Ionization Cone Research Articles

MOSEL Survey: Spatially Offset Lyman-continuum Emission in a New Emitter at z = 3.088 Can Explain the Low Number Density of Observed LyC Leakers

We present the discovery of a unique Lyman-continuum (LyC) emitter at z = 3.088. The LyC emission was detected using the Hubble Space Telescope WFC3/UVIS F336W filter, covering a rest-frame wavelength range of 760–900 Å. The peak signal-to-noise ratio of LyC emission is 3.9 in an r = 0.″24 aperture and is spatially offset by 0.″29 ± 0.″04 (∼2.2 ± 0.3 kpc) from the peak of rest-UV emission (F606W). By combining imaging and spectroscopic data from the James Webb Space Telescope (JWST) JADES, FRESCO, and JEMS surveys, along with VLT/MUSE data from the MXDF survey, we estimate that the probability of random alignment with an interloper galaxy causing the LyC emission is less than 6 × 10−5. The interstellar medium (ISM) conditions in the galaxy are similar to those in other LyC emitters at high redshift ( 12+log(O/H)=7.79−0.05+0.06 , logU=−3.27−0.12+0.14 , O32 = 0.63 ± 0.03), although the single-peaked Lyα profile and lack of rest-UV emission lines suggest an optically thick ISM. Our observations indicate that LyC photons are leaking through a narrow cone of optically thin neutral ISM, most likely created by a past merger (as evidenced by medium-band F210M and F182M images). Using the constraints on escape fraction from individual leakers and a simple model, we estimate that the opening half-angle of ionization cones can be as small as 16° (2% ionized fraction) to reproduce some of the theoretical constraints on the average escape fraction for galaxies. The narrow opening angle required can explain the low number density of confirmed LyC leakers.

O iii] λ5007 emissions in extremely red quasars (ERQs) are compact

ABSTRACT ‘Extremely red quasars’ (ERQs) are a non-radio-selected, intrinsically luminous population of quasars at cosmic noon selected by their extremely red colour from rest-frame UV to mid-IR. ERQs are uniquely associated with exceptionally broad and blueshifted [O iii] $\lambda$5007 emission reaching speeds $\gt $6000 km s$^{-1}$. We obtained adaptive optics integral-field spectroscopic observations using Keck/OSIRIS and Gemini/NIFS of a sample of 10 ERQs with bolometric luminosities (10$^{47.0}$–10$^{47.9}$) erg s$^{-1}$ at $z\sim$ (2.3–3.0). The goal is to measure the sizes and spatially resolved kinematics of the [O iii]-emitting regions. We study the surface brightness maps and aperture-extracted spectra and model the point-spread functions. We identify signs of merger activities in the continuum emissions. We identify physically distinct [O iii] kinematic components that are bimodal and respectively trace ERQ-driven outflows of velocity dispersion $\gtrsim$250 km s$^{-1}$ and dynamically quiescent interstellar media. We find that the ERQ-driven ionized outflows are typically at $\sim$1 kpc scales whereas the quiescent ionized gas extend to a few kpc. Compared to normal quasars the extremely fast ERQ-driven [O iii] outflows tend to be more compact, supporting the notion that ERQs are in a young stage of quasar/galaxy evolution and represent unique physical conditions beyond orientation differences with normal quasar populations. The kinematically quiescent [O iii] emissions in ERQs tend to be spatially resolved but less extended than in normal quasars, which can be explained by global and patchy dust obscuration. The hint of ionization cones suggests some of the obscuration can be partially explained by a patchy torus.

