Pc Region Research Articles

Assessing GNSS hydrological monitoring capability across different climatic settings in China

Vertical position changes of ground-based Global Navigation Satellite System (GNSS) stations have been used to study regional terrestrial water storage (TWS) changes. However, the feasibility is still unclear in many areas due to diverse local effects. This study aims to evaluate the capability of GNSS vertical displacements in monitoring hydrological variations in four climate settings over Chinese mainland. The spatial and temporal variations of hydrological load-induced (HYDL) vertical displacements at 208 GNSS sites during 2011–2020 were analyzed by comparing with Gravity Recovery and Climate Experiment (GRACE)/GRACE Follow-On (GFO) and Global Land Data Assimilation System (GLDAS) derived TWS changes. The results indicate that GNSS vertical positions show different capabilities in capturing seasonal and non-seasonal hydrological dynamics in different climate regions. Among the four climatic settings, the subtropical monsoon climate (SMC) region, with the largest deformation fluctuation (the regional mean root mean square (RMS) is 7.97 mm), has the highest regional mean HYDL-GRACE and HYDL-GLDAS anti-correlation coefficients (CCs) of −0.47 and −0.45 at the seasonal scale, respectively. For the individual GNSS site, the number of the sites with CC <−0.40 between HYDL and GRACE/GLDAS-derived TWS changes accounts for 55.1% and 55.1% (SMC), 13.0% and 7.4% (temperate monsoon climate, TMC), 6.7% and 13.3% (temperate continental climate, TCC), 32.3% and 38.7% (plateau climate, PC), respectively. For the non-seasonal term, although the proportion with CC <−0.40 in each climate type decreases mainly due to the influence of local geodynamic and human activities, especially in the SMC and PC regions, GNSS site vertical deformations still show good capability in monitoring hydrological extremes. The results provide valuable information for better application of GNSS to hydrology.

The fountain of the luminous infrared galaxy Zw049.057 as traced by its OH megamaser

High-resolution ($0 $10-35$\,pc ) e-MERLIN ($ cm) and ($0 $6.5$\,pc ) ALMA ($ 1.1$ mm) observations have been used to image OH (hydroxyl) and H$_2$CO (formaldehyde) megamaser emission, and HCN $3 2$ emission toward the nuclear ($&lt;100$ pc) region of the luminous infrared galaxy Zw049.057. Zw049.057 hosts a compact obscured nucleus (CON), and thus represents a class of galaxies that are often associated with inflow and outflow motions. Formaldehyde megamaser emission has been detected toward the nuclear region, $ 30$ pc ($0 and traces a structure along the disk major axis. OH megamaser (OHM) emission has been detected along the minor axis of the disk, $ 30$\,pc ($0 from the nucleus, where it exhibits a velocity gradient with extrema of $-20$ $ northwest (NW) of the disk. HCN $3 2$ emission reveals extended emission, along the disk minor axis out to $ 60$\,pc ($0 Analysis of the minor axis HCN emission reveals high-velocity features extending out to $) and collimated outflow that is enveloped by a wide-angle and slow ($ $) outflow that is traced by the OHM emission. Analysis of the outflow kinematics suggests that the slow wide-angle outflow will not reach escape velocity and will instead fall back to the galaxy disk, evolving as a so-called fountain flow, while the fast collimated outflow traced by HCN emission will likely escape the nuclear region. We suggest that the absence of OHM emission in the nuclear region is due to high densities there. Even though OHMs associated with outflows are an exception to conventional OHM emission, we expect them to be common in CON sources that host both OHM and H$_2$CO megamasers.

