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Single dish observations of NGC 1068 have shown the presence of a 3.4 μ m aliphatic hydrocarbon absorption feature similar to diffuse lines of sight towards the Galactic Centre. Both, the single dish spectra and the correlated fluxes obtained by MATISSE, present a broad absorption profile in the L band as well, that vary from baseline to baseline. A new CRIRES spectrum with a slit width comparable to the MATISSE aperture also reveals a wide feature around 3.4 μ m. We aim to analyse these features to learn about their origin and the distribution of the carriers across the source. We argue that all these features are caused by absorption of aliphatic hydrocarbons. The 3.4 μ m absorption features in the interferometric MATISSE correlated fluxes vary in optical depth over scales of 0.2-1.4 parsec in the plane of the sky, although probably placed at a larger distance from the AGN along the line of sight. The absorption in the extended areas seems to peak in the direction of the inner jet, close to the center of the ionization cone. These results support the theory of a clumpy torus. In comparing our results to the N-band surface density previously reported, we have discovered a mass ratio of carbonaceous to silicate olivine dust at ∼2 - 3.6 per cent, which is similar to those found in several lines of sight in the diffuse interstellar medium of our Galaxy. [ABSTRACT FROM AUTHOR]

In the widely accepted ‘unified model’1 solution of the classification puzzle of active galactic nuclei, the orientation of a dusty accretion torus around the central black hole dominates their appearance. In ‘type-1’ systems, the bright nucleus is visible at the centre of a face-on torus. In ‘type-2’ systems the thick, nearly edge-on torus hides the central engine. Later studies suggested evolutionary effects2 and added dusty clumps and polar winds3 but left the basic picture intact. However, recent high-resolution images4 of the archetypal type-2 galaxy NGC 10685,6, suggested a more radical revision. The images displayed a ring-like emission feature that was proposed to be hot dust surrounding the black hole at the radius where the radiation from the central engine evaporates the dust. That ring is too thin and too far tilted from edge-on to hide the central engine, and ad hoc foreground extinction is needed to explain the type-2 classification. These images quickly generated reinterpretations of the dichotomy between types 1 and 27,8. Here we present new multi-band mid-infrared images of NGC 1068 that detail the dust temperature distribution and reaffirm the original model. Combined with radio data (J.F.G. and C.M.V.I., manuscript in preparation), our maps locate the central engine that is below the previously reported ring and obscured by a thick, nearly edge-on disk, as predicted by the unified model. We also identify emission from polar flows and absorbing dust that is mineralogically distinct from that towards the Milky Way centre.Mid-infrared observations of the dusty structures of the galaxy NGC 1068 support the unified model of active galactic nuclei. [ABSTRACT FROM AUTHOR]

We present the largest currently existing subarcsecond 3–5 μm atlas of 119 local (z < 0.3) active galactic nuclei (AGNs). This atlas includes AGNs of five subtypes: 22 are Seyfert 1; five are intermediate Seyferts; 46 are Seyfert 2; 26 are low-ionization nuclear emission regions; and 20 are composites/starbursts. Each active galactic nucleus was observed with the Very Large Telescope Infrared Spectrometer and Array Camera (ISAAC) in the L and/or M bands between 2000 and 2013. We detected at 3σ confidence 92 sources in the L band and 83 sources in the M band. We separated the flux into unresolved nuclear flux and resolved the flux through two-Gaussian fitting. We report the nuclear flux, extended flux, apparent size, and position angle of each source, giving 3σ upper limits for sources that are undetected. Using Wide-field Infrared Survey Explorer (WISE) W1- and W2-band photometry we derived relations predicting the nuclear L and M fluxes for Sy1 and Sy2 AGNs based on their W1–W2 color and WISE fluxes. Lastly, we compare the measured mid-infrared colors to those predicted by dusty torus models SKIRTOR, CLUMPY, CAT3D, and CAT3D-WIND, finding the best agreement with the latter. We find that models including polar winds best reproduce the 3–5 μm colors, indicating that it is an important component of dusty torus models. We found that several AGNs are bluer than models predict. We discuss several explanations for this and find that it is most plausibly stellar light contamination within the ISAAC L-band nuclear fluxes. [ABSTRACT FROM AUTHOR]

