Abstract:The energy released by an active galactic nucleus (AGN) has a strong impact on the surrounding interstellar medium (ISM). This feedback is considered to be the regulating factor for the growth of the central massive black hole, and for the rate of star formation in a galaxy. We have located, using Very Long Baseline Interferometry (VLBI), the fast outflow of neutral hydrogen in the young, restarted radio loud AGN 4C12.50. The outflow is located 100 pc from the nucleus where the radio jet interacts with the ISM, as well as around the associated radio lobe. These observations show that the radio plasma drives the outflow and removes gas from the central regions, and that jet driven outflows can play a relevant role in feedback mechanisms.

The extremely high redshift (z=5.3) radio source SDSS J102623.61+254259.5 (J1026+2542) is among the most distant and most luminous radio-loud active galactic nuclei (AGN) known to date. Its one-sided radio jet structure on milli-arcsecond (mas) and ∼10-mas scales typical for blazars was first imaged at 5 GHz with very long baseline interferometry (VLBI) in 2006. Here we report on our dual-frequency (1.7 and 5 GHz) imaging observations performed with the European VLBI Network (EVN) in 2013. The prominent jet structure allows us to identify individual components whose apparent displacement can be detected over the time span of 7.33 yr. This is the first time when jet proper motions are directly derived in a blazar at z>5. The small values of up to ∼0.1 mas yr −1 are consistent with what is expected in a relativistic cosmological model if redshift is a measure of distance. The apparent superluminal jet speeds, considered tentative because derived from two epochs only, exceed 10 c for three different components along the jet. Based on modeling its spectral energy distribution, J1026+2542 is known to have its X-ray jet oriented close to the line of sight, with significant Doppler boosting and a large bulk Lorentz factor (Γ≈13). The new VLBI observations, indicating ∼ 2.3 × 10 12 K lower limit to the core brightness temperature, are consistent with this picture. The spectral index in the core region is −0.35.

We report the results of a pilot study of CO(4 − 3) emission line of three Wide-field Infrared Survey Explorer (WISE)-selected hyper-luminous, dust-obscured quasars (QSOs) with sensitive ALMA Band 3 observations. These obscured QSOs with L bol >10 14 L e are among the most luminous objects in the universe. All three QSO hosts are clearly detected both in continuum and in CO(4 − 3) emission line. Based on CO(4 − 3) emission line detection, we derive the molecular gas masses (∼10 10−11 M e), suggesting that these QSOs are gas-rich systems. We find that the obscured QSOs in our sample follow the similar ¢-L L CO FIR relation as unobscured QSOs at high redshifts. We also find the complex velocity structures of CO(4 − 3) emission line, which provide the possible evidence for a gas-rich merger in W0149+2350 and possible molecular outflow in W0220+0137 and W0410−0913. Massive molecular outflow can blow away the obscured interstellar medium and make obscured QSOs evolve toward the UV/optical bright, unobscured phase. Our result is consistent with the popular active galactic nucleus (AGN) feedback scenario involving the co-evolution between the supermassive black holes and host galaxy.

Based on its broad-band spectral energy distribution, and the X-ray spectrum in particular, the radio-loud active galactic nucleus (AGN) SDSS J102623.61+254259.5 (J1026+2542) has recently been classified as a blazar. The extremely high redshift of the source, z=5.3, makes it one of the most distant and most luminous radioloud AGN known to date. From published 5-GHz very long baseline interferometry (VLBI) imaging data obtained in 2006, the source has a typical blazar appearance on mas scales, with a prominent one-sided jet extending to ∼20 mas. We estimate the brightness temperature of J1026+2542 and find no strong evidence for Doppler boosting. The jet viewing angle is possibly at least ∼20 • . The bulk Lorentz factor and the viewing angle of the jet could reliably be determined in the near future from multi-epoch VLBI observations.

