Too dense to go through: The importance of low-mass clusters for satellite quenching

We study the evolution of satellite galaxies in clusters of the C-EAGLE simulations, a suite of 30 high-resolution cosmological hydrodynamical zoom-in simulations based on the EAGLE code. We find that the majority of galaxies that are quenched at $z=0$ ($\gtrsim$ 80$\%$) reached this state in a dense environment (log$_{10}$M$_{200}$[M$_{\odot}$]$\geq$13.5). At low redshift, regardless of the final cluster mass, galaxies appear to reach their quenching state in low mass clusters. Moreover, galaxies quenched inside the cluster that they reside in at $z=0$ are the dominant population in low-mass clusters, while galaxies quenched in a different halo dominate in the most massive clusters. When looking at clusters at $z>0.5$, their in-situ quenched population dominates at all cluster masses. This suggests that galaxies are quenched inside the first cluster they fall into. After galaxies cross the cluster's $r_{200}$ they rapidly become quenched ($\lesssim$ 1Gyr). Just a small fraction of galaxies ($\lesssim 15\%$) is capable of retaining their gas for a longer period of time, but after 4Gyr, almost all galaxies are quenched. This phenomenon is related to ram pressure stripping and is produced when the density of the intracluster medium reaches a threshold of $\rho_{\rm ICM}$ $\sim 3 \times 10 ^{-5}$ n$_{\rm H}$ (cm$^{-3}$). These results suggest that galaxies start a rapid-quenching phase shortly after their first infall inside $r_{200}$ and that, by the time they reach $r_{500}$, most of them are already quenched.Comment: 14 pages, 8 figures, Submitted to MNRA

Pre- and post-processing of cluster galaxies out to 5×R2005 \times R_{200}: The extreme case of A2670

We study galaxy interactions in the large scale environment around A2670, a massive ($M_{200}$ = $8.5 \pm 1.2~\times 10^{14} \mathrm{M_{\odot}}$) and interacting galaxy cluster at z = 0.0763. We first characterize the environment of the cluster out to 5$\times R_{200}$ and find a wealth of substructures, including the main cluster core, a large infalling group, and several other substructures. To study the impact of these substructures (pre-processing) and their accretion into the main cluster (post-processing) on the member galaxies, we visually examined optical images to look for signatures indicative of gravitational or hydrodynamical interactions. We find that $\sim 21$ % of the cluster galaxies have clear signs of disturbances, with most of those ($\sim60$ %) likely being disturbed by ram pressure. The number of ram-pressure stripping candidates found (101) in A2670 is the largest to date for a single system, and while they are more common in the cluster core, they can be found even at $> 4 \times R_{200}$, confirming cluster influence out to large radii. In support of a pre-processing scenario, most of the disturbed galaxies follow the substructures found, with the richest structures having more disturbed galaxies. Post-processing also seems plausible, as many galaxy-galaxy mergers are seen near the cluster core, which is not expected in relaxed clusters. In addition, there is a comparable fraction of disturbed galaxies in and outside substructures. Overall, our results highlight the complex interplay of gas stripping and gravitational interactions in actively assembling clusters up to $5\times R_{200}$, motivating wide-area studies in larger cluster samples.Comment: Accepted for publication in MNRA

On the evolution of low-mass central galaxies in the vicinity of massive structures

