arXiv subjects

Ralf-Jürgen Dettmar

Publications and source records attributed to Ralf-Jürgen Dettmar.

At least 37 records · Page 2Linked to original sources

arXiv2023

Disc-halo gas outflows driven by stellar clusters as seen in multiwavelength tracers

We consider the dynamics of and emission from growing superbubbles in a stratified interstellar gaseous disc driven by energy release from supernovae explosions in stellar clusters with {masses $M_{cl}= 10^5-1.6\times 10^6~M_\odot$}. Supernovae are spread randomly within a sphere of $r_c=60$ pc, and inject energy episodically with a specific rate $1/130~M_\odot^{-1}$ proportional to the star formation rate (SFR) in the cluster. Models are run for several values of SFR in the range $0.01$ to $0.1~M_\odot$ yr$^{-1}$, with the corresponding average surface energy input rate $\sim 0.04-0.4$ erg cm$^{-2}$ s$^{-1}$. We find that the discrete energy injection by isolated SNe are more efficient in blowing superbubbles: asymptotically they reach heights of up to 3 to 16 kpc for $M_{cl}=10^5-1.6\times 10^5~M_\odot$, correspondingly, and stay filled with a hot and dilute plasma for at least 30 Myr. During this time they emit X-ray, H$α$ and dust infrared emission. X-ray liminosities $L_X\propto {\rm SFR}^{3/5}$ that we derive here are consistent with observations in star-forming galaxies. Even though dust particles of small sizes $a\leq 0.03~μ$m are sputtered in the interior of bubbles, larger grains still contribute considerably ensuring the bubble luminosity $L_{\rm IR}/{\rm SFR}\sim 5\times 10^7 L_\odot M_\odot^{-1} ~{\rm yr}$. It is shown that the origin of the North Polar Spur in the Milky Way can be connected with activity of a cluster with the stellar mass of $\sim 10^5~M_\odot$ and the ${\rm SFR}\sim 0.1~M_\odot$ yr$^{-1}$ some 25--30 Myr ago. Extended luminous haloes observed in edge-on galaxies (NGC 891 as an example) can be maintained by disc spread stellar clusters of smaller masses $M_\ast \simlt 10^5~M_\odot$.

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arXiv2022

Multi-epoch variability of AT 2000ch (SN 2000ch) in NGC 3432 -- A radio continuum and optical study

AT 2000ch is a highly variable massive star and supernova imposter in NGC 3432 first detected in 2000. It is similar and often compared to SN 2009ip, and it is therefore expected to undergo a core-collapse supernova -- a SN imposter of similar brightness -- in the near future. We characterize the long-term variability of AT 2000ch in the radio and optical regimes with archival data reaching back to the year 1984. We use these newly reduced observations in addition to observations in the literature to restrict the mass-loss rates of AT 2000ch at multiple epochs based on different approaches, and to infer the general properties of its circumstellar nebula with respect to the detected radio brightness. We extend the known optical light curve of AT 2000ch up to the beginning of 2022 by performing point spread function photometry on archival data from the Palomar Transient Factory and the Zwicky Transient Facility. We reduced archival radio continuum observations obtained with the Very Large Array using standard calibration and imaging methods and complemented these with pre-reduced \changes observations as well as observations obtained with the Westerbork Synthesis Radio Telescope and LOw Frequency ARray. For the analysis of AT 2000ch, we consider the optical light curve and color evolution, its radio continuum brightness at different frequencies and times, and the corresponding spectral indices. We estimated mass-loss rates and optical depths based on radio continuum brightnesses and Ha fluxes. We report two newly detected outbursts of AT 2000ch similar to those found in the 2000s and 13 re-brightening events, of which at least four are not conclusively detected because of insufficient sampling of the light curve. The dates of all outbursts and significant, well-sampled re-brightening events are consistent with a period of $\sim 201 \pm 12\,$days over a total time-span of two decades. Such a behavior has never been found for any SN imposter, especially not for candidate SN~2009ip analogs. During 2010 to 2012 and 2014 to 2018, we only have a few detections, which is insufficient to come to any conclusion as to a possible less eruptive phase of the transient. We find steady dimming after the most recent re-brightening events and possible evidence of porosity in the circumstellar envelope, suggesting AT~2000ch may currently be in transition to a state of relative calm. We identified a second, unrelated source at a projected distance of $\sim 23\,$pc ($\sim0.5^{\prime\prime}$) that has contaminated the optical measurements of AT~2000ch at its minimum luminosity over the last two decades probably on a $5\%-10\,\%$ level, but this does not affect our overall findings and is negligible during re-brightening. We are able to restrict the mass-loss rate of AT~2000ch to range between several $10^{-6}\,\textrm{M}_{\odot}/\textrm{yr}$ and several $10^{-5}\,\textrm{M}_{\odot}/\textrm{yr}$. The fresh ejecta appear to be optically thick to radio continuum emission at least within the first $\sim 25\,$days after significant re-brightening.

