Investigation of the obscuring circumnuclear torus in the active galaxy Mrk231

Here we report on observations of powerful hydroxyl (OH) line emissions that trace the obscuring material within the circumnuclear environment of the galaxy Markarian 231. The hydroxyl (mega)-maser emission shows the characteristics of a rotating, dusty, molecular torus (or thick disk) located between 30 and 100 pc from the central engine. We now have a clear view of the physical conditions, the kinematics and the spatial structure of this material on intermediate size scales, confirming the main tenets of unification models.Comment: 10 pages, including 3 Figures, published in Nature Vol 421 2003; the published pdf--file and higher quality images are available at http://www.astro.rug.nl/~hrkloeck/np/pubmrk231.htm

LeMMINGs: V. Nuclear activity and bulge properties: A detailed multi-component decomposition of e -MERLIN Palomar galaxies with HST*

We used high-resolution HST imaging and e-MERLIN 1.5-GHz observations of galaxy cores from the LeMMINGs survey to investigate the relation between optical structural properties and nuclear radio emission for a large sample of galaxies. We performed accurate, multi-component decompositions of new surface brightness profiles extracted from HST images for 163 LeMMINGs galaxies and fitted up to six galaxy components (e.g. bulges, discs, AGN, bars, rings, spiral arms, and nuclear star clusters) simultaneously with Sérsic and/or core-Sérsic models. By adding such decomposition data for ten LeMMINGs galaxies from our past work, the final sample of 173 nearby galaxies (102 Ss, 42 S0s, 23 Es, plus six Irr) with a typical bulge stellar mass of M∗,bulge ~ 106 -1012.5 M⊙ encompasses all optical spectral classes: low-ionisation nuclear emission-line region (LINER), Seyfert, Absorption Line Galaxy (ALG), and H′ ¯II. We show that the bulge mass can be significantly overestimated in many galaxies when components such as bars, rings, and spirals are not included in the fits. We additionally implemented a Monte Carlo method to determine errors on the bulge, disc, and other fitted structural parameters. Moving (in the opposite direction) across the Hubble sequence, that is from the irregular to elliptical galaxies, we confirm that bulges become larger, more prominent, and round. Such bulge dominance is associated with a brighter radio core luminosity. We also find that the radio detection fraction increases with bulge mass. At M∗,bulge ≫ 1011 M⊙, the radio detection fraction is 77%, declining to 24% for M∗,bulge < 1010 M⊙. Furthermore, we observe that core-Sérsic bulges tend to be systematically round and to possess high radio core luminosities and boxy-distorted or pure elliptical isophotes. However, there is no evidence for the previously alleged strong tendency of galaxies'central structures (i.e. a sharp Sérsic, core-Sérsic dichotomy) with their radio loudness, isophote shape, and flattening

LeMMINGs. VI. Connecting nuclear activity to bulge properties of active and inactive galaxies: radio scaling relations and galaxy environment

Multiwavelength studies indicate that nuclear activity and bulge properties are closely related, but the details remain unclear. To study this further, we combine Hubble Space Telescope bulge structural and photometric properties with 1.5 GHz, e-MERLIN nuclear radio continuum data from the LeMMINGs survey for a large sample of 173 'active' galaxies (LINERs and Seyferts) and 'inactive' galaxies (H IIs and absorption line galaxies, ALGs). Dividing our sample into active and inactive, they define distinct (radio core luminosity)-(bulge mass), LR,core − M∗,bulge, relations, with a mass turnover at M∗,bulge ∼ 109.8±0.3M☉ (supermassive blackhole mass MBH ∼ 106.8±0.3M☉), which marks the transition from AGN-dominated nuclear radio emission in more massive bulges to that mainly driven by stellar processes in low-mass bulges. None of our 10/173 bulge-less galaxies host an AGN. The AGN fraction increases with increasing M∗,bulge such that foptical_AGN ∝ M∗,bulge0.24±0.06 and fradio_AGN ∝ M∗,bulge0.24±0.05. Between M∗,bulge ∼ 108.5 and 1011.3M☉, foptical_AGN steadily rises from 15 ± 4 to 80 ± 5 per cent. We find that at fixed bulge mass, the radio loudness, nuclear radio activity, and the (optical and radio) AGN fraction exhibit no dependence on environment. Radio-loud hosts preferentially possess an early-type morphology than radio-quiet hosts, the two types are however indistinguishable in terms of bulge Sérsic index and ellipticity, while results on the bulge inner logarithmic profile slope are inconclusive. We finally discuss the importance of bulge mass in determining the AGN triggering processes, including potential implications for the nuclear radio emission in nearby galaxies

LeMMINGs - I. The eMERLIN legacy survey of nearby galaxies. 1.5-GHz parsec-scale radio structures and cores