GN-z11: The environment of an active galactic nucleus atz = 10.603

Recent observations with theJames WebbSpace Telescope (JWST) have further refined the spectroscopic redshift of GN-z11, one of the most distant galaxies identified with theHubbleSpace Telescope, atz = 10.603. The presence of extremely dense gas (> 1010cm−3), the detection of high-ionisation lines and of CII*1335 emission, and the presence of an ionisation cone indicate that GN-z11 also hosts an active galactic nucleus. Further photometric and spectroscopic follow-up demonstrates that it lies in a large-scale, overdense structure with possible signatures of Population III stars in its halo. Surprisingly, Lyαhas also been detected despite the expected largely neutral intergalactic medium at such a redshift. We exploit recent JWST/NIRSpec integral field unit observations to demonstrate that the Lyαemission in GN-z11 is part of an extended halo with a minimum size of 0.8–3.2 kpc, depending on the definition used to derive the halo size. The surface brightness of the Lyαhalo around GN-z11 appears consistent with Lyαhalos observed aroundz ∼ 6 quasars. At the wavelength of Lyαatz ∼ 10.6, we identify three other emission line candidates within the integral field unit field of view with no UV rest-frame counterpart visible in deep images from the JWST/NIRCam. If confirmed, this could be the first evidence that the local region of GN-z11 represents a candidate protocluster core, forming just 400 Myr after the Big Bang. We give a first estimate of the dark matter halo mass of this structure (Mh = 2.96−0.39+0.44 × 1010 M⊙), which is consistent with a Coma-like cluster progenitor.

JADES

Finding the first generation of stars formed out of pristine gas in the early Universe, known as Population III (PopIII) stars, is one of the most important goals of modern astrophysics. Recent models have suggested that PopIII stars may form in pockets of pristine gas in the halo of more evolved galaxies. We present NIRSpec integral field spectroscopy and micro-shutter array spectroscopic observations of the region around GN-z11, an exceptionally luminous galaxy atz = 10.6, that reveal a greater than 5σdetection of a feature consistent with being HeIIλ1640 emission at the redshift of GN-z11. The very high equivalent width of the putative HeII emission in this clump (log(EWrest(HeII)/Å) = 1.79−0.25+0.15) and a lack of metal lines can be explained in terms of photoionisation by PopIII stars, while photoionisation by PopII stars is inconsistent with the data. The high equivalent width would also indicate that the putative PopIII stars likely have an initial mass function with an upper cutoff reaching at least 500M⊙. The PopIII bolometric luminosity inferred from the HeII line would be ∼7 × 109 L⊙, which would imply a total stellar mass formed in the burst of ∼2 × 105 M⊙. We find that photoionisation by the active galactic nucleus (AGN) in GN-z11 cannot account for the HeII luminosity observed in the clump but can potentially be responsible for an additional HeII emission observed closer to GN-z11. We also consider the possibility of in situ photoionisation by an accreting direct collapse black hole hosted by the HeII clump. We find that this scenario is less favoured, but it remains a possible alternative interpretation. We also report the detection of a Lyαhalo stemming out of GN-z11 and extending out to ∼2 kpc as well as resolved funnel-shaped CIII emission likely tracing the ionisation cone of the AGN.

Criticality of Spray Solvent Choice on the Performance of Next Generation, Spray-Based Ambient Mass Spectrometric Ionization Sources: A Case Study Based on Synthetic Cannabinoid Forensic Evidence

Mass spectrometry (MS) is a highly selective and sensitive analytical tool with a myriad of applications, but such techniques are typically used in laboratory settings due to the handling and preparations that are necessary. The merging of two streams of robust research, portable MS systems and next-generation ambient ionization methods, now provides the ability to perform high-performance chemical screening in an on-site and on-demand manner, with natural applications in disciplines such as forensic science, where samples of interest are typically found in field environments (i.e., traffic stops, crime scenes, etc.). Correspondingly, investigations regarding the suitability and robustness of these methodologies when they are utilized for authentic forensic evidence processing are prudent. This work reports critical insights into the role that choice of spray solvent system plays regarding analytical performance of two spray-based ambient ionization sources, paper spray ionization (PSI) and filter cone spray ionization (FCSI), when employed for evidence types containing emerging synthetic cannabinoids. The systematic characterization studies reported herein show that the applied spray solvent can dramatically affect both spectral intensity and signal duration, and in some circumstances, yield deleterious false negative responses. Overall, acetonitrile-based systems are shown to strike a balance between analyte solubility concerns and spray ionization dynamics of the novel ion sources employed on portable MS systems.

