Research of the Infrared/Submillimeter Group at MPE

Research of the Infrared and Submillimeter Group is focused on the fields of evolution of galaxies and galactic nuclei, including the center of our own Galaxy and starburst phenomena as well as studies of the dense interstellar medium in star- and planet-forming regions. See this link for a list of highly cited IR group papers, with at least 100 citations.

The Galactic Center

(See also dedicated Galactic Center page)

Our own Galactic Center is a unique astrophysical laboratory for studying black holes. It provides the best evidence for the existence of massive black holes in galactic nuclei. Due to its relative proximity, we can study the stellar dynamics in the central parsec around the massive black hole, the composition of the stellar population, and the flaring emission from the immediate vicinity of the massive black hole in unprecedented detail.

To this end, we have employed diffraction-limited infrared imaging and spectroscopy, using ESO’s NTT from 1992 to 2002, and the adaptive-optics instruments NACO and SINFONI mounted at ESO’s VLT from 2002 to 2019. Recently, we have started using GRAVITY, an interferometer that can simultaneously combine the light of the four 8m telescopes of the VLT, reaching a resolution of around 3 milliarcseconds in the astronomical K-band, and an astrometric accuracy of 30 microarcseconds. This has enabled us to detect relativistic effects in the motions of the stars around the massive black hole.

Our work has received the highest possible recognition with the award of the 2020 physics Nobel prize to Reinhard Genzel.

Key publications:

Evolution of Galaxies

Dynamics and Evolution of High-Redshift Galaxies
(See also dedicated Galaxy Evolution page)

Observations of distant galaxies are essential to determine the physical processes that drive their growth and evolution over cosmic time. Spatially and spectrally resolved data of rest-frame optical line emission are a powerful tool to characterize these processes.  By using integral field spectroscopy with SINFONI, KMOS, and soon ERIS at the VLT, we investigate the dynamics, structure, star formation, gas excitation and metallicity, and outflows of representative samples of z ~ 0.5–3 galaxies, spanning six billion years around the peak epoch of cosmic star formation activity.

Review articles:

Key publications:

  • Rotation Curves in z ~ 1 – 2 Star-forming Disks: Evidence for Cored Dark Matter Distributions, Genzel et al. 2020, ApJ, 902, 98
  • The KMOS3D Survey: Demographics and Properties of Galactic Outflows at z = 0.6 - 2.7, N.M. Förster Schreiber et al. 2019, ApJ, 875, 21
  • The SINS/zC-SINF Survey of z ~ 2 Galaxy Kinematics: SINFONI Adaptive Optics-assisted Data and Kiloparsec-scale Emission-line Properties, Förster Schreiber et al. 2018, ApJS, 238, 21
  • Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago, Genzel et al. 2017, Nature 543, 397
  • Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF, Lang et al. 2017, ApJ, 840, 92
  • The Evolution of the Tully-Fisher Relation between z ~ 2.3 and z ~ 0.9 with KMOS3D, Übler et al. 2017, ApJ, 842, 121
  • KMOS3D: Dynamical Constraints on the Mass Budget in Early Star-forming Disks, Wuyts et al. 2016, ApJ, 831, 149
  • The KMOS3D Survey: Design, First Results, and the Evolution of Galaxy Kinematics from 0.7 < z < 2.7, Wisnioski et al. 2015, ApJ 799, 209
  • The SINS/zC-SINF Survey of z ~ 2 Galaxy Kinematics: Evidence for Powerful Active Galactic Nucleus-Driven Nuclear Outflows in Massive Star-Forming Galaxies, Förster Schreiber et al. 2014, ApJ 787, 28
  • The SINS/zC-SINF Survey of z ~ 2 Galaxy Kinematics: Evidence for Gravitational Quenching, Genzel et al. 2014, ApJ 785, 75
  • The SINS Survey of z ~ 2 Galaxy Kinematics: Properties of the Giant Star-forming Clumps, Genzel et al. 2011, ApJ 733, 101
  • The SINS Survey: SINFONI Integral Field Spectroscopy of z ~ 2 Star-forming Galaxies, Förster Schreiber et al. 2009, ApJ 706, 1364
  • The rapid formation of a large rotating disk galaxy three billion years after the Big Bang, Genzel et al. 2006, Nature 442, 786
  • SINFONI Integral Field Spectroscopy of z ~ 2 UV-selected Galaxies: Rotation Curves and Dynamical Evolution, Förster Schreiber et al. 2006, ApJ 645, 1062