astro-ph.SR↗

arXiv2022

Solving the multi-messenger puzzle of the AGN-starburst composite galaxy NGC 1068

Multi-wavelength observations indicate that some starburst galaxies show a dominant non-thermal contribution from their central region. These active galactic nuclei (AGN)-starburst composites are of special interest, as both phenomena on their own are potential sources of highly-energetic cosmic rays and associated gamma-ray and neutrino emission. In this work, a homogeneous, steady-state two-zone multi-messenger model of the non-thermal emission from the AGN corona as well as the circumnuclear starburst region is developed and subsequently applied to the case of NGC 1068, which has recently shown some first indications of high-energy neutrino emission. Here, we show that the entire spectrum of multi-messenger data - from radio to gamma-rays including the neutrino constraint - can be described very well if both, starburst and AGN corona, are taken into account. Using only a single emission region is not sufficient.

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arXiv2022

The extended HI halo of NGC 4945 as seen by MeerKAT

Observations of the neutral atomic hydrogen (HI) in the nuclear starburst galaxy NGC 4945 with MeerKAT are presented. We find a large amount of halo gas, previously missed by HI observations, accounting for 6.8% of the total HI mass. This is most likely gas blown into the halo by star formation. Our maps go down to a $3σ$ column density level of $5\times10^{18} cm^{-2}$ . We model the HI distribution using tilted-ring fitting techniques and find a warp on the galaxy's approaching and receding sides. The HI in the northern side of the galaxy appears to be suppressed. This may be the result of ionisation by the starburst activity in the galaxy, as suggested by a previous study. The origin of the warp is unclear but could be due to past interactions or ram pressure stripping. Broad, asymmetric HI absorption lines extending beyond the HI emission velocity channels are present towards the nuclear region of NGC 4945. Such broad lines suggest the existence of a nuclear ring moving at a high circular velocity. This is supported by the clear rotation patterns in the HI absorption velocity field. The asymmetry of the absorption spectra can be caused by outflows or inflows of gas in the nuclear region of NGC 4945. The continuum map shows small extensions on both sides of the galaxy's major axis that might be signs of outflows resulting from the starburst activity.

astro-ph.CO↗

arXiv2022

A depolarizing HI tidal tail in the western lobe of Fornax A

Recent MeerKAT neutral hydrogen (HI) observations of Fornax A reveal tidal material intersecting in projection the western lobe of this radio galaxy. We found a spatial coincidence between the northern HI tail and a depolarized structure observed for the first time with the Australian Square Kilometre Array Pathfinder (ASKAP) at 1.2 GHz. We analyzed the properties of the rotation measure (RM) image obtained with ASKAP data at the location of the HI tail and in its neighborhood. We modeled the observed RM structure function to investigate the magnetic field power spectrum at the location of the HI tail and in a nearby control region. We found that the observed RM, in the control region and in a region enclosing the HI tail, cannot be due to the intracluster Faraday screen caused by the Fornax cluster. An intragroup magnetized medium with a central magnetic field strength of 18.5 $\rmμ$G can explain the control region RM, but it is clear that there is an excess in correspondence with the HI tail region. We evaluated several scenarios in which the HI tail is either in the lobe foreground or embedded in the lobe. We determined a magnetic field strength on the order of $\sim$9.5$-$11 $μ$G in the HI tail, a value consistent with constraints derived from narrowband H$α$ imaging of the ionized gas. The spatial coincidence between HI tail and depolarization analyzed in this paper could be the first observed evidence of a magnetic field that either has passed through a radio galaxy lobe or has survived the lobe expansion.