Resolving the Mechanical and Radiative Feedback in J1044+0353 with Keck Cosmic Web Imager Spectral Mapping

We present integral field spectroscopy toward and around J1044+0353, a rapidly growing, low-metallicity galaxy that produces extreme [O iii] line emission. A new map of the O32 flux ratio reveals a density-bounded ionization cone emerging from the starburst. The interaction of the hydrogen-ionizing radiation, produced by the very young starburst, with a cavity previously carved out by a galactic outflow, whose apex lies well outside the starburst region, determines the pathway for global Lyman continuum (LyC) escape. In the region within a few hundred parsecs of the young starburst, we demonstrate that superbubble breakthrough and blowout contribute distinct components to the [O iii] line profile: broad and very broad emission line wings, respectively. We draw attention to the large [O iii] luminosity of the broad component and argue that this emission comes from photoionized, superbubble shells rather than a galactic wind as is often assumed. The spatially resolved He ii λ4686 nebula appears to be photoionized by young star clusters. Stellar wind emission from these stars is likely the source of line wings detected on the He ii line profile. This broader He ii component indicates slow stellar winds, consistent with an increase in stellar rotation (and a decrease in effective escape speed) at the metallicity of J1044+0353. At least in J1044+0353, the recent star formation history plays a critical role in generating a global pathway for LyC escape, and the anisotropic escape would likely be missed by direct observations of the LyC.

JWST discovers an AGN ionization cone but only weak radiatively driven feedback in a powerful z ≈ 3.5 radio-loud AGN

We present the first results from a JWST program studying the role played by powerful radio jets in the evolution of the most massive galaxies at the onset of cosmic noon. Using NIRSpec integral field spectroscopy, we detected 24 rest-frame optical emission lines from the z = 3.5892 radio galaxy 4C+19.71, which contains one of the most energetic radio jets known, making it perfect for testing radio mode feedback on the interstellar medium (ISM) of a M⋆ ∼ 1011 M⊙ galaxy. The rich spectrum enables line ratio diagnostics, showing that the radiation from the active galactic nucleus (AGN) dominates the ionization of the entire ISM out to at least 25 kpc, the edge of the detection. Subkiloparsec resolution reveals filamentary structures and emission blobs in the warm ionized ISM distributed on scales of ∼5 to ∼20 kpc. A large fraction of the extended gaseous nebula is located near the systemic velocity. This nebula thus may be the patchy ISM that is illuminated by the AGN after the passage of the jet. A radiative-driven outflow was observed within ∼5 kpc from the nucleus. The inefficient coupling (≲10−4) between this outflow and the quasar and the lack of extreme gas motions on galactic scales are inconsistent with other high-z powerful quasars. Combining our data with ground-based studies, we conclude that only a minor fraction of the feedback processes is happening on < 25 kpc scales.

Deep Chandra Observation of the Remarkable Ionization Cones of NGC 5252

Seyfert galaxy NGC 5252 harbors enormously extended ionization cones that have been previously detected in the optical and X-ray band, offering a unique opportunity to investigate the interaction between the central active galactic nucleus (AGN) and the surrounding gas in the AGN host galaxy. We present deep Chandra imaging spectroscopy of NGC 5252 with a total exposure time of 230 ks. The morphology in the soft X-rays shows resolved extended structure from the nucleus to a large radial distance, and for the first time we detect the outermost X-ray arc at ∼20 kpc. The X-ray cone mostly follows the direction of the optical ionization cones in the southeast and northwest directions, about 20° misaligned with the major axis of the galactic disk of NGC 5252. Fitting the spectra extracted from radial sectors with photoionization models supports that extended emission is mainly photoionized by the central AGN. We also examine the variation of the photoionization parameter along the radial extension and infer a decreasing ionizing continuum of the central engine by a factor of ∼50 over the past 64,000 yr. These findings are consistent with previous suggestions that NGC 5252 resembles a quasar relic with an M ∼ 109 M ⊙ supermassive black hole that went through a minor merger event and switched to a low accretion rate state.