ALMA Confirmation of Millimeter Time Variability in the Gamma-Ray Detected Seyfert Galaxy GRS 1734-292

GRS 1734-292 is a radio-quiet galaxy, exhibiting neither intense starburst nor jet activities. However, Fermi-LAT detected this object in the GeV band. The origin of nonthermal activity in this Seyfert galaxy is an intriguing question. We report Atacama Large Millimeter/submillimeter Array observations of GRS 1734-292 at frequencies of 97.5, 145, and 225 GHz. These observations confirmed the millimeter excess within the central ⪅100 pc region and its time variability based on two separate observations conducted 4 days apart. The timescale of variability aligns with the light-crossing time for a compact source smaller than <100 Schwarzschild radius. If we take into account the power-law synchrotron emission originating from the corona (i.e., the hot plasma located above the accretion disk), the millimeter spectrum indicates the coronal magnetic field of ≈10 G and the size of ≈10 Schwarzschild radius. An alternative explanation for this millimeter emission could be synchrotron and free–free emission from disk winds (i.e., fast wide-opening angle outflows from the disk) with the size of ≈10 pc, although it may be difficult to explain the fast variability. Future millimeter observations with higher resolution (<0.″01) will enable the differentiation between these two scenarios. Such observations will provide insights into the acceleration sites of high-energy particles at the core of active galactic nuclei.

Evaporation ages: A new dating method for young star clusters

Context. The ages of young star clusters are fundamental clocks to constrain the formation and evolution of pre-main-sequence stars and their protoplanetary disks and exoplanets. However, dating methods for very young clusters often disagree, casting doubts on the accuracy of the derived ages. Aims. We propose a new method to derive the kinematic age of star clusters based on the evaporation ages of their stars. Methods. The method was validated and calibrated using hundreds of clusters identified in a supernova-driven simulation of the interstellar medium forming stars for approximately 40 Myr within a 250 pc region. Results. We demonstrate that the clusters’ evaporation-age uncertainty can be as small as about 10% for clusters with a large enough number of evaporated stars and small but with realistic observational errors. We have obtained evaporation ages for a pilot sample of ten clusters, finding a good agreement with their published isochronal ages. Conclusions. The evaporation ages will provide important constraints for modeling the pre-main-sequence evolution of low-mass stars, as well as allow for the star formation and gas-evaporation history of young clusters to be investigated. These ages can be more accurate than isochronal ages for very young clusters, for which observations and models are more uncertain.

Radio survey of the stellar population in the infrared dark cloud G14.225-0.506

Context. The infrared dark cloud (IRDC) G14.225-0.506 is part of the extended and massive molecular cloud located to the southwest of the H II region M17. The cloud is associated with a network of filaments, which result in two different dense hubs, as well as with several signposts of star formation activity and a rich population of protostars and young stellar objects (YSOs). Aims. The aim of this work is to study the centimeter continuum emission in order to characterize the stellar population in both regions, as well as to study the evolutionary sequence across the IRDC G14.225-0.506. Methods. We performed deep (~ 1.5–3 μJy) radio continuum observations at 6 and 3.6 cm toward the IRDC G14.225-0.506 using the Karl G. Jansky Very Large Array (VLA) in its most extended A configuration (~0.3″). Data at both C and X bands were imaged using the same (u,v) range in order to derive spectral indices. We have also made use of observations taken during different days to study the presence of variability at short timescales toward the detected sources. Results. We detected a total of 66 sources, 32 in the northern region G14.2-N and 34 in the southern region G14.2-S. Ten of the sources are found to be variable, with three located in G14.2-N and seven in G14.2-S. Based on their spectral index, the emission in G14.2-N is mainly dominated by nonthermal sources while G14.2-S contains more thermal emitters. Approximately 75% of the sources present a counterpart at other wavelengths. When considering the inner 0.4 pc region around the center of each hub, the number of infrared (IR) sources in G14.2-N is larger than in G14.2-S by a factor of 4. We also studied the relation between the radio luminosity and the bolometric luminosity, finding that the thermal emission of the studied sources is compatible with thermal radio jets. For our sources with X-ray counterparts, the nonthermal emitters follow a Güdel-Benz relation with κ = 0.03, as previously suggested for other similar regions. Conclusions. We found similar levels of fragmentation between G14.2-N and G14.2-S, suggesting that both regions are most likely twin hubs. The nonthermal emission found in the less evolved objects, mainly coming from G14.2-N, suggests that G14.2-N may be composed of more massive YSOs as well as being in a more advanced evolutionary stage, consistent with the “filament-halo” gradient in age and mass from previous works. Overall, our results confirm a wider evolutionary sequence from the southwest to northeast starting in G14.2-S as the youngest part, followed by G14.2-N, and ending with the most evolved region M17.

