Recent News

  • 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.

  • First [CII] map taken with SOFIA FIFI-LS published

    Thursday, September 27, 2018

    The CARS team published the first results from the SOFIA FIFI-LS instrument of spatially-resolved [CII] 158micron emission in a nearby luminous AGN host galaxy at redshift z~0.04. The work is led by Dr. G. Busch from the University of Cologne and shows that the [CII] emission largely follows the expectations from the amount and distribution of ongoing star formation in the host galaxy as mapped with the VLT-MUSE integral-field spectrograph at high spatial resolution in the optical. It shows that AGN do not necessarily impact the [CII] excitation, but a larger sample is currently under investigation to confirm this result. The SOFIA FIFI-LS instrument also detected [CII] emission far beyond the host galaxy which has an unknown origin. We speculated that neutral gas in the outskirts of the disc is excited either by the UV background or a diffuse radiation field from the galaxy itself. In summary, the CARS team has successfully shown that the SOFIA airborne observatory is able to capture [CII] emission not only in our Milky Way but also in nearby galaxies out to significant redshifts. The article will appear in the upcoming SOFIA focus issue of the Astrophysical Journal Letters.

    Comparison of the predicted [CII] map from Ha observed with VLT-MUSE and the real [CII] map observed with SOFIA FIFI-LS. The elongated [CII] structure of the prominent star forming bar in this galaxy is well visible even at the limited spatial resolution of SOFIA. The [CII] surface brightness follows nicely previous relations established for star forming galaxies observed with Herschel.

  • 3rd CARS team meeting

    Monday, August 6, 2018

    Twelve CARS team members met again for the annual meeting from 6-10 August 2018 in Heidelberg. We discussed the most recent results related to AGN outflows, star formation in AGN host galaxies, environment and kinematic properties of our 40 AGN host galaxies. Of course our changing-look AGN Mrk1018 got some special attention during the week, but the core of this galaxy still does not want to reveal it secrets. All aspects of our multi-wavelength data was discussed in detail and challenged with all the different experience we cover in the team.Again a hugely productive CARS with lots of exciting science results to be released on all aspect of AGN host galaxies. Stay tuned!

    CARS team members having fun during our 3rd team meeting in Heidelberg. Picture was taken in front of the famous Heidelberg castle on the old bridge of the old town. 

  • No evidence of galaxy-scale hot outflows in two nearby AGN!

    Tuesday, July 3, 2018

    Based on deep Chandra X-ray observations of two nearby AGN (HE0227-0913 and HE0351+0240), M. Powell et al. reported no evidence of galaxy-wide hot gas outflows. After careful analysis of the Chandra PSF to deal with the bright type 1 AGN core, no significant extended emission could be detected. This is a surprising result since current theoretical models predict rather bright X-ray emission from hot gas outflows on kpc-scales powered by the AGN.

    This shows that the prediced outflows are not necessarily ubiquitos in AGN host galaxies. Either the multi-phase gas composition is different than predicited, the AGN is too young to show outflows on large scales, or the AGN is actually not capable of diriving a powerful outflow. Of course, with two objects we cannot systematically explore these effects, but these X-ray observations needed are expensive were done here as a pilot study. We expect that the CARS team is going to obtain additional Chandra observations in the future.

     

    Chandra X-ray images of HE0227-0913 and HE0351+0240 together with their matched simulated PSFs. Below is the X-ray spectrum extracted from the read-out strike that is modelled with a single power-law model.

  • Dimming of Mrk1018 has stopped!

    Wednesday, October 25, 2017

    Our team continued to monitor the changing-look AGN Mrk1018 after its rapid decline. Our new paper led by Mirko Krumpe nicely shows that the dimming of Mrk1018 surprisingly halted by now and has likely reached a minimum in activity. This already rules out some scenarios like a tidal-disruption event. It opens the possibility that Mrk1018 is turning bright again at some point. Our multi-wavelength monitoring of Mrk1018 is therefore continuing and we are expected to present exciting results on this enigmatic AGN in the next years.

    U-band light curve of Mrk1018 after deblending the AGN and host galaxy light using galfit. The strong decline of the changling-look AGN has clearly stopped and shows variabiliy on yearly timescales.

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