation intensity. Theratios of the rain to cloud water mixing ratio (qr/qc) at Eaccr=1.07 andEaccr=2.0 are 0.063 and 0.142, respectively, from observations,further suggesting that the prescribed value of Eaccr=1.07 used inMG08 is too small to simulate precipitation intensity correctly. BothEauto and Eaccr increase when the boundary layer becomesless stable, and the values are larger in precipitating clouds (CLWP>75 gm−2) than thosemore »in non-precipitating clouds (CLWP<75 gm−2). Therefore, the selection of Eauto andEaccr values in GCMs should be regime- and resolution-dependent.« less