Fossil group origins

Zarattini, S.; Girardi, M.; Aguerri, J. A. L.; Boschin, W.; Barrena, R.; Burgo, C. del; Castro-Rodríguez, N.; Corsini, E. M.; D’Onghia, Elena; Kundert, A.; Méndez-Abreu, J.; Sánchéz-Janssen, R.

doi:10.1051/0004-6361/201527175

Cited by 26 publications

(25 citation statements)

References 74 publications

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“…This lack of substructure in fossil halos has been interpreted as a challenge for the hierarchical formation (D'Onghia & Lake 2004); nevertheless, this is still a puzzle and a matter of debate (Zibetti et al 2009). The galaxy population in FSs also shows evidence of substructure similar to nonFSs, arguing against the relaxed and old dynamical age of FSs (Zarattini et al 2016). …”

Section: Introductionmentioning

confidence: 93%

“…The catalog turned out to have 89 galaxies brighter than m r ∼ 18.0 with measured radial velocities. Using this data-set from SDSS-DR6, Zarattini et al (2016) reported that the mean velocity of group (V c ) was 15498 km s −1 , and the velocity dispersion σ c = 259 km s −1 . The estimate of L X allowed us to calculate r 200 = 0.96 Mpc (Zarattini et al 2014) using the relations from Böhringer et al (2007) and Arnaud et al (2005).…”

Section: The Data For Rxj0752436+455653mentioning

confidence: 99%

“…This project aims at a multiwavelength characterization of a large sample of FSs (see Aguerri et al 2011). We have analyzed so far the properties of their (i) dark matter halos Kundert et al 2015), (ii) the central BGGs (Méndez-Abreu et al 2012;Zarattini et al 2014), and (iii) the galaxy populations (Zarattini et al 2015(Zarattini et al , 2016. These observational properties have been compared with state-of-the-art cosmological simulations (Kundert et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Fossil group origins

Aguerri

Longobardi

Zarattini

et al. 2018

A&A

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Context. It is thought that fossil systems are relics of structure formation in the primitive Universe. They are galaxy aggregations that have assembled their mass at high redshift with few or no subsequent accretion. Observationally these systems are selected by large magnitude gaps between their 1st and 2nd ranked galaxies (∆m 12 ). Nevertheless, there is still debate over whether or not this observational criterium selects dynamically evolved ancient systems. Aims. We have studied the properties of the nearby fossil group RXJ075243.6+455653 in order to understand the mass assembly of this system. Methods. Deep spectroscopic observations allow us to construct the galaxy luminosity function (LF) of RXJ075243.6+455653 down to M * r + 6. The analysis of the faint-end of the LF in groups and clusters provides valuable information about the mass assembly of the system. In addition, we have analyzed the nearby large-scale structure around this group. The LF of the group shows a flat faint-end slope (α = −1.08 ± 0.33). This low density of dwarf galaxies is confirmed by the low value of the dwarf-to-giant ratio (DGR = 0.99 ± 0.49) for this system. Both the lack of dwarf galaxies and the low luminosity of the BGG suggests that RXJ075243.6+455653 still has to accrete mass from its nearby environment. This mass accretion will be achieved because it is the dominant structure of a rich environment formed by several groups of galaxies (15) within ∼ 7 Mpc from the group center and with ±1000 km s −1 . Conclusions. RXJ075243.6+455653 is a group of galaxies that has not yet completed the process of its mass assembly. This new mass accretion will change the fossil state of the group. This group is an example of a galaxy aggregation selected by a large magnitude gap but still in the process of the accretion of its mass.

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Section: Introductionmentioning

confidence: 93%

Section: The Data For Rxj0752436+455653mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fossil group origins

Aguerri

Longobardi

Zarattini

et al. 2018

A&A

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“…Aguerri et al (2011) analyzed one FG finding no significant galaxy substructure. Nevertheless, the study from Zarattini et al (2016) on a larger sample of fossils, found that FGs show similar amounts of galaxy substructure as non-FGs. In addition, no differences have been found on the large-scale structure around fossil systems.…”

Section: Introductionmentioning

confidence: 95%

Are Fossil Groups Early-forming Galaxy Systems?

Kundert

D’Onghia

Aguerri

2017

ApJ

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Using the Illustris cosmological simulation, we investigate the origin of fossil groups in the M 200 = 10 13 − 10 13.5 M /h mass regime. We examine the formation of the two primary features of fossil groups: the large magnitude gap between their two brightest galaxies, and their exceptionally luminous brightest group galaxy (BGG). For fossils and non-fossils identified at z = 0, we find no difference in their halo mass assembly at early times, departing from previous studies. However, we do find a significant difference in the recent accretion history of fossil and non-fossil halos; in particular, fossil groups show a lack of recent accretion and have in majority assembled 80% of their M 200 (z = 0) mass before z ∼ 0.4. For fossils, massive satellite galaxies accreted during this period have enough time to merge with the BGG by the present day, producing a more massive central galaxy; and, the lack of recent group accretion prevents replenishment of the bright satellite population, allowing for a large magnitude gap to develop within the past few Gyr. We thus find that the origin of the magnitude gap and overmassive BGG of fossils in Illustris depends on the recent accretion history of the groups and merger history of the BGG after their collapse at z ∼ 1. This indicates that selecting galaxy groups by their magnitude gap does not guarantee obtaining neither early-forming galaxy systems nor undisturbed central galaxies.

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“…Extreme examples of the correlation between group age and the central-to-satellite mass ratio are fossil groups and clusters (e.g. Jones et al 2003;Zarattini et al 2016), in which the most massive satellite of the system is at least two magnitudes fainter than the central, brightest galaxy. D' Onghia et al (2005) and Dariush et al (2010), among others, showed that in a hierarchical universe, these fossil groups are expected to have been formed at much higher redshift than other groups of the same mass.…”

Section: Discussionmentioning

confidence: 99%

Assembly bias evidence in close galaxy pairs

Ferreras

Hopkins

Lagos

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The growth channel of massive galaxies involving mergers can be studied via close pairs as putative merger progenitors, where the stellar populations of the satellite galaxies will be eventually incorporated into the massive primaries. We extend our recent analysis of the GAMA-based sample of close pairs presented in Ferreras et al. to the general spectroscopic dataset of SDSS galaxies (DR14), for which the high S/N of the data enables a detailed analysis of the differences between satellite galaxies with respect to the mass of the primary galaxy. A sample of approximately two thousand satellites of massive galaxies is carefully selected within a relatively narrow redshift range (0.07

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Fossil group origins

Cited by 26 publications

References 74 publications

Fossil group origins

Fossil group origins

Are Fossil Groups Early-forming Galaxy Systems?

Assembly bias evidence in close galaxy pairs

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