Ram pressure at work in the Shapley supercluster core

Ram pressure at work in the Shapley supercluster core

Investigating ram-pressure stripping from integral-field spectroscopy and multi-band observations

P. Merluzzi 1,G. Busarello1, M. Dopita2, C.P. Haines3, D. Steinhauser4,

A. Mercurio1, A. Rifatto1, R.J. Smith5, S. Schindler4

1 - INAF – Osservatorio di Capodimonte, Napoli Italy2 - Australian National University3 – Steward Observatory, University of Arizona, Tucson US4 – Institute of Astro- and Particle Physics, University of Innsbruck, Austria4 – Department of Physics, University of Durham, UK

Monash University, 11 May 2012

Thursday, January 31, 2013


A galaxy’s environment has a profound effect on its global properties

morphology - density relation(Dressler 1980, Dreseler et al. 1997)

star formation – density relation(Butcher & Oemler 1984, Lewis et al. 2002, Kauffmann et al. 2004)

colour – density relation(Bamford et al. 2009)



Physical processes acting in clusters

Gravitational - tidal interactions:galaxy-galaxy, galaxy-cluster, harassment.

Hydrodynamic interactions between galaxy’s ISM and the hot ICM:ram pressure stripping, viscous stripping, thermal evaporation.

Hybrid processes:“starvation” (removal of the gas feeding the SF), “preprocessing” (taking place in groups of galaxies falling into clusters).(See Boselli & Gavazzi 2006)



Ram pressure stripping Efficient to deplete the gas reservoir of galaxies in cluster environment (Gunn & Gott 1972)

May extend to poorer environments for low-mass galaxies (Marcolini et al. 2003)

Directly affects the density and temperature of the hot gas halo of galaxies, starvation (Bekky et al. 2002, McCarthy et al. 2008, Vollmer et al. 2009)

It proceeds in different phases: instantaneous, intermediate and continuous viscous stripping (Roedigger & Hensler 2005)



Ram pressure stripping phenomenology

Presence of gas outflowDistortion and ultimate truncation of the gas disc

Undisturbed old stellar componentCompression and shock of the ISM

Enhanced star formation in the inner disc and in the gas tail



Role of IFS observations• Dynamical disturbances of the stellar component(Moore et al. 1995; Rubin et al. 1999; Duc et al. 2008; Pracy et al. 2009)• Disturbed gas velocity fields and asymmetric rotation curves (Kronberger et al. 2006, 2007, 2008)• Truncation of the gas disc(Gunn & Gott 1972; Roedigger & Brugger 2005)• Local enhancement of star formation(Barnes et al. 1991; Kromberger at al. 2008; Kapferer et al. 2008, 2009)• Outside-in truncation of star formation(Bekki et al. 2009)• Detached gas(Roedigger & Brugger 2008; Tonnensen et al. 2010; Yoshida et al. 2008; Hester et al. 2010, Sivanandam et al. 2010)



A Complete CEnsus of Star formation and nuclear activity in the Shapley supercluster

INAF – Osservatorio Astronomico di Capodimonte – Italy,University of Bimingham – UK, University of Durham - UK

Australian National University…

FP7-PEOPLE-IRSES-2008 www.na.astro.it/ACCESS



Where?

supercluster environment

higher fraction of galaxies interacting with

the dense ICM respect to isolated clusters;

high infall and encounter velocities of galaxies

(> 1000 km/s);

groups and clusters are still merging.



Shapley Supercluster CoreThe richest supercluster in the nearby universe

25 Abell clusters in the redshift range 0.035 < z < 0.055

(Bardelli et al. 2000; Quintana, Carrasco & Reisenegger 2000; Drinkwater et al. 2004)

SSC: three Abell clusters (A3558, A3562, A3556) and two groups SC1327-312 and SC1329-313.



Shapley WiFeS sample

• 24 galaxies belonging to the SSC• star-forming galaxies (AAOmega)• with disturbed morphologies• the most luminous in K band (K<K*+2) and 24µm Observed:• 15 galaxies, all but one spirals• a sequence in specific star formation rate



40 kpc

WiFeS field of view

WiFeS field of view



Shapley WiFeS sample

They are mainly in low- and intermediate-density regions



WiFeS at ANU 2.3m telescopeDual beam image-slicing integral field spectrographSpectral range: 3300 – 9800 ÅIt records optical spectra over a contiguous 25 x 38 arcsec fov25 1 arcsec – wide ‘slitlets’ with 0.5 arcsec sampling along the 38 arcsec length.



