XMM-Newton view of X-ray halo of NGC 4634

This three-colour XMM-Newton image of NGC 4634 was created from merged EPIC pn and MOS images. Red, green and blue represent emission in the (0.2-1.0) keV, (1.0-2.0) keV, and (2.0-4.5) keV energy bands, respectively. The ellipse indicates the outer border of the H-alpha emitting disc. Besides NGC 891, NGC 4634 is the second non-starburst late-type spiral galaxy with a prominent diffuse soft X-ray halo. In addition to a hot corona, this galaxy also possesses a cosmic ray and a diffuse ionised gas halo. There are strong indications that these multi-phase gaseous halos are triggered by star formation related processes in the disk plane.