Recent Results of the MPE Infrared/Submillimeter Group

 

Molecular gas, extinction, star formation and kinematics in the z=1.5 star forming galaxy EGS130111661

<p>In the top row, the molecular gas is shown as the backdrop image in color and the contours display the stellar light (from left to right: H band map, stellar mass, extinction corrected star formation rate). In the bottom row (center image), the backdrop shows the extinction and the white contours show the CO integrated flux map -- demonstrating how well the absorption seen in the rest-frame optical coincide with the CO emission. The high-resolution HST H-band maps show clumps of star formation, typical for galaxies at the peak of the cosmic star formation rate (see results from the high-redshift galaxy survey SINS)&nbsp;</p> Zoom Image

In the top row, the molecular gas is shown as the backdrop image in color and the contours display the stellar light (from left to right: H band map, stellar mass, extinction corrected star formation rate). In the bottom row (center image), the backdrop shows the extinction and the white contours show the CO integrated flux map -- demonstrating how well the absorption seen in the rest-frame optical coincide with the CO emission. The high-resolution HST H-band maps show clumps of star formation, typical for galaxies at the peak of the cosmic star formation rate (see results from the high-redshift galaxy survey SINS) 

<p>Comparison of CO (IRAM/PdB) and H-alpha (LBT/LUCI) data at the same resolution of FWHM 0.75". There is a remarkable agreement between the kinematics as derived from the molecular (traced by the sub-mm CO line) and ionized gas (traced by the H-alpha line) that shows that both tracers can be used equally well to study rotation curve and kinematics in high-redshift galaxies.</p> Zoom Image

Comparison of CO (IRAM/PdB) and H-alpha (LBT/LUCI) data at the same resolution of FWHM 0.75". There is a remarkable agreement between the kinematics as derived from the molecular (traced by the sub-mm CO line) and ionized gas (traced by the H-alpha line) that shows that both tracers can be used equally well to study rotation curve and kinematics in high-redshift galaxies.

As a follow-up to the high-redshift molecular gas survey PHIBBS (Tacconi et al. 2013; see news item below), a detailed study was performed of one of the most massive galaxies in this survey. For the study of the galaxy named EGS13011166, CO 3-2 line observations from the IRAM Plateau de Bure millimeter interferometer were combined with Large Binocular Telescope (LBT) LUCI observations of the H-alpha line in this galaxy, at matched spatial resolutions of 0.75 arcseconds. The galaxy was scanned perpendicular to the slit with LUCI to obtain spatially resolved spectra both along and perpendicular to the slit. Additionally, Hubble Space Telescope (HST) V-I-J-H band maps were used. Together these data allow to derive the stellar surface density and star formation rate, molecular gas surface density, optical extinction and gas kinematics.

More information

  • Research paper: Genzel et al. 2013, The Astrophysical Journal (in press); preprint available

Discovery of a comet factory in a protoplanetary disk with ALMA

June 7, 2013

Using the new Atacama Large Millimeter/submillimeter Array (ALMA), a huge asymmetry has been found in the mm emission from a dust disk surrounding a young star. In contrast, the gas and micron-sized dust grains show a full ring. The data strongly suggests the presence of a dust trap around 60 AU from the star where dust particles can grow by clumping together. This is the first time that such a dust trap has been clearly observed and modelled. It solves a long-standing mystery about how dust particles in disks grow to larger sizes so that they can eventually form comets, planets and other rocky bodies. The images also demonstrate the excellent quality of ALMA data even at the highest frequencies (690 GHz, 0.45 mm, Band 9).

