Context. New generation low-frequency telescopes are exploring a new parameter space in terms of depth and resolution. The data taken with these interferometers, for example with the LOw Frequency ARray (LOFAR), are often calibrated in a low signal-to-noise ratio regime and the removal of critical systematic effects is challenging. The process requires an understanding of their origin and properties. Aims. In this paper we describe the major systematic effects inherent to next generation low-frequency telescopes, such as LOFAR. With this knowledge, we introduce a data processing pipeline that is able to isolate and correct these systematic effects. The pipeline will be used to calibrate calibrator observations as the first step of a full data reduction process. Methods. We processed two LOFAR observations of the calibrator 3C 196: the first using the Low Band Antenna (LBA) system at 42-66 MHz and the second using the High Band Antenna (HBA) system at 115-189 MHz. Results. We were able to isolate and correct for the effects of clock drift, polarisation misalignment, ionospheric delay, Faraday rotation, ionospheric scintillation, beam shape, and bandpass. The designed calibration strategy produced the deepest image to date at 54 MHz. The image has been used to confirm that the spectral energy distribution of the average radio source population tends to flatten at low frequencies.Conclusions. We prove that LOFAR systematic effects can be described by a relatively small number of parameters. Furthermore, the identification of these parameters is fundamental to reducing the degrees of freedom when the calibration is carried out on fields that are not dominated by a strong calibrator.

We report the discovery with the Atacama Pathfinder EXperiment (APEX) of an outflow of molecular gas in the radio-loud Seyfert galaxy IC 5063 (z = 0.0110). In addition to the emission of the large-scale CO disk, a prominent blueshifted wing is observed in the CO(2−1) spectrum. IC 5063 represents one of the best cases of a fast jet-driven H I (and ionized gas) outflow, which is located at the site of a radio-bright feature about 0.5 kpc from the nucleus. It is possible that the blueshifted part of the molecular gas is associated with this outflow and is accelerated by the interaction with the radio jet. The outflow of molecular gas is characterized by an H 2 mass of the outflowing component of between 2.25±0.70×10 7 M and 1.29±0.40×10 8 M and a mass outflow rate between 22 and 129 M yr −1 depending on the assumption for α X and assuming a luminosity ratio L CO(2-1)/L CO(1-0) = 1. This confirms that this may indeed be the dominant component in outflows driven by the nuclear activity as also found in other objects. However, this high mass outflow rate cannot easily be supported for a long time, suggesting that the gas outflow in IC 5063 happens in bursts and is in a particularly strong phase at present. Owing to its proximity, IC 5063 serves as an excellent laboratory for understanding the impact of radio jets on the gas-rich inter-stellar medium.

Context. Surveys of protoplanetary disks in nearby star-forming regions (SFRs) have provided important information on their demographics. However, due to their sample sizes, these surveys cannot be used to study how disk properties vary with the environment. Aims. We conduct a survey of the unresolved millimeter continuum emission of 873 protoplanetary disks identified by Spitzer in the L1641 and L1647 regions of the Orion A cloud. This is the largest such survey yet, allowing us to identify even weak trends in the median disk mass as a function of position in the cloud and cluster membership. The sample detection rates and median masses are also compared to those of nearby (<300 pc) SFRs. Methods. The sample was observed with the Atacama Large Millimeter/submillimeter Array (ALMA) at 225 GHz, with a median rms of 0.08 mJy beam−1, or 1.5 M⊕. The data were reduced and imaged using an innovative parallel data processing approach. Results. We detected 58% (502/873) of the observed disks. This includes 20 disks with dust masses >100 M⊕, and two objects associated with extended dust emission. By fitting a log-normal distribution to the data, we infer a median disk dust mass in the full sample of 2.2−0.2+0.2 M⊕. In L1641 and L1647, median dust masses are 2.1−0.2+0.2M⊕ and 2.6−0.5+0.4M⊕, respectively. Conclusions. The disk mass distribution of the full sample is similar to that of nearby low-mass SFRs at similar ages of 1–3 Myr. We find only weak trends in disk (dust) masses with galactic longitude and between the Young Stellar Object (YSO) clusters identified in the sample, with median masses varying by ≲50%. Differences in age may explain the median disk mass variations in our subsamples. Apart from this, disk masses are essentially constant at scales of ~100 pc. This also suggests that the majority of disks, even in different SFRs, are formed with similar initial masses and evolve at similar rates, assuming no external irradiation, with disk mass loss rates of ~10−8 M⊙ yr−1.