Origin of an orbiting star around the galactic supermassive black hole

The tremendous tidal force that is linked to the supermassive black hole (SMBH) at the center of our galaxy is expected to strongly subdue star formation in its vicinity. Stars within 1'' from the SMBH thus likely formed further from the SMBH and migrated to their current positions. In this study, spectroscopic observations of the star S0-6/S10, one of the closest (projected distance from the SMBH of ≈0''.3) late-type stars were conducted. Using metal absorption lines in the spectra of S0-6, the radial velocity of S0-6 from 2014 to 2021 was measured, and a marginal acceleration was detected, which indicated that S0-6 is close to the SMBH. The S0-6 spectra were employed to determine its stellar parameters including temperature, chemical abundances ([M/H], [Fe/H], [α/Fe], [Ca/Fe], [Mg/Fe], [Ti/Fe]), and age. As suggested by the results of this study, S0-6 is very old (≳10 Gyr) and has an origin different from that of stars born in the central pc region.

The early evolution of young massive clusters

Context. Characterising the outcome of the star formation process is key to understand and predict the evolution of stellar populations. Especially the fraction of massive stars in young stellar clusters is of importance as they are the dominant sources of both mechanical and radiative feedback, strongly influencing the thermal and dynamical state of their birth environments, and beyond. Their supernovae may trigger the formation of new generations of stars in neighbouring regions. It turns out that a significant fraction of massive stars escape from their parent cluster via dynamical interactions of single stars and/or multiple stellar systems. Aims. M 17 is the nearest giant H II region hosting a very young and massive cluster: NGC 6618. Our aim is to identify stars brighter than G ≲ 21 mag that belong to NGC 6618, including the (massive) stars that may have escaped since its formation, and to determine the cluster distance and age. Methods. The Gaia DR3 database was used to identify members of NGC 6618 based on parallax and proper motion within 9′ from the cluster centre. We searched for nearby stars in a field of 5° around the cluster centre that may have originated from the cluster, and we determined their transverse velocity, kinematic age, and impact parameter. Results. We identified 42 members of NGC 6618 of which eight have a spectral type of O, with a mean distance of 1675−18+19 pc and a (transversal) velocity dispersion of about 3 km s−1, and a radial velocity dispersion of ∼6 km s−1. Another ten O stars are associated with NGC 6618, but they cannot be classified as members due to poor astrometry and/or high extinction. We have also identified six O star runaways. The relative transverse velocity of these runaways ranges from 10 to 70 km s−1 and their kinematic age ranges from about 100 to 750 kyr. Given the already established young age of NGC 6618 (≲1 Myr), this implies that massive stars are being ejected from the cluster already directly after (or during) the cluster formation process. Conclusions. When constructing the initial mass function, one has to take into account the massive stars that have already escaped from the cluster, that is, about 30% of the O stars of the original population of NGC 6618. The trajectories of the O runaways can be traced back to the central 0.2–0.3 pc region of NGC 6618. The good agreement between the evolutionary and kinematic age of the runaways implies that the latter provides an independent way to estimate (a lower limit to) the age of the cluster.

Evidence for Low-power Radio Jet–ISM Interaction at 10 pc in the Dwarf AGN Host NGC 4395