Observations and data reductionWiFeS observations

• B3000 + R3000 gratings (~1.7Å, ~3Å FWHM, 110 kms-1, 130 kms-1)• 4.5 h (6 x 45 min) exposures• 1 exposure on empty sky each 2 galaxy exposures• night calibrations: bias, arcs, flux and telluric standard stars

Data reduction

• WiFeS pipeline (bias subtraction to correction for telluric absorption)• subtraction of spatially smoothed sky frames• spatial scale correction along the slices direction of B (15%) and R (4%) cubes to match the B,R WFI images• registration of individual exposures (CC with WFI images)• final cubes sampled at 1” x 1” x 1 Å / pxl



Stellar componentAccurate model of stellar component is fundamental to extract robust Balmer emission line measurements.

MILES stellar population models(Vazdekis et al. 2010, Sánchez-Blázquez et al. 2006)Model resolution: 2.3 Å WiFeS FWHM: 3 Å and 1.7 ÅThe emission lines are masked40 different SSPs:• 3 metallicities (0.4Zʘ, Zʘ, 2.5Zʘ)• 23 ages (60Myr – 12.6 Gyr)

The blue continuum (3750<λ<5300) is fitted with 8-9 stellar populations



Stellar component

The blue continuum (3750<λ<5300) is fitted with 8-9 stellar populations



Observations and data reductionData analysis• fit and subtraction of the stellar component• Gaussian fit to the emission lines FORTRAN code fitting each line independently (for checking) + 50 simulations to derive uncertainties of the fits• subtraction of the instrumental width from velocity dispersion• spatial binning to achieve SNR>20 for flux ratios (Weighted Voronoj Tessellation, Diehl & Statler 2006) Uncertaintiesfor emission line SNR>5/pxl (line peak / continuum stdev) : • radial velocity: < 5 km/s (+13 km/s from wavelength calibration)• velocity dispersion: < 15 km/s (+5 km/s from instrum. width) • flux: < 30% (+10% from flux calibration)

SNR = 5 flux = 0.5 - 1 x 10-17 erg s-1cm-2arcsec-2



Observations and data reduction

Observed emission lines: ([OII] 3727-9, Hβ (Hγ - Hε), [OIII] 4959-5007, HeI 5876, [OI] 6300, [NII] 6548-83, Hα, [SII] 6717-31)



SOS-114372FUV = 17.11 ± 0.05NUV = 16.68 ± 0.03B = 15.08 ± 0.04R = 14.19 ± 0.04K = 11.50 ± 0.02F24= 42 ± 2 mJyF70= 758 ± 40 mJy

LTIR=1.1 · 1011LʘMstar≈ 6·1010 Mʘ

Mdyn≈ 2·1011MʘMhalo≈ 1.2·1012Mʘ

rd≈ 5.3 kpcn ~ 1 82° inclinationB/D = 0.44

BRK composite



SOS-114372ρ = 0.88 gals arcmin-2

1 Mpc from the clustercentre

z=0.0506z=0.0477 (Smith et al. 2004)



SOS-114372ρ = 0.88 gals arcmin-2

1 Mpc from the clustercentre

z=0.0506z=0.00477 (Smith et al. 2004)

4.5 h

1.5 h



SOS-114372: gas outflow13 kpc in projection out of the galaxy disc

• gas and stellar kinematics• nature of the gas emission• star formation across the galaxy

Ram pressure stripping?



Gas kinematics

• complex velocity field with the kinematics of the outflowing gas still dominated by the galaxy potential



Gas kinematics

• high velocity dispersion (» “normal” HII regions, σ~20-30 km s-1) • due to the spatial sampling and related to the complex gas motions



Gas kinematics

major axis: asymmetric rotation curve

minor axis:gas approaching the observedSW from the centre



Gas kinematics

Numerical simulations predict these asymmetries in the RC for tidal interacting and ram-pressure stripped galaxies.(Kronberger et al. 2006, 2008)

The asymmetry of our RC is consistent with RPS:50 Myr of ram pressure acting face-on, the gas RC of the model galaxy resembles that of SOS-114372

(Dale et al. 2001)

= 0.2



Stellar kinematics

• regular velocity field and symmetric RC

• symptoms of the presence of a bar



Physical properties of the gas

Diagnostic diagrams (Veilleux & Osterbrok, Kauffmann et al. 2003, Kewley et al. 2006)

HII

AGN

Comp

Seyfert

LINERHIIHII

LINER

Seyfert



Physical properties of the gasPhotoionization and shock excitation models (Rich et al.2011)

PM: Starburst99 (Leitherer et al. 1999)

SM: MAPPING IIIr (Sutherland & Dopita 1993) with velocities 100-200 km s-1



Physical properties of the gas

The regions dominated by star formation are located in the SW portion of the galaxy.

