Design and Synthesis of Novel Quinone Inhibitors Targeted to the Redox Function of Apurinic/Apyrimidinic Endonuclease 1/Redox Enhancing Factor-1 (Ape1/Ref-1)

The multifunctional enzyme apurinic endonuclease 1/redox enhancing factor 1 (Ape1/ref-1) maintains genetic fidelity through the repair of apurinic sites and regulates transcription through redox-dependent activation of transcription factors. Ape1 can therefore serve as a therapeutic target in either a DNA repair or transcriptional context. Inhibitors of the redox function can be used as either therapeutics or novel tools for separating the two functions for in vitro study. Presently there exist only a few compounds that have been reported to inhibit Ape1 redox activity; here we describe a series of quinones that exhibit micromolar inhibition of the redox function of Ape1. Benzoquinone and naphthoquinone analogues of the Ape1-inhibitor E3330 were designed and synthesized to explore structural effects on redox function and inhibition of cell growth. Most of the naphthoquinones were low micromolar inhibitors of Ape1 redox activity, and the most potent analogues inhibited tumor cell growth with IC50 values in the 10−20 μM range

GEMS: Galaxy Evolution from Morphologies and SEDs

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 Field South, it covers an area of ~28'x28', or about 120 Hubble Deep Field areas, to a depth of m_AB(F606W)=28.3 (5sigma and m_AB(F850LP)=27.1 (5sigma) for compact sources. In its central ~1/4, GEMS incorporates ACS imaging from the GOODS project. Focusing on the redshift range 0.2<=z<=1.1, GEMS provides morphologies and structural parameters for nearly 10,000 galaxies where redshift estimates, luminosities and SEDs exist from COMBO-17. At the same time, GEMS contains detectable host galaxy images for several hundred faint AGN. This paper provides an overview of the science goals, the experiment design, the data reduction and the science analysis plan for GEMS.Comment: 24 pages, TeX with 6 eps Figures; to appear in ApJ Supplement. Low resolution figures only. Full resolution at http://zwicky.as.arizona.edu/~rix/Misc/GEMS.ps.g

Evolution of optically faint AGN from COMBO-17 and GEMS

We have mapped the AGN luminosity function and its evolution between z=1 and z=5 down to apparent magnitudes of $R<24$. Within the GEMS project we have analysed HST-ACS images of many AGN in the Extended Chandra Deep Field South, enabling us to assess the evolution of AGN host galaxy properties with cosmic time.Comment: to appear in proceedings 'Multiwavelength AGN Surveys', Cozumel 200

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

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 major mergers between spheroid-dominated galaxies with little cold gas (dry mergers) since z = 0.7. A set of N-body merger simulations was used to explore the morphological signatures of such interactions: they are recognizable either as < 5kpc separation close pairs or because of broad, low surface brightness tidal features and asymmetries. Data with the depth and resolution of GEMS are sensitive to dry mergers between galaxies with M_V < -20.5 for z < 0.7; dry mergers at higher redshifts are not easily recovered in single-orbit HST imaging. Six dry mergers (12 galaxies) with luminosity ratios between 1:1 and 4:1 were found from a sample of 379 red early-type galaxies with M_V < -20.5 and 0.1 < z < 0.7. The simulations suggest that the morphological signatures of dry merging are visible for ~250Myr and we use this timescale to convert the observed merger incidence into a rate. On this basis we find that present day spheroidal galaxies with M_V < -20.5 on average have undergone between 0.5 and 2 major dry mergers since z ~ 0.7. We have compared this result with the predictions of a Cold Dark Matter based semi-analytic galaxy formation model. The model reproduces the observed declining major merger fraction of bright galaxies and the space density of luminous early-type galaxies reasonably well. The predicted dry merger fraction is consistent with our observational result. Hence, hierarchical models predict and observations now show that major dry mergers are an important driver of the evolution of massive early-type galaxies in recent epochs.Comment: ApJ, in press. The paper has been extensively modified, detailing the automated+visual selection and dry merger classification. 11 pages emulateapj with 9 reduced-quality figures. A high quality copy is available at http://www.mpia-hd.mpg.de/homes/bell/papers/dry.ps.g

GEMS: Galaxy fitting catalogues and testing parametric galaxy fitting codes

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 fitting single-component Sersic models to the light profiles of both simulated and real galaxy data. We find that fitting accuracy depends sensitively on galaxy profile shape. Exponential disks are well fit with Sersic models and have small measurement errors, whereas fits to de Vaucouleurs profiles show larger uncertainties owing to the large amount of light at large radii. We find that both codes provide reliable fits and little systematic error, when the effective surface brightness is above that of the sky. Moreover, both codes return errors that significantly underestimate the true fitting uncertainties, which are best estimated with simulations. We find that GIM2D suffers significant systematic errors for spheroids with close companions owing to the difficulty of effectively masking out neighboring galaxy light; there appears to be no work around to this important systematic in GIM2D's current implementation. While this crowding error affects only a small fraction of galaxies in GEMS, it must be accounted for in the analysis of deeper cosmological images or of more crowded fields with GIM2D. In contrast, GALFIT results are robust to the presence of neighbors because it can simultaneously fit the profiles of multiple companions thereby deblending their effect on the fit to the galaxy of interest. We find GALFIT's robustness to nearby companions and factor of >~20 faster runtime speed are important advantages over GIM2D for analyzing large HST/ACS datasets. Finally we include our final catalog of fit results for all 41,495 objects detected in GEMS.Comment: Accepted for publication in ApJS October 2007, v172n2; 25 pages, 16 Figures, 9 Tables; for hi-resolution version, see http://www.mpia.de/homes/bhaeussl/galaxy_fitting.pdf. For results, catalogues and files for code-testing, see http://www.mpia.de/GEMS/fitting_paper.htm

