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Recent News

  • New Paper: IFU survey data and the BH mass dependence of long-term AGN variability

    Monday, November 22, 2021

    This paper lead by CARS PI Bernd Husemann from the Max Planck Institute for Astronomy in Heidelberg presents the optical IFU data including processing and analysis as the core data for CARS. The paper describes the sample in details and reports some basic host galaxy parameters including morphological information. A key scientific analysis in this paper is the mapping of the excitation conditions of the ionized gas and the size of the AGN-ionized region, which is often referred to as the extended narrow-line region (ENLR). Quite unexpected, we observed that the maximum size of the ENLR correlates most strongly with the central BH mass. Assuming that the maximum ENLR is a time-scale indicator for a single optically-bright BH accretion episode, we infer a tight relation between the AGN episode and the BH mass. Adopting a simple "light-bulb" model for the light intensity during the episode and random sampling of the age of each AGN, we were able to infer the underlying relation using a Bayesian approach. This relation nicely agrees with similar estimates of the AGN episode timescale for more massive BH at high redshift using the proximity zone technique.

    Maximum ENLR size against BH mass. The light travel time implied by the ENLR size (red line) can be converted into an AGN episode lifetime (blue line) using "light bulb" light curve and a random sampling assumption during the lifetime with a Bayesian approach. This AGN lifetime relation agrees with the inferred lifetime of higher mass BH at z~3 from the HeII proximity zones using the same methodology.

  • New Paper: No obvious signature of AGN feedback on star formation, but subtle trends

    Monday, November 22, 2021

    This new paper (after minor revision requested by the referee) for CARS DR1 was lead by PhD student Irina Smirnova-Pinchukova from the Max Planck Institute for Astronomy in Germany. Here, we focused on accurate measurements of the stellar masses and star formation rates of the AGN host galaxies to study if AGN feedback had an immediate impact on star formation. We were not able to recover any significant change of the star formation rates, but noted that it is important to consider the gas content to quantify the expectation of the star formation rate for each galaxy which was often not done in past literature. This allowed us to provide new scaling relations to predict the "normal" star formation rate of AGN host galaxies in the nearby Universe. Comparing the star formation rate inferred from the Halpha and FIR diagnostics revealed a systematic offset which is likely due to obscuration effects. However, there are some subtle indications that the relative difference of star formation rates may also be related to recent star formation history of a given system. Moreover,  there is some subtle tendency for more edge-on galaxies to exhibit lower star formation rates than expected even using FIR diagnostics which may suggest that the relative orientation of the ionization cones and the host galaxy does impact the efficiency of energy dissipation from the black hole to the galaxy.

    Comparison of the Ha and IR-based star formation main sequences with the CARS data using only the stellar mass as a proxy for the star formation rate.  The scatter around the main relation decrease significantly if cold gas mass is taken into account as well.

  • New Paper: Locating the [OIII] wing component in luminous local Type 1 AGN

    Monday, November 22, 2021

    Another newly accepted paper was lead by PhD student Mainak Singha from the University of Manitoba in Canada for the CARS DR1. We explored the spatial location and distribution of the so-called wing [OIII] emission line component. This component has been thought to originate from an AGN-driven ionized gas outflow and is present in virtually all optically bright AGN. Applying a technique called spectroastrometry, we found that more than 50% of the AGN showed rather compact outflows which originate less than 100parcsec away from the nucleus. This is much smaller than typically assumed for AGN of this luminosity and is supported by significantly higher electron density measurements in compact outflows compared to extended outflow cases. This can have significant implications for outflow energetic calculations when they are based on previously assumed scaling relations for outflow size and electron density rather than actual measurements.

    Results of the spectroastrometry results for AGN HE0040-1105. The [OIII] wing light distribution follows a PSF which is slightly offset with respect to the AGN location as implied by the BLR broad Hbeta light distribution. The much narrow core [OIII] component is clearly extended as expected for the AGN-ionized NLR.