Regions in the stripped gas to the NW of the galaxy have much higher shock excitation0.5≤ f ≤ 0.8

Concentration of shock-exited gas along the minor axis SW to the nucleus and in another region along the leading edge.



Dust attenuation

Dust attenuation derived from the Hα/Hβ ratio (Fishera & Dopita 2005).

• dust attenuation asymmetric along the major axis• highest dust extinction in the centre • high extinction also in the SW disc ~12 kpc from the centre• high extinction in the detached gas



Thus…

ram pressure compresses and strips the gas out of the galaxy

forming a tail of turbulent shock-ionized gas and dust

Reduced dust disc in HI-deficient Virgo galaxies (Cortese et al. 2010)

Observed tails of ionized gas (Sun et al. 2007, Yagi et al 2010)swept out from the giant molecular clouds (Gavazzi et al. 2001)or excited directly by the ram pressure (Vollmer et al. 2009, our case)



Current star formation

Hα flux corrected for dust extinction(Kennictt 1998)

Maximum in the centre and local maximum in the SW disc.

In agreement with the 24µm observations

The current SFR occurs in the highly dust-extinguished molecular clouds

Logarithmic SFR density

Integrated Hα-derived SFR of SOS-114372: 7.2±2.2 Mʘ yr-1

50% of which in the centre and in the SW disc region



Recent star-formation history

Spectrum dominated by old stars (>1 Gyr), but also young stars (<1Gyr) contributing 30% of the luminosity and 1% of the stellar mass




Spectrum dominated by young stars (<1 Gyr) contributing 60% of the luminosity and 4% of the stellar mass.

The stellar population modelling suggests: continuous star formation from 100 Myr to 1 Gyr

a short starburst has just been shut down.




Spectrum dominated by young stars (<1 Gyr) contributing 60% of the luminosity and 3.5% of the stellar mass while the rest is

described as a single ~10-15 Gyr old stellar population.

The young stellar population is dominated by <100 Myr old starsThe spectral modelling suggests:

a starburst with 5x increase in the SFR over the last 100 Myr.




Simulations of RPS:SF in the inner disc and/or in the stripped gas (Kronberger et al. 2008)

Depending on the surrounding gas density (Kapferer et al. 2009)

ρICM= 1.3 10-28 g cm-3 (Sanderson & Ponman 2010)at the projected distance of the galaxy from the clustercentre

The newly formed stars are confined into the disceither because of the low ICM density

or because the RPS started less than 100 Mry ago



N-body hydrodynamical simulations of RPS

AIM: to reproduce the observed gas velocity field with RPS

In the early phases of RPS the direction of the ICM wind cannot be inferred from the apparent direction of the gas outflow (e.g. Roedigger & Brüggen 2006).

β: the angle between the galaxy rotation axis and the wind direction

from close to edge-on: 85° ------- to close to face-on: 15° with intervals of 10°

Vwind: from Vlos ~ 830 km s-1 to the escape velocity ~2600 km s-1

830, 1100, 1400, 1700, 2000, 2200, 2400, 2600 km s-1

two different disc scale heights: 10% and 20% of the disc radius rd

8 values of β – 7 values of Vwin – 2 values of rd



N-body hydrodynamical simulations of RPS

GADGET-2 (Springel 2005)

• hydrodynamical part: SPH scheme (Gingold & Monaghan 1977)• gravitational interaction: tree code for the short range force (Barnes & Hut 1986) + treePM code based on the Fourier techniques for the long range force• GADGET-2 includes radiative cooling (Kattz et al. 1996) and recipes for star formation, stellar feedback and galactic winds (Springel & Hernquist 2003)

Simulation setup as Kapferer et al. 2009 and Kronberger et al. 2008

The model galaxy includes:a dark matter halo, a stellar disc, a gaseous disc and a stellar bulgematching the observed properties of SOS-114372



The model galaxy evolves in isolation for 1 Gyr and from the onset of the ram pressure to 100 Myr.

The model galaxy

Stellar and gaseous disc: exponential surfacedensity profile.