Black-hole-driven outflows in galaxies hosting active galactic nuclei (AGN) may interact with their interstellar medium (ISM) affecting star formation (SF). Such feedback processes, reminiscent of those seen in massive galaxies, have been reported recently in some dwarf galaxies. However, such studies have usually been on kiloparsec and larger scales and our knowledge of the smallest spatial scales to which these feedback processes can operate is unclear. Here we demonstrate radio jet−ISM interaction on the scale of an asymmetric triple radio structure of ∼10 pc size in NGC 4395. This triple radio structure is seen in the 15 GHz continuum image and the two asymmetric jet-like structures are situated on either side of the radio core that coincides with the optical Gaia position. The high-resolution radio image and the extended [O iii]λ5007 emission, indicative of an outflow, are spatially coincident and are consistent with the interpretation of a low-power radio jet interacting with the ISM. Modelling of the spectral lines using MAPPINGS, and estimation of temperature using optical integral field spectroscopic data suggest shock ionization of the gas. The continuum emission at 237 GHz, though weak, was found to spatially coincide with the AGN. However, the CO(2−1) line emission was found to be displaced by around 20 pc northward of the AGN core. The spatial coincidence of molecular H2 λ2.4085 along the jet direction, the morphology of ionized [O iii]λ5007, and displacement of the CO(2−1) emission argues for conditions less favorable for SF in the central ∼10 pc region.

Statistical analysis of the gravitational anomaly in Gaia wide binaries

ABSTRACT The exploration of the low acceleration a &amp;lt; a0 regime, where a0 = 1.2 × 10−10 m s−2 is the acceleration scale of MOND around which gravitational anomalies at galactic scale appear, has recently been extended to the much smaller mass and length scales of local wide binaries thanks to the availability of the Gaia catalogue. Statistical methods to test the underlying structure of gravity using large samples of such binary stars and dealing with the necessary presence of kinematic contaminants in such samples have also been presented. However, an alternative approach using binary samples carefully selected to avoid any such contaminants, and consequently much smaller samples, has been lacking a formal statistical development. In the interest of having independent high-quality checks on the results of wide binary gravity tests, we here develop a formal statistical framework for treating small, clean, wide binary samples in the context of testing modifications to gravity of the form G → γG. The method is validated through extensive tests with synthetic data samples, and applied to recent Gaia DR3 binary star observational samples of relative velocities and internal separations on the plane of the sky, v2D and r2D, respectively. Our final results for a high acceleration r2D &amp;lt; 0.01 pc region are of γ = 1.000 ± 0.096, in full accordance with Newtonian expectations. For a low acceleration r2D &amp;gt; 0.01 pc region, however, we obtain γ = 1.5 ± 0.2, inconsistent with the Newtonian value of γ = 1 at a 2.6σ level, and much more indicative of MOND AQUAL predictions of close to γ = 1.4.

The centimeter-to-submillimeter broad-band radio spectrum of the central compact component in a nearby type-II Seyfert galaxy NGC 1068

Abstract We analyze all the available Atacama Large Millimeter/submillimeter Array archival data for the nearby type-II Seyfert galaxy NGC 1068, including new 100 GHz data with an angular resolution of 005, which was not included in previous continuum spectral analyses. By combining with the literature data based on the Very Large Array, we investigate the broad-band radio continuum spectrum of the central ≲7 pc region of NGC 1068. We find that the flux density is between ≈10 and 20 mJy at 5–700 GHz. Due to the inability of the model in previous studies to account for the newly added 100 GHz data point, we proceeded to update the models and make the necessary adjustments to the parameters. One possible interpretation of this broad-band radio spectrum is a combination of emission from the jet base, the dusty torus, and the compact X-raying corona with a magnetic field strength of ≈20 G on scales of ≈30 Schwarzschild radii from the central black hole. In order to firmly identify the compact corona by omitting any other possible extended components (e.g., free–free emission from ionized gas in the vicinity), high-resolution/sensitivity observations achieved by next-generation interferometers will be necessary.