astro-ph.GA↗

arXiv2021

Role of magnetic fields in ram pressure stripped galaxies

Ram-pressure stripping is a crucial evolutionary driver for cluster galaxies and jellyfish galaxies, characterized by very extended tails of stripped gas, are the most striking examples of it in action. Recently, those extended tails are found to show on-going star formation raising the question how the stripped, cold gas can survive long enough to form new stars outside the stellar disk. In this work, we summarize the most recent results achieved within the GASP collaboration to provide a holistic explanation for this phenomenon. We focus on two textbook examples of jellyfish galaxies, JO206 and JW100 for which, via multi-wavelength observations from radio to X-ray and numerical simulations, we have explored the different gas phases (neutral, molecular, diffuse-ionized, and hot). Based on additional multi-phase gas studies we now propose a scenario of stripped tail evolution including all phases that is driven by a magnetic draping sheath, where the intracluster turbulent magnetized plasma condenses onto the galaxy disk and tail and produces a magnetized interface that protects the stripped galaxy tail gas from evaporation. In such a scenario, the accreted environmental plasma can cool down and eventually join the tail gas, hence providing additional gas to form stars. The implications of our findings can shed light on the more general scenario of draping, condensation, and cooling of hot gas surrounding cold clouds that is fundamental in many astrophysical phenomena.

astro-ph.GA↗

arXiv2021

Two striking head-tail galaxies in the galaxy cluster IIZW108: insights into transition to turbulence, magnetic fields and particle re-acceleration

We present deep JVLA observations at 1.4 GHz and 2.7 GHz (full polarization), as well as optical OmegaWINGS/WINGS and X-ray observations of two extended radio galaxies in the IIZW108 galaxy cluster at z = 0.04889. They show a bent tail morphology in agreement with a radio lobed galaxy falling into the cluster potential. Both galaxies are found to possess properties comparable with {narrow-angle} tail galaxies in the literature even though they are part of a low mass cluster. We find a spectral index steepening and an increase in fractional polarization through the galaxy jets and an ordered magnetic field component mostly aligned with the jet direction. This is likely caused by either shear due to the velocity difference of the intracluster medium and the jet fluid and/or magnetic draping of the intracluster medium across the galaxy jets. We find clear evidence that one source is showing two active galactic nuclei (AGN) outbursts from which we expect the AGN has never turned off completely. We show that pure standard electron cooling cannot explain the jet length. We demonstrate therefore that these galaxies can be used as a laboratory to study gentle re-acceleration of relativistic electrons in galaxy jets via transition from laminar to turbulent motion.

astro-ph.GA↗

arXiv2021

An AGN-starburst composite multi-messenger model of NGC 1068

Recent multi-wavelength observations indicate that some starburst galaxies show a dominant nonthermal contribution from its central region. These active galactic nuclei (AGN)-starburst composites are of special interest, as both phenomena on their own are potential sources of the high-energetic cosmic rays and their accompanied gamma-ray and neutrino emission. Here, we will focus on NGC 1068, which is known since several years from its atypical radio-gamma-ray correlation. Recently this source has also shown strong indications of high energy neutrino emission. A first semi-analytical, two-component multi-messenger model is presented that already gives some constraints on the AGN-starburst composite characteristics of NGC 1068 and exposes the need to include both starburst \emph{and} AGN corona to describe the multi-messenger data.

astro-ph.HE↗

arXiv2021

Anomalous gas in ESO 149-G003: A MeerKAT-16 View

ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen (HI) deviating from the kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar HI component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy's morphology, which shows a high degree of asymmetry. By comparing our model with the observed HI, we find that in our model we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube we estimate that at least 7%-8% of the HI in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1% for the morphologically confirmed extraplanar component. We investigate a number of global scaling relations and find that, besides being gas-dominated with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any obvious global peculiarities. Given its isolation, as confirmed by optical observations, we conclude that the galaxy is likely currently acquiring neutral gas. It is either re-accreting gas expelled from the galaxy or accreting pristine intergalactic material.