Stellar bulge and dark matter halo: Hernquist profile

Mstar≈ 6·1010 Mʘ

Mdyn≈ 2·1011MʘMhalo≈ 1.2·1012MʘB/D = 0.32

ρICM= 1.3 10-28 g cm-3

ρISM= 10-24 g cm-3



Comparison with the observations

Observations

2-D velocity field and surface brightness

Models

6-D particle distribution(xi,yi,zi,Vxi,Vyi,Vzi); i=1,...,Nparticles

orientation of the observer(projection along the line of sight)

seeing (blurring of ~ 1.5 arcsec FWHM)

spatial sampling (1”×1” pixels)




Observations

2-D velocity field and surface brightness

Models

6-D particle distribution(xi,yi,zi,Vxi,Vyi,Vzi); i=1,...,Nparticles

orientation of the observer(projection along the line of sight)

seeing (blurring of ~1.5 arcsec FWHM)

spatial sampling (1”×1” pixels)

Vmodelij

Σmodelij

Vobsij

Fobsij

comparison in pixel space (i,j)

assuming ionized gas traces neutral gase.g. Abramson et al. 2011, Tonnesen & Bryan 2010



Selection of ‘best’ models

Similarity of the radial velocity field:

- estimated by Χ2 =∑(Vmodelij - Vobs.

ij)2/(Npix-1)

Similarity of gas distribution :

- maximum common spatial coverage (simulated gas overlaps by more than 90% to the observed gas) - broad consistency of the shape of gas distribution(smallest scatter of Σmodel at the “borders” of observed gas)

The 10% models with lowest Χ2 values and with consistent gas distributions were considered for further visual inspection.

High-resolution simulations were run for surviving models.



Vwind= 1400 km s-1



t = 60 Myr



Comparison with the observationslow-resolution selection

β = 45° and 55°Vwind = 1400 and 1700 km s-1

rd ~ 10% of the disc scale length



Comparison with the observationshigh-resolution

β = 45° Vwind = 1400 km s-1 β < 45° or β > 55°

Vwind > 1700 km s-1 or Vwind < 1400 km s-1

t<50 Myr or t>65 Myr

model data



ConclusionsSOS 114372: L* spiral galaxy ~1Mpc from the centre of A3558

detected gas out of the disc

With: IFS + multi-wavelength dataWe study: gas and stellar kinematics and propertiesUsing: emission-line diagnostics, stellar population synthesis and photoionization shock models N-body/hydrodynamical simulations



Conclusions• Complex gas velocity field although still dominated by the galaxy potential• High gas velocity dispersion with maxima in the regions of the detached gas and in the opposite disc side



Conclusions• The outflowing gas and three regions in the opposite disc side are dominated by shock-excited gas and attenuated by dust• These regions also show the highest velocity dispersions



Conclusions

• 7.2±2.2 Mʘ yr-1 current SFR with two prominent peaks• a starburst with 5x increase in SFR over the last 100 Mry (SW disc)• a short starburst (300 Myr) just quenched (NW disc)• old stellar populations dominate the galaxy centre with newly formed stars



Conclusions• N-body/hydrodynamical simulations support the RPS scenario

constraining β = 45° Vwind = 1400 km s-1

t ~ 60 Myr

the gas is still bound the burst in the SW disc < 100 Myr ago

RPS can efficiently affect L* galaxies also out of the cluster coreObserved in Virgo (Chung et al. 2007)May affect galaxies also in the cluster outskirts (Roedigger & Hensler 2005)

affecting also the galaxy structure?See simulations (Kapferer et al. 2009)



Vradkm/s



Vradkm/s

70 kpc



120 kpc

Vradkm/s

cluster centre



VST-ACCESS

It will map a large region (~260 Mpc2) of the Shapley supercluster at z=0.048: six Abell cluster and two poor clusters forming a network

Aiming to identify the primary locations (groups, filaments, clusters?) and mechanisms for the transformation of spirals into S0s and dEs i.e to follow the evolution of galaxies from the field, through filaments and groups, to the cluster cores

The VST survey will be the essential foundation of a multi-wavelength survey already available for the Shapley supercluster core.