Cosmological weak lensing with the HST GEMS survey

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 square arcmin in the Chandra Deep Field South. We detect weak lensing by large-scale structure in high resolution F606W GEMS data from ~60 resolved galaxies per square arcminute. We measure the two-point shear correlation function, the top-hat shear variance and the shear power spectrum, performing an E/B mode decomposition for each statistic. We show that we are not limited by systematic errors and use our results to place joint constraints on the matter density parameter Omega_m and the amplitude of the matter power spectrum sigma_8. We find sigma_8(Omega_m/0.3)^{0.65}=0.68 +/- 0.13 where the 1sigma error includes both our uncertainty on the median redshift of the survey and sampling variance. Removing image and point spread function (PSF) distortions are crucial to all weak lensing analyses. We therefore include a thorough discussion on the degree of ACS PSF distortion and anisotropy which we characterise directly from GEMS data. Consecutively imaged over 20 days, GEMS data also allows us to investigate PSF instability over time. We find that, even in the relatively short GEMS observing period, the ACS PSF ellipticity varies at the level of a few percent which we account for with a semi-time dependent PSF model. Our correction for the temporal and spatial variability of the PSF is shown to be successful through a series of diagnostic tests.Comment: 17 pages, 16 figures. Version accepted by MNRA

GEMS Survey Data and Catalog

We describe the data reduction and object cataloging for the GEMS survey, a large-area (800 arcmin(2)) two-band (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on the Hubble Space Telescope, centered on the Chandra Deep Field-South.STScI HST-GO-9500.01NASA GO-9500, NAS5-26555, NAG5-13063, NAG5-13102European Community’s Human Potential Programunder contractHPRN-CT-2002-00316, HPRN-CT-2002-00305McDonald Observator

An Explanation for the Observed Weak Size Evolution of Disk Galaxies

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 disks from z~1 to the present day. Using a sample of nearby disk-dominated galaxies from the Sloan Digital Sky Survey (SDSS), and high redshift data from the GEMS (Galaxy Evolution from Morphology and SEDs) survey, we investigate whether this result is consistent with theoretical expectations within the hierarchical paradigm of structure formation. The relationship between virial radius and mass for dark matter halos in the LCDM model evolves by about a factor of two over this interval. However, N-body simulations have shown that halos of a given mass have less centrally concentrated mass profiles at high redshift. When we compute the expected disk size-stellar mass distribution, accounting for this evolution in the internal structure of dark matter halos and the adiabatic contraction of the dark matter by the self-gravity of the collapsing baryons, we find that the predicted evolution in the mean size at fixed stellar mass since z~1 is about 15-20 percent, in good agreement with the observational constraints from GEMS. At redshift z~2, the model predicts that disks at fixed stellar mass were on average only 60% as large as they are today. Similarly, we predict that the rotation velocity at a given stellar mass (essentially the zero-point of the Tully-Fisher relation) is only about 10 percent larger at z~1 (20 percent at z~2) than at the present day.Comment: 13 pages, 6 figures, accepted for publication in ApJ. Revised in response to referee's comments to improve clariry. Results are unchange

Evolution and Impact of Bars over the Last Eight Billion Years: Early Results from GEMS

Bars drive the dynamical evolution of disk galaxies by redistributing mass and angular momentum, and they are ubiquitous in present-day spirals. Early studies of the Hubble Deep Field reported a dramatic decline in the rest-frame optical bar fraction f_opt to below 5% at redshifts z>0.7, implying that disks at these epochs are fundamentally different from present-day spirals. The GEMS bar project, based on ~8300 galaxies with HST-based morphologies and accurate redshifts over the range 0.2-1.1, aims at constraining the evolution and impact of bars over the last 8 Gyr. We present early results indicating that f_opt remains nearly constant at ~30% over the range z=0.2-1.1,corresponding to lookback times of ~2.5-8 Gyr. The bars detected at z>0.6 are primarily strong with ellipticities of 0.4-0.8. Remarkably, the bar fraction and range of bar sizes observed at z>0.6 appear to be comparable to the values measured in the local Universe for bars of corresponding strengths. Implications for bar evolution models are discussed.Comment: Submitted June 25, 2004. 10 pages 5 figures. To appear in Penetrating Bars through Masks of Cosmic Dust: The Hubble Tuning Fork Strikes a New Note, eds. D. Block, K. Freeman, R. Groess, I. Puerari, & E.K. Block (Dordrecht: Kluwer), in pres

GEMS: The Size Evolution of Disk Galaxies

We combine HST imaging from the GEMS survey with photometric redshifts from COMBO-17 to explore the evolution of disk-dominated galaxies since z<1.1. The sample is comprised of all GEMS galaxies with Sersic indices n<2.5, derived from fits to the galaxy images. We account fully for selection effects through careful analysis of image simulations; we are limited by the depth of the redshift and HST data to the study of galaxies with absolute magnitudes M(V)10. We find strong evolution in the magnitude-size scaling relation for galaxies with M(V)<-20, corresponding to a brightening of 1 mag per sqarcsec in rest-frame V-band by z=1. Yet, disks at a given absolute magnitude are bluer and have lower stellar mass-to-light ratios at z=1 than at the present day. As a result, our findings indicate weak or no evolution in the relation between stellar mass and effective disk size for galaxies with log(M)>10 over the same time interval. This is strongly inconsistent with the most naive theoretical expectation, in which disk size scales in proportion to the halo virial radius, which would predict that disks are a factor of two denser at fixed mass at z=1. The lack of evolution in the stellar mass-size relation is consistent with an ``inside-out'' growth of galaxy disks on average (galaxies increasing in size as they grow more massive), although we cannot rule out more complex evolutionary scenarios.Comment: 22 pages, 16 figures, submitted to Ap