  • CARS Data release 1 is public

    Tuesday, November 23, 2021

    After significant delays caused by the ongoing pandemic, the CARS team is happy to announce that the first public data release became public as of 23. November 2021. This has been a great team effort and possible with strong support from the eScience group at the Leibniz Institute for Astronomy (AIP) in Heidelberg. The website for the CARS DR1 is

    What we made available so far are:

    • reduced optical IFU data cubes
    • processed optical IFU data cubes
    • high-level IFU data products, like kinematics and emission line fluxes
    • spectroastrometric analysis of ionized gas outflows
    • AGN spectral analysis and parameters
    • host galaxy morphologies
    • integrated panchromatic spectral energy distribution (SEDs) from  FIR to UV
    • stellar masses and star formation rates

    The entire astronomical community is invited to use provided information for future research.

  • Successful year 2019 - Happy new year 2020 to all!

    Tuesday, December 31, 2019

    The year 2019 is closing. It was a very successful year for the CARS team with three published papers, a press release and an award for one of our PhD students. 

    We wish all our team members, collaborators, colleagues and families all the best for 2020. This year will hopefully be as successful as 2019 for the CARS team as 2019 and a lot of exciting results can be expected. Stay tuned!


    Key plots from the three CARS papers in 2019. Credits: Miguel Perez-Torres

  • Press release and publication award for work PhD student

    Friday, November 29, 2019

    On 29th of November our PhD Student Irina Smirnova-Pinchukova got awared one of the Ernst-Patzer-Prizes 2019 honouring the best publication by young astronomy researches in Heidelberg. Irina got the price for her very first paper on the [CII] excess discovered in the CARS AGN HE1353-1917. 

    At the same day on "Black Hole Friday" NASA issued a press release based on Irina's work title "Black Hole or Newborn Stars? SOFIA Finds Galactic Puzzle".

    Congratulations for Irina from the entire CARS team for her awesome work and the entire team which has made this discovery possible. 

    Artist’s concept of a jet from an active black hole that is perpendicular to the host galaxy (left) compared to a jet that is launching directly into the galaxy (right) illustrated over an image of a spiral galaxy from the Hubble Space Telescope. SOFIA found a strange black hole with jets that are irradiating the host galaxy, called HE 1353-1917. The galaxy has 10 times more ionized carbon than its stars could produce. The gas, illustrated in blue in the right image, is concentrated near the galaxy’s center, which indicates that the intense radiation from the black hole’s jet is the source of the excess gas. This contradicts the long-held assumption that ionized carbon is a good indicator of newborn stars, and forces scientists to re-evaluate the effect black holes have on galaxies. Credit: ESA/Hubble&NASA and NASA/SOFIA/L. Proudfit

  • CARS meeting 2019 in Zaragosa

    Sunday, September 1, 2019

    The yearly face-to-face meeting of the CARS team in 2019 was hosted at the CSIC headquater in Zaragoza. While only 5 members could make the way to Zaragoza this time, about 10 people remotely connected along the week so we had a very productive meeting again. Lot's of ongoing and new paper ideas were discussed and future observing proposal were designed. The wonderful meeting was organized by Miguel Perez-Torres with many social acitivies. Everyone enjoyed the food, weather, city and being together for a week doing great science. The community can expect a lot of exciting papers in the year 2020.

    During the CARS team meeting we visited also the Aljaferia Palace which is also housing the Parliament of Aragon. The weather was very nice and everyone enjoyed the time in Zaragoza thanks to the great organization by Miguel Perez-Torres.