P. Merluzzi (PI), G. Busarello, C.P. Haines, M.A. Dopita, A. Mercurio, A. Rifatto, K.A. Pimbblet, S. Raychaudhury, G.P. Smith, R.J. Smith, F. Vogt, A. Gargiulo

Partners:INAF (O.A. Capodimonte, Brera-Milano), University of Birmingham, University of Durham. Australian National University, Monash University, Univerity of Arizona



VLT survey Telescope (VST)- 2.6-m wide field optical survey telescope- located on the VLT platform at Cerro Paranal, Chile- operates from the u to the z band- corrected field of view of 1°x1° (0.21 arcsec/pxl)- one focal plane instrument, OmegaCAM, a large format (16k x16k pixels) CCD camera

(VST-ACCESS g-band image)

1°x1°


http://www.eso.org/sci/facilities/paranal/instruments/images/vlt+instr_2009-10.jpg

http://www.eso.org/sci/facilities/paranal/instruments/images/vlt+instr_2009-10.jpg

http://www.eso.org/sci/facilities/paranal/instruments/omegacam/inst

http://www.eso.org/sci/facilities/paranal/instruments/omegacam/inst


VST-ACCESS

Survey specs:Bands: u', g', r', i'.Area: 23deg2 centred in the Shapley supercluster core.

Limiting magnitude: r'AB = 24.6mag (S/N=5 within a 3” aperture) which allows us to study the galaxy properties down to r'AB = 23.5mag (S/N∼20 limit for the galaxy/star separation), i.e. down to Lr*+8.5 at z∼0.05, well into the dwarf regime.



VST-ACCESS

Complementary data/programs:

Already available: • Optical, NIR, FUV/NUV, MIR/FIR imaging (SSC) (ESO/WFI, UKIRT/WFCAM, GALEX, Spitzer/MIPS) •X-ray spectro-imaging (XMM mosaic) (SSC)• radio (VLA 1.4GHz radio continuum)•.Spectroscopy (AAOmega, 6dF) 1200 galaxies – 90% complete to r’<16.5 in the 23deg2 survey field• WISE near- and mid-infrared (M*+4.5) in the 23deg2 survey field

Foreseen: • Optical spectroscopy (AAOmega) for a mass selected galaxy sample down to R=18.7mag (L*+4). • NIR survey with VISTA



VST-ACCESS

First two years plan and scientific goals:

- i’-band coverage over the the full survey region AAOmega spectroscopy survey; mapping of the overall LSS over the 23deg2 field, in terms of the filamentary structure and groups connecting the clusters.

- combination of the VST data of the SSC with the existing multi-wavelength data. relation of the quenching of star-formation to the morphological transformation in the SSC.



VST-ACCESSCoverage at 10 May 2012:



VST-ACCESSFirst reduced data:Pipeline: VST-Tube (Grado et al. 2012)g band: 78000 sources/deg2, seeing=0.57, mcomp=24.2 mAB (~L*+8.5) i band: 68000 sources/deg2, seeing=0.47, mcomp=22.2 mAB (~L*+7.5)



VST-ACCESS



VST-ACCESSScience AimsThe VST survey will provide the fundamental reference for the planned multi-band survey and will effectively contribute to detect some important signatures of galaxy evolution.

To achieve the survey goal the VST data (u', g', r', i') will be used to:

•·select supercluster galaxies through photo-z (M*+6 e.g. D’Ambrusco et al. 2007, Abazajian et al. 2009) ;•·define the environment through the local galaxy density (Haines et al. 2006,2007);•·derive surface photometry to compute internal colour gradients down to Mr * + 6 (e.g. La Barbera et al. 2005);• obtain the morphological classification for a sub-sample of the supercluster galaxies (Conselice et al. 2003);• separate dusty and passive red sequence galaxies (Wolf et al. 2009);• use the calibrated u’-band luminosity as star formation rate indicator (e.g. Moustakas et al. 2006);• use the highest-quality r’–band images for mass estimates and detailed weak-lensing mass maps (e.g. Gavazzi et al. 2009).



VST-ACCESSTimingAt the present detailed studies using panoramic datasets have allowed to follow the evolution of star-formation and galaxy morphologies with redshift for both the general field (e.g. Z-COSMOS, VIRMOS) and massive clusters (e.g. LoCuSS and STAGES at z~0.2, MACS/EdiSCs at 0.4<z<1.0).

One key missing ingredient to understand the morphology-density and SF-density relations, is a panoramic dataset of high-quality optical imaging of nearby galaxy clusters, from the cluster cores to the virial radius and beyond (≥ 5Mpc), following the infall of galaxies along filaments, within groups, or directly from the field (e.g. Balogh et al. 2009, Wilman et al. 2009, Moran et al. 2005).