More information

The relation between molecular gas and star formation over half the cosmic time

April 16, 2013

<p>Dependence of normalized gas fraction on stellar mass. The normalisation is to the gas fraction of a galaxy with a stellar mass of 5 x 10^10 solar masses. Measurements at high redshift from the new PHIBSS survey are shown in black (here the redshift slice z=1-1.5 is used) and results from a local survey of molecular gas are shown as open squares (Saintonge et al. 2011a). The green shaded area gives an estimate of the gas fractions at high redshift corrected for incompleteness of the PHIBSS survey.</p> Zoom Image

Dependence of normalized gas fraction on stellar mass. The normalisation is to the gas fraction of a galaxy with a stellar mass of 5 x 10^10 solar masses. Measurements at high redshift from the new PHIBSS survey are shown in black (here the redshift slice z=1-1.5 is used) and results from a local survey of molecular gas are shown as open squares (Saintonge et al. 2011a). The green shaded area gives an estimate of the gas fractions at high redshift corrected for incompleteness of the PHIBSS survey.

<p>Specific star formation rate (sSFR) as a function of redshift. The big black and red points are entirely independent estimates of the sSFR over redshift: The black points use the molecular gas masses derived from the PHIBSS and other molecular gas surveys and derive the sSFR using stellar mass and the given dependency of gas depletion time with redshift (see label in plot). The red points, on the other hand, are the average values of direct measurements of the sSFR from imaging surveys (the individual measurements are shown underlying in gray).</p> Zoom Image

Specific star formation rate (sSFR) as a function of redshift. The big black and red points are entirely independent estimates of the sSFR over redshift: The black points use the molecular gas masses derived from the PHIBSS and other molecular gas surveys and derive the sSFR using stellar mass and the given dependency of gas depletion time with redshift (see label in plot). The red points, on the other hand, are the average values of direct measurements of the sSFR from imaging surveys (the individual measurements are shown underlying in gray).


An unprecedented survey of molecular gas at high redshift provides 52 CO detections in two redshift slices at a redshift z of about 1.2 and 2.2, with stellar masses (M_star) above 10^10.4 solar masses (M_sun) and star formation rates (SFR) above 10^1.5 M_sun per year. The survey is named PHIBSS which stands for the IRAM Plateau de Bure high-z blue sequence CO 3–2 survey of the molecular gas properties in massive, main-sequence star-forming galaxies (SFGs) near the cosmic star formation peak. Including a correction for the incomplete coverage of the M_star – SFR plane, and adopting a "Galactic" value for the CO–H2 conversion factor, average gas fractions are inferred of about 0.33 at z of about 1.2 and about 0.47 at z of about 2.2. Gas fractions drop with stellar mass, in agreement with cosmological simulations including strong star formation feedback. Most of the SFGs between redshifts of about 1 and 3 are rotationally supported turbulent disks. The sizes of CO and UV/optical emission are comparable. The molecular-gas–star-formation relation for the z = 1–3 SFGs is near-linear, with a gas depletion timescale of about 0.7 Gyr; changes in depletion time are only a secondary effect. Since this timescale is much less than the Hubble time in all SFGs between redshifts of about 0 and 2, fresh gas must be supplied with a fairly high duty cycle over several billion years. At given z and M_star, gas fractions correlate strongly with the specific star formation rate (sSFR). The variation of sSFR between redshifts of 0 and 3 is mainly controlled by the fraction of baryonic mass that resides in cold gas.

More information:

New observations on the Galactic Center gas cloud "G2"

September 12, 2012

New observations on the gas cloud "G2" falling towards the Galactic Center confirm its highly elliptical orbit, but with updated orbital parameters. With the new data, the cloud is now expected to come even closer -- the updated pericenter distance is 2200 Schwarzschild radii -- to the super-massive black hole at the center of our galaxy. While its origin is still unclear, its apocenter is near the inner edge of the disk of young stars. This supports speculations that the cloud, which has a mass of only about three earth masses, originated as a wind of one of these stars.