Context. With infrared interferometry it is possible to resolve the nuclear dust distributions that are commonly associated with the dusty torus in active galactic nuclei (AGN). The Circinus galaxy hosts the closest Seyfert 2 nucleus and previous interferometric observations have shown that its nuclear dust emission is particularly well resolved. Aims. The aim of the present interferometric investigation is to better constrain the dust morphology in this active nucleus. Methods. To this end, extensive new observations were carried out with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer, leading to a total of 152 correlated flux spectra and differential phases between 8 and 13 μm. To interpret this data, we used a model consisting of black-body emitters with a Gaussian brightness distribution and with dust extinction. Results. The direct analysis of the data and the modelling confirm that the emission is distributed in two distinct components: a disklike emission component with a size (FWHM) of ~0.2×1.1 pc and an extended component with a size of ~0.8×1.9 pc. The disk-like component is elongated along PA ~ 46° and oriented perpendicular to the ionisation cone and outflow. The extended component is responsible for 80% of the mid-infrared emission. It is elongated along PA ~ 107°, which is roughly perpendicular to the disk component and thus in polar direction. It is interpreted as emission from the inner funnel of an extended dust distribution and shows a strong increase in the extinction towards the south-east. We find both emission components to be consistent with dust at T ~ 300 K, that is we find no evidence of an increase in the temperature of the dust towards the centre. From this we infer that most of the near-infrared emission probably comes from parsec scales as well. We further argue that the disk component alone is not sufficient to provide the necessary obscuration and collimation of the ionising radiation and outflow. The material responsible for this must instead be located on scales of ~1 pc, surrounding the disk. We associate this material with the dusty torus. Conclusions. The clear separation of the dust emission into a disk-like emitter and a polar elongated source will require an adaptation of our current understanding of the dust emission in AGN. The lack of any evidence of an increase in the dust temperature towards the centre poses a challenge for the picture of a centrally heated dust distribution. [ABSTRACT FROM AUTHOR]

We present new interferometric data obtained with mid-infrared interferometric instrument (MIDI) for the type II Seyfert galaxy NGC 1068, with an extensive coverage of 16 u v points. These observations resolve the nuclear mid-infrared emission from NGC 1068 in unprecedented detail with a maximum resolution of 7 mas. For the first time, sufficient u v points have been obtained, allowing us to generate an image of the source using maximum entropy image reconstruction. The features of the image are similar to those obtained by modelling. We find that the mid-infrared emission can be represented by two components, each with a Gaussian brightness distribution. The first, identified as the inner funnel of the obscuring torus, is hot (∼800 K), 1.35 parsec long and 0.45 parsec thick in full width at half-maximum (FWHM) at a (from north to east). It has an absorption profile different than standard interstellar dust and with evidence for clumpiness. The second component is in FWHM with , and we identify it with the cooler body of the torus. The compact component is tilted by with respect to the radio jet and has similar size and orientation to the observed water maser distribution. We show how the dust distribution relates to other observables within a few parsec of the core of the galaxy, such as the nuclear masers, the radio jet and the ionization cone. We compare our findings to a similar study of the Circinus galaxy and other relevant studies. Our findings shed new light on the relation between the different parsec-scale components in NGC 1068 and the obscuring torus. [ABSTRACT FROM AUTHOR]

We investigate the properties of optically passive spirals and dusty red galaxies in the A901/2 cluster complex at redshift ∼0.17 using rest-frame near-ultraviolet–optical spectral energy distributions, 24-μm infrared data and Hubble Space Telescope morphologies from the STAGES data set. The cluster sample is based on COMBO-17 redshifts with an rms precision of . We find that ‘dusty red galaxies’ and ‘optically passive spirals’ in A901/2 are largely the same phenomenon, and that they form stars at a substantial rate, which is only four times lower than that in blue spirals at fixed mass. This star formation is more obscured than in blue galaxies and its optical signatures are weak. They appear predominantly in the stellar mass range of where they constitute over half of the star-forming galaxies in the cluster; they are thus a vital ingredient for understanding the overall picture of star formation quenching in clusters. We find that the mean specific star formation rate (SFR) of star-forming galaxies in the cluster is clearly lower than in the field, in contrast to the specific SFR properties of blue galaxies alone, which appear similar in cluster and field. Such a rich red spiral population is best explained if quenching is a slow process and morphological transformation is delayed even more. At , such galaxies are rare, suggesting that their quenching is fast and accompanied by morphological change. We note that edge-on spirals play a minor role; despite being dust reddened they form only a small fraction of spirals independent of environment. [ABSTRACT FROM AUTHOR]

