Dissecting Galaxies: Separating Star Formation, Shock Excitation and AGN Activity in the Central Region of NGC 613

The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion onto supermassive black holes. Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 $\times$ 3 kpc$^2$ region of the active barred spiral galaxy NGC$\sim$613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong $H_2$ and [Fe II] emission and with regions of high ionized gas velocity dispersion ($\sigma > 100$ km s$^{-1}$). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.Comment: 16 pages, 12 figures. Accepted for publication in MNRA

Typology of new psychoactive substance use among the general Australian population

© 2018 Elsevier B.V. Aim: The aim of this study was to examine the typology of Australian illicit drug consumers to determine whether those who use new psychoactive substances (NPS) differ from those using other illicit substances. Methods: Data were from the 2013 National Drug Strategy Household Survey, a representative population study; analyses were limited to participants reporting past year illicit drug use (including NPS; n = 3309). Latent class analysis identified groups based on past year substance use, and a weighted multivariable, multinomial regression model was used to examine characteristics associated with group membership. Results: Six consumer typologies were identified: cannabis consumers (46%), pharmaceutical consumers (21%), ecstasy and cocaine consumers (19%), amphetamine and cannabis consumers (7%), polysubstance consumers (6%), and inhalant consumers (2%). Sixteen participants (total sample: 0.07%; NPS consumers: 5.7%) reported exclusive NPS use. Synthetic cannabinoid receptor agonist use was highest among amphetamine and cannabis consumers and polysubstance consumers; other NPS use was highest among polysubstance consumers. Polysubstance consumers were younger than all other groups, and more likely to engage in dangerous activities while under the influence of substances, inject drugs and report hazardous alcohol consumption. Amphetamine and cannabis consumers were more likely to report trouble ceasing their drug use. Conclusion: We found no distinct profile of NPS-only consumers; however, NPS use was a marker for more problematic patterns of use. Our findings suggest that specialised NPS interventions or harm reduction messages may not be required in the Australian context; rather, they could be based upon existing responses to drug use