Knud Jahnke

The environmental dependence of the stellar mass-size relation in STAGES galaxies (2009)

Maltby, David T., Aragón-Salamanca, Alfonso, Gray, Meghan E., Barden, Marco, Haeussler, Boris, Wolf, Christian, ...

We present the stellar mass-size relations for elliptical, lenticular, and spiral galaxies in the field and cluster environments using HST/ACS imaging and data from the Space Telescope A901/2 Galaxy...

The Nature of Optically Dull Active Galactic Nuclei in COSMOS (2009)

Trump, Jonathan R., Impey, Chris D., Taniguchi, Yoshi, Brusa, Marcella, Civano, Francesca, Elvis, Martin, ...

We present infrared, optical, and X-ray data of 48 X-ray bright, optically dull AGNs in the COSMOS field. These objects exhibit the X-ray luminosity of an active galactic nucleus (AGN) but lack broad...

Less than 10 percent of star formation in z=0.6 massive galaxies is triggered by major interactions (2009)

Robaina, Aday R., Bell, Eric F., Skelton, Rosalind E., McIntosh, Daniel H., Somerville, Rachel S., Zheng, Xianzhong, ...

Both observations and simulations show that major tidal interactions or mergers between gas-rich galaxies can lead to intense bursts of starformation. Yet, the average enhancement in star formation...

Optically-passive spirals: The missing link in gradual star formation suppression upon cluster infall (2009)

Wolf, Christian, Aragón-Salamanca, Alfonso, Balogh, Michael, Barden, Marco, Bell, Eric F., Gray, Meghan E., ...

Galaxies migrate from the blue cloud to the red sequence when their star formation is quenched. Here, we report on galaxies quenched by environmental effects and not by mergers or strong AGN as often...

The QSO HE0450-2958: Scantily dressed or heavily robed? A normal quasar as part of an unusual ULIRG (2009)

Jahnke, Knud, Elbaz, David, Pantin, Eric, Böhm, Asmus, Wisotzki, Lutz, Letawe, Geraldine, ...

(Abridged) The luminous z=0.286 quasar HE0450-2958 is interacting with a companion galaxy at 6.5 kpc distance and the whole system is a ULIRG. A so far undetected host galaxy triggered the hypothesis...

The COSMOS Active Galactic Nucleus Spectroscopic Survey. I. XMM-Newton Counterparts (2009)

Trump, Jonathan R., Impey, Chris D., Elvis, Martin, McCarthy, Patrick J., Huchra, John P., Brusa, Marcella, ...

We present optical spectroscopy for an X-ray and optical flux-limited sample of 677 XMM-Newton selected targets covering the 2 deg^2 Cosmic Evolution Survey field, with a yield of 485 high-confidence...

History of Galaxy Interactions and their Impact on Star Formation over the Last 7 Gyr from GEMS (2009)

Jogee, Shardha, Miller, Sarah H., Penner, Kyle, Skelton, Rosalind E., Conselice, Christopher J., Somerville, Rachel S., ...

We perform a comprehensive estimate of the frequency of galaxy mergers and their impact on star formation over z~0.24--0.80 (lookback time T_b~3--7 Gyr) using 3698 (M*>=1e9 Msun) galaxies with GEMS...

FERENGI: Redshifting galaxies from SDSS to GEMS, STAGES and COSMOS (2008)

Barden, Marco, Jahnke, Knud, Häußler, Boris

We describe the creation of a set of artificially "redshifted" galaxies in the range 0.1

The STAGES view of red spirals and dusty red galaxies: Mass-dependent quenching of star-formation in cluster infall (2008)

Wolf, Christian, Aragon-Salamanca, Alfonso, Balogh, Michael, Barden, Marco, Bell, Eric F., Gray, Meghan E., ...

We investigate the properties of optically passive spirals and dusty red galaxies in the A901/2 cluster complex at redshift ~0.17 using restframe near-UV-optical SEDs, 24 micron IR data and HST...