The Role of Molecular Gas in Galaxy Evolution
(See also dedicated PHIBBS page)

Continuing technological progress, in particular at the IRAM Plateau de Bure with the NOEMA interferometer, enables us to study the cosmic evolution of the galactic molecular gas reservoirs as well as to map its distribution and kinematics within galaxies. Our observational programs have greatly advanced the characterization of the cold gas content across the massive star-forming galaxy population at z ~ 0.4–3.  With the higher sensitivity and angular resolution afforded by NOEMA's most recent upgrades, our observations are revealing more directly the importance of disk and bulge buildup via gravitational instabilities and gas transport.

Key publications:

  • PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions, Tacconi et al. 2018, ApJ 853, 179
  • Ionized and Molecular Gas Kinematics in a z = 1.4 Star-forming Galaxy, Übler et al. 2018, ApJL, 854, 24
  • The Metallicity Dependence of the CO → H2 Conversion Factor in z≥1 Star-forming Galaxies, Genzel et al. 2012, ApJ 746, 69
  • High molecular gas fractions in normal massive star-forming galaxies in the young Universe, Tacconi et al. 2010, Nature 463, 781
  • A study of the gas-star formation relation over cosmic time, Genzel et al. 2010, MNRAS 407, 2091
  • Submillimeter Galaxies at z ~ 2: Evidence for Major Mergers and Constraints on Lifetimes, IMF, and CO-H2 Conversion Factor, Tacconi et al. 2008, ApJ 680, 246


The Nature of High-Redshift Infrared Sources
(See also PEP page)

Surveys at mid-infrared and (sub-)millimeter wavelengths with ISO, SCUBA, MAMBO, Spitzer, and Herschel have uncovered populations of massively star-forming galaxies at high redshift that constitute a major part of the total cosmic star-forming activity and a key phase in the evolution of massive galaxies. We are studying the nature of these objects in the context of the evolution of massive galaxies.

Key publications:

  • The evolution of the dust temperatures of galaxies in the SFR-M plane up to z ∼ 2, Magnelli et al. 2014, A&A 561, A86
  • The mean star formation rate of X-ray selected active galaxies and its evolution from z ~ 2.5: results from PEP-Herschel, Rosario et al. 2012 A&A 545, A45
  • Galaxy Structure and Mode of Star Formation in the SFR-Mass Plane from z ~ 2.5 to z ~ 0.1, Wuyts et al. 2011, ApJ 742, 96
  • Building the cosmic infrared background brick by brick with Herschel/PEP, Berta et al. 2011, A&A 532, A49
  • A Mid-Infrared Spectroscopic Study of Submillimeter Galaxies: Luminous Starbursts at High Redshift, Valiante et al. 2007, ApJ 660, 1060


The Structure of AGN


(See also AGN Page)

Our tools like high-spatial-resolution near-infrared spectroscopy, near-infrared and millimeter interferometry, and mid-infrared spectroscopy are ideal for addressing questions on active galactic nuclei and their environment. Among others, projects have dealt with the characterization of circumnuclear starbursts, the distribution and dynamics of circumnuclear gas, and the properties of the obscuring material. Recent work has focused on spatially resolving the BLR and hot dust on subparsec scales through a large program with GRAVITY.