VLA FRAMEx. I. Wideband Radio Properties of the AGN in NGC 4388

We present the first results from Karl G. Jansky Very Large Array (VLA) observations as a part of the Fundamental Reference Active Galactic Nucleus (AGN) Monitoring Experiment, a program to understand the relationship between AGN accretion physics and wavelength-dependent position as a function of time. With this VLA survey, we investigate the radio properties from a volume-complete sample of 25 hard X-ray-selected AGNs using the VLA in its wideband mode. We observed the targets in the A-array configuration at 4–12 GHz with all polarization products. In this work, we introduce our calibration and imaging methods for this survey, and we present our results and analysis for the radio-quiet AGN NGC 4388. We calibrated and imaged these data using the multiterm, multifrequency synthesis imaging algorithm to determine its spatial, spectral, and polarization structure across a continuous 4–12 GHz band. In the AGN, we measure a broken power law spectrum with α = − 0.06 below a break frequency of 7.3 GHz and α = − 0.34 above. We detect polarization at subarcsecond resolution across both the AGN and a secondary radio knot. We compare our results to ancillary data and find that the VLA radio continuum is likely due to AGN winds interacting with the local interstellar medium that gets resolved away at subparsec spatial scales as probed by the Very Long Baseline Array. A well-known ionization cone to the southwest of the AGN appears likely to be projected material onto the underside of the disk of the host galaxy.

The narrow-line region properties of ESO 138-G001 unveiled by SOAR/SIFS observations

ABSTRACT We study in detail the inner ∼600 pc of the Seyfert 2 galaxy ESO 138-G001 by means of the Soar Integral Field Spectrograph attached to the SOAR telescope. This source is known for displaying a very rich coronal line spectrum and a blob of high-excitation emission ∼3 arcsec south-east (SE) of the active galactic nucleus (AGN). The nature of this emission has not been fully understood yet. The excellent spatial and spectral resolution of SIFS allows us to confirm that the bulk of the coronal line forest emission region is very compact, of ∼0.8 arcsec in diameter, centred on the AGN and most likely powered by radiation from the AGN. In addition, evidence of a nuclear outflow, restricted to the inner 1 arcsec centred at the nucleus is found based on the detection of broad components in the most important emission lines. The gas in the inner few tens of parsecs filters out the AGN continuum so that the NLR is basically illuminated by a modified SED. This scenario is confirmed by means of photoionization models that reproduce the most important lines detected in the SIFS field of view. From the modelling, we also found that the black hole mass MBH of the AGN is about 105.50 M⊙, in agreement with previous X-ray observations. The spectrum of the SE blob is dominated by emission lines of low- to mid-ionization, with no hints of coronal lines. Our results show that it represents gas in the ionization cone that is photoionized by the filtered central AGN continuum.

Ionizing Spotlight of Active Galactic Nucleus

Ionization cones and relativistic jets give us one of the most large-scale example of active galactic nuclei (AGN) influence on the surrounding gas environment in galaxies and beyond. The study of ionization cones makes it possible not only to test the predictions of the unified model of galactic activity, but also to probe galaxy gas environment and trace how the luminosity of the nucleus changes over time (a light echo). In the external galactic or even extragalactic gas ionization cones create Extended Emission-Line Regions (EELRs) which can span distances from several to hundreds kpc away a host galaxy. We review the recent results of studying the gas kinematics and its ionization properties in EELRs with a special attention to search of fading AGN radiation on the time scale few×(104−105) years.The role of modern narrow-band and integral-field surveys in these researches is also considered.

