NASA Astronomy Picture of the Day Collection

Molecular Torus Surrounds Black Hole

Why do some black hole surroundings appear brighter than others? In the centers of active galaxies [ http://imagine.gsfc…], supermassive black holes [ http://antwrp.gsfc.…] at least thousands of times the mass of our Sun [ http://antwrp.gsfc.…] dominate. Many, called Seyfert Type I [ http://www.astro.um…], are very bright in visible light. Others, called Seyfert Type II [ http://www.astro.um…], are rather dim. The difference might be caused by some black holes accreting [ http://antwrp.gsfc.…] much more matter than others. Alternatively, the black holes in the center of Seyfert [ http://antwrp.gsfc.…] Type II galaxies might be obscured by a surrounding torus [ http://mathworld.wo…]. To help choose between these competing hypotheses, the nearby Seyfert II galaxy NGC 4388 [ http://antwrp.gsfc.…] has been observed in X-ray light [ http://chandra.harv…] recently by many recent Earth-orbiting X-ray observatories, including CGRO [ http://antwrp.gsfc.…], SIGMA [ http://hea.iki.rssi…], BeppoSAX [ http://www.asdc.asi…], INTEGRAL [ http://www.esa.int/…], Chandra [ http://chandra.harv…], and XMM-Newton [ http://antwrp.gsfc.…]. Recent data [ http://arxiv.org/ab…] from INTEGRAL and XMM-Newton have found [ http://www.gsfc.nas…] that the X-ray flux in some X-ray colors varies rapidly, while flux in other X-ray colors is quite steady. The constant flux and apparent absorption of very specific X-ray colors by cool iron [ http://pearl1.lanl.…] together give evidence [ http://www.esa.int/…] that the central black hole in NGC 4388 is seen through a thick torus [ http://www.esa.int/…] composed of molecular gas and dust [ http://antwrp.gsfc.…].

V. Beckmann [ http://lheawww.gsfc…] (NASA [ http://www.nasa.gov/]'s GSFC [ http://www.gsfc.nas…]) et al. [ http://arxiv.org/ab…], ESA

Goddard Space Flight Center (GSFC)

Washington, D.C.

Earth

Sun

XMM-Newton

USERS

Visible Light

INTEGRAL

Granat

black hole

http://antwrp.gsfc.…

SPD-APOD-ap040908