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: RM0

Pseudo-regular field: an anisotropic random one: <Bx2> > <By2> RM=0

A merging pair

NGC 4038/39 4.85 GHz DSS+TP+B-vec

40%

15%

1%

10%

Fundamental work by

Chyży & Beck 2004,

A merging pair

NGC 4038/39 4.85 GHz DSS+TP+B-vec

Fundamental work by

Chyży & Beck 2004,

Highly polarized „collisionregion”

Low-polarization hidden SF region

Highly polarized, steep spectrum outflow region

NGC 877

Drzazga, Chyży in prep.

a magnetic bridge?

TP conts + PI B-vecs

NGC4490/85 another interacting pair

Knapik et. al. in prep.

Late type, no AGN

HI image: Clemens, Alexander, Green 1998

NGC 4490/85 a magnetized stream??

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

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

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?

Stephan’s Quintet

IR – Appleton et al. Spitzer gallery

X-rays – Trinchieri et al.. 2003

Soida et al. in prep.

Genuine intergalactic (quasi) regular magnetic field

TP conts+PI B-vecs VLA 6cm

Bt = 8G Bu = 2G

Bt = 7G Bu = 1.5 G

Vollmer et al. 2007 + Kraków+Bonn& NRAO teams

85%

15%

NGC 4501 in the Virgo Cluster

TP+PI B-vecs, VLA 6cm

Motion?

NGC 4501 rectified: Assymmetry of the magnetic pitch angles

Data from Vollmer et al. 2007 + Kraków+Bonn & NRAO teams

Polarization used to constrain the model

Vollmer et al. (incl. Krakow, Bonn &NRAO teams) 2008

Pmax=2000cm-3(km s-1)2 twind = 80Myr

????

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.

NGC 4402 blown from the bottom?

TP conts + PI vecs VLA 6cmVollmer 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

M86 environment

NGC 4438

H (red) Kenney et al. 2008

X-rays (green) M. Weżgowiec from archive NEWTON-XMM data

Motion?

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.)