The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies

We present radio very long baseline interferometry (VLBI) and X-ray studies of the starburst galaxy NGC 3628. The VLBI observation at 1.5 GHz reveals seven compact (0.7−7 pc) radio sources in the central ∼250 pc region of NGC 3628. Based on their morphology, high radio-brightness temperatures (105–107 K), and steep radio spectra, none of these seven sources can be associated with active galactic nuclei (AGNs); instead, they can be identified as supernova remnants (SNRs), with three of them appearing consistent with partial shells. Notably, one of them (W2) is likely a nascent radio supernova (SN) and appears to be consistent with the star formation rate of NGC 3628 when assuming a canonical initial mass function. The VLBI observation provides the first precise measurement of the diameter of the radio sources in NGC 3628, which allow us to fit a well-constrained radio surface brightness—diameter (Σ–D) correlation by including the detected SNRs. Furthermore, future VLBI observations can be conducted to measure the expansion velocity of the detected SNRs. In addition to our radio VLBI study, we analyze Chandra and XMM-Newton spectra of NGC 3628. The spectral fitting indicates that the SNR activities could well account for the observed X-ray emissions. Along with the Chandra X-ray image, it further reveals that the X-ray emission is likely maintained by the galactic-scale outflow triggered by SN activities. These results provide strong evidence that SN-triggered activities play a critical role in generating both radio and X-ray emissions in NGC 3628.

How Ram Pressure Drives Radial Gas Motions in the Surviving Disk

Galaxy evolution can be dramatically affected by the environment, especially by the dense environment of a galaxy cluster. Recent observational studies show that massive galaxies undergoing strong ram-pressure stripping (RPS) have an enhanced frequency of nuclear activity. We investigate this topic using a suite of wind-tunnel hydrodynamical simulations of a massive M star = 1011 M ⊙ disk galaxy with 39 pc resolution and including star formation and stellar feedback. We find that RPS increases the inflow of gas to the galaxy center regardless of the wind impact angle. This increase is driven by the mixing of interstellar and nonrotating intracluster media at all wind angles, and by increased torque on the inner disk gas, mainly from local pressure gradients when the intracluster medium (ICM) wind has an edge-on component. In turn, the strong pressure torques are driven by rising ram pressure. We estimate the black hole (BH) accretion using Bondi–Hoyle and torque models, and compare it with the mass flux in the central 140 pc region. We find that the torque model predicts much less accretion onto the BH of a RPS galaxy than the Bondi–Hoyle estimator. We argue that both models are incomplete: the commonly used torque model does not account for torques caused by the gas distribution or local pressure gradients, while the Bondi–Hoyle estimator depends on the sound speed of the hot gas, which includes the ICM in stripped galaxies. An estimator that accounts for this missing physics is required to capture BH accretion in a RPS galaxy.

X-Ray Properties of NGC 253's Starburst-driven Outflow

We analyze image and spectral data from ≈365 ks of observations from the Chandra X-ray Observatory of the nearby, edge-on starburst galaxy NGC 253 to constrain properties of the hot phase of the outflow. We focus our analysis on the −1.1 to +0.63 kpc region of the outflow and define several regions for spectral extraction where we determine best-fit temperatures and metal abundances. We find that the temperatures and electron densities peak in the central ∼250 pc region of the outflow and decrease with distance. These temperature and density profiles are in disagreement with an adiabatic spherically expanding starburst wind model and suggest the presence of additional physics such as mass loading and nonspherical outflow geometry. Our derived temperatures and densities yield cooling times in the nuclear region of a few million years, which may imply that the hot gas can undergo bulk radiative cooling as it escapes along the minor axis. Our metal abundances of O, Ne, Mg, Si, S, and Fe all peak in the central region and decrease with distance along the outflow, with the exception of Ne, which maintains a flat distribution. The metal abundances indicate significant dilution outside of the starburst region. We also find estimates of the mass outflow rates, which are 2.8 M ⊙ yr−1 in the northern outflow and 3.2 M ⊙ yr−1 in the southern outflow. Additionally, we detect emission from charge exchange and find it makes a significant contribution (20%–42%) to the total broadband (0.5–7 keV) X-ray emission in the central and southern regions of the outflow.

Apparent diffusion coefficient of piriform cortex and seizure outcome in mesial temporal lobe epilepsy after MR-guided laser interstitial thermal therapy: a single-institution experience.