astro-ph.GA↗

arXiv2020

Highly ordered magnetic fields in the tail of the jellyfish galaxy JO206

Jellyfish galaxies have long tails of gas that is stripped from the disc by ram pressure due to the motion of galaxies in the intracluster medium in galaxy clusters. We present the first measurement of the magnetic field strength and orientation within the disc and the (90$\,$kpc-long) $\rm Hα$-emitting tail of the jellyfish galaxy JO206. The tail has a large-scale magnetic field ($>4.1\,μ$G), a steep radio spectral index ($α\sim -2.0$), indicating an aging of the electrons propagating away from the star-forming regions, and extremely high fractional polarisation ($>50\,$%), indicating low turbulent motions. The magnetic field vectors are aligned with (parallel to) the direction of the ionised-gas tail and stripping direction. High-resolution simulations of a large, cold gas cloud that is exposed to a hot, magnetised turbulent wind show that the high fractional polarisation and the ordered magnetic field can be explained by accretion of draped magnetised plasma from the hot wind that condenses onto the external layers of the tail, where it is adiabatically compressed and sheared. The ordered magnetic field, preventing heat and momentum exchange, may be a key factor in allowing in-situ star formation in the tail.

astro-ph.GA↗

arXiv2020

A novel analytical model of the magnetic field configuration in the Galactic Center

Context: Cosmic-ray propagation is strongly dependent on the large-scale configuration of the Galactic magnetic field. In particular, the Galactic center (GC) region provides highly interesting cosmic-ray data from gamma-ray maps and it is clear that a large fraction of the cosmic rays detected at Earth originate in this region of the Galaxy. Yet because of confusion from line-of-sight integration, the magnetic field structure in the Galactic center is not well known and no large-scale magnetic field model exists at present. Aims: In this paper, we develop a magnetic field model, derived from observational data on the diffuse gas, nonthermal radio filaments, and molecular clouds. Methods. We derive an analytical description of the magnetic field structure in the central molecular zone by combining observational data with the theoretical modeling of the basic properties of magnetic fields. Results. We provide a first description of the large-scale magnetic field in the Galactic center region. We present first test simulations of cosmic-ray propagation and the impact of the magnetic field structure on the cosmic-ray distribution in the three dimensions. Conclusions: Our magnetic field model is able to describe the main features of polarization maps; it is particularly important to note that they are significantly better than standard global Galactic magnetic field models. It can also be used to model cosmic-ray propagation in the Galactic Center region more accurately.

astro-ph.GA↗

arXiv2020

CHANG-ES XXII: Coherent Magnetic Fields in the Halos of Spiral Galaxies

Context. The magnetic field in spiral galaxies is known to have a large-scale spiral structure along the galactic disk and is observed as X-shaped in the halo of some galaxies. While the disk field can be well explained by dynamo action, the 3-dimensional structure of the halo field and its physical nature is still unclear. Aims. As first steps towards understanding the halo fields, we want to clarify whether the observed X-shaped field is a wide-spread pattern in the halos of spiral galaxies and whether these halo fields are just turbulent fields ordered by compression or shear (anisotropic turbulent fields), or have a large-scale regular structure. Methods. The analysis of the Faraday rotation in the halo is the tool to discern anisotropic turbulent fields from large-scale magnetic fields. This, however, has been challenging until recently because of the faint halo emission in linear polarization. Our sensitive VLA broadband observations C-band and L-band of 35 spiral galaxies seen edge-on (called CHANG-ES) allowed us to perform RM-synthesis in their halos and to analyze the results. We further accomplished a stacking of the observed polarization maps of 28 CHANG-ES galaxies at C-band. Results. Though the stacked edge-on galaxies were of different Hubble types, star formation and interaction activities, the stacked image clearly reveals an X-shaped structure of the apparent magnetic field. We detected a large-scale (coherent) halo field in all 16 galaxies that have extended polarized intensity in their halos. We detected large-scale field reversals in all of their halos. In six galaxies they are along lines about vertical to the galactic midplane (vertical RMTL) with about 2 kpc separation. Only in NGC 3044 and possibly in NGC 3448 we observed vertical giant magnetic ropes (GMRs) similar to those detected recently in NGC 4631.

