The ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO): Constraints on disk turbulence, fragmentation velocity, and inner pebble fluxes

Abstract

How substructures and disk properties affect dust evolution and the delivery of solids and volatiles into planet-forming regions remains an open question. We present results from tailored dust evolution modeling of the AGE-PRO ALMA large program, a sample of 30 protoplanetary disks spanning different evolutionary stages. Visibility fitting of the AGE-PRO ALMA data (at 1.3\,mm) reveals that approximately half of the disks exhibit radial substructures. Combined with stellar properties, disk inclinations, and gas mass estimates from CO isotopologues and N$_2$H$^+$, this well-characterized set of disks provides an ideal testbed to constrain dust evolution models across different ages and disk morphologies. Using the dust evolution code \texttt{DustPy}, we simulate dust evolution in each disk under four model configurations, varying two key free parameters: the turbulent viscosity ($α= 10^{-4}, 10^{-3}$) and fragmentation velocity ($v_{\rm{frag}} = 1 \mathrm{m\,s^{-1}}, 10 \mathrm{m\,s^{-1}}$). Pressure traps are incorporated by perturbing the gas surface density based on the continuum intensity profiles, and synthetic observations generated with \texttt{RADMC-3D} are compared to these profiles. While no single model fits all disks, nearly half are best reproduced by the configuration with low turbulence and low fragmentation velocity ($α= 10^{-4}, v_{\rm{frag}} = 1\,\mathrm{m\,s^{-1}}$). Models of smooth disks underpredict dust mass, possibly indicating unresolved substructures. Pebble fluxes into inner disk regions correlate more strongly with disk age than with the presence of substructures, highlighting time-dependent dust transport as a key factor in shaping inner disk composition. Our results also provide a comparative baseline for interpreting multiwavelength and JWST water vapor observations.

Figures (16)

• Figure 1: Dust continuum emission of all the disks in the AGE-PRO sample, in ALMA Band 6 (1.3 mm). The disks with substructures inferred from the visibility models are enclosed by a red square. The beam size and shape is shown in each panel.The disk ID follows the definition in 2025Ruiz_Rodriguez2025Deng2025Agurto-Gangas, for Ophiuchus, Lupus, and Upper Sco, respectively.
• Figure 2: Two examples of Gaussian fits applied to the normalized radial brightness profiles obtained from FRANK using curve_fit. The left panel shows Lupus 10, an extended disk which exhibits multiple prominent rings and gaps, while the right panel shows Oph 2, featuring two distinct bumps. These fits are used to infer the location and relative amplitude of pressure bumps for the dust evolution models.
• Figure 3: Dust surface density distributions from DustPy simulations for three representative disks — Oph 2 (top row), Lup 2 (middle row), and Upp Sco 1 (bottom row). Each column corresponds to a different model configuration, varying the turbulence parameter $\alpha$ and fragmentation velocity $v_{\mathrm{frag}}$. The red dashed line shows the fragmentation limit ($a_{\mathrm{frag}}$) and the white shows the drift limit ($a_{\mathrm{drift}}$) at each radius. Models with low $\alpha$ and high $v_{\mathrm{frag}}$ (rightmost column) allow the most efficient grain growth and trapping, while high $\alpha$ and low $v_{\mathrm{frag}}$ (leftmost column) lead to smaller grains and inefficient dust trapping.
• Figure 4: Evolution of the dust mass within the 75$\pm$10 AU ring of Upp Sco 1 over time, shown for the four model configurations combining turbulence parameter $\alpha = 10^{-4}, 10^{-3}$ and fragmentation velocity $v_{\rm frag} = 1, 10\,\mathrm{m\,s^{-1}}$. We illustrate how different disk evolution parameters affect local dust retention and depletion. Models with lower $\alpha$ and higher $v_{\rm frag}$ sustain higher dust mass over longer timescales, highlighting more efficient grain growth and trapping.
• Figure 5: Comparison of synthetic Band 6 continuum images (RADMC-3D) with ALMA observations for Oph 2, Lup 2, and Upp Sco 1. Each row corresponds to one disk, and the columns show ALMA observations followed by synthetic images from four model configurations varying in $\alpha$ and $v_{\mathrm{frag}}$. The spatial resolution and beam size are matched with the ALMA observation.