Piriform cortex (PC) is one of the critical structures in the epileptogenesis of mesial temporal lobe epilepsy (mTLE), but its role is poorly understood. The authors examined the utility of apparent diffusion coefficient (ADC; an MR-based marker of tissue pathology) of the PC as a predictor of seizure outcome in patients with mTLE undergoing MR-guided laser interstitial thermal therapy (MRgLITT). A total of 33 patients diagnosed with mTLE who underwent MRgLITT at the authors' institution were included in the study. The 6-month postoperative seizure outcomes were classified using the International League Against Epilepsy (ILAE) system as good (complete seizure freedom, ILAE class I) and poor (seizure present, ILAE classes II-VI). The PC and ablation volumes were manually segmented from both the preoperative and intraoperative MRI sequences, respectively. The mean ADC intensities of 1) preablation PC; 2) total ablation volume; 3) ablated portion of PC; and 4) postablation residual PC were calculated and compared between good and poor outcome groups. Additionally, the preoperative PC volumes and proportion of PC volume ablated were examined and compared between the subjects in the two outcome groups. The mean age at surgery was 36.5 ± 3.0 years, and the mean follow-up duration was 1.9 ± 0.2 years. Thirteen patients (39.4%) had a good outcome. The proportion of PC ablated was significantly associated with seizure outcome (10.16 vs 3.30, p < 0.05). After accounting for the variability in diffusion tensor imaging acquisition parameters, patients with good outcome had a significantly higher mean ADC of the preablation PC (0.3770 vs -0.0108, p < 0.05) and the postoperative residual PC (0.4197 vs 0.0309, p < 0.05) regions compared to those with poor outcomes. No significant differences in ADC of the ablated portion of PC were observed (0.2758 vs -0.4628, p = 0.12) after performing multivariate analysis. A higher proportion of PC ablated was associated with complete seizure freedom. Preoperative and postoperative residual ADC measures of PC were significantly higher in the good seizure outcome group in patients with mTLE who underwent MRgLITT, suggesting that ADC analysis can assist with postablation outcome prediction and patient stratification.

Filamentary structures of ionized gas in Cygnus X

Context.Ionized gas probes the influence of massive stars on their environment. The Cygnus X region (d~ 1.5 kpc) is one of the most massive star-forming complexes in our Galaxy, within which the Cyg OB2 association (age of 3–5 Myr and stellar mass 2 × 104M⊙) has a dominant influence.Aims.We observe the Cygnus X region at 148 MHz using the Low Frequency Array (LOFAR) and take short-spacing information into account during image deconvolution into account. Together with data from the Canadian Galactic Plane Survey, we investigate the morphology, distribution, and physical conditions of low-density ionized gas in a 4° × 4° (~100 pc × 100 pc) region at a resolution of 2′ (0.9 pc).Methods.The Galactic radio emission in the region analyzed is almost entirely thermal (free-free) at 148 MHz, with emission measures (EM) of 103&lt; EM [pc cm−6] &lt; 106. As filamentary structure is a prominent feature of the emission, we use DisPerSE and Fil ChaP to identify filamentary ridges and characterize their radial (EM) profiles.Results.The distribution of radial profiles has a characteristic width of 4.3 pc and a power-law distribution (β= −1.8 ± 0.1) in peak EM down to our completeness limit of 4200 pc cm−6. The electron densities of the filamentary structure range between 10 ≲ne[cm−3] ≲ 400 with a median value of 35 cm−3, remarkably similar to [N II] surveys of ionized gas.Conclusions.Cyg OB2 may ionize at most two-thirds of the total ionized gas and the ionized gas in filaments. More than half of the filamentary structures are likely photoevaporating surfaces flowing into a surrounding diffuse (~5 cm−3) medium. However, this is likely not the case for all ionized gas ridges. A characteristic width in the distribution of ionized gas indicates that the stellar winds of Cyg OB2 create a fraction of the ionized filaments through swept-up ionized gas or dissipated turbulence.

