Magnetic and X-ray diagnostics of interactions of spiral galaxies in a cluster environment

1. M. Weżgowiec1, M. Ehle2, M. Urbanik1, R. Beck3, B. Vollmer4, K.T. Chyży1, M. Soida1, Ch. Balkowski5 1Obserwatorium Astronomiczne Uniwersytetu Jagiellońskiego, Kraków, Poland 2ESAC, XMM-Newton Science Operations Centre, Villanueva de la Cańada, Madrid, Spain 3Max-Planck-Institut für Radioastronomie, Bonn, Germany 4CDS, Observatoire astronomique de Strasbourg, Strasbourg, France 5Observatoire de Paris, GEPI, CNRS, and Universite Paris 7, Meudon Cedex, France Magnetic and X-ray diagnostics of interactions of spiral galaxies in a cluster environment

2. What & How • An attempt to study cluster environment • Polarization as a very useful tool • X-ray extended emission as an another very useful tool • Objects and instruments • Up to date results • First scientific conclusions • Future aims

3. Polarized intensity studies • Clues about the magnetic fields • Good tool to investigate perturbations in galaxies (compression effects, distorted ISM distribution)

4. X-ray studies • Soft X-ray emission traces hot gas  extended emission helps to examine past or present perturbations of the hot ICM, via spatial and spectral analysis

5. Objects and instruments

6. Results • Altogether 12 Virgo spirals at 2.8, 3.6 and 6 cm (both TP and PI measured) • For most of them RM maps possible • So far 2 Virgo spirals in X-rays (0.2 – 0.8 keV for extended emission) • More needed !!

7. Results – NGC 4254 • NGC 4254 (M 99) • In the cluster outskirts • Perturbed galaxy, X-ray emission (compression or high SF?) - Chyzy et al. 2007 • Perturbation most likely produced by gravitational interaction – with dark cloud VIRGOHI 21?

8. Results – NGC 4302/4298 • NGC 4302 interacting (?) with companion galaxy NGC 4298 • Interesting polarized structures (i.e. extraplanar features), however, better resolution would help

9. Results – NGC 4388 • NGC 4388 in the heart of VC • Strong stripping possible • Central activity • Extraplanar features – better seen with the VLA (Vollmer et al. 2007)

10. Results – NGC 4438 • NGC 4438. Galaxy near the cluster core • Central activity • Peculiar overall shape due to tidal interactions with the NGC 4435 companion

11. Results – NGC 4501 • NGC 4501 – an „upside down” galaxy • Strong compression in SW (85% of polarized intensity distributed west of major axis) • 3D localization thanks to polarization and kinematic studies!!

12. Results – NGC 4535 • NGC 4535 in the southern subcluster • So far, the most extreme case polarization asymmetry • Polarized intensity peaks in the outer optical arm • Even at better resolution

13. Results – NGC 4569 • NGC 4569 (M90) with giant radio lobes in an otherwise normal spiral • Extended X-ray emission suggestive for hot gas outflows • Probable nuclear starburst in the past

14. Results – NGC 4654 • NGC 4654 - a comet-like galaxy - compression leaves no doubts about the direction in which this galaxy moves • Possibly a good candidate for a „ram-pressure pushing”

15. First scientific conclusions • Cluster galaxies show signs of interaction with the ICM as well as with each other • Ram-pressure stripping concept seems to work quite well • High density ICM exists not necessarily only in the cluster core (NGC 4535)  we might detect it by observing a single galaxy in radio polarization and in X-rays • Because of a high density of galaxies tidal interactions may lead to a higher fractions of active galaxies than among the field objects • Together with the CO, Hα and H I observations we might eventually get a full picture (preferably sculpture) of this cluster as a whole (first successes  3D localizations of NGC 4501 and 4654)

16. Future aims • Combination of existing Effelsberg and VLA data (for almost all presented galaxies) • Obtain X-ray observations of as many as possible of our target galaxies; search for spatial & spectral signatures for interactions in the hot gas • Putting everything together, kinematic analysis, simulations (already performed for NGC 4654 and NGC 4501)