AGN feedback and star formation in the peculiar galaxy NGC 232: insights from VLT-MUSE observations

ABSTRACT We use VLT-MUSE integral field unit data to study the ionized gas physical properties and kinematics as well as the stellar populations of the Seyfert 2 galaxy NGC 232 as an opportunity to understand the role of AGN feedback on star formation. The data cover a field of view of 60 × 60 arcsec2 at a spatial resolution of ∼850 pc. The emission-line profiles have been fitted with two Gaussian components, one associated to the emission of the gas in the disc and the other due to a bi-conical outflow. The spectral synthesis suggests a predominantly old stellar population with ages exceeding 2 Gyr, with the largest contributions seen at the nucleus and decreasing outwards. Meanwhile, the young and intermediate age stellar populations exhibit a positive gradient with increasing radius and a circum-nuclear star-forming ring with radius of ∼0.5 kpc traced by stars younger than 20 Myr, is observed. This, along with the fact that AGN and SF dominated regions present similar gaseous oxygen abundances, suggests a shared reservoir feeding both star formation and the AGN. We have estimated a maximum outflow rate in ionized gas of ∼1.26 M⊙ yr−1 observed at a distance of ∼560 pc from the nucleus. The corresponding maximum kinetic power of the outflow is ∼3.4 × 1041 erg s−1. This released energy could be sufficient to suppress star formation within the ionization cone, as evidenced by the lower star formation rates observed in this region.

The first X-ray polarimetric observation of the black hole binary LMC X-1

ABSTRACT We report on an X-ray polarimetric observation of the high-mass X-ray binary LMC X-1 in the high/soft state, obtained by the Imaging X-ray Polarimetry Explorer (IXPE) in 2022 October. The measured polarization is below the minimum detectable polarization of 1.1 per cent (at the 99 per cent confidence level). Simultaneously, the source was observed with the Neutron Star Interior Composition Explorer (NICER), Nuclear Spectroscopic Telescope Array (NuSTAR), and Spectrum-Rontgen-Gamma (SRG)/Astronomical Roentgen Telescope – X-ray Concentrator (ART-XC) instruments, which enabled spectral decomposition into a dominant thermal component and a Comptonized one. The low 2–8 keV polarization of the source did not allow for strong constraints on the black hole spin and inclination of the accretion disc. However, if the orbital inclination of about 36° is assumed, then the upper limit is consistent with predictions for pure thermal emission from geometrically thin and optically thick discs. Assuming the polarization degree of the Comptonization component to be 0, 4, or 10 per cent, and oriented perpendicular to the polarization of the disc emission (in turn assumed to be perpendicular to the large-scale ionization cone orientation detected in the optical band), an upper limit to the polarization of the disc emission of 1.0, 0.9, or 0.9 per cent, respectively, is found (at the 99 per cent confidence level).

Direct Collapse to Precursors of Supermassive Black Hole Seeds: Radiation-feedback-generated Outflows

We use high-resolution zoom-in cosmological simulations to model outflow triggered by radiation and thermal drivers around the central mass accumulation during direct collapse within the dark matter (DM) halo. The maximal resolution is 1.3 × 10−5 pc, and no restrictions are put on the geometry of the inflow/outflow. The central mass is considered prior to the formation of the supermassive black hole seed at a redshift of z ∼ 15.9 and can constitute either a supermassive star (SMS) of ∼105 M ⊙ surrounded by a growing accretion disk or a self-gravitating disk. The radiation transfer is modeled using the ray-tracing algorithm. Due to the high accretion rate of ∼1 M ⊙ yr−1 determined by the DM halo, accretion is mildly supercritical, resulting in mildly supercritical luminosity that has only a limited effect on the accretion rate, with a duty cycle of ∼0.9. We observe a fast development of hot cavities, which quickly extend into polar funnels and expand dense shells. Within the funnels, fast winds, ∼103 km s−1, are mass-loaded by the accreting gas. We follow the expanding shells to ∼1 pc, when the shell velocity remains substantially (∼5 times) above the escape speed. The ionization cones formed by the central UV/X-ray completely ionize the cavities. Extrapolating the outflow properties shows that the halo material outside the shell will have difficulty stopping it. We therefore conclude that the expanding wind-driven shell will break out of the central parsec and will reach the halo virial radius. Finally, the anisotropic accretion flow on subparsec scales will attenuate the UV/soft X-rays on the H2. Hence, the formation of funnels and powerful outflows around, e.g., SMSs can have interesting observational corollaries.

