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8 results on '"Margoniner, Vera E."'

2. Discovery of a Dissociative Galaxy Cluster Merger with Large Physical Separation

Author

Dawson, William A., Wittman, David, Jee, Myungkook, Gee, Perry, Hughes, John P., Tyson, J. Anthony, Schmidt, Samuel, Thorman, Paul, Bradac, Marusa, Miyazaki, Satoshi, Lemaux, Brian, Utsumi, Yousuke, and Margoniner, Vera E.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

We present DLSCL J0916.2+2951 (z=0.53), a newly discovered major cluster merger in which the collisional cluster gas has become dissociated from the collisionless galaxies and dark matter. We identified the cluster using optical and weak lensing observations as part of the Deep Lens Survey. Our follow-up observations with Keck, Subaru, Hubble Space Telescope, and Chandra show that the cluster is a dissociative merger and constrain the dark matter self-interaction cross-section {\sigma}_{DM}m_{DM}^{-1}\leq7 cm^2g^{-1}. The system is observed at least 0.7\pm0.2 Gyr since first pass-through, thus providing a picture of cluster mergers 2-5 times further progressed than similar systems observed to date. This improved temporal leverage has implications for our understanding of merging clusters and their impact on galaxy evolution., Comment: Accepted ApJ Letters. [v2] changes: 1 new figure (2b), figure 3 made color, and minor improvements to the text. 6 pages, 4 figures, 1 table

Published
2011
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3. The Northern Sky Optical Cluster Survey

Author

Gal, Roy R., Carvalho, Reinaldo R. de, Odewahn, Stephen C., Djorgovski, S. George, Brunner, Robert J., Margoniner, Vera E., Banday, Anthony J., editor, Zaroubi, Saleem, editor, and Bartelmann, Matthias, editor

Published
2001
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5. DISCOVERY OF A DISSOCIATIVE GALAXY CLUSTER MERGER WITH LARGE PHYSICAL SEPARATION

Author

Dawson, William A., primary, Wittman, David, additional, Jee, M. James, additional, Gee, Perry, additional, Hughes, John P., additional, Tyson, J. Anthony, additional, Schmidt, Samuel, additional, Thorman, Paul, additional, Bradač, Maruša, additional, Miyazaki, Satoshi, additional, Lemaux, Brian, additional, Utsumi, Yousuke, additional, and Margoniner, Vera E., additional

Published
2012
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6. The Northern Sky Optical Cluster Survey

Author

Banday, Anthony J., Zaroubi, Saleem, Bartelmann, Matthias, Gal, Roy R., de Carvalho, Reinaldo R., Odewahn, Stephen C., Djorgovski, S. George, Brunner, Robert J., Margoniner, Vera E., Banday, Anthony J., Zaroubi, Saleem, Bartelmann, Matthias, Gal, Roy R., de Carvalho, Reinaldo R., Odewahn, Stephen C., Djorgovski, S. George, Brunner, Robert J., and Margoniner, Vera E.

Abstract

The Northern Sky Optical Cluster Survey aims to create an objective catalog of galaxy clusters over the entire high-galactic-latitude Northern sky. We use the catalogs generated from the Digitized Second Palomar Sky Survey (DPOSS, Djorgovski et al. 1999) as the basis for this survey. We apply a color criterion to select against field galaxies, and use a simple adaptive kernel technique to create galaxy density maps, combined with the bootstrap technique to make significance maps, from which density peaks are selected. We find a mean surface density of ∼1.5 clusