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Galaxy Wakes – Theory & Observations

Galaxy Wakes – Theory & Observations. Irini Sakelliou University of Birmingham D.M. Acreman, T.J. Ponman, I.R. Stevens University of Birmingham M.R. Merrifield University of Nottingham J. Pinkney University of Michigan.

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Galaxy Wakes – Theory & Observations

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  1. Galaxy Wakes – Theory & Observations Irini Sakelliou University of Birmingham D.M. Acreman, T.J. Ponman, I.R. Stevens University of Birmingham M.R. Merrifield University of Nottingham J. Pinkney University of Michigan

  2. physical processes that take place as a galaxy moves through the ICM: • Bondi-Hoyle accretion = the accretion of ICM onto and behind the galaxy Ignition of an AGN? Creation of a wake? • Ram pressure stripping = the removal of ISM from the galaxy Enrichment of the ICM with metals? Reduction of the star formation rate in the galaxy? Creation of a metal rich wake? • Compression of the ISM & ICM in front of the galaxy. Inducing star formation? ICM-galaxy interactions modify the properties of both: the galaxy & the cluster Irini Sakelliou The environment of galaxies – Crete 2004

  3. X-ray (purple), Optical (yellow), Radio (red), Optical [OII] (green) A moving galaxy in Abell 2125 Chandra press realease (06/01/2004) Each panel is 34 arcsec per side Irini Sakelliou The environment of galaxies – Crete 2004

  4. Talk plan • Results of simulations • X-ray data of wake systems • Using wakes as probes for cluster dynamics Irini Sakelliou The environment of galaxies – Crete 2004

  5. Simulations of a moving galaxy in a cluster • A galaxy falling towards the cluster centre • The galaxy has a pre-existing halo • MDH=(1, 2, 4) x 1012 M • kTICM~3keV Temperature map Acreman et al. (2004), Stevens et al. (1999) Irini Sakelliou The environment of galaxies – Crete 2004

  6. ∗ ∗ ∗ Gas mass MDH= 4 x 1012 M ∗ ∗ ∗ MDH= 1 x 1012 M Most of the gas is stripped during the first in-fall. ∗cluster core passage Irini Sakelliou The environment of galaxies – Crete 2004

  7. 4C34.16 – XMM observations Radio core back profile ~20ksec XMM (0.3-5.0)keV MOS1 + MOS2 + PN co-added images in front profile 4C34.16 is a wide-angle radio galaxy (WAT) wake Sakelliou et al. (2004) Irini Sakelliou The environment of galaxies – Crete 2004

  8. ICMWake kT 3.2±0.5 1.1±0.7 (keV) n1.3±0.3 4.5+11.2 (x10-3 cm-3) NH1.7±0.3 6.9±5.0 (x1021 cm-2) XMM results -1.3 Hard image (5-8)keV (0.3-5.0)keV contours on the optical image Vgal>1200 km s-1 Supersonic motion Hard `bar’ in front of the galaxy Irini Sakelliou The environment of galaxies – Crete 2004

  9. Supersonic motion (vgal > 1200 km s-1) • Large wake mass, comparable to the mass of X-ray halos. • A large amount of pre-existing ISM is required Comparison with simulations galactic motion↤ measured kTwake 1200 km s-1 5000 km s-1 Irini Sakelliou The environment of galaxies – Crete 2004

  10. The dumb-bell galaxy NGC 4782/3 – seen by Chandra The two galaxies are members of a loose group, form a bound pair, with a separation of ~12kpc, and are spinning around each other. 50ksec raw Chandra Image Irini Sakelliou The environment of galaxies – Crete 2004

  11. Abell 160 – ~60ksecChandra observations A160 is a poor cluster (kT~3keV) z=0.045 Acreman et al. (2004) Irini Sakelliou The environment of galaxies – Crete 2004

  12. A160 – wakes associated with the cluster galaxies • 3 statistical measures are used to determine the direction of the wakes • Wakes behind ~26 galaxies are found • There is a significant preference for radial orbits Raw (0.5-2.0)keV image of a cluster galaxy. The circle has R=30kpc. Irini Sakelliou The environment of galaxies – Crete 2004

  13. Summary Open questions (X-rays): 1) metalicities of wakes, 2) bow shock and its temperature • Simulations: Most of the ISM is stripped during the first in-fall • XMM data of 4C34.16: the properties of the wake are consistent with the simulations; there is a hot region in front of the galaxy • Chandra data of Abell 160: wakes were found associated with a number of cluster galaxies; there is a preference for radial orbits. Irini Sakelliou The environment of galaxies – Crete 2004

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