STAGES: the Space Telescope A901/2 Galaxy Evolution Survey (2008)

Gray, M. E., Wolf, Christian, Barden, Marco, Peng, Chien Y., Haeussler, Boris, Bell, Eric F., ...

We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range...

The COSMOS AGN Spectroscopic Survey I: XMM Counterparts (2008)

Trump, Jonathan R., Impey, Chris D., Elvis, Martin, McCarthy, Patrick J., Huchra, John P., Brusa, Marcella, ...

We present optical spectroscopy for an X-ray and optical flux-limited sample of 677 XMM-Newton selected targets covering the 2 deg^2 COSMOS field, with a yield of 485 high-confidence redshifts. The...

Properties of the molecular gas in a starbursting QSO at z=1.83 in the COSMOS field (2008)

Aravena, Manuel, Bertoldi, Frank, Schinnerer, Eva, Weiss, Axel, Jahnke, Knud, Carilli, Chris L., ...

Using the IRAM 30m telescope, we have detected the CO J=2-1, 4-3, 5-4, and 6-5 emission lines in the millimeter-bright, blank-field selected AGN COSMOS J100038+020822 at redshift z=1.8275. The...

First catalog of strong lens candidates in the COSMOS field (2008)

Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...

We present the first catalog of 67 strong galaxy-galaxy lens candidates discovered in the 1.64 deg^2 Hubble Space Telescope COSMOS survey. Twenty of these systems display multiple images or strongly...

First catalog of strong lens candidates in the COSMOS field (2008)

Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...

We present the first catalog of 67 strong galaxy-galaxy lens candidates discovered in the 1.64 square degree Hubble Space Telescope COSMOS survey. Twenty of these systems display multiple images or...

The dark matter environment of the Abell 901/902 supercluster: a weak lensing analysis of the HST STAGES survey (2008)

Heymans, Catherine, Gray, Meghan E., Peng, Chien Y., Van Waerbeke, Ludovic, Bell, Eric F., Wolf, Christian, ...

We present a high resolution dark matter reconstruction of the z=0.165 Abell 901/902 supercluster from a weak lensing analysis of the HST STAGES survey. We detect the four main structures of the...

An explanation for the observed weak size evolution of disk galaxies (2008)

Somerville, Rachel S., Barden, Marco, Rix, Hans-Walter, Bell, Eric F., Beckwith, Steven V. W., Borch, Andrea, ...

Surveys of distant galaxies with the Hubble Space Telescope and from the ground have shown that there is only mild evolution in the relationship between radial size and stellar mass for galactic...

The dark matter environment of the Abell 901/902 supercluster: a weak lensing analysis of the HST STAGES survey (2008)

Heymans, Catherine, Gray, Meghan E., Peng, Chien Y., Van Waerbeke, Ludovic, Bell, Eric F., Wolf, Christian, ...

We present a high-resolution dark matter reconstruction of the z = 0.165 Abell 901/902 supercluster from a weak lensing analysis of the Hubble Space Telescope STAGES survey. We detect the four main...

First catalog of strong lens candidates in the COSMOS field (2008)

Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...

We present the first catalog of 67 strong galaxy-galaxy lens candidates discovered in the 1.64 deg2 Hubble Space Telescope COSMOS survey. Twenty of these systems display multiple images or strongly...

Towards an automatic classification of distortions as merging indicators in AGN host galaxies (2008)

Cisternas, Mauricio, Jahnke, Knud, Inskip, Katherine J.

Does a merging event always precede AGN activity? In this starting PhD project, we will try to address this question by quantifying the distortions and interaction signatures that can be detected on...

GEMS survey data and catalog (2008)

Caldwell, John A. R., McIntosh, Daniel H., Rix, Hans-Walter, Barden, Marco, Beckwith, Steven V. W., Bell, Eric F., ...

We describe the data reduction and object cataloging for the GEMS survey, a large-area (800 arcmin2) two-band (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on the Hubble...