Fil: Palma, Daniela. Universidad de Atacama. Instituto de Astronomía y Ciencias Planetarias de Atacama; Chile.Fil: Lacerna, Ivan. Universidad de Atacama. Instituto de Astronomía y Ciencias Planetarias de Atacama; Chile.Fil: Lacerna, Ivan. Millennium Institute of Astrophysics; Chile.Fil: Artale, Maria Celeste. Universidad Andres Bello. Facultad de Ciencias Exactas. Departamento de Ciencias Físicas. Instituto de Astrofísica; Chile.Fil: Montero Dorta, Antonio David. Universidad Técnica Federico Santa Maria. Departamento de Física; Chile.Fil: Ruiz, Andrés Nicolás. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Ruiz, Andrés Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Cora, Sofía Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astrofísica de La Plata; Argentina.Fil: Cora, Sofía Alejandra. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina.Fil: Rodriguez, Facundo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Rodriguez, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Pallero, Diego. Universidad Técnica Federico Santa María. Departamento de Física; Chile.Fil: O’Mill, Ana. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: O’Mill, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Choque-Challapa, Nelvy. Universidad de Atacama. Instituto de Astronomía y Ciencias Planetarias de Atacama; Chile.Fil: Choque-Challapa, Nelvy. Universidad Técnica Federico Santa Maria. Departamento de Física; Chile.We investigate low-mass central galaxies with Mstar = 109.5−1010 Msun/h, located near massive groups and galaxy clusters using the TNG300 and MDPL2-SAG simulations. We set out to study their evolution, aiming to find hints about the large-scale conformity signal they produce. We also use a control sample of low-mass central galaxies located far away from massive structures. For both samples, we find a sub-population of galaxies that were accreted by another halo in the past but are now considered central galaxies; we refer to these objects as former satellites. The fraction of former satellites is higher for quenched central galaxies near massive systems: 45% in TNG300 and 17% in MDPL2-SAG. Our results in TNG300 show that former satellites were typically hosted by massive dark matter halos (M200 ≥1013 Msun/h) at z∼0.3, followed by a drop in halo mass at lower redshifts. In addition, we find a strong drop in the total gas mass at z≤1 for quenched central galaxies near galaxy groups and clusters produced by these former satellites as well. By removing former satellites, the evolution of quenched central galaxies is fairly similar to those of the quenched control galaxies, showing small differences at low-z. For MDPL2-SAG, former satellites were hosted by less massive halos, with a mean halo mass around 1011 Msun/h, and the evolution remains equal before and after removing former satellites. We also measure the two-halo conformity, i.e., the correlation in the specific SFR between low-mass central galaxies and their neighbors at Mpc scales, and how former satellites contribute to the signal at z=0, 0.3, and 1. The conformity signal decreases from z=0 to z=1 in MDPL2-SAG but it increases in TNG300. However, after removing former satellites in TNG300, the signal is strongly reduced but almost does not change at z≤0.3, and it disappears at z=1 (abridged).info:eu-repo/semantics/acceptedVersionFil: Palma, Daniela. Universidad de Atacama. Instituto de Astronomía y Ciencias Planetarias de Atacama; Chile.Fil: Lacerna, Ivan. Universidad de Atacama. Instituto de Astronomía y Ciencias Planetarias de Atacama; Chile.Fil: Lacerna, Ivan. Millennium Institute of Astrophysics; Chile.Fil: Artale, Maria Celeste. Universidad Andres Bello. Facultad de Ciencias Exactas. Departamento de Ciencias Físicas. Instituto de Astrofísica; Chile.Fil: Montero Dorta, Antonio David. Universidad Técnica Federico Santa Maria. Departamento de Física; Chile.Fil: Ruiz, Andrés Nicolás. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Ruiz, Andrés Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Cora, Sofía Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astrofísica de La Plata; Argentina.Fil: Cora, Sofía Alejandra. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina.Fil: Rodriguez, Facundo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Rodriguez, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Pallero, Diego. Universidad Técnica Federico Santa María. Departamento de Física; Chile.Fil: O’Mill, Ana. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: O’Mill, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Choque-Challapa, Nelvy. Universidad de Atacama. Instituto de Astronomía y Ciencias Planetarias de Atacama; Chile.Fil: Choque-Challapa, Nelvy. Universidad Técnica Federico Santa Maria. Departamento de Física; Chile

An environmental dependence of the physical and structural properties in the Hydra cluster galaxies