Data were recorded with the integral-field spectrograph SINFONI which produces data cubes containing a spectrum for each pixel. From this cube, data were extracted along a curved slit that matches the trajectory of the gas cloud and from a fit to the gas emission lines in the spectra, the velocity of the cloud was deduced for each position along the slit. The resulting plot shows at which velocity (x axis) the gas is moving depending on its position on the orbit (y axis) and color-coded for the epoch of observation (2008: red, 2011: blue, 2012: green). Apart from the cloud itself, a slow moving tail with velocities &lt; 1000 km/s is seen. While the observations clearly show that the gas cloud is being disrupted, up to now the evolution of the cloud can be fully explained with a simple test particle simulation without any hydrodynamical effects. Zoom Image
Data were recorded with the integral-field spectrograph SINFONI which produces data cubes containing a spectrum for each pixel. From this cube, data were extracted along a curved slit that matches the trajectory of the gas cloud and from a fit to the gas emission lines in the spectra, the velocity of the cloud was deduced for each position along the slit. The resulting plot shows at which velocity (x axis) the gas is moving depending on its position on the orbit (y axis) and color-coded for the epoch of observation (2008: red, 2011: blue, 2012: green). Apart from the cloud itself, a slow moving tail with velocities < 1000 km/s is seen. While the observations clearly show that the gas cloud is being disrupted, up to now the evolution of the cloud can be fully explained with a simple test particle simulation without any hydrodynamical effects.

In the course of this year, more observations of the cloud are planned, of course, and not only in the infrared but campaigns have been started by many groups to observe this accretion event in the whole electromagnetic spectrum. A wiki page has been set up to collect all information on "G2".

More information:

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This composite image shows the positions of the gas cloud in 2002, 2007, and 2011 marked in colour. The cross indicates the position of the black hole in the galactic centre.
Image: MPE

Galactic Black Hole disrupts Gas Cloud

Over the next few years, astronomers will be able to observe first-hand how the super massive black hole at the centre of our Milky Way is being fed: an international team of astronomers led by the Max Planck Institute for Extraterrestrial Physics has found a gas cloud that is falling towards the black hole in the galactic centre. While some distortion due to the huge gravitational pull of the black hole can already be seen, the gas cloud will be completely disrupted and ultimately swallowed by the black hole, resulting in largely increased X-ray emission. The observations and analysis are described in a Nature paper, published online on 14 December 2011.



For more information see
    MPE Press Release.
(Dec 14, 2011)

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This illustration shows an Ultra-Luminous InfraRed Galaxy (ULIRG) that exhibits massive outflows of molecular gas.
Image: MPE

Caught in the act: Herschel detects gigantic storms sweeping entire galaxies clean

With observations from the PACS instrument on board the ESA Herschel space observatory, an international team of scientists led by the Max Planck Institute for Extraterrestrial Physics have found gigantic storms of molecular gas gusting in the centres of many galaxies. Some of these massive outflows reach velocities of more than 1000 kilometres per second, i.e. thousands of times faster than in terrestrial hurricanes. The observations show that the more active galaxies contain stronger winds, which can blow away the entire gas reservoir in a galaxy, thereby inhibiting both further star formation and the growth of the central black hole. This finding is the first conclusive evidence for the importance of galactic winds in the evolution of galaxies.



For more information see
    MPE Press Release.
(May 09, 2011)

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This image of the GOODS-S field with the Herschel PACS instrument demonstrates that the weak cosmic infrared radiation is produced mainly by individual galaxies.
Image: MPE

Herschel Space Telescope: Successful first year for German researchers

One year after the launch of ESA's Herschel space telescope, German scientists have reason to celebrate: The instruments' performance and first results have exceeded all expectations. Initial observations with the largest telescope currently in space, which was designed primarily to study the coldest matter in our Universe, have led to new insights into the formation of stars, the properties of dust in distant galaxies and the presence of molecules in interstellar clouds.