First Results from the JWST Early Release Science Program Q3D: Ionization Cone, Clumpy Star Formation, and Shocks in a z = 3 Extremely Red Quasar Host

Massive galaxies formed most actively at redshifts z = 1–3 during the period known as “cosmic noon.” Here we present an emission-line study of the extremely red quasar SDSSJ165202.64+172852.3’s host galaxy at z = 2.94, based on observations with the Near Infrared Spectrograph integral field unit on board JWST. We use standard emission-line diagnostic ratios to map the sources of gas ionization across the host and a swarm of companion galaxies. The quasar dominates the photoionization, but we also discover shock-excited regions orthogonal to the ionization cone and the quasar-driven outflow. These shocks could be merger-induced or—more likely, given the presence of a powerful galactic-scale quasar outflow—these are signatures of wide-angle outflows that can reach parts of the galaxy that are not directly illuminated by the quasar. Finally, the kinematically narrow emission associated with the host galaxy presents as a collection of 1 kpc–scale clumps forming stars at a rate of at least 200 M ⊙ yr−1. The interstellar medium within these clumps shows high electron densities, reaching up to 3000 cm−3, with metallicities ranging from half to a third solar with a positive metallicity gradient, and V-band extinctions up to 3 mag. The star formation conditions are far more extreme in these regions than in local star-forming galaxies but consistent with those of massive galaxies at cosmic noon. The JWST observations simultaneously reveal an archetypal rapidly forming massive galaxy undergoing a merger, a clumpy starburst, an episode of obscured near-Eddington quasar activity, and an extremely powerful quasar outflow.

The carbonaceous dust at sub-parsec scales in the nucleus of NGC 1068

ABSTRACT Single dish observations of NGC 1068 have shown the presence of a 3.4 μm 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 μm. 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 μm 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.

A radio-jet-driven outflow in the Seyfert 2 galaxy NGC 2110?

We present a spatially resolved study of the ionized gas in the central 2 kpc of the Seyfert 2 galaxy NGC 2110 and investigate the role of its moderate-luminosity radio jet (kinetic radio power of Pjet = 2.3 × 1043 erg s−1). We used new optical integral-field observations taken with the MEGARA spectrograph at the Gran Telescopio Canarias, which cover the 4300 − 5200 Å and 6100 − 7300 Å ranges with a spectral resolution of R ≃ 5000 − 5900. We fitted the emission lines with a maximum of two Gaussian components, except at the position of the active galactic nucleus (AGN), where we used three. Aided by existing stellar kinematics, we used the observed velocity and velocity dispersion (σ) of the emission lines to classify the different kinematic components. The disk component is characterized by lines with σ ≃ 60 − 200 km s−1. The outflow component has typical values of σ ≃ 700 km s−1 and is confined to the central 2.5″ ≃ 400 pc, which is coincident with the linear part of the radio jet detected in NGC 2110. At the AGN position, the [O III]λ5007 line shows high velocity components that reach at least 1000 km s−1. This and the high velocity dispersions indicate the presence of outflowing gas outside the galaxy plane. Spatially resolved diagnostic diagrams reveal mostly low ionization (nuclear) emitting region-like excitation in the outflow and some regions in the disk, which could be due to the presence of shocks. However, there is also Seyfert-like excitation beyond the bending of the radio jet, which probably traces the edge of the ionization cone that intercepts with the disk of the galaxy. NGC 2110 follows the observational trends between the outflow properties and the jet radio power found for a few nearby Seyfert galaxies. All these pieces of information suggest that part of the observed ionized outflow in NGC 2110 might be driven by the radio jet. However, the radio jet was bent at radial distances of ∼200 pc (in projection) from the AGN, and beyond there, most of the gas in the galaxy disk is rotating.