astro-ph.GA↗

arXiv2019

A Novel Analytical Model of the Magnetic Field Configuration in the Galactic Center Explaining the Diffuse Gamma-Ray Emission (ICRC-2019)

Reliable identification of the origin of the high-energy non-thermal emission from the Galactic Center (GC) is not achievable without adequate consideration of the ambient conditions such as the magnetic field configuration or gas distribution. In a first step, we present a model that can explain the diffuse gamma-ray emission as measured by H.E.S.S. for small longitudes in the Galactic Center region but comes to grief with higher longitudes. The model is given via the solution of a transport equation that allows for a radial dependency of the mass distribution. In order to move from this semi-analytical approximation toward a full understanding of the PeVatron signature, we present a new 3D analytical model of the gas distribution in the Central Molecular Zone (CMZ). Furthermore, we derive for the first time a 3D model of the magnetic field configuration and strength in the CMZ, which is analytical and divergence-free. The model is built via a combination of a model for the diffuse inter-cloud medium, local molecular clouds and non-thermal filaments at which local information are based on investigations from previous works and the molecular gas density. It can be shown that without an efficient longitudinal CR entrapment, a single source at the center does not facilely suffice the diffuse gamma-ray detection. Further, we show that the new magnetic field model GBFD19 is compatible with recent polarization data and has a significant impact on the longitudinal profiles of CR propagation.

astro-ph.GA↗

arXiv2018

Sharpening up Galactic all-sky maps with complementary data - A machine learning approach

Galactic all-sky maps at very disparate frequencies, like in the radio and $γ$-ray regime, show similar morphological structures. This mutual information reflects the imprint of the various physical components of the interstellar medium. We want to use multifrequency all-sky observations to test resolution improvement and restoration of unobserved areas for maps in certain frequency ranges. For this we aim to reconstruct or predict from sets of other maps all-sky maps that, in their original form, lack a high resolution compared to other available all-sky surveys or are incomplete in their spatial coverage. Additionally, we want to investigate the commonalities and differences that the ISM components exhibit over the electromagnetic spectrum. We build an $n$-dimensional representation of the joint pixel-brightness distribution of $n$ maps using a Gaussian mixture model and see how predictive it is: How well can one map be reproduced based on subsets of other maps? Tests with mock data show that reconstructing the map of a certain frequency from other frequency regimes works astonishingly well, predicting reliably small-scale details well below the spatial resolution of the initially learned map. Applied to the observed multifrequency data sets of the Milky Way this technique is able to improve the resolution of, e.g., the low-resolution Fermi LAT maps as well as to recover the sky from artifact-contaminated data like the ROSAT 0.855 keV map. The predicted maps generally show less imaging artifacts compared to the original ones. A comparison of predicted and original maps highlights surprising structures, imaging artifacts (fortunately not reproduced in the prediction), and features genuine to the respective frequency range that are not present at other frequency bands. We discuss limitations of this machine learning approach and ideas how to overcome them.

astro-ph.GA↗

arXiv2017

CHANG-ES IX: Radio scale heights and scale lengths of a consistent sample of 13 spiral galaxies seen edge-on and their correlations

The vertical halo scale height is a crucial parameter to understand the transport of cosmic-ray electrons (CRE) and their energy loss mechanisms in spiral galaxies. Until now, the radio scale height could only be determined for a few edge-on galaxies because of missing sensitivity at high resolution. We developed a sophisticated method for the scale height determination of edge-on galaxies. With this we determined the scale heights and radial scale lengths for a sample of 13 galaxies from the CHANG-ES radio continuum survey in two frequency bands. The sample average value for the radio scale heights of the halo are 1.1 +/- 0.3kpc in C-band and 1.4 +/- 0.7kpc in L-band. From the frequency dependence analysis of the halo scale heights we found that the wind velocities (estimated using the adiabatic loss time) are above the escape velocity. We found that the halo scale heights increase linearly with the radio diameters. In order to exclude the diameter dependence, we defined a normalized scale height which is quite similar for all sample galaxies at both frequency bands and does not depend on the star formation rate or the magnetic field strength. However, the normalized scale height shows a tight anticorrelation with the mass surface density. The sample galaxies with smaller scale lengths are more spherical in the radio emission, while those with larger scale lengths are flatter. The radio scale height depends mainly on the radio diameter of the galaxy. The sample galaxies are consistent with an escape-dominated radio halo with convective cosmic ray propagation, indicating that galactic winds are a widespread phenomenon in spiral galaxies. While a higher star formation rate or star formation surface density does not lead to a higher wind velocity, we deceleration of CRE outflow, e.g. a lowering of the wind velocity from the galactic disk.