The accretion origin of the Milky Way's stellar halo (2008)

Bell, Eric F., Zucker, Daniel B., Belokurov, Vasily, Sharma, Sanjib, Johnston, Kathryn V., Bullock, James S., ...

We have used data from the Sloan Digital Sky Survey (SDSS) Data Release 5 to explore the overall structure and substructure of the stellar halo of the Milky Way using ~4 million color-selected...

The accretion origin of the Milky Way's stellar halo (2007)

Bell, Eric F., Zucker, Daniel B., Belokurov, Vasily, Sharma, Sanjib, Johnston, Kathryn V., Bullock, James S., ...

We have used data from the Sloan Digital Sky Survey (SDSS) Data Release 5 to explore the overall structure and substructure of the stellar halo of the Milky Way using about 4 million color-selected...

GEMS: Galaxy fitting catalogues and testing parametric galaxy fitting codes (2007)

Ler, Boris Häu\ss, McIntosh, Daniel H., Barden, Marco, Bell, Eric F., Rix, Hans-Walter, Borch, Andrea, ...

In the context of measuring structure and morphology of intermediate redshift galaxies with recent HST/ACS surveys, we tune, test, and compare two widely used fitting codes (GALFIT and GIM2D) for...

Spatial decomposition of on-nucleus spectra of quasar host galaxies (2007)

Jahnke, Knud, Wisotzki, Lutz, Courbin, Frederic, Letawe, Geraldine

In order to study the host galaxies of type 1 (broad-line) quasars, we present a semi-analytic modelling method to decompose the on-nucleus spectra of quasars into nuclear and host galaxy channels....

GEMS: galaxy fitting catalogs and testing parametric galaxy fitting codes: GALFIT and GIM2D (2007)

Häußler, Boris, McIntosh, Daniel H., Barden, Marco, Bell, Eric F., Rix, Hans-Walter, Borch, Andrea, ...

In the context of measuring the structures of intermediate-redshift galaxies with HST ACS surveys, we tune, test, and compare two widely used fitting codes (GALFIT and GIM2D) for fitting...

An Explanation for the Observed Weak Size Evolution of Disk Galaxies (2006)

Somerville, Rachel S., Barden, Marco, Rix, Hans-Walter, Bell, Eric F., Beckwith, Steven V. W., Borch, Andrea, ...

Surveys of distant galaxies with the Hubble Space Telescope and from the ground have shown that there is only mild evolution in the relationship between radial size and stellar mass for galactic...

A weak lensing estimate from GEMS of the virial to stellar mass ratio in massive galaxies to z~0.8 (2006)

Heymans, Catherine, Bell, Eric F., Rix, Hans-Walter, Barden, Marco, Borch, Andrea, Caldwell, John A. R., ...

We present constraints on the evolution of the virial to stellar mass ratio of galaxies with high stellar masses in the redshift range 0.2

The evolution of QSO host colours (2006)

Wisotzki, Lutz, Jahnke, Knud, Sanchez, Sebastian F., Schramm, Malte

We summarise the evidence that the hosts of luminous QSOs are systematically bluer than normal (inactive) galaxies of comparable morphological type. We particularly emphasize the importance of...

Host galaxies of luminous high redshift quasars (2006)

Schramm, Malte, Wisotzki, Lutz, Jahnke, Knud

We have observed a sample of 7 luminous QSOs in the redshift range z = 1.8--2.9 selected from the Hamburg/ESO survey (HES). The aim of this study is to detect the galaxies that host the quasar and to...

Decoupling the host and nuclear spectra of type I AGNs using integral field spectroscopy: A test on 3C 120 (2006)

Sánchez, Sebastián F., García-Lorenzo, Begoña, Jahnke, Knud, Mediavilla, Evencio, González-Serrano, José Ignacio, Christensen, Lise, ...

We have developed a new technique to decouple the spectra of the host and the nucleus of type I AGNs using integral field spectroscopy data. The technique is a simple extension of methods widely...