We present the first data release of high-resolution ($\leq0.2$ arcsec) 1.5-GHz radio images of 103 nearby galaxies from the Palomar sample, observed with the eMERLIN array, as part of the LeMMINGs survey. This sample includes galaxies which are active (LINER and Seyfert) and quiescent (HII galaxies and Absorption line galaxies, ALG), which are reclassified based upon revised emission-line diagrams. We detect radio emission $\gtrsim$ 0.2 mJy for 47/103 galaxies (22/34 for LINERS, 4/4 for Seyferts, 16/51 for HII galaxies and 5/14 for ALGs) with radio sizes typically of $\lesssim$100 pc. We identify the radio core position within the radio structures for 41 sources. Half of the sample shows jetted morphologies. The remaining half shows single radio cores or complex morphologies. LINERs show radio structures more core-brightened than Seyferts. Radio luminosities of the sample range from 10$^{32}$ to 10$^{40}$ erg s$^{-1}$: LINERs and HII galaxies show the highest and the lowest radio powers respectively, while ALGs and Seyferts have intermediate luminosities. We find that radio core luminosities correlate with black hole (BH) mass down to $\sim$10$^{7}$ M$_{\odot}$, but a break emerges at lower masses. Using [O III] line luminosity as a proxy for the accretion luminosity, active nuclei and jetted HII galaxies follow an optical fundamental plane of BH activity, suggesting a common disc-jet relationship. In conclusion, LINER nuclei are the scaled-down version of FR I radio galaxies; Seyferts show less collimated jets; HII galaxies may host weak active BHs and/or nuclear star-forming cores; and recurrent BH activity may account for ALG properties

LeMMINGs - II. The e-MERLIN legacy survey of nearby galaxies. The deepest radio view of the Palomar sample on parsec scale

We present the second data release of high-resolution ($\leq0.2$ arcsec) 1.5-GHz radio images of 177 nearby galaxies from the Palomar sample, observed with the e-MERLIN array, as part of the LeMMINGs (Legacy e-MERLIN Multi-band Imaging of Nearby Galaxy Sample) survey. Together with the 103 targets of the first LeMMINGs data release, this represents a complete sample of 280 local active (LINER and Seyfert) and inactive galaxies HII galaxies and Absorption Line Galaxies, ALG). This large program is the deepest radio survey of the local Universe, $\gtrsim$10$^{17.6}$ W Hz$^{-1}$, regardless of the host and nuclear type: we detect radio emission $\gtrsim$0.25 mJy beam$^{-1}$ for 125/280 galaxies (44.6 per cent) with sizes of typically $\lesssim$100 pc. Of those 125, 106 targets show a core which coincides within 1.2 arcsec with the optical nucleus. Although we observed mostly cores, around one third of the detected galaxies features jetted morphologies. The detected radio core luminosities of the sample range between $\sim$10$^{34}$ and 10$^{40}$ erg s$^{-1}$. LINERs and Seyferts are the most luminous sources, whereas HII galaxies are the least. LINERs show FRI-like core-brightened radio structures, while Seyferts reveal the highest fraction of symmetric morphologies. The majority of HII galaxies have single radio core or complex extended structures, which probably conceal a nuclear starburst and/or a weak active nucleus (seven of them show clear jets). ALGs, which are typically found in evolved ellipticals, although the least numerous, exhibit on average the most luminous radio structures, similar to LINERs

A "clear" view of the nucleus:the Megamaser perspective

Extragalactic emission from the hydroxyl and the water molecule was first detected in the early eighties, revealing a new class of maser emission with unexpected isotropic luminosities of many magnitudes higher than their galactic counterparts. Galaxies that harbor this so-called Megamaser emission show enhanced core activity in the form of a nuclear starburst or an active-galactic-nucleus. The exceptional maser properties together with the nuclear activity indicate that the line radiation originates in the circumnuclear environment close to the central engine. The environment for producing maser emission in our Galaxy fulfills some unique requirements that will be compared with those of the extra-galactic Megamaser emission. Using very-long-baseline-interferometry, the observational data show that the radio and the molecular line emission structure reveal a rather more complex picture of the circumnuclear environment where the masers occur. At such scale-sizes the individual Megamaser galaxies display diverse maser- and nuclear properties, which all contribute to the understanding of the molecular environment in active nuclei.</p

How to Reap the CSR Fruits: The Crucial Role Played by Customers

In times of unprecedented relevance of Corporate Social Responsibility (CSR), companies need to gain a deeper understanding of actual and prospective customers, shedding light on the antecedents of their behavioral choices as to better address their needs and ambitions, in order to get a competitive edge. By adopting a chronological approach, the present chapter provides an overview of the development of research on responsible consumers over time. From early studies focusing on market segmentation based on socio-demographic and psychographic variables, the focus shifts to sophisticated models based either on cognitive processes or on habits, or on a mixture of both. Given the complexity of the phenomenon and its dynamic and ever-evolving nature, the chapter ends with a discussion of cutting-edge perspectives of analysis that represent the latest advancements of the discipline. These new streams of studies focus on the need to adopt holistic, dynamic, crosscultural, and trust-based approaches, and pave the way for future research