For more information see
    MPE Press Release.
(May 06, 2010)

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Star forming region in the Milky Way

Making the invisible visible

The Large Binocular Telescope (LBT) partners in Germany, the U.S.A. and Italy are pleased to announce that the first of two new innovative near-infrared cameras/spectrographs for the LBT is now available to astronomers for scientific observations at the telescope on Mt. Graham in south-eastern Arizona. After more than a decade of design, manufacturing and testing, the new instrument, dubbed LUCI 1, provides a powerful tool to gain spectacular insights into the universe, from the Milky Way up to extremely distant galaxies. LUCI 1 has been built by a consortium of German institutes and will be followed by an identical twin instrument that will be delivered to the telescope in early 2011.



For more information see
    MPE Press Release.
(April 21, 2010)

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Herschel image of the Rosette nebula
Image: ESA/PACS & SPIRE Consortium/HOBYS Key Programme Consortia

Where stars are born...

Herschel's latest image reveals the formation of previously unseen large stars, each one up to ten times the mass of our Sun. These are the stars that will influence where and how the next generation of stars are formed. The Rosette Nebula resides some 5,000 light years from Earth and is associated with a larger cloud that contains enough dust and gas to make the equivalent of 10,000 Sun-like stars. The Herschel image shows half of the nebula and most of the Rosette cloud. The massive stars powering the nebula lie to the right of the image but are invisible at these wavelengths. Each colour represents a different temperature of dust, from -263°C (only 10ºC above absolute zero) in the red emission to -233ºC in the blue.

ESA's Herschel space observatory collects the infrared light given out by dust. This image is a combination of three infrared wavelengths, colour-coded blue, green and red in the image. It was created using observations from Herschel's Photoconductor Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE). PACS has been designed and built by a consortium of institutes and university departments from across Europe under the leadership of Principal Investigator Albrecht Poglitsch at Max Planck Institute for Extraterrestrial Physics, Garching.

For more information see
    ESA Press Release
and the pages of the
    PACS-Project at MPE.

(April 14, 2010)

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  MPE Highlight:


IRAM

Galaxy EGS 1305123
Copyright: MPE/IRAM

Young galaxies gorge on gas

Scientists find explanation for higher star formation rate in young galaxies

Stars form from giant gas clouds in galaxies - the star formation rate however has changed over cosmic timescales. In the young universe many more stars were born. Scientists from the Max Planck Institute for extraterrestrial Physics, together with an international team of astronomers have found a plausible explanation: a few billion years after the Big Bang, normal star forming galaxies contained five to ten times more cold gas than today, providing more "food" to fuel the star formation process.
(Nature, February 11, 2010)

[ more ]

(February 10, 2010)

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  MPE Press Release:




IRAS 4B in NGC 1333 in the radio

Pin-pointing water in space

For the first time, scientists succeeded in localising large amounts of water in a disk around a young star

Water is regarded as a key ingredient for life - and water exists plenty in the universe. Now scientists have found the precious element in a disk around a young star, similar to our Sun. This disk, supposedly the birth place for future planets, contains a hundred times more than all oceans on Earth. The astronomical observations obtained with the IRAM interferometer appear very promising to solve the mystery around the origin of water in our solar system

[ more ]

(February 8, 2010)

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  MPE Highlight and Press Release:


Herschel-PACS images of the 'GOODS-N' field in the constellation of Ursa Major at far-infrared wavelengths of 100 and 160 µm.
Image: MPE

Herschel Space Telescope uncovers the sources of the Cosmic Infrared Background

A weak cosmic infrared radiation field that reaches Earth from all directions contains not yet deciphered messages about the evolution of galaxies. Using first observations with the PACS Instrument on board ESA's Herschel Space Telescope, scientists from the Max Planck Institute for Extraterrestrial Physics and other institutions have for the first time resolved more than half of this radiation into its constituting sources. Observations with Herschel open the road towards understanding the properties of these galaxies, and trace the dusty side of galaxy evolution.
[ more ]

(December 16, 2009)

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Hα velocity fields

SINS: Gas kinematics and star formation of 100 high redshift galaxies with SINFONI