Young stars in high-z QSO host galaxies (2006)

Jahnke, Knud, Wisotzki, Lutz, Sánchez, Sebastián F.

We study the stellar properties of type 1 QSO host galaxies at redshifts to z ˜ 3 using the HST within the GEMS project as well as ground based adaptive optics. The host galaxies have a tendency for...

A weak lensing estimate from GEMS of the virial to stellar mass ratio in massive galaxies to z ~ 0.8 (2006)

Heymans, Catherine, Bell, Eric F., Rix, Hans-Walter, Barden, Marco, Borch, Andrea, Caldwell, John A. R., ...

We present constraints on the evolution of the virial to stellar mass ratio of galaxies with high stellar masses in the redshift range 0.2 < z < 0.8, by comparing weak lensing measurements of virial...

Dry mergers in GEMS: The dynamical evolution of massive early-type galaxies (2006)

Bell, Eric F., Naab, Thorsten, McIntosh, Daniel H., Somerville, Rachel S., Caldwell, John A. R., Barden, Marco, ...

We have used the 28'×28' Hubble Space Telescope image mosaic from the GEMS (Galaxy Evolution from Morphology and SEDs) survey in conjunction with the COMBO-17 photometric redshift survey to...

Discovery of a bright quasar without a massive host galaxy (2005)

Magain, Pierre, Letawe, Geraldine, Courbin, Frederic, Jablonka, Pascale, Jahnke, Knud, Wisotzki, Lutz, ...

Quasars are thought to be powered by the infall of matter onto a supermassive black hole at the centre of massive galaxies. As the optical luminosity of quasars exceeds that of their host galaxy,...

Dry Mergers in GEMS: The Dynamical Evolution of Massive Early-Type Galaxies (2005)

Bell, Eric F., Naab, Thorsten, McIntosh, Daniel H., Somerville, Rachel S., Caldwell, John A. R., Barden, Marco, ...

We have used the 28'x 28' HST image mosaic from the GEMS (Galaxy Evolution from Morphology and SEDs) survey in conjunction with the COMBO-17 photometric redshift survey to constrain the incidence of...

On the periodic clustering of cosmic ray exposure ages of iron meteorites (2005)

Jahnke, Knud

Two recent papers claimed to have found a periodic variation of the galactic cosmic ray (CR) flux over the last 1-2 Gyr, using the CR exposure ages of iron meteorites. This was attributed to higher...

GEMS: The Size Evolution of Disk Galaxies (2005)

Barden, Marco, Rix, Hans-Walter, Somerville, Rachel S., Bell, Eric F., Haeussler, Boris, Peng, Chien Y., ...

We combine HST imaging from the GEMS survey with photometric redshifts from COMBO-17 to explore the evolution of disk-dominated galaxies since z

The evolution of early-type red galaxies with the GEMS survey: Luminosity-size and stellar mass-size relations since z=1 (2005)

McIntosh, Daniel H., Bell, Eric F., Rix, Hans-Walter, Wolf, Christian, Heymans, Catherine, Peng, Chien Y., ...

We combine imaging from the Hubble Space Telescope Advanced Camera for Surveys, as part of the GEMS (Galaxy Evolution from Morphologies and SEDs) survey, with redshifts and rest-frame quantities from...

Cosmological weak lensing with the HST GEMS survey (2005)

Heymans, Catherine, Brown, Michael L., Barden, Marco, Caldwell, John A. R., Jahnke, Knud, Peng, Chien Y., ...

We present our cosmic shear analysis of GEMS, one of the largest wide-field surveys ever undertaken by the Hubble Space Telescope. Imaged with the Advanced Camera for Surveys (ACS), GEMS spans 795...

Weak Lensing Results from GEMS (2005)

Heymans, Catherine, Brown, Michael L., Barden, Marco, Caldwell, John A. R., Jahnke, Knud, Rix, Hans-Walter, ...

We present our cosmic shear analysis of the Galaxy Evolution from Morphology and SEDs (GEMS) survey. Imaged with the Advanced Camera for Surveys (ACS) on HST, GEMS provides high resolution imaging...

