Neon-5, thin galaxies and Dr. Shobita Satyapal

NGC 3621 some 22 million light years from us
NASA APOD

Heavy-weight elliptical galaxies have bulking central bars shining so brightly in the deep space. In their center exists one of the more amusing misnomers of Astronomy, supermassive black hole, which is so called as light cannot escape from its enormous gravity field. But around the core of the galaxy there is plenty going on releasing photons and "Black holes" are not black at all - actually they among the brightest things seen in the cosmos.

But what about skinny spiral galaxies that do not have such a brilliantly shining central bulk? Are they exceptions to the rules science has established about the forming of galaxies missing the black hole?

Paul Rincon published in BBC Science Nature an interesting article on work done on this question by Dr. Shobita Satuapal and her associates. The article was published online 11 January 2008.  Here are some excerpts from it; you can read the entire article from here.

Now, Shobita Satyapal, of George Mason University in Virginia, US, and her colleagues have discovered eight active supermassive black holes in skinny galaxies with minimal star bulges.

"Prior to this discovery there was only one example of an active black hole in a galaxy with no bulge," said Dr Satyapal.

"These observations show that it's not an anomaly for a super-thin galaxy to harbour a supermassive black hole. This constitutes the best evidence yet that a bulge is not a necessary ingredient for a black hole to exist and grow."
BBC Science

How would she know?

Dr. Shobita Satyapal, Physicist
NASA Goddard Space Flight Cent

I may be partial to women in Astronomy but it seems to me that associate professor Shobita Satyapal is an exceptionally smart human being. For in studying the data from Spitzer she picked an unusual fingerpint among all the elements in the spectra of galaxy light, neon-5. This must have been a somewhat brave move in Astrophysics since the creation of neon isotopes is currently still "a hot scientific debate" - which is a polite way of saying "we do not know enough about it".

In this case, Dr Satyapal discovered the unique fingerprint of neon-5, a highly ionised form of this element. Stars are incapable of producing neon-5 - only a feeding black hole has the energy to excite the element to this ionised state.
BBC Science

Seeing through dust 

"Prior to this discovery there was only one example of an active black hole in a galaxy with no bulge," said Dr Satyapal.

"These observations show that it's not an anomaly for a super-thin galaxy to harbour a supermassive black hole. This constitutes the best evidence yet that a bulge is not a necessary ingredient for a black hole to exist and grow."

These have been difficult to detect in the past, because bulgeless galaxies also tend to be very dusty. The dust lets little visible light escape.

But by looking at objects in the infrared part of the electromagnetic spectrum, astronomers are able to see through cosmic dust. Using Spitzer, they were able to detect the signatures of active black holes in galaxies millions of light-years from Earth.

Black holes swallow matter in their vicinity. But these "feeding" black holes also spit out high energy light that ionises much of the gas in the core of a galaxy.

In this case, Dr Satyapal discovered the unique fingerprint of neon-5, a highly ionised form of this element. Stars are incapable of producing neon-5 - only a feeding black hole has the energy to excite the element to this ionised state.

The researchers are to publish their research in an upcoming issue of the Astrophysical Journal. BBC Science

Scientific publications
The following articles give some idea about the scope and methods of Dr. Satyapal and her colleagues

A Chandra View Of NGC 3621: A Bulgless Galaxy Hosting An AGN In Its Eearly Phase?	Mario Gliozzi, Shobita Satyapal, Michael Eracleous, Lev Titarchuk and Chi C. Cheung	The Astrophysical Journal 700 (2) 1759. 2009
A Spitzer Spectroscopic Survey of Low-Ionization Nuclear Emission-Line Regions: Characterization of the Central Source	R. P. Dudik, S. Satyapal and D. Marcu	The Astrophysical Journal 691 (2)1501. 2009
The Incidence of Active Galactic Nuclei in Pure Disk Galaxies:The Spitzer View	S. Satyapal, T. Böker, W. Mcalpine, et al.	The Astrophysical Journal704 (1) 439. 2009
A joint mid-infrared spectroscopic and X-ray imaging investigation of LINER galaxies	S. Satyapal, R. M. Sambruna, and R. P. Dudik	Astronomy & Astrophysics 414 (3) 825. 2004
Mid Infrared Fine Structure Line Ratios in Active Galactic Nuclei Observed with the Spitzer IRS: Evidence for Extinction by the Torus	R. P. Dudik, J. C. Weingartner, S. Satyapal, et al.	The Astrophysical Journal 664 (1) 71. 2007
Spitzer Uncovers Active Galactic Nuclei Missed by Optical Surveys in Seven Late‐Type Galaxies	S. Satyapal, D. Vega, R. P. Dudik, N. P. Abel and T. Heckman	The Astrophysical Journal677 (2) 926. 2008
A Chandra Snapshot Survey of Infrared‐bright LINERs: A Possible Link Between Star Formation, Active Galactic Nucleus Fueling, and Mass Accretion	R. P. Dudik, S. Satyapal, M. Gliozzi and R. M. Sambruna	The Astrophysical Journal 620 (1) 113. 2005
The Link between Star Formation and Accretion in LINERs: A Comparison with Other Active Galactic Nucleus Subclasses	S. Satyapal, R. P. Dudik, B. O’Halloran and M. Gliozzi	The Astrophysical Journal633(1) 86. 2005