astro-ph.GA↗

arXiv2017

On the non-thermal electron-to-proton ratio at cosmic acceleration sites

The luminosity ratio of electrons to protons as it is produced in stochastic acceleration processes in cosmic ray sources is an important quantity relevant for several aspects of the modeling of the sources themselves. It is usually assumed to be around 1:100 in the case of Galactic sources, while a value of 1:10 is typically assumed when describing extragalactic sources. It is supported by observations that the average ratios should be close to these values. At this point, however, there is no possibility to investigate how each individual source behaves. When looking at the physics aspects, a 1:100 ratio is well supported in theory when making the following assumptions: (1) the total number of electrons and protons that is accelerated are the same; (2) the spectral index of both populations after acceleration is $a_e=a_p\approx 2.2$. In this paper, we reinvestigate these assumptions. In particular, assumption (2) is not supported by observational data of the sources and PIC simulation yield different spectral indices as well. We present the detailed calculation of the electron-to-proton ratio, dropping the assumption of equal spectral indices. We distinguish between the ratio of luminosities and the ratio of the differential spectral behavior, which becomes necessary for cases where the spectral indices of the two particle populations are not the same. We discuss the possible range of values when allowing for different spectral indices concerning the spectral behavior of electrons and protons. Additionally, it is shown that the minimum energy of the accelerated population can have a large influence on the results.

astro-ph.HE↗

arXiv2015

Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era

Magnetic fields are an important ingredient of the interstellar medium (ISM). Besides their importance for star formation, they govern the transport of cosmic rays, relevant to the launch and regulation of galactic outflows and winds, which in turn are pivotal in shaping the structure of halo magnetic fields. Mapping the small-scale structure of interstellar magnetic fields in many nearby galaxies is crucial to understand the interaction between gas and magnetic fields, in particular how gas flows are affected. Elucidation of the magnetic role in, e.g., triggering star formation, forming and stabilising spiral arms, driving outflows, gas heating by reconnection and magnetising the intergalactic medium has the potential to revolutionise our physical picture of the ISM and galaxy evolution in general. Radio polarisation observations in the very nearest galaxies at high frequencies (>= 3 GHz) and with high spatial resolution (<= 5") hold the key here. The galaxy survey with SKA1 that we propose will also be a major step to understand the galactic dynamo, which is important for models of galaxy evolution and for astrophysical magnetohydrodynamics in general. Field amplification by turbulent gas motions, which is crucial for efficient dynamo action, has been investigated so far only in simulations, while compelling evidence of turbulent fields from observations is still lacking.

astro-ph.GA↗

arXiv2013

AGN feedback works both ways

Simulations of galaxy growth need to invoke strong negative feedback from active galactic nuclei (AGN) to suppress the formation of stars and thus prevent the over-production of very massive systems. While some observations provide evidence for such negative feedback, other studies find either no feedback, or even positive feedback, with increased star formation associated with higher AGN luminosities. Here we report an analysis of several hundred AGN and their host galaxies in the Chandra Deep Field South using X-ray and radio data for sample selection. Combined with archival far infrared data as a reliable tracer of star formation activity in the AGN host galaxies, we find that AGN with pronounced radio jets exhibit a much higher star formation rate than the purely X-ray selected ones, even at the same X-ray luminosities. This difference implies that positive AGN feedback plays an important role, too, and therefore has to be accounted for in all future simulation work. We interpret this to indicate that the enhanced star formation rate of radio selected AGN arises because of jet-induced star formation, as is hinted by the different jet powers among our AGN samples, while the suppressed star formation rate of X-ray selected AGN is caused by heating and photo-dissociation of molecular gas by the hot AGN accretion disc.

astro-ph.CO↗