scholarly journals GASP XXIX – unwinding the arms of spiral galaxies via ram-pressure stripping

2020 ◽  
Vol 500 (1) ◽  
pp. 1285-1312
Author(s):  
Callum Bellhouse ◽  
Sean L McGee ◽  
Rory Smith ◽  
Bianca M Poggianti ◽  
Yara L Jaffé ◽  
...  
Keyword(s):  
Spiral Galaxies ◽  
Control Group ◽  
Original Structure ◽  
Gas Stripping ◽  
Spiral Arms ◽  
Cluster Galaxies ◽  
Pile Up ◽  
Ram Pressure ◽  
Disc Rotation ◽  
Gravitational Influence

ABSTRACT We present the first study of the effect of ram pressure ‘unwinding’ the spiral arms of cluster galaxies. We study 11 ram-pressure stripped galaxies from GASP (GAs Stripping Phenomena in galaxies) in which, in addition to more commonly observed ‘jellyfish’ features, dislodged material also appears to retain the original structure of the spiral arms. Gravitational influence from neighbours is ruled out and we compare the sample with a control group of undisturbed spiral galaxies and simulated stripped galaxies. We first confirm the unwinding nature, finding that the spiral arm pitch angle increases radially in 10 stripped galaxies and also simulated face-on and edge-on stripped galaxies. We find only younger stars in the unwound component, while older stars in the disc remain undisturbed. We compare the morphology and kinematics with simulated ram-pressure stripping galaxies, taking into account the estimated inclination with respect to the intracluster medium (ICM) and find that in edge-on stripping, unwinding can occur due to differential ram pressure caused by the disc rotation, causing stripped material to slow and ‘pile up’. In face-on cases, gas removed from the outer edges falls to higher orbits, appearing to ‘unwind’. The pattern is fairly short-lived (<0.5 Gyr) in the stripping process, occurring during first infall and eventually washed out by the ICM wind into the tail of the jellyfish galaxy. By comparing simulations with the observed sample, we find that a combination of face-on and edge-on ‘unwinding’ effects is likely to be occurring in our galaxies as they experience stripping with different inclinations with respect to the ICM.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A20 ◽  
Author(s):  
E. Koulouridis ◽  
M. Ricci ◽  
P. Giles ◽  
C. Adami ◽  
M. Ramos-Ceja ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
High Mass ◽  
Host Galaxy ◽  
Gas Stripping ◽  
X Ray ◽  
Cluster Galaxies ◽  
Cluster Mass ◽  
Ram Pressure ◽  
Low Mass

Context. We present the results of a study of the active galactic nucleus (AGN) density in a homogeneous and well-studied sample of 167 bona fide X-ray galaxy clusters (0.1 < z < 0.5) from the XXL Survey, from the cluster core to the outskirts (up to 6r500). The results can provide evidence of the physical mechanisms that drive AGN and galaxy evolution within clusters, testing the efficiency of ram pressure gas stripping and galaxy merging in dense environments. Aims. The XXL cluster sample mostly comprises poor and moderately rich structures (M = 1013–4 × 1014 M⊙), a poorly studied population that bridges the gap between optically selected groups and massive X-ray selected clusters. Our aim is to statistically study the demographics of cluster AGNs as a function of cluster mass and host galaxy position. Methods. To investigate the effect of the environment on AGN activity, we computed the fraction of spectroscopically confirmed X-ray AGNs (LX [0.5-10 keV] > 1042 erg cm−1) in bright cluster galaxies with Mi* − 2 < M < Mi* + 1, up to 6r500 radius. The corresponding field fraction was computed from 200 mock cluster catalogues with reshuffled positions within the XXL fields. To study the mass dependence and the evolution of the AGN population, we further divided the sample into low- and high-mass clusters (below and above 1014M⊙, respectively) and two redshift bins (0.1–0.28 and 0.28–0.5). Results. We detect a significant excess of X-ray AGNs, at the 95% confidence level, in low-mass clusters between 0.5r500 and 2r500, which drops to the field value within the cluster cores (r < 0.5r500). In contrast, high-mass clusters present a decreasing AGN fraction towards the cluster centres, in agreement with previous studies. The high AGN fraction in the outskirts is caused by low-luminosity AGNs, up to LX [0.5-10 keV] = 1043 erg cm−1. It can be explained by a higher galaxy merging rate in low-mass clusters, where velocity dispersions are not high enough to prevent galaxy interactions and merging. Ram pressure stripping is possible in the cores of all our clusters, but probably stronger in deeper gravitational potentials. Compared with previous studies of massive or high-redshift clusters, we conclude that the AGN fraction in cluster galaxies anti-correlates strongly with cluster mass. The AGN fraction also increases with redshift, but at the same rate with the respective fraction in field galaxies.