The 1.28 GHz MeerKAT Galactic Center Mosaic

Abstract The inner ∼200 pc region of the Galaxy contains a 4 million M⊙ supermassive black hole (SMBH), significant quantities of molecular gas, and star formation and cosmic-ray energy densities that are roughly two orders of magnitude higher than the corresponding levels in the Galactic disk. At a distance of only 8.2 kpc, the region presents astronomers with a unique opportunity to study a diverse range of energetic astrophysical phenomena, from stellar objects in extreme environments, to the SMBH and star-formation-driven feedback processes that are known to influence the evolution of galaxies as a whole. We present a new survey of the Galactic center conducted with the South African MeerKAT radio telescope. Radio imaging offers a view that is unaffected by the large quantities of dust that obscure the region at other wavelengths, and a scene of striking complexity is revealed. We produce total-intensity and spectral-index mosaics of the region from 20 pointings (144 hr on-target in total), covering 6.5 square degrees with an angular resolution of 4″ at a central frequency of 1.28 GHz. Many new features are revealed for the first time due to a combination of MeerKAT’s high sensitivity, exceptional u, v-plane coverage, and geographical vantage point. We highlight some initial survey results, including new supernova remnant candidates, many new nonthermal filament complexes, and enhanced views of the Radio Arc bubble, Sagittarius A, and Sagittarius B regions. This project is a South African Radio Astronomy Observatory public legacy survey, and the image products are made available with this article.

Observations of multiple NH3 transitions in W33

At a distance of 2.4 kpc, W33 is an outstanding massive and luminous 10 pc-sized star forming complex containing quiescent infrared dark clouds as well as highly active infrared bright cloud cores heated by young massive stars. We report measurements of ammonia (NH3) inversion lines in the frequency range 18–26 GHz obtained with the 40′′ resolution of the 100 m Effelsberg telescope. We detect the (J, K) = (1,1), (2,2), (3,3), (4,4), (5,5), (6,6), (2,1), and (3,2) transitions. There is a maser line in the (3,3) transition towards W33 Main. Brightness temperature and line shape indicate no significant variation during the last ~36 yr. We determined kinetic temperatures, column densities, and other physical properties of NH3 and the molecular clouds in W33. For the total-NH3 column density inside 40′′ (0.5 pc) regions, we find 6.0 (±2.1) × 1014, 3.5 (±0.1) × 1015, 3.4 (±0.2) × 1015, 3.1 (±0.2) × 1015, 2.8 (±0.2) × 1015, and 2.0 (±0.2) × 1015 cm−2 at the peak positions of W33 Main, W33 A, W33 B, W33 Main1, W33 A1, and W33 B1, respectively. W33 Main has a total-NH3 fractional abundance of 1.3 (±0.1) × 10−9 at the peak position. High values of 1.4 (±0.3) × 10−8, 1.6 (±0.3) × 10−8, 3.4 (±0.5) × 10−8, 1.6 (±0.5) × 10−8, and 4.0 (±1.2) × 10−8 are obtained at the central positions of W33 A, W33 B, W33 Main1, W33 A1, and W33 B1. From this, we confirm the previously proposed variation in the evolutionary stages of the six W33 clumps and find that there is no hot core in the region approaching the extreme conditions encountered in W51-IRS2 or Sgr B2. The ortho-to-para-NH3 abundance ratios suggest that ammonia should have been formed in the gas phase or on dust grain mantles at kinetic temperatures of ≳20 K. We determine kinetic temperatures only using NH3 (1,1) and (2,2), and from this we provide gas volume densities for the six main sources in the W33 region. With our new Tkin values, we find that our volume densities are similar to those estimated by Immer et al. (2014, A&amp;A, 572, A63), suggesting that ammonia beam-filling factors are close to unity.

Diagnostic accuracy of [18F]PSMA-1007 PET/CT in biochemical recurrence of prostate cancer

