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SatGen: a semi-analytical satellite galaxy generator – I. The model and its application to Local-Group satellite statistics

Jiang, Fangzhou and Dekel, Avishai and Freundlich, Jonathan and van den Bosch, Frank C. and Green, Sheridan B. and Hopkins, Philip F. and Benson, Andrew and Du, Xiaolong (2021) SatGen: a semi-analytical satellite galaxy generator – I. The model and its application to Local-Group satellite statistics. Monthly Notices of the Royal Astronomical Society, 502 (1). pp. 621-641. ISSN 0035-8711. doi:10.1093/mnras/staa4034.

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We present a semi-analytical model of satellite galaxies, SatGen, which can generate large statistical samples of satellite populations for a host halo of desired mass, redshift, and assembly history. The model combines dark matter (DM) halo merger trees, empirical relations for the galaxy–halo connection, and analytical prescriptions for tidal effects, dynamical friction, and ram-pressure stripping. SatGen emulates cosmological zoom-in hydrosimulations in certain aspects. Satellites can reside in cored or cuspy DM subhaloes, depending on the halo response to baryonic physics that can be formulated from hydrosimulations and physical modelling. The subhalo profile and the stellar mass and size of a satellite evolve depending on its tidal mass-loss and initial structure. The host galaxy can include a baryonic disc and a stellar bulge, each described by a density profile that allows analytic satellite orbit integration. SatGen complements simulations by propagating the effect of halo response found in simulated field galaxies to satellites (not properly resolved in simulations) and outperforms simulations by sampling the halo-to-halo variance of satellite statistics and overcoming artificial disruption due to insufficient resolution. As a first application, we use the model to study satellites of Milky Way (MW)- and M31-sized hosts, making it emulate simulations of bursty star formation and of smooth star formation, respectively, and to experiment with a disc potential in the host halo. We find that our model reproduces the observed satellite statistics reasonably well. Different physical recipes make a difference in satellite abundance and spatial distribution at the 25 per cent level, not large enough to be distinguished by current observations given the halo-to-halo variance. The MW/M31 disc depletes satellites by ∼20 per cent and has a subtle effect of diversifying the internal structure of satellites, which is important for alleviating certain small-scale problems. We discuss the conditions for a massive satellite to survive in MW/M31.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemCode
Jiang, Fangzhou0000-0001-6115-0633
Dekel, Avishai0000-0003-4174-0374
Freundlich, Jonathan0000-0002-5245-7796
van den Bosch, Frank C.0000-0003-3236-2068
Green, Sheridan B.0000-0001-9100-6237
Hopkins, Philip F.0000-0003-3729-1684
Benson, Andrew0000-0001-5501-6008
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2020 December 23. Received 2020 December 23; in original form 2020 May 11. Published: 06 January 2021. The authors are thankful to Yuval Birnboim, Timothy Carleton, Nicolas Cournuault, Andrew Emerick, Omri Ginzburg, Sharon Lapiner, Mariangela Lisanti, Lina Necib, Jacob Shen, Oren Slone, and Coral Wheeler for helpful discussions. FJ is supported by the Israeli Planning and Budgeting Committee (PBC) Fellowship, and by the Troesh Fellowship from the California Institute of Technology. FJ is thankful to Jo Bovy for publicly sharing his code design wisdom through the software GALPY (Bovy 2015). FCvdB is supported by the National Aeronautics and Space Administration through grant numbers 17-ATP17-0028 and 19-ATP19-0059 issued as part of the Astrophysics Theory Program, and received addition support from the Klaus Tschira foundation. SBG is supported by the US National Science Foundation Graduate Research Fellowship under grant number DGE-1752134. Data Availability: The model that generates the data used in this article is available at The specific model realizations underlying this article will be shared on reasonable request to the corresponding author.
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
Planning and Budgeting Committee (Israel)UNSPECIFIED
Troesh Family Distinguished Scholars FundUNSPECIFIED
Klaus Tschira FoundationUNSPECIFIED
NSF Graduate Research FellowshipDGE-1752134
Subject Keywords:methods: numerical – galaxies: dwarf – galaxies: evolution – galaxies: haloes – galaxies: interactions – galaxies: structure
Issue or Number:1
Record Number:CaltechAUTHORS:20200626-150127283
Persistent URL:
Official Citation:Fangzhou Jiang, Avishai Dekel, Jonathan Freundlich, Frank C van den Bosch, Sheridan B Green, Philip F Hopkins, Andrew Benson, Xiaolong Du, SatGen: a semi-analytical satellite galaxy generator – I. The model and its application to Local-Group satellite statistics, Monthly Notices of the Royal Astronomical Society, Volume 502, Issue 1, March 2021, Pages 621–641,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104102
Deposited By: George Porter
Deposited On:29 Jun 2020 14:19
Last Modified:26 May 2021 22:13

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