Our data resolve the emission line distributions and kinematics (primarily Hα) on scales of ~1-5 kpc. About 1/3 of the galaxies are rotation-dominated yet turbulent disks, 1/3 are more compact dispersion dominated objects, and 1/3 are clear mergers (illustrated with the Hα velocity fields of 30 of the 103 sources below). The data imply comparable current and past-averaged SFRs, high gas mass fractions of ~30% and baryonic mass fractions of ~60%-80% within ~10kpc. The high z disks are more turbulent and gas-rich than their z~0 counterparts, often showing luminous massive (~107.5-109.5Mo) kpc-sized "clumps", as expected for Toomre-unstable gas-rich disks. A picture emerges in which the gas reservoirs of the galaxies are constantly replenished, fueling intense star formation over a substantial part of their stellar lifetimes and ~10 dynamical timescales. This suggests steady gas accretion via cold flows or rapid series of minor mergers (as opposed to violent dissipative major mergers) is at play, heating the disks without destroying the highly ordered gas motions.

For more information see
    SINS web pages.

(December 1, 2009)

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  MPE Highlight:


Part of the milkyway in IR
Image: MPE
( high resolution)

Herschel views deep-space pearls on a cosmic string

Europe's new space observatory Herschel has delivered marvellous vistas of cold gas clouds lying near the plane of the Milky Way.
The dark, cool region is dotted with stellar factories, like pearls on a cosmic string, unveiling unexpected activity in spectacular details as we have never seen it before! These infrared pictures prove that Herschel is on par with the Hubble Space Telescope, complementing Hubble's view of the universe in visible light with the missing "other half" in the infrared.

Links:

ESA web release
ESA's Herschel web page

Further MPE/PACS milestones:

Looking deep into the Cat's Eye with Herschel/PACS
HerschelÂ’s first glimpse into space

Contact:   E. Sturm

(October 14, 2009)

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Far-infrared colour image of the "Whirlpool Galaxy" M51.

Herschel's first glimpse of the Universe

The PACS team at MPE is all excited: After the successful opening of the satellite's cryostat lid on Sunday, June 14, the instruments on board had their first view of the Universe. Against all odds, the Photodetector Array Camera and Spectrometer (PACS) was immediately able to capture some images, which far exceeded all our expectations. They already demonstrated - at this early phase of the mission - the superiority of Herschel, the largest infrared space telescope. [  more ]

MPG Press Release
    

ESA's Herschel web site
(June 19, 2009)

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Gas Streamers in NGC1068

Gas Streamers in NGC 1068

Although a prototypical Seyfert 2, NGC 1068 is in fact rather unusual. The H2 emission in the central 250pc originates in an expanding off-centre shell with particularly bright and massive clumps around the north east side. Filaments of gas extend from the ring at a radius of about 30pc to the AGN on both sides. Modelling the morphology and kinematics of the filaments has shown that the only way to simultaneously account for both constraints is if they trace gas that is falling almost directly in towards the AGN. These models indicate that the infall timescale is about 1.3Myr. One of the filaments lies across the front of the AGN, suggesting that inelastic collisions may allow the gas to settle on scales of a few parsecs.

For more information see
    MPE AGN Web Pages.

(January 20, 2009)

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  MPE Highlight:

The central 25 arcseconds of our Milky Way.

Unprecedented 16-Year Long Study Tracks Stars Orbiting Milky Way Black Hole

In a 16-year long study, using several of ESO's flagship telescopes, a team of German astronomers has produced the most detailed view ever of the surroundings of the monster lurking at our Galaxy's heart — a supermassive black hole. The research has unravelled the hidden secrets of this tumultuous region by mapping the orbits of almost 30 stars, a five-fold increase over previous studies. One of the stars has now completed a full orbit around the black hole.

MPE press release (in German language)
MPE Galactic Center Pages
MPG press release (in German language)

ESO press release
Pictures and videos of the ESO press release
(December 10, 2008)

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