AimDespite increasing use for the detection of biochemically recurrent prostate cancer (rPC), the diagnostic accuracy of positron emission tomography/computed tomography (PET/CT) with [18F]PSMA-1007 remains only partially investigated. The aim of this study was to determine the sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) for PC-local recurrence and metastases on a per region basis.Materials and methodsOne hundred seventy-seven consecutive patients undergoing [18F]PSMA-1007 PET/CT for rPC were retrospectively analysed. Six body regions were defined: prostate fossa, pelvic lymph nodes (LN), retroperitoneal LN, supradiaphragmatic LN, bones, and soft tissue. A region was counted positive if at least one PSMA-positive lesion suspicious for PC was observed. Confirmation of a true-positive PSMA-avid lesion was defined as positive by histopathology, fall in serum prostate-specific antigen (PSA) (> 50%) after targeted therapy or confirmatory further CT, MRI, PET/CT, or bone scan imaging. Regions where additional imaging was able to confirm the absence of suspicious PC lesions or regions outside exclusively targeted RT with serum PSA decline (> 50%) were counted as true-negative regions. SE, SP, PPV, and NPV were calculated for all six regions.ResultsThe overall PET-positivity rate was 91%. Conclusive follow-up for affirmation or refutation of a PSMA-positive lesion was available for 81/152 patients on a per region basis. In this subgroup, overall sensitivity, specificity, PPV, and NPV were 95% (CI: 0.90–0.98), 89% (CI: 0.83–0.93), 86% (0.80–0.90), and 96% (CI: 0.92–0.98), respectively. On a per region basis, PPV was 97% (CI: 0.83–0.99) for local recurrence, 93% (CI: 0.78–0.98) for pelvic LN, 87% (CI: 0.62–0.96) for retroperitoneal LN, 82% (CI: 0.52–0.95) for supradiaphragmatic LN, and 79% (0.65–0.89) for bone lesions. The number of solid organ metastases (n = 6) was too small for an accurate statistical analysis.ConclusionThe known high PET-positivity rate of [18F]PSMA-1007 PET/CT in rPC was confirmed, with corresponding high (> 90%) sensitivity and NPV on a per region basis. However, overall PPV was limited (86%), particularly for bone lesions (79%), which are a potential diagnostic weaknesses when using this tracer.

The Detection of a Hot Molecular Core in the Extreme Outer Galaxy

Abstract Interstellar chemistry in low-metallicity environments is crucial to understand chemical processes in the past metal-poor universe. Recent studies of interstellar molecules in nearby low-metallicity galaxies have suggested that metallicity has a significant effect on the chemistry of star-forming cores. Here we report the first detection of a hot molecular core in the extreme outer Galaxy, which is an excellent laboratory to study star formation and the interstellar medium in a Galactic low-metallicity environment. The target star-forming region, WB 89–789, is located at a galactocentric distance of 19 kpc. Our Atacama Large Millimeter/submillimeter Array observations in 241–246, 256–261, 337–341, and 349–353 GHz have detected a variety of carbon-, oxygen-, nitrogen-, sulfur-, and silicon-bearing species, including complex organic molecules (COMs) containing up to nine atoms, toward a warm (&gt;100 K) and compact (&lt;0.03 pc) region associated with a protostar (∼8 × 103 L ☉). Deuterated species such as HDO, HDCO, D2CO, and CH2DOH are also detected. A comparison of fractional abundances of COMs relative to CH3OH between the outer Galactic hot core and an inner Galactic counterpart shows a remarkable similarity. On the other hand, the molecular abundances in the present source do not resemble those of low-metallicity hot cores in the Large Magellanic Cloud. The results suggest that great molecular complexity exists even in the primordial environment of the extreme outer Galaxy. The detection of another embedded protostar associated with high-velocity SiO outflows is also reported.

Morphological Transition of the Compact Radio Lobe in 3C 84 via the Strong Jet–Cloud Collision

Abstract We report multiepoch very long baseline interferometric observations of the compact radio lobe in the radio galaxy 3C 84 (NGC 1275) during 2016–2020. The image sequence of 3C 84 reveals that the hotspot in the radio lobe showed the 1 year long frustration in 2017 within a compact region of about 0.07 pc, suggesting a strong collision between the jet and a compact dense cloud with an estimated average density of about (4–6) × 105 cm−3. Although the hotspot and the radio lobe began to move south again after its breakout, the radio lobe showed a morphological transition from an FR II- to FR I-class radio lobe and its radio flux became fainter. This is the first detection of the dynamical feedback from the cloud to the jet where the cloud located on the jet axis significantly interferes with the jet propagation and evolution at the central 1 pc region in the active galactic nucleus.