  • New Paper Published: A massive multi-phase outflow in HE1353-1917

    Tuesday, May 28, 2019

    A new paper from the CARS team has been published which demonstrates the full diagnostic power of our unique spatially-resolved multi-wavelength data set. The edge-on host galaxy of HE1353-1917 shows a unique orientation of the AGN's ionization cone which is turned towards the disc of the galaxy. A small radio-jet is associated with the ionization cone an extends about 1kpc into the host galaxy. Our spatially-resolved spectroscopy in the optical with MUSE at the VLT, in the NIR with NIFS at Gemini-N and in the sub-mm with ALMA reveals a massive outflow in all those gas phase at the tip of the jet. The energetics of the outflows shows a high mass outflow rate at 1kpc which clearly exceed the star formation rate of the entire galaxy and therefore has the potential to impact the evolution of the galaxy. However, the current SFR is at most mildly reduced which would be restricted to the central 1kpc so far. Energetically, the driven mechanisms of the outflow is not fully clear, but the size of the jet and its directional power suggests that it plays a crucial role for the injection of the energy.

    While this is just a single case study, the CARS team is working on a systematic analysis of the entire CARS sample of AGN host galaxies. A lot of interesting results can be expected.

    Velocity dispersion map in [OIII], H2, and CO(1-0) showing highly turbulent motion associated with a bipolar outflow within the central 1kpc of the AGN host galaxy HE1353-1917.  The spectra in all hot spots reveal a distinct kinematic feature closely associated with a radio jet structure as the likely powering source of the outflow.

  • New Paper Published: [CII] excess in HE1353-1917

    Tuesday, May 28, 2019

    Our PhD student Irina Smirnova-Pinchukova used FIR observations with the flying observatory SOFIA aboard Boeing 747SP to study the [CII] 158µm emission line in a sample of 5 AGN host galaxies from the CARS sample. Irina discovered that, surprisingly, one of the targeted galaxies, named HE1353-1917 at z=0.035, exhibits ten times higher [CII] luminosity than expected from the star formation rate. Hence, there is an additional excitation mechanism at work in this specific galaxy that is injecting additional energy in the ISM which cooling through the [CII] line. A companion paper by the PI of CARS, Bernd Husemann, is discussing the properties of a massive multi-phase AGN-driven outflow on kpc scales also discovered in this galaxy. Since the [CII] excess is confirmed to originate from the galaxy center, Irina argues that the [CII] excess is directly powered by the shocked-heated gas in the outflows. Our observations at low redshift are crucial to interpret [CII] observations of high redshift galaxies with ALMA.

    [CII] 158µm luminosity as a function of FIR luminosity as a proxy for the ongoing star formation rate. All of our CARS targets observed with SOFIA follow the same relation as all galaxies in the local Universe. Only the galaxy HE1353-1917 is clearly deviating from the trend and shows an order of magnitude excess of [CII].

  • New Paper Published: Only flat bars are actively forming stars!

    Wednesday, May 15, 2019

    As part of the CARS survey PhD student Justus Neuman from the Leibniz-Intstitute for Astrophysics in Potsdam systematically studied the star formation along bars in the AGN host galaxies, which has been accepted to be published in the journal A&A. In this work Justus compared the amount of SFR along the bar as traced using the optical Halpha line with morphological properties of the bar as measured through detailed 2D photometric decompositions of the galaxy images. He found that the sample appears bimodal clearly separating into star-forming and non-star-forming bars. In comparison with the surface brightness of the bar, Justus found that only the bars with very flat surface brightness profiles were forming stars. The lack of star formation in less flat bars may be connected also to the presence of inner rings in those galaxies.

    Bars are also thought to be one mechanisms through which gas is funneled towards the center of the galaxy to fuel AGN at their centers. However, no correlation between the star formation rate along the bar with AGN bolometric luminosity was found. Whether such a non-correlation is caused by time-scale difference or implies an insignificant link between bars and AGN fueling remains to be understood in the future.

    Justus work is the first step in characterizing the star formation properties of AGN host galaxies. More work on AGN outflows and potential impact on the star formation will be studied in future CARS publications in more detail.

    Comparison between star formation rate of the bar with the Sersic parameter n which indicates the steepness/flatness of the bars surface brightness profile. The observations show a clear bimodal distribution in SFR and Sersic parameter which highlights that only bars with a very flat surface brightness profile are actively forming stars.