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The Morphology-Density-Relation: Impact on the Satellite Fraction
Astrophysics of Galaxies · Submitted 21 Feb 2017
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim Thus, due to the density-morphological-relation the number of satellites is not a good tracer for the halo mass, unless samples are restricted to the central galaxies of DM haloes.
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The abstract, sentence by sentence
In the past years several authors studied the abundance of satellites around galaxies in order to better estimate the halo masses of host galaxies. To investigate this connection, we analyze galaxies with $M_\mathrm{star}\geq\,10^{10}\,M_{\odot}$ from the hydrodynamical cosmological simulation Magneticum. We find that the satellite fraction of centrals is independent of their morphology. With the exception of very massive galaxies at low redshift, our results do not support the assumption that the dark matter (DM) haloes of spheroidal galaxies are significantly more massive than those of disc galaxies at fixed $M_\mathrm{star}$. We show that the density-morphology-relation starts to build up at $z\sim2$ and is independent of the star-formation properties of central galaxies. We conclude that environmental quenching is more important for satellites than for centrals. Our simulations indicate that conformity is already in place at $z=2$, where formation redshift and current star-formation rate (SFR) of central and satellite galaxies correlate. Centrals with low SFRs have formed earlier (at fixed $M_\mathrm{star}$) while centrals with high SFR formed later, with typical formation redshifts well in agreement with observations. However, we confirm the recent observations that the apparent number of satellites of spheroidal galaxies is significantly larger than for disc galaxies. This difference completely originates from the inclusion of companion galaxies, i.e. galaxies that do not sit in the potential minimum of a DM halo. Thus, due to the density-morphological-relation the number of satellites is not a good tracer for the halo mass, unless samples are restricted to the central galaxies of DM haloes.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | In the past years several authors studied the abundance of satellites around galaxies in order to better estimate the halo masses of host galaxies. | background 1.00 | 0.03 | 0.01 | asserted 0.98 |
| s1 | To investigate this connection, we analyze galaxies with $M_\mathrm{star}\geq\,10^{10}\,M_{\odot}$ from the hydrodynamical cosmological simulation Magneticum. | method 0.93 | 0.90 | 0.02 | asserted 0.61 |
| s2 | We find that the satellite fraction of centrals is independent of their morphology. | result 1.00 | 0.97 | 0.45 | asserted 1.00 |
| s3 | With the exception of very massive galaxies at low redshift, our results do not support the assumption that the dark matter (DM) haloes of spheroidal galaxies are significantly more massive than those of disc galaxies at fixed $M_\mathrm{star}$. | result 0.81 | 0.93 | 0.26 | asserted 0.74 |
| s4 | We show that the density-morphology-relation starts to build up at $z\sim2$ and is independent of the star-formation properties of central galaxies. | result 1.00 | 0.93 | 0.08 | asserted 1.00 |
| s5 | We conclude that environmental quenching is more important for satellites than for centrals. | interpretation 0.90 | 0.81 | 0.26 | asserted 0.99 |
| s6 | Our simulations indicate that conformity is already in place at $z=2$, where formation redshift and current star-formation rate (SFR) of central and satellite galaxies correlate. | result 0.99 | 0.92 | 0.06 | asserted 0.70 |
| s7 | Centrals with low SFRs have formed earlier (at fixed $M_\mathrm{star}$) while centrals with high SFR formed later, with typical formation redshifts well in agreement with observations. | result 0.97 | 0.91 | 0.04 | asserted 0.99 |
| s8 | However, we confirm the recent observations that the apparent number of satellites of spheroidal galaxies is significantly larger than for disc galaxies. | result 0.98 | 0.46 | 0.10 | asserted 0.95 |
| s9 | This difference completely originates from the inclusion of companion galaxies, i.e. galaxies that do not sit in the potential minimum of a DM halo. | result 0.60 | 0.87 | 0.17 | asserted 1.00 |
| s10 | Thus, due to the density-morphological-relation the number of satellites is not a good tracer for the halo mass, unless samples are restricted to the central galaxies of DM haloes. | interpretation 0.98 | 0.80 | 0.66 | asserted 0.99 |
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The paper
Original abstract
In the past years several authors studied the abundance of satellites around galaxies in order to better estimate the halo masses of host galaxies. To investigate this connection, we analyze galaxies with $M_\mathrm{star}\geq\,10^{10}\,M_{\odot}$ from the hydrodynamical cosmological simulation Magneticum. We find that the satellite fraction of centrals is independent of their morphology. With the exception of very massive galaxies at low redshift, our results do not support the assumption that the dark matter (DM) haloes of spheroidal galaxies are significantly more massive than those of disc galaxies at fixed $M_\mathrm{star}$. We show that the density-morphology-relation starts to build up at $z\sim2$ and is independent of the star-formation properties of central galaxies. We conclude that environmental quenching is more important for satellites than for centrals. Our simulations indicate that conformity is already in place at $z=2$, where formation redshift and current star-formation rate (SFR) of central and satellite galaxies correlate. Centrals with low SFRs have formed earlier (at fixed $M_\mathrm{star}$) while centrals with high SFR formed later, with typical formation redshifts well in agreement with observations. However, we confirm the recent observations that the apparent number of satellites of spheroidal galaxies is significantly larger than for disc galaxies. This difference completely originates from the inclusion of companion galaxies, i.e. galaxies that do not sit in the potential minimum of a DM halo. Thus, due to the density-morphological-relation the number of satellites is not a good tracer for the halo mass, unless samples are restricted to the central galaxies of DM haloes.
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How the literature uses it
3 arXiv papers cite this in 3 sentences
What it cites · 16 sentences without a confident label
Compares with 3 papers
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Especially, the results obtained by [ref] resemble very closely the simulation result.
Stellar mass -- halo mass relation and star formation efficiency in high-mass halos · The Relation between the Stellar and Halo Mass of Central Galaxies · 1.00
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This trend is in good agreement with observations by [ref] , who also find that at higher redshift the fraction of quiescent galaxies does not depend on the environment, while it does at low redshift.
Effects of Local Environment and Stellar Mass on Galaxy Quenching out to z~3 · The Relation between the Environment and the Star Formation Rate · 0.87
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At $z=2$ we find a median formation redshift for star-forming galaxies to be 3.36, which is in line with recent observations by [ref] , who evaluate a median formation redshift of $∼3.22$ for their galaxy sample observed at $2<z<6.5$ when using a formation redshift based on mean stellar ages similar to ours.
The extended epoch of galaxy formation: age dating of ~3600 galaxies with 2<z<6.5 in the VIMOS Ultra-Deep Survey · Evolution of the SFR-$z_form$ relation · 0.93
Cites as background 2 papers
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Indirect measurement methods are needed to infer the halo mass from observable quantities, for example from hot X-ray halo gas [ref] , weak galaxy-galaxy lensing [ref] , satellite velocities [ref] or the number of satellites [ref] , although discrepancies exist between the results of the different methods [ref] .
Stellar mass -- halo mass relation and star formation efficiency in high-mass halos · Introduction · 0.89
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Over the past years several studies investigated the stellar-to-halo-mass relation [ref] .
The Correlation Between Halo Mass and Stellar Mass for the Most Massive Galaxies in the Universe · The Relation between the Stellar and Halo Mass of Central Galaxies · 1.00
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