scholarly journals Ram Pressure Stripping of Spiral Galaxies in Clusters

2004 ◽  
Vol 217 ◽  
pp. 376-381
Author(s):  
Elke Schumacher ◽  
Gerhard Hensler
Keyword(s):  
Mass Loss ◽  
Spiral Galaxies ◽  
Disk Galaxies ◽  
Helmholtz Instability ◽  
Restoring Force ◽  
Ram Pressure ◽  
First Results ◽  
Two Phases ◽  
Gas Loss ◽  
Long Timescales

We investigate the process of ram pressure stripping by means of numerical simulations with a 2D hydrodynamical code. We present some first results of a set of simulations with varying galaxy velocities and ICM densities. We find that in typical cluster core environments disk galaxies lose a substantial amount of their gas, whereas in the outskirts of galaxy clusters the mass loss is quite small. Furthermore, the gas loss happens in two phases: In the initial phase gas is pushed out of regions where the ram pressure overcomes the gravitational restoring force; most of the overall gas loss happens in this phase. Afterwards the Kelvin-Helmholtz instability leads to a further mass loss at a small rate, that could be important on long timescales.

DARK MATTER AND DYNAMICS IN HERCULES CLUSTER

1994 ◽  
Vol 03 (supp01) ◽  
pp. 93-100
Author(s):  
Christina M. Bird ◽  
John M. Dickey ◽  
E.E. Salpeter
Keyword(s):  
Dark Matter ◽  
Total Mass ◽  
Virial Theorem ◽  
Spiral Galaxies ◽  
Large Body ◽  
Statistical Test ◽  
Mass Determination ◽  
Dynamical Mass ◽  
Cluster Galaxies ◽  
Abell Cluster

We present new 21-cm observations of faint (15.7<mpg<16.5) spiral galaxies in the Abell cluster 2151. These results, when combined with the large body of velocities available in the literature for Hercules, permit us to study the dynamics throughout the cluster core, out to a projected radius of 1.8h−1 Mpc. We calculate the global dynamical mass of Hercules using 3 different but related methods: two versions of the virial theorem and the projected mass estimator. These masses lie in the range 3–6×1014 M⊙. We investigate the importance of subclustering in A2151 using the statistical test of Dressler and Shectman1 and the effects of the detected substructure on the dynamical mass determination. The clumpy distribution of galaxies is interpreted as a sign that the galaxies in the cluster have not reached dynamical equilibrium in the gravitational potential, which means that dynamical mass estimates are prone to significant errors. In spite of this uncertainty, we estimate that the virial theorem errors due to the presence of substructure are not larger than 30% in A2151. Finally, we use the 21-cm linewidths to estimate the minimum total mass in the cluster which is contained within the HI radii of the cluster galaxies is about 3×1014 M⊙. This number may be compared with the dynamical mass and used to separate the contribution of dark matter inside and outside the HI envelopes of galaxies, and the fraction of DM which cannot be associated with individual galaxies, about 90–95%.

scholarly journals IR imaging of spiral galaxy bulges

1993 ◽  
Vol 153 ◽  
pp. 441-442
Author(s):  
Dennis Zaritsky ◽  
Marcia Rieke ◽  
Hans-Walter Rix
Keyword(s):  
Spiral Galaxy ◽  
Stellar Population ◽  
Spiral Galaxies ◽  
Spiral Arms ◽  
Ir Imaging ◽  
The Impact

Imaging in the infrared (2.2μ) minimizes the impact of dust obscuration and allows reliable mapping of the mass-tracing stellar population in spiral galaxies. We find dramatic differences compared to photometry at shorter wavelengths (e.g. 0.8μ). As an example, the observations of the mini-bar and inner spiral arms of M 51 are discussed.

scholarly journals The Tully-Fisher relation: evolution with redshift and environment

2006 ◽  
Vol 2 (S235) ◽  
pp. 8-11 ◽  
Author(s):  
Alfonso Aragón-Salamanca
Keyword(s):  
Spiral Galaxies ◽  
Rotation Velocity ◽  
Disk Galaxies ◽  
Cluster Galaxies ◽  
Fundamental Properties ◽  
Look Back ◽  
Formation And Evolution ◽  
Fisher Relation

AbstractThe Tully-Fisher Relation (TFR) links two fundamental properties of disk galaxies: their luminosity and their rotation velocity (mass). The pioneering work of Vogt et al. in the 1990's showed that it is possible to study the TFR for spiral galaxies at considerable look-back-times, and use it as a powerful probe of their evolution. In recent years, several groups have studied the TFR for galaxies in different environments reaching redshifts beyond one. In this brief review I summarise the main results of some of these studies and their consequences for our understanding of the formation and evolution of disk galaxies. Particular emphasis is placed on the possible environment-driven differences in the behaviour of the TFR for field and cluster galaxies.

