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We have mapped the central region of the Seyfert 1 galaxy NGC 1097 in 12CO(J=2-1) with the Submillieter Array (SMA). The 12CO(J=2-1) map shows a central concentration and a surrounding ring, which coincide respectively with the Seyfert nucleus and a starburst ring. The line intensity peaks at the nucleus, whereas in a previously published 12CO(J=1-0) map the intensity peaks at the starburst ring. The molecular ring has an azimuthally averaged 12CO(J=2-1)/(J=1-0) intensity ratio (R21) of about unity, which is similar to those in nearby active star forming galaxies, suggesting that most of the molecular mass in the ring is involved in fueling the starburst. The molecular gas can last for only about 1.2times10^8 years without further replenishment assuming a constant star formation rate and a perfect conversion of gas to stars. The velocity map shows that the central molecular gas is rotating with the molecular ring in the same direction, while its velocity gradient is much steeper than that of the ring. This velocity gradient of the central gas is similar to what is usually observed in some Seyfert 2 galaxies. To view the active nucleus directly in the optical, the central molecular gas structure can either be a low-inclined disk or torus but not too low to be less massive than the mass of the host galaxy itself, be a highly-inclined thin disk or clumpy and thick torus, or be an inner part of the galactic disk. The R21 value of ~1.9 of the central molecular gas component, which is significantly higher than the value found at the molecular gas ring, indicates that the activity of the Seyfert nucleus may have a significant influence on the conditions of the molecular gas in the central component.
The nearby Sy 1 galaxy NGC 1097 represents an ideal laboratory to explore the molecular chemistry in the presence and surroundings of an active galactic nucleus. Exploring the distribution of different molecular species allows us to understand the ph
We present 13CO(1-0) and 12CO(2-1) aperture synthesis maps of the barred spiral galaxy NGC1530. The angular resolutions are respectively 3.1 and 1.6. Both transitions show features similar to the 12CO(1-0) map, with a nuclear feature (a ring or unres
The Seyfert 2 galaxy NGC 2110 has been observed with BeppoSAX between 0.5 and 150 keV. The high energy instrument onboard, PDS, has succeeded in measuring for the first time the spectrum of this source in the 13-150 keV range. The PDS spectrum, havin
We report the transition towards a type 1 Seyfert experienced by the classical type 2 Seyfert nucleus in NGC 7582. The transition, found at most 20 days from its maximum peak, presents a unique opportunity to study these rare events in detail. At max
A large reverberation mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hbeta 4861 and He II 4686 and a central black hole mass measurement of about 10 million solar masses, consistent with previous measurements. A ver