Clump survival and migration in VDI galaxies: an analytical model versus simulations and observations

Avishai Dekel*, Nir Mandelker, Frederic Bournaud, Daniel Ceverino, Yicheng Guo, Joel Primack

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We address the nature of the giant clumps in high-z galaxies that undergo violent disc instability, distinguishing between long-lived and short-lived clumps. We study the evolution of long-lived clumps during migration through the disc via an analytical model tested by simulations and confront theory with CANDELS-HST observations. The clump ‘bathtub’ model, which considers gas and stellar gain and loss, involves four parameters: the accretion efficiency α, the star formation rate (SFR) efficiency d, and the outflow mass-loading factors for gas and stars, η and ηs. The corresponding time-scales are comparable to the migration time, two-three orbital times. The accretion-rate dependence on clump mass, gas, and stars, allows an analytical solution involving exponential growing and decaying modes. For the fiducial parameter values there is a main evolution phase where the SFR and gas mass are constant and the stellar mass is rising linearly with time. This makes the inverse specific SFR an observable proxy for clump age. When η or d are high, or α is low, the decaying mode induces a decline of SFR and gas mass till the migration ends. Later, the masses and SFR approach an hypothetical exponential growth with a constant specific SFR. The model matches simulations with different, moderate feedbacks, both in isolated and cosmological settings. The observed clumps agree with our predictions, indicating that the massive clumps are long-lived and migrating. A challenge is to model feedback that is non-disruptive in massive clumps but suppresses SFR to match the galactic stellar-to-halo mass ratio.

Original languageAmerican English
Pages (from-to)316-340
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.


  • dynamics
  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift
  • galaxies: kinematics


Dive into the research topics of 'Clump survival and migration in VDI galaxies: an analytical model versus simulations and observations'. Together they form a unique fingerprint.

Cite this