1. Magnetic fields in perturbed galaxies: a sensitive measure of external influences or Why to observe abnormal galaxies when we don’t yet fully understand normal ones? Some terminology: Regular magnetic field: a unidirectional one: RM  0 Pseudo-regular field: an anisotropic random one: > RM=0

2. A merging pair NGC 4038/39 4.85 GHz DSS+TP+B-vec 40% 15% 1% 10% Fundamental work by Chyży & Beck 2004,

3. A merging pair NGC 4038/39 4.85 GHz DSS+TP+B-vec Fundamental work by Chyży & Beck 2004, Highly polarized „collision region” Low- polarization hidden SF region Highly polarized, steep spectrum outflow region

4. NGC 877 Drzazga, Chyży in prep. a magnetic bridge? TP conts + PI B-vecs

5. NGC4490/85 another interacting pair Knapik et. al. in prep. Late type, no AGN

6. HI image: Clemens, Alexander, Green 1998 NGC 4490/85 a magnetized stream??

7. Soida et al. 2001` PV along this line and analogous along the NW arm

8. NW normal region Diffuse CO(1-0) gas IRAM dish (Reuter et al. 1996) Clumpy CO(1-0) gas OVRO interf. (Soida et al. in prep) SE abnormal region Diifuse CO gas Clumpy CO gas

9. Colour – clumpy cool gas seen by OVRO, conts – HHT 3-2 upper panel: polarized intensity Colour – clumpy cool gas seen by OVRO, conts – IRAM 1-0 upper panel: polarized intensity Soida et al. in prep. Data: OVRO –M. Soida, IRAM – Reuter et al. 1006 CO(3-2) HHT – Krakow + Bonn (M. Dumke, M. Krause, R. Wielebinski), in prep. A very personal remark: Without polarization observations probably these anomalies would remain unnoticed?

10. Stephan’s Quintet IR – Appleton et al. Spitzer gallery X-rays – Trinchieri et al.. 2003

11. Soida et al. in prep. Genuine intergalactic (quasi) regular magnetic field TP conts+PI B-vecs VLA 6cm Bt = 8  G Bu = 2  G Bt = 7  G Bu = 1.5  G

12. Vollmer et al. 2007 + Kraków+Bonn& NRAO teams 85% 15% NGC 4501 in the Virgo Cluster TP+PI B-vecs, VLA 6cm Motion?

13. NGC 4501 rectified: Assymmetry of the magnetic pitch angles Data from Vollmer et al. 2007 + Kraków+Bonn & NRAO teams

14. Polarization used to constrain the model Vollmer et al. (incl. Krakow, Bonn &NRAO teams) 2008 Pmax=2000cm -3 (km s -1 ) 2 t wind = 80Myr

15. ???? Colour - HI NGC 4654 TP contours +PI vecs VLA 20cm Radio data Vollmer et al. 2007 (incl. Krakow, Bonn & NRAO teams) HI Phookun & Mundy 1995.

16. NGC 4402 blown from the bottom? TP conts + PI vecs VLA 6cm Vollmer et al. (incl. Krakow, Bonn & NRAO teams) 2007 Galaxy motion? Edge-on „no reason” case NGC 4535 – in southern Virgo extension – a „no reason” face-on case

17. M86 environment NGC 4438 H  (red) Kenney et al. 2008 X-rays (green) M. Weżgowiec from archive NEWTON- XMM data Motion?

18. Attempt to summarize We have observed: 1.Magnetic bridges 2.Anomalous arms 3.Compressional ridges 4.Magnetized outflows 5.Intergalactic magnetic fields Magnetic field as seen in polarization is a very good „preselector” of anomalies to be studied in detail in other domains (X-rays, HI dynamics etc.)