The nearby Hydra cluster (∼50 Mpc) is an ideal laboratory to understand, in detail, the influence of the environment on the morphology and quenching of galaxies in dense environments. We study the Hydra cluster galaxies in the inner regions (1R200) of the cluster using data from the Southern Photometric Local Universe Survey, which uses 12 narrow and broad-band filters in the visible region of the spectrum. We analyse structural (Sérsic index, effective radius) and physical (colours, stellar masses, and star formation rates) properties. Based on this analysis, we find that ∼88 per cent of the Hydra cluster galaxies are quenched. Using the Dressler–Schectman test approach, we also find that the cluster shows possible substructures. Our analysis of the phase-space diagram together with density-based spatial clustering algorithm indicates that Hydra shows an additional substructure that appears to be in front of the cluster centre, which is still falling into it. Our results, thus, suggest that the Hydra cluster might not be relaxed. We analyse the median Sérsic index as a function of wavelength and find that for red [(u − r) ≥2.3] and early-type galaxies it displays a slight increase towards redder filters (13 and 18 per cent, for red and early type, respectively), whereas for blue + green [(u − r)<2.3] galaxies it remains constant. Late-type galaxies show a small decrease of the median Sérsic index towards redder filters. Also, the Sérsic index of galaxies, and thus their structural properties, do not significantly vary as a function of clustercentric distance and density within the cluster; and this is the case regardless of the filter.CL-D acknowledges scholarship from CONICYT-PFCHA/Doctorado Nacional/2019-21191938. CL-D and AM acknowledge support from FONDECYT Regular grant 1181797. CL-D acknowledges also the support given by the ‘Vicerrectoría de Investigacion de la Universidad de La Serena’ program ‘Apoyo al fortalecimiento de grupos de investigacion’. CL-D and AC acknowledges to Steven Bamford and Boris Haeussler with the MegaMorph project. CL-D and DP acknowledge support from fellowship ‘Becas Doctorales Institucionales ULS’, granted by the ‘Vicerrectoría de Investigacion y Postgrado de la Universidad de La Serena’. AM and DP acknowledge funding from the Max Planck Society through a ‘Partner Group’ grant. DP acknowledges support from FONDECYT Regular grant 1181264. This work has used the computing facilities of the Laboratory of Astroinformatics (Instituto de Astronomia, Geofísica e Ciencias Atmosféricas, Departamento de Astronomia/USP, NAT/Unicsul), whose purchase was made possible by FAPESP (grant 2009/54006-4) and the INCT-A. YJ acknowledges financial support from CONICYT PAI (Concurso Nacional de Inserción en la Academia 2017) No. 79170132 and FONDECYT Iniciación 2018 No. 11180558. LS thanks the FAPESP scholarship grant 2016/21664-2. AAC acknowledges support from FAPERJ (grant E26/203.186/2016), CNPq (grants 304971/2016-2 and 401669/2016-5), and the Universidad de Alicante (contract UATALENTO18-02). AMB thanks the FAPESP scholarship grant 2014/11806-9. RA acknowedges support from ANID FONDECYT Regular grant 1202007

Formation of S0s in extreme environments III: the role of environment in the formation pathways

It is well established that there are at least two main channels to form lenticular (or S0) galaxies. The first, which we name "faded spiral" scenario, includes quenching events that led to consumption or removal of gas from a spiral progenitor. The second, which we call "merger" scenario, includes merger-like events and interactions between galaxies. Each scenario leaves characteristic signatures in the newly-formed lenticular galaxy. However, the conditions that trigger one mechanism over another are still unknown. This paper is the third of a series aimed at understanding the role of the environment in the formation of lenticular galaxies. In this study, we combine the kinematics, morphology, and properties of the stellar populations of 329 S0s from the SAMI and MaNGA surveys in order to highlight the role of the environment in the process.We divide the S0s into two classes (A and B) according to their global properties, that we can associate to the products of a faded spiral scenario (class A) or a merger scenario (class B). We then study how the various classes are distributed within different environments. Our study reveals that the "faded spiral" pathway is the most efficient channel to produce S0s, and it becomes more efficient as the mass of the group or cluster or local density of galaxies increase. The merger pathway is also a viable channel, and its efficiency becomes higher with decreasing local density or environment mass.Comment: 12 pages, 9 figures, accepted for publication in MNRA

Linking the brightest stellar streams with the accretion history of Milky Way like galaxies

According to the current galaxy-formation paradigm, mergers and interactions play an important role in shaping present-day galaxies. The remnants of this merger activity can be used to constrain galaxy-formation models. In this work, we use a sample of 30 hydrodynamical simulations of Milky Way mass haloes, from the AURIGA project, to generate surface brightness maps and search for the brightest stream in each halo as a function of varying limiting magnitude. We find that none of the models shows signatures of stellar streams at μlimr≤25 mag arcsec−2. The stream detection increases significantly between 28 and 29 mag arcsec−2. Nevertheless, even at 31 mag arcsec−2, 13 per cent of our models show no detectable streams. We study the properties of the brightest streams progenitors (BSPs). We find that BSPs are accreted within a broad range of infall times, from 1.6 to 10 Gyr ago, with only 25 per cent accreted within the last 5 Gyrs; thus, most BSPs correspond to relatively early accretion events. We also find that 37 per cent of the BSPs survive to the present day. The median infall times for surviving and disrupted BSPs are 5.6 and 6.7 Gyr, respectively. We find a clear relation between infall time and infall mass of the BSPs, such that more massive progenitors tend to be accreted at later times. However, we find that the BSPs are not, in most cases, the dominant contributor to the accreted stellar halo of each galaxy