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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 physical processes affecting the ISM both in the AGN vicinity as well as in the outer star forming molecular ring. We carried out 3 mm ALMA observations of HCN, HCO+, CCH, CS, HNCO, SiO, HC3N, and SO as well as the 13C isotopologues. All species were imaged over the central 2 kpc (~30") of the galaxy at a resolution of ~2.2"x1.5 (150 pc x 100 pc). HCO+ and CS appear to be slightly enhanced in the star forming ring. CCH, showing the largest variations across NGC 1097, is suggested to be a good tracer of both obscured and early stage star formation. HNCO, SiO and HC3N are significantly enhanced in the inner circumnuclear disk surrounding the AGN. Differences in the molecular abundances are observed between the star forming ring and the inner circumnuclear disk. We conclude that the HCN/HCO+ and HCN/CS differences observed between AGN dominated and starburst galaxies are not due to a HCN enhancement due to X-rays, but rather this enhancement is produced by shocked material at distances of 200 pc from the AGN. Additionally we claim the lower HCN/CS to be a combination of a small under-abundance of CS in AGNs together with excitation effects, where a high dense gas component (~10^6 cm^-3) may be more prominent in SB galaxies. However the most promising are the differences found among the dense gas tracers which, at our modest spatial resolution, seem to outline the physical structure of the molecular disk around the AGN. In this picture, HNCO probes the well shielded gas in the disk, surrounding the dense material moderately exposed to X-ray radiation traced by HC3N. Finally SiO might be the innermost molecule in the disk structure., Comment: 14 pages, 9 figures, A&A Accepted for publication

We present the initial results of a spectral line survey of L1157 B1 with the Nobeyama 45 m telescope. So far, we have covered the frequencey range of 13.7 GHz (82.0–94.5 GHz and 96.3–97.5 GHz), and have detected 22 species including CH3 CHO, HCOOH, HCOOCH3 , HNCO, NH2 CHO, CH3 CN, and CCS. We have also detected the line of CH2 DOH. These results demonstrate rich chemistry in this shocked region, which would mainly originate from evaporation of ice mantles by means of shocks.

Aims. To study the abundance and temperature of ammonia in the center of a nearby galaxy M 51 and to compare them with those in other nearby galaxies, we observed its (J,K) = (1, 1), (2, 2), (3, 3), and (4, 4) inversion transitions at the wavelength of 1.3 cm. Methods. The observations were carried out with the Effelsberg 100-m radio telescope. Results. The (1, 1), (2, 2), and (3, 3) transitions are clearly detected, but the (4, 4) transition is barely detected. The rotational temperature obtained from the (1, 1) and (2, 2) transitions of para-ammonia is 25 ± 2 K, which is similar to those of M 82 and the Large Magellanic Cloud (N 159 W), but significantly lower than those of IC 342 and NGC 1068 among the nearby galaxies. The column density of ammonia is (8.1 ± 2.4) × 10 13 cm −2 , and the abundance relative to H2 is ∼4.5 × 10 −9 . The abundance in M 51 is about a factor of 5 lower than those of NGC 253 and IC 342, but about one order of magnitude higher than those of M 82 and the Large Magellanic Cloud. The addition of the data of M 51 further supports the exceptionally low abundances of ammonia reported previously in these two galaxies. For understanding the abundance of ammonia in M 51 and other nearby galaxies, their temperatures were compared. As a result, we found that the galaxies with low temperature tend to have low abundance of ammonia. In addition, the photodissociation rate of ammonia was compared to those of related molecules detected in the nearby galaxies to discuss the effect of photodissociation. We found that the low abundance of ammonia in some galaxies cannot be explained only by the effect of photodissociation.

Aims. We have observed the N = 1−0 lines of CCH and its 13 C isotopic species toward a cold dark cloud, TMC-1 and a star-forming region, L1527, to investigate the 13 C abundances and formation pathways of CCH. Methods. The observations have been carried out with the IRAM 30 m telescope. Results. We have successfully detected the lines of 13 CCH and C 13 CH toward the both sources and found a significant intensity difference between the two 13 C isotopic species. The [C 13 CH]/[ 13 CCH] abundance ratios are 1.6 ± 0. 4( 3σ )a nd 1.6 ± 0. 1( 3σ )f or TMC-1 and L1527, respectively. The abundance difference between C 13 CH and 13 CCH means that the two carbon atoms of CCH are not equivalent in the formation pathway. On the other hand, the [CCH]/[C 13 CH] and [CCH]/[ 13 CCH] ratios are evaluated to be larger than 170 and 250 toward TMC-1, and to be larger than 80 and 135 toward L1527, respectively. Therefore, both of the 13 C species are significantly diluted in comparison with the interstellar 12 C/ 13 C ratio of 60. The dilution is discussed in terms of a behavior of 13 Ci n