SDSS provides coverage of many rich local clusters, but it image quality limits robust morphological classifications to massive galaxies (>~L*).

VST-ACCESS will fill this gap a local counterpart to the 0.2<z<1.5, surveys.High-quality optical imaging: FWHM~0.7" at z~0.05 corresponding to 0.7 kpc comparable to HST imaging at z∼0.7 (FWHM~0.1") for galaxy clusters at intermediate redshifts.

The scientific goals of VST-ACCESS cannot be pursued with data from shallower and wider survey (e.g. SkyMapper, VST-ATLAS) or studying less wide and complex structure (e.g. Coma 3-degree Survey)



Ruling out tidal interaction scenario

z K MSOS 144372 0.0506 11.5 6E10SOS 114493 0.050 13.5 2E10SOS 112392 0.046 12.6 7E10SOS 115228 ? 17.0 1.6E08

Unequal mass merger - before the encounterIs the gas RV of SOS 114372 enhanced toward the companion?No gas outflow is predicted.- after the encounterA gas tail directed toward the companion is predicted, but not observed



Ruling out tidal interaction scenario

z K MSOS 144372 0.0506 11.5 6E10SOS 114493 0.050 13.5 2E10SOS 112392 0.046 12.6 7E10SOS 115228 ? 17.0 1.6E08

Equal mass merger - before the encounterNo gas outflow is predicted.- after the encounterBridge directed toward the companion is predicted, but not observeDisc almost completely distroyedRC not flattering toward the companion, but only in the opposite side




2-D velocity field

Seeing effect: associating to each particle a Gaussian with FWHM = seeing

each surface element has

surface density of particlesΣ = the sum of contributions from the Gaussiansradial velocityV = 1/n ∑i vi/Σi

3-D particle distributioneach with its own velocity vector



How to compare Hα flux with Σ

In the intersection between the observed area and Σ>0 with the nuclear and the SW disc regions masked

Χ2 = ∑(Fij-Σij)2/(Npix-1)

In this way we cut the models consistently with the data

I




In the intersection between the observed area and Σ>0 with the nuclear and the SW disc regions masked


BUT the ionized gas is limited by the detection limit while the neutral gas is everywhere

a = 1/N ∑ Σij/Fij (F=1-10)

10% ranked: a=1.21±0.23particle surface density corresponding to our lowest detection

II




Σ>a with the nuclear and the SW disc regions masked


Only models covering at least 80% of the observed area

38% on the cases survived at these selection

II



The global properties of galaxies have been found to be bimodally distributed,

indicating two separate populations:

• colours (Driver et al. 2006)

• morphologies (Driver et al. 2006)

• spectral indices (Kauffmann et al. 2003)

• mean stellar ages (Haines et al. 2006)



Specific star formation rate: passive-evolving ellipticals and star-forming spirals

F24: current SFK band: stellar mass

Green: confirmed supercluster membersBlue: photometric selected supercluster galaxies

Haines et al. 2011



Conclusions• Complex gas velocity field although still dominated by the galaxy potential• High gas velocity dispersion with maxima in the regions of the detached gas and in the opposite disc side• The galaxy regions of the outflowing gas and three regions in the opposite disc side are dominated by shock-excited gas and attenuated by dust• These regions also show the highest velocity dispersions• 7.2±2.2 Mʘ yr-1 current SFR with two prominent peaks• a starburst with 5x increase in SFR over the last 100 Mry (SW disc)• a short starburst (300 Myr) just quenched (NW disc)• old stellar population dominates the galaxy centre with newly formed stars



112 models run in low-resolution

“observed” at least at 10 Myr intervals from the onset of RPS to 100 Myr

from 2 to 4 viewing angles

results are based on the analysis of ~3000 realizations of the simulations




3-D particle distributioneach with its own velocity vector 2-D velocity field




2-D velocity field

Constraints on the viewing directions:i) the inclination angle of 82°ii) Vgal project into Vlos

models can be observed by 2 or 4 directions depending on β

3-D particle distributioneach with its own velocity vector




2-D velocity field3-D particle distributioneach with its own velocity vector

surface density of particles Σij vs. Iij(Hα)




Issue: the simulations reproduce the velocity field of the whole gas while the data refer to the ionized gas only

We assume that the neutral and ionized gas are mixed (e.g. Abramson et al. 2011, Tonnesen & Bryan 2010)

The ionized gas traces the HI column density and the general gas velocity field


Ram pressure at work in the Shapley supercluster core

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