The gas content of galaxies is a key factor for their growth, starting from star formation and black hole accretion to galaxy mergers. Thus, characterising its properties through observations of tracers like the CO emission line is of big importance in order to understand the bigger picture of galaxy evolution. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of dust continuum, CO(5-4) and CO(8-7) line emission in the quasar-star-forming companion system SMM J04135+10277 (z = 2.84). Earlier low-J CO studies of this system found a huge molecular gas reservoir associated to the companion galaxy, while the quasar appeared gas-poor. Our CO observations revealed that the host galaxy of the quasar is also gas-rich, with an estimated molecular gas mass of ∼ (0.7−2.3)×10 10 M . The CO line profiles of the companion galaxy are very broad (∼ 1000 km s −1 ), and show signs of rotation of a compact, massive system. In contrast to previous far-infrared observations, we resolve the continuum emission and detect both sources, with the companion galaxy dominating the dust continuum and the quasar having a ∼ 25% contribution to the total dust emission. By fitting the infrared spectral energy distribution of the sources with MR-MOOSE and empirical templates, the infrared luminosities of the quasar and the companion are in the range of L IR,QSO ∼ (2.1 − 9.6) × 10 12 L and L IR,Comp. ∼ (2.4 − 24) × 10 12 L , while the estimated star formation rates are ∼ 210 − 960 M yr −1 and ∼ 240 − 2400 M yr −1 , respectively. Our results demonstrate that non-detection of low-J CO transition lines in similar sources does not necessarily imply the absence of massive molecular gas reservoir but that the excitation conditions favour the excitation of high-J transitions.

Context. In the last decade several massive molecular gas reservoirs were found < 100 kpc distance from active galactic nuclei (AGNs), residing in gas-rich companion galaxies. The study of AGN-gas-rich companion systems opens the opportunity to determine whether the stellar mass of massive local galaxies was formed in their host after a merger event or outside of their host galaxy in a close starbursting companion and later incorporated via mergers. Aims. Our aim is to study the quasar-companion galaxy system of SMM J04135+10277 (z = 2.84) and investigate the expected frequency of quasar-starburst galaxy pairs at high redshift using a cosmological galaxy formation model. Methods. We use archive data and new APEX ArTeMiS data to construct and model the spectral energy distribution of SMM J04135+10277 in order to determine its properties. We also carry out a comprehensive analysis of the cosmological galaxy formation model galform with the aim of characterising how typical the system of SMM J04135+10277 is and whether quasar-starforming galaxy pairs may constitute an important stage in galaxy evolution. Finally, we compare our results to observations found in the literature at both large and small scales (1 Mpc-100 kpc). Results. The companion galaxy of SMM J04135+10277 is a heavily dust-obscured starburst galaxy with a median star formation rate (SFR) of 700 M yr −1 , median dust mass of 5.1 × 10 9 M and median dust luminosity of 9.3 × 10 12 L . Our simulations, performed at z = 2.8, suggest that SMM J04135+10277 is not unique. In fact, at a distance of < 100 kpc, 22% of our simulated quasar sample have at least one companion galaxy of a stellar mass > 10 8 M , and 0.3% have at least one highly star-forming companion (SFR > 100 M yr −1 ). Conclusions. Our results suggest that quasar-gas-rich companion galaxy systems are common phenomena in the early Universe and the high incidence of companions makes the study of such systems crucial to understand the growth and hierarchical build-up of galaxies and black holes.

Both theoretical and observational results suggest that high-redshift radio galaxies (HzRGs) inhabit overdense regions of the universe and might be the progenitors of local, massive galaxies residing in the centre of galaxy clusters. In this paper, we present CO(3–2) line observations of the HzRG TXS 0828+193 (z = 2.57) and its environment using the Atacama Large Millimeter/submillimeter Array. In contrast to previous observations, we detect CO emission associated with the HzRG and derive a molecular gas mass of $(0.9\pm 0.3)\times 10^{10}\, \rm M_{\odot }$. Moreover, we confirm the presence of a previously detected off-source CO emitting region (companion #1), and detect three new potential companions. The molecular gas mass of each companion is comparable to that of the HzRG. Companion #1 is aligned with the axis of the radio jet and has stellar emission detected by Spitzer. Thus, this source might be a normal star-forming galaxy or alternatively a result of jet-induced star formation. The newly found CO sources do not have counterparts in any other observing band and could be high-density clouds in the halo of TXS 0828+193 and thus potentially linked to the large-scale filamentary structure of the cosmic web.

We present CO(1–0) observations of the high-redshift quasar SDSS J160705+533558 (z = 3.653) using the Karl G. Jansky Very Large Array (VLA). We detect CO emission associated with the quasar and at ∼16.8 kpc projected distance from it, separated by ∼800 km s−1 in velocity. The total molecular gas mass of this system is ∼5 × 1010 M⊙. By comparing our CO detections with previous submillimetre (submm) observations of the source, an offset between the different emission components is revealed: the peak of the submm emission is offset from the quasar and from the CO companion detected in our VLA data. To explain our findings, we propose a scenario similar to that for the Antennae galaxies: SDSS J160705+533558 might be a merger system in which the quasar and the CO companion are the merging galaxies, whose interaction resulted in the formation of a dusty, star-forming overlap region between the galaxies that is dominant at the submm wavelengths.