Key publications:

  • Spatially resolved rotation of the broad-line region of a quasar at sub-parsec scale, GRAVITY Collaboration et al. 2018, Nature 563, 657
  • A Close Look at Star Formation around Active Galactic Nuclei, Davies et al. 2007, ApJ 671, 1388
  • The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects, Lutz et al. 2004, A&A 418, 465
  • 2.5-45μm SWS spectroscopy of the Circinus Galaxy, Moorwood et al. 1996, A&A 315, L109


Ultraluminous Infrared Galaxies and QSOs

(See also SHINING Page)

UltraLuminous InfraRed Galaxies (ULIRGs) play a key role in scenarios for the formation of Quasars and of elliptical galaxies, and serve as possible local analogues to high-redshift sources above the star-forming sequence. We have tested the energy sources of ULIRGs and QSOs using ISO, Spitzer, and Herschel mid- and far-infrared spectroscopy and near-infrared imaging spectroscopy.

Key publications:

  • Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS, Sturm et al. 2011, ApJ 733, L16
  • Spitzer Quasar and ULIRG Evolution Study (QUEST). I. The Origin of the Far-Infrared Continuum of QSOs, Schweitzer et al. 2006, ApJ 649, 79
  • What Powers Ultraluminous IRAS Galaxies?, Genzel et al. 1998, ApJ 498, 579

      Studies of Star and Planet Formation and the Dense Interstellar Medium

      Structure and Evolution of Protoplanetary Disks

      Most young pre-main sequence stars are surrounded by disks of gas and dust out of which planets can form. We are carrying out a number of combined observations and modeling projects to understand their physical and chemical structure by using submillimeter data from ALMA, complemented by infrared spectroscopy with VLT-CRIRES+, VLTI-GRAVITY, Herschel, and soon JWST-MIRI. The transitional disks with large inner holes are of particular interest, as they are at the crucial stage between the gas-rich and debris-disk phases when planet formation appears to be actively taking place. ALMA now allows us to resolve both the gas and the dust in detail and reveal clues regarding their origin. In addition, large surveys of disks are carried out to characterize the disk population. Infrared spectroscopy probes the gas in the inner region of disks, which can be linked to that of ices in the outer disk, thus measuring directly the composition of the material that forms planets.

      Key publications:


      Water and Organic Molecules in Star-Forming Regions

      Water is one of the most abundant and important molecules in star- and planet-forming regions: it acts as a major reservoir of oxygen, as a gas coolant, and (as ice) assists planet formation. Both water and complex organic molecules gas are directly associated with the biology of living organisms on Earth. We are using ALMA, NOEMA, Herschel HIFI and PACS, VLT, and soon JWST-MIRI to observe water and organic molecules toward a large sample of protostars. These include a wide range of masses and luminosities, from the lowest- to the highest-mass protostars, and a great variety of evolutionary stages, from the first stages of clouds prior to collapse to the last stages represented by pre-main sequence stars surrounded by protoplanetary disks. A suite of molecular excitation and radiative transfer tools has been developed. The data reveal the physics and chemistry of hot cores and dense irradiated shocks in protostars, and allow us to probe the water reservoir of gas and ice from clouds to disks.

      Key publications:

      Studying the ISM and Gas-Star Cycle in Galaxies at Molecular Cloud Scale

      To grasp the growth and evolution of galaxies requires an understanding of the physics that regulate the gas-star cycle within galaxies. We are carrying out state-of-the-art hydrodynamical simulations of the physical, chemical, and dynamical properties of the multi-phase ISM driven by supernovae in star-forming galaxies, especially at high redshift, at a range of scales and in different environments down to low metallicities. The simulations can be compared with several legacy-type surveys, carried out by the infrared group using ALMA, NOEMA, VLT, VLA, and HST, and ranging from kiloparsec scales down to a few parsecs. Such studies are important for relating the detailed but small-scale studies inside our Milky Way to the full but poorly resolved galaxy population in the (local) universe and for determining how galactic properties and galaxy evolution are regulated by the small-scale process of star formation and vice versa.

      Key publications:


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