We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multicluster system at has been the subject of an 80-orbit F606W Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) mosaic covering the full span of the supercluster. Extensive multiwavelength observations with XMM–Newton, GALEX, Spitzer, 2dF, Giant Metrewave Radio Telescope and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star formation rate, nuclear activity and stellar mass. In addition, with the multiwavelength data set and new high-resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of an environment we will be able to evaluate the relative importance of the dark matter haloes, the local galaxy density and the hot X-ray gas in driving galaxy transformation. This paper describes the HST imaging, data reduction and creation of a master catalogue. We perform the Sérsic fitting on the HST images and conduct associated simulations to quantify completeness. In addition, we present the COMBO-17 photometric redshift catalogue and estimates of stellar masses and star formation rates for this field. We define galaxy and cluster sample selection criteria, which will be the basis for forthcoming science analyses, and present a compilation of notable objects in the field. Finally, we describe the further multiwavelength observations and announce public access to the data and catalogues. [ABSTRACT FROM AUTHOR]

We present a high-resolution dark matter reconstruction of the Abell 901/902 supercluster from a weak lensing analysis of the Hubble Space Telescope STAGES survey. We detect the four main structures of the supercluster at high significance, resolving substructure within and between the clusters. We find that the distribution of dark matter is well traced by the cluster galaxies, with the brightest cluster galaxies marking out the strongest peaks in the dark matter distribution. We also find a significant extension of the dark matter distribution of Abell 901a in the direction of an infalling X-ray group Abell 901α. We present mass, mass-to-light and mass-to-stellar mass ratio measurements of the structures and substructures that we detect. We find no evidence for variation of the mass-to-light and mass-to-stellar mass ratio between the different clusters. We compare our space-based lensing analysis with an earlier ground-based lensing analysis of the supercluster to demonstrate the importance of space-based imaging for future weak lensing dark matter ‘observations’. [ABSTRACT FROM AUTHOR]

We present far-ultraviolet (far-UV) observations at ∼150 nm of the jet of quasar 3C 273 obtained with the Advanced Camera for Surveys (ACS) Solar Blind Channel onboard the Hubble Space Telescope. While the jet morphology is very similar to that in the optical and near-UV, the spectral energy distributions of the jet's subregions show an upturn in at 150 nm compared to 300 nm everywhere in the jet. Moreover, the 150-nm flux is compatible with extrapolating the X-ray power law down to the UV region. This constitutes strong support for a common origin of the jet's far-UV and X-ray emission. It implies that even a substantial fraction of the visible light in the X-ray brightest parts of the jet arises from the same spectral component as the X-rays, as had been suggested earlier based on Spitzer Space Telescope observations. We argue that the identification of this UV/X-ray component opens up the possibility to establish the synchrotron origin of the X-ray emission by optical polarimetry. [ABSTRACT FROM AUTHOR]

We present constraints on the evolution of the virial to stellar mass ratio of galaxies with high stellar masses in the redshift range , by comparing weak lensing measurements of virial mass with estimates of stellar mass . For a complete sample of galaxies with , where the majority show an early-type morphology, we find that the virial mass to stellar mass ratio is given by . Assuming a baryon fraction from the concordance cosmology, this corresponds to a stellar fraction of baryons in massive galaxies of . Analysing the galaxy sample in different redshift slices, we find little or no evolution in the virial to stellar mass ratio, and place an upper limit of ∼2.5 on the growth of massive galaxies through the conversion of gas into stars from to the present day. [ABSTRACT FROM AUTHOR]

We observed four nearby AGN with MIDI at the VLTI to investigate the mid-infrared emission from these sources. With our measurements we resolve the dusty structure around the nucleus of the Circinus galaxy. We find two dust components: a hot, small elongated structure with a size of 0.4 pc and a cooler, almost round component with a size of 1.9 pc. We interpret the emission to be originating in a geometrically thick dusty torus oriented perpendicular to the ionisation cone. Hence our finding nicely confirms the unified picture. We also observed the nucleus of Centaurus A and find that 70% of the mid infrared flux originates from an unresolved source with a size of less than 0.2 pc. In this case, the majority of the emission comes from a synchrotron source at the base of the radio jet. Two further galaxies, Mrk 1239 (Seyfert 1) and MCG -05-23-016 (Seyfert 2), also show unresolved mid infrared sources limiting the size of the dust distribution to less than 5 and 2 pc respectively. [ABSTRACT FROM PUBLISHER]