Ensemble mapping the inner structure of luminous quasars

ABSTRACT A simple prediction of the well-known unification model of active galactic nuclei is that a sample of sources should exhibit an anticorrelation between the solid angle of the dusty torus and of the ionization cone (as the sum of them shall equal 4π); however, this has never been detected. In this work, we analyse the correlation between the [O iii] 5007 narrow emission line equivalent width and LIR(λ)/Lbol for a large sample of luminous quasars. For the first time, we detect a clear intrinsic anticorrelation between them, which immediately verifies the torus/ionization-cone geometry in luminous quasars. More interestingly, the anticorrelation significantly weakens with increasing wavelength from ∼2 to 12 $\mu$m, and disappears at ∼12 $\mu$m. Simulations show that a cool dust component (in addition to the equatorial torus) with its strength positively correlating with the solid angle of the ionization cone is required to explain the observations. This shows that the polar dust seen in nearby active galaxies also exists in luminous quasars, with its contribution to total dust emission increasing with λ (from ∼2 to 12 $\mu$m) and reaching between 39 per cent and 62 per cent (model dependent) at rest frame 12 $\mu$m. Our findings provide a unique approach to map the otherwise spatially unresolvable inner structure of quasars.

Rapid screening of high-priority N-nitrosamines in pharmaceutical, forensic, and environmental samples with paper spray ionization and filter cone spray ionization-mass spectrometry.

The burgeoning concern of N-nitrosamine (NAM) contamination found in various pharmaceutical compositions has increased the demand for rapid and reliable screening methods to better assess the breadth of the problem. These carcinogenic compounds are also found in food, water, and soil, and they have been used in poison-related homicides. A combination of complementary, ambient ionization methods, paper spray ionization (PSI) and filter cone spray ionization (FCSI)-mass spectrometry (MS), was characterized towards trace-level residue screening of select NAMs (e.g., N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine) directly from complex and problematic matrices of interest, including prescription and over-the-counter tablets, drinking water, soil, and consumable goods. Spectral data for analyte confirmation and detection limit studies were collected using a Thermo LCQ Fleet ion trap mass spectrometer. PSI-MS and FCSI-MS readily produced mass spectral data marked by their simplicity (e.g., predominantly protonated molecular ions observed) and congruence with traditional electrospray ionization mass spectra in under 2min. per sample. Both methods proved robust to the complex matrices tested, yielding ion signatures for target NAMs, as well as active pharmaceutical ingredients for analyzed tablets, flavorants inherent to food products, etc. Low part-per-million detection limits were observed but were shown dependent on sample composition. PSI-MS and FCSI-MS were successful in detecting trace-level NAMS in complex liquid- and solid-phase matrices with little to no prior preparation. This work suggests that these methodologies can provide a means for assessing problematic pharmaceutical adulterants/degradants for expedited quality control, as well as enhancing environmental stewardship efforts and forensic investigations.

Dissecting the active galactic nucleus in Circinus – III. VLT/FORS2 polarimetry confirms dusty cone illuminated by a tilted accretion disc

ABSTRACT We present polarimetric maps of the Circinus galaxy nucleus in the BVRI bands, obtained with VLT/FORS2. Circinus is the closest Seyfert 2 galaxy and harbours an archetypal obscured active galactic nucleus (AGN). Recent high angular resolution imaging revealed that a major fraction of its mid-infrared (MIR) emission is coming from the polar region. Previously, we demonstrated that these observations are consistent with a model of a compact dusty disc and a hyperboloid shell, resembling a hollow cone on larger scales. Here, we focus on the AGN core, up to 40 pc from the central engine, and compare the observations to the radiative transfer models. Polarization maps reveal a conical structure, coinciding with the ionization cone. The wavelength-dependence of the polarization degree indicates that scattering on dust grains is producing polarization. The observed polarization degree ($\approx 1-3{{\ \rm per\ cent}}$) is lower than predicted by the models; however, this is only a lower limit, since stellar emission dominates the total flux in the optical. The observed polarization angle (≈30°) is reproduced by the model of a dusty disc with a hollow cone that is illuminated by a tilted anisotropic central source. An accretion disc aligned with the ionization cone axis, and alternative dust geometries, such as a paraboloid shell, or a torus enveloped by ambient dust, are inconsistent with the data. We conclude that the optical polarimetric imaging supports earlier evidence for the presence of dust in the polar region, tentatively associated with dusty outflows.