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. Prepared by Marek Urbanik Based on observations made in cooperation with  K. Chyży, M. Soida, M. Weżgowiec, K. Otmianowska-Mazur - Astronomical Observatory, Jagiellonian University, Kraków  R. Beck – Max-Planck-Institut für Radioastronomie, Bonn  B. Vollmer - CDS, Observatoire Astronomique de Strasbourg  Ch. Balkowski - Observatoire de Paris, GEPI, CNRS, and Université Paris 7  A. Chung - Smithsonian Astrophysical Observatory  J. van Gorkom - Department of Astronomy, Columbia University  J.D. Kenney - Yale University Astronomy Department

3. A merging pair NGC 4038/39 4.85 GHz DSS+TP+B-vec 40% 15% 1% 10% The fundamental work by Chyży & Beck (2004) A&A, 417, 541 HST image credit: B. Whitmore (STScI) and NASA Courtesy K. Chyży

4. A merging pair NGC 4038/39 4.85 GHz DSS+TP+B-vec The fundamental work by Chyży & Beck (2004) A&A, 417, 541 A highly polarized „collision region” A low- polarization hidden SF region A highly polarized, steep spectrum outflow region Courtesy K. Chyży

5. NGC 877 Drzazga, Chyży in prep. A magnetic bridge? VLA TP conts + PI B-vecs VLA archive data Courtesy K. Chyży

6. Knapik et. al. in prep. Note the vertically polarized plume north of the centre. Unlikely to be an AGN- borne jet as NGC 4490 is of late type. NGC4490/85 another interacting pair

7. NGC 4490/85 a magnetized stream?? The vertically polarized structure north of the centre of NGC 4490 exactly corresponds in position and orientation (marked by a red line) with the HI spur seen there by Clemens et al. (1998 – ADS link here) and by Clemens & Alexander (2002 – ADS link here).ADS link here

8. Pol. vectors – see Soida et al., 2001, A&A 378, 40 (VLA) PV along this line and analogous along the NW arm NGC 3627 Image credit: M. Neeser (Univ.-Sternwarte Munchen), P. Barthel (Kapteyn Astron. Institute), H. Heyer, H. Boffin (ESO),

9. 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

10. 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 All the analyses to be found in: Soida et al. in prep. Data: OVRO inrerferometer (colour) – M. Soida, IRAM – Reuter et al. 1996 A&A 306, 721 CO(3-2) HHT – Krakow (M. Soida, M. Urbanik) + Bonn (M. Dumke, M. Krause, R. Wielebinski), in prep. A very personal remark: Without polarization observations probably these anomalies would remain unnoticed?

11. Stephan’s Quintet Intergalactic hot X-ray gas pool See Trinchieri et al. 2003, A&A, 401, 173

12. Stephan’s Quintett 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 Optical image credit: NASA, ESA, and the Hubble SM4 ERO Team

13. Vollmer et al. + Kraków+Bonn& USA teams, 2007,A&A 464, L37 85% Fractions of pol. flux on both sides of a major axis 15% NGC 4501 in the Virgo Cluster TP+PI B-vecs, VLA 6cm Motion?

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

15. Polarization used to constrain the model Vollmer et al.(incl. Krakow, Bonn & USA teams, 2008), A&A 483, 89

16. ???? NGC 4654 TP contours +PI vecs VLA 20cm Colour - HI data: Phookun & Mundy 1995 ApJ, 453, 154, kindly provided by Dr Phookun Radio data Vollmer et al. (incl. Krakow, Bonn & USA teams) 2007 see also A&A 464, L37

17. NGC 4402 blown from the bottom? TP conts + PI vecs VLA 6cm Vollmer et al. (incl. Krakow, Bonn & NRAO teams) 2007 Galaxy motion? Vollmer et al. (+Krakow +Bonn+USA teams): Vollmer et al., 2010, A&A 512, A36 Edge-on „no reason” case NGC 4535 – in southern Virgo extension – a „no reason” face-on case Effelsberg 6 cm Weżgowiec et al., 2007, A&A 471, 93

18. NGC 4438 X-rays (green) M. Weżgowiec from archive NEWTON- XMM data Motion? Now green contours are TP while bars denote pol. int. B-vectors (VLA at 6cm) see Vollmer et al. (incl. Krakow, Bonn & USA teams), 2007, A&A 464, L37

19. 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.)