We present our cosmic shear analysis of GEMS, one of the largest wide-field surveys ever undertaken by the Hubble Space Telescope. Imaged with the Advanced Camera for Surveys (ACS), GEMS spans 795 arcmin2 in the Chandra Deep Field South. We detect weak lensing by large-scale structure in high-resolution F606W GEMS data from ∼60 resolved galaxies per square arcminute. We measure the two-point shear correlation function, the top-hat shear variance and the shear power spectrum, performing an E/B mode decomposition for each statistic. We show that we are not limited by systematic errors and use our results to place joint constraints on the matter density parameter Ωm and the amplitude of the matter power spectrum σ8. We find where the 1σ error includes both our uncertainty on the median redshift of the survey and sampling variance. Removing image and point spread function (PSF) distortions are crucial to all weak lensing analyses. We therefore include a thorough discussion on the degree of ACS PSF distortion and anisotropy which we characterize directly from GEMS data. Consecutively imaged over 20 d, GEMS data also allow us to investigate PSF instability over time. We find that, even in the relatively short GEMS observing period, the ACS PSF ellipticity varies at the level of a few per cent which we account for with a semi-time-dependent PSF model. Our correction for the temporal and spatial variability of the PSF is shown to be successful through a series of diagnostic tests. [ABSTRACT FROM AUTHOR]

We present our cosmic shear analysis of the Galaxy Evolution from Morphology and SEDs (GEMS) survey. Imaged with the Advanced Camera for Surveys (ACS) on HST, GEMS provides high resolution imaging spanning some 800 square arcmins in the Chandra Deep Field South (CDFS). We discuss the benefits of using space-based data for weak lensing studies and show that the ACS is a very powerful instrument in this regard. We find that we are not limited by systematic errors arising from the anisotropic ACS point spread function distortion and use our cosmic shear results to place joint constraints on the matter density parameter $\Omega_m$ and the amplitude of the matter power spectrum $\sigma_8$, finding $\sigma_8(\Omega_m/0.3)^{0.62}=0.73 \pm 0.12$.To investigate the impact of atmospheric seeing on weak lensing analysis we compare the shear measured from CDFS galaxies resolved by the COMBO-17 survey and imaged by GEMS. We find good agreement between the two surveys and a higher dispersion in the intrinsic ellipticity distribution of COMBO-17. This dispersion implies that a space-based cosmic shear analysis would yield higher signal-to-noise results compared to a ground-based cosmic shear analysis of the same galaxy sample.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html [ABSTRACT FROM PUBLISHER]

We estimate and remove the contamination of weak gravitational lensing measurements by the intrinsic alignment of close pairs of galaxies. We do this by investigating both the aperture mass B mode statistic, and the shear correlations of close and distant pairs of galaxies. These can be used to quantify non-lensing effects in weak lensing surveys. We reanalyse the COMBO-17 survey, and study published results from the Red-sequence Cluster Survey and the VIRMOS–DESCART survey, concluding that the intrinsic alignment effect is at the lower end of the range of theoretical predictions. We also revisit this theoretical issue, and show that misalignment of baryon and halo angular momenta may be an important effect which can reduce the intrinsic ellipticity correlations estimated from numerical simulations to the level that we and the SuperCOSMOS survey observe. We re-examine the cosmological parameter estimation from the COMBO-17 survey, using the shear correlation function, and now marginalizing over the Hubble constant. Assuming no evolution in galaxy clustering, and marginalizing over the intrinsic alignment signal, we find the mass clustering amplitude is reduced by 0.03 to , where is the matter density parameter. We consider the forthcoming SuperNova/ Acceleration Probe ( SNAP) wide weak lensing survey, and the Canada–France–Hawaii Telescope Legacy wide synoptic survey; we expect them to be contaminated on scales >1 arcmin by intrinsic alignments at the level of ∼1 and ∼2 per cent, respectively. Division of the SNAP survey for lensing tomography significantly increases the contamination in the lowest redshift bin to ∼7 per cent and possibly higher. Removal of the intrinsic alignment effect by the downweighting of nearby galaxy pairs will therefore be vital for SNAP. [ABSTRACT FROM AUTHOR]