STRUCTURES OUT OF CHAOS IN BARRED-SPIRAL GALAXIES

2012 ◽  
Vol 22 (09) ◽  
pp. 1230029 ◽  
Author(s):  
P. A. PATSIS
Keyword(s):  
Near Infrared ◽  
Spiral Galaxies ◽  
Morphological Features ◽  
Infrared Images ◽  
Chaotic Motions ◽  
Spiral Arms ◽  
Gravitational Fields ◽  
Pattern Speed ◽  
Barred Spiral Galaxies ◽  
Kinematical Data

We review the dynamical mechanisms we have found to support the morphological features in barred-spiral galaxies based on chaotic motions of stars in their gravitational fields. These morphological features are the spiral arms, that emerge out of the ends of the bar, but also shape the bar itself. The potentials used have been estimated directly from near-infrared images of barred-spiral galaxies. In this paper, we present the results from the study of the dynamics of the potentials of the galaxies NGC 4314, NGC 1300 and NGC 3359. The main unknown parameter in our models is the pattern speed of the system Ωp. By varying Ωp, we have investigated several cases trying to match the results of our modeling with available photometrical and kinematical data. We found realistic models with stars on spirals in chaotic motion, while their bars are built by stars usually on regular orbits. However, we also encountered cases, where a major part of trajectories of the stars even in the bar is chaotic as well. Finally, we examined the gas dynamics of barred-spiral systems, and found that the presence of gas reinforces the intensity of the "chaotic" spiral arms.

scholarly journals Environmental Mechanisms Shaping the Nature of Dwarf Spheroidal Galaxies: The View of Computer Simulations

2010 ◽  
Vol 2010 ◽  
pp. 1-21 ◽  
Author(s):  
Lucio Mayer
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
Feedback Mechanism ◽  
Gas Stripping ◽  
Morphological Transformation ◽  
Dwarf Spheroidal Galaxies ◽  
Tidal Forces ◽  
Ram Pressure ◽  
Low Metallicity

We review numerical works carried out over the last decade on the role of environmental mechanisms in shaping nature of the faintest galaxies known, dwarf spheroidals (dSphs). The combination of tidally induced morphological transformation, termed tidal stirring, with mass loss due to tidal and ram-pressure stripping aided by heating due to the cosmic ionizing background can turn late-type dwarfs resembling present-day dIrrs into classic dSphs. The time of infall into the primary halo is shown to be a key parameter. Dwarfs accreting at when the cosmic ultraviolet ionizing flux was much higher than today, and was thus able to keep the gas in the dwarfs warm and diffuse, were rapidly stripped of their baryons via ram pressure and tidal forces, producing very dark-matter-dominated objects with truncated star-formation histories, such as the Draco dSph. The low star-formation efficiency expected in such low-metallicity objects prior to their infall was crucial for keeping their disks gas dominated until stripping took over.Therefore gas stripping along with inefficient star-formation provides a new feedback mechanism, alternative to photoevaporation or supernovae feedback, playing a crucial role in dwarf galaxy formation and evolution. We also discuss how the ultra-faint dSphs belong to a different population of lower-mass dwarf satellites that were mostly shaped by reionization rather than by environmental mechanisms (“reionization fossils”). Finally, we scrutinize the various caveats in the current understanding of environmental effects as well as other recent ideas on the origin of Local Group dSphs.

scholarly journals A Gaseous Group with Unusual Remote Star Formation

2011 ◽  
Vol 28 (3) ◽  
pp. 271-279 ◽  
Author(s):  
N. Santiago-Figueroa ◽  
M. E. Putman ◽  
J. Werk ◽  
G. R. Meurer ◽  
E. Ryan-Weber
Keyword(s):  
Star Formation ◽  
Spiral Galaxy ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Spiral Arms ◽  
Gaseous Disk ◽  
Ram Pressure ◽  
The Galaxy ◽  
Galaxy Center ◽  
Region 10

AbstractWe present VLA 21-cm observations of the spiral galaxy ESO 481-G017 to determine the nature of remote star formation traced by an Hii region found 43 kpc and ∼800 km s−1 from the galaxy center (in projection). ESO 481-G017 is found to have a 120 kpc Hi disk with a mass of 1.2 × 1010M⊙ and UV GALEX images reveal spiral arms extending into the gaseous disk. Two dwarf galaxies with Hi masses close to 108M⊙ are detected at distances of ∼200 kpc from ESO 481-G017 and a Hi cloud with a mass of 6 × 107M⊙ is found near the position and velocity of the remote Hii region. The Hii region is somewhat offset from the Hi cloud spatially and there is no link to ESO 481-G017 or the dwarf galaxies. We consider several scenarios for the origin of the cloud and Hii region and find the most likely is a dwarf galaxy that is undergoing ram pressure stripping. The Hi mass of the cloud and Hi luminosity of the Hii region (1038.1 erg s−1) are consistent with dwarf galaxy properties, and the stripping can trigger the star formation as well as push the gas away from the stars.

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