GEMS: The surface brightness and surface mass density evolution of disk galaxies (2005)

Barden, Marco, Rix, Hans-Walter, Somerville, Rachel S., Bell, Eric F., Häußler, Boris, Peng, Chien Y., ...

We combine HST imaging from the GEMS (Galaxy Evolution from Morphologies and SEDs) survey with photometric redshifts from COMBO-17 to explore the evolution of disk-dominated galaxies since z

The Evolution of Early-type Red Galaxies with the GEMS Survey: Luminosity-size and Stellar Mass-size Relations Since z=1 (2004)

McIntosh, Daniel H., Bell, Eric F., Rix, Hans-Walter, Wolf, Christian, Heymans, Catherine, Peng, Chien Y., ...

We combine HST/ACS imaging from the GEMS survey with redshifts and rest-frame quantities from COMBO-17 to study the evolution of morphologically early-type galaxies with red colors since z=1. We use...

Cosmological weak lensing with the HST GEMS survey (2004)

Heymans, Catherine, Brown, Michael L., Barden, Marco, Caldwell, John A. R., Jahnke, Knud, Peng, Chien Y., ...

We present our cosmic shear analysis of GEMS, one of the largest wide-field surveys ever undertaken by the Hubble Space Telescope. Imaged with the Advanced Camera for Surveys (ACS), GEMS spans 795...

HE 0047-1756: A new gravitationally lensed double QSO (2004)

Wisotzki, Lutz, Schechter, Paul L., Chen, Hsiao-Wen, Richstone, Douglas, Jahnke, Knud, Sanchez, Sebastian F., ...

The quasar HE 0047-1756, at z=1.67, is found to be split into two images 1.44" apart by an intervening galaxy acting as a gravitational lens. The flux ratio for the two components is roughly 3.5:1,...

GEMS: Galaxy Evolution from Morphologies and SEDs (2004)

Rix, Hans-Walter, Barden, Marco, Beckwith, Steven V. W., Bell, Eric F., Caldwell, John A. R., Haeussler, Boris, ...

GEMS, Galaxy Evolution from Morphologies and SEDs, is a large-area (800 arcmin2) two-color (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on HST. Centered on the Chandra Deep...

GEMS: Galaxy evolution from morphologies and SEDs (2004)

Rix, Hans-Walter, Barden, Marco, Beckwith, Steven V. W., Bell, Eric F., Borch, Andrea, Caldwell, John A. R., ...

GEMS (Galaxy Evolution from Morphologies and SEDs) is a large-area (800 arcmin2) two-color (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on the Hubble Space Telescope....

GEMS imaging of red-sequence galaxies at z~0.7: Dusty or old? (2004)

Bell, Eric F., McIntosh, Daniel H., Barden, Marco, Wolf, Christian, Caldwell, John A. R., Rix, Hans-Walter, ...

We have used the 30'‚‚times;30' Hubble Space Telescope image mosaic from the Galaxy Evolution from Morphology and Spectral energy distributions (GEMS) project in conjunction with the COMBO-17 deep...

Bar evolution over the last 8 billion years: A constant fraction of strong bars in the GEMS survey (2004)

Jogee, Shardha, Barazza, Fabio D., Rix, Hans-Walter, Shlosman, Isaac, Barden, Marco, Wolf, Christian, ...

One-third of present-day spirals host optically visible strong bars that drive their dynamical evolution. However, the fundamental question of how bars evolve over cosmological times has yet to be...

GEMS Imaging of Red Sequence Galaxies at z~0.7: Dusty or Old? (2003)

Bell, Eric F., McIntosh, Daniel H., Barden, Marco, Wolf, Christian, Caldwell, John A. R., Rix, Hans-Walter, ...

We have used the 30'x30' Hubble Space Telescope image mosaic from the Galaxy Evolution from Morphology and SEDs (GEMS) project in conjunction with the COMBO-17 deep photometric redshift survey to...