The COMBO-17 survey (Wolf et al., 2002) contains &assymp; 40000 galaxies down to R=24 mag on an area of one square degree, obtained with the wide field imager at the 2.2 m telescope at La Silla. A multi-colour classification on the basis of 5 broadband and 12 medium band filters (=17 bands) yields accurate redshifts (σz ≤ 0.01 at the bright end up to σz &assymp; 0.1 at the faint end) and spectral energy distribution types (SEDs) when using observed galaxy templates from (Kinney et al., 1996). However, there is an obvious weakness in this classification scheme: The relation between star formation history and SED remains unclear. It is therefore impossible to draw firm conclusions about the age of the underlying stellar population and the expected aging between z&assymp;1 and z&assymp;0 can not be quantified. We will present first results of our attempt to replace the observed templates with model spectra from the PEGASE code (Fioc and Rocca­Volmerange, 1997), in order to get a better handle on the star formation history. [ABSTRACT FROM AUTHOR]

We present results of an investigation of clustering evolution of field galaxies between a redshift of z ∼ 1 and the present epoch. The current analysis relies on a sample of ∼ 14000 galaxies in two fields of the COMBO 17 survey. The redshift distribution extends to z ∼ 1. The amplitude of the three-dimensional correlation function can be estimated by means of the projected correlation function w(rp). The validity of the deprojection was tested on the Las Campanas Redshift Survey (LCRS). In a flat cosmology with non-zero cosmological constant for bright galaxies (MB ≤ −18) the clustering growth is proportional to (1+z)-2. However, the measured clustering evolution clearly depends on Hubble type. While locally the clustering strength of early type galaxies is equal to that of the bright galaxies, at high redshifts they are much stronger clustered, and thus the clustering has to evolve much more slowly. [ABSTRACT FROM AUTHOR]

Klaus Meisenheimer and Christian Wolf look forward to COMBO-17, a deep sky survey that should make it possible to bridge the gap between matter in the early universe and the pattern of galaxies that we see today. Abstract The COMBO-17 survey should significantly improve our understanding of galaxy evolution during the last 10 billion years in detail, given its multicolour method to determine redshifts and spectral types for 40 000 galaxies within more than a square degree of sky. In addition, mass determination in the supercluster A901/902 should give significant information about the total mass and distribution of dark matter in the universe. In particular, it should be possible to derive new results about the relative distribution of luminous and dark matter. We see this as a significant step in order to answer a decisive question of cosmology: how did the galaxies form from the density peaks in the early universe? [ABSTRACT FROM AUTHOR]

We have taken N-band spectra of the nuclear dust regions of NGC 1068 with the newly commissioned Mid-InfrareD-Interferometer (MIDI), with a spatial resolution of <10 milliarcsec (<1 pc). We resolve the near-nuclear emission into a warm component (<300 K) 2.1×3.4 pc in size and a smaller hot component. We see a strong silicate absorption in front of the central component that differs in form from normal olivine-type profiles. This thick dust structure cannot be supported for the length of the active phase of the AGN by gas pressure or turbulent motions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html [ABSTRACT FROM PUBLISHER]

Reports the possible detection of a Lyman-alpha forest absorption cloud in front of the radio galaxy 4C41.17. Lyman-alpha emission halo of 4C41.17; Lyman-alpha profiles for the center of 4C41.17 and for the western part; Fits to the depression in the Lyman-alpha profile; Extended emission line region (EELR); Conclusion.

Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of ∼1″.8 radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a PRG not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1″.5, provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1″.02) and B (0″.61) are about 0.4 ± 0.3 and 0.55 ± 0.3. The mass to i-band light ratios of A and B, , appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CfA-Arizona Space Telescope LEns Survey, Lenses Structure and Dynamics, and Strong Lenses in the Legacy Survey samples. The lensed SMG is extremely bright with observed f(250 μm) = 440 mJy owing to a magnification factor μ ∼ 10. The SMG spectrum shows luminous, narrow C IV λ1549 Å emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a dust-enshrouded nucleus. [ABSTRACT FROM AUTHOR]

One of the key predictions of hierarchical galaxy formation models is that a significant fraction of elliptical galaxies form in late merging events. One of the most important diagnostics of such an assembly is the existence of blue spheroidal galaxies, which have spheroid-dominated morphologies and blue colors indicating recent star formation, as an intermediate step in the evolution of elliptical galaxies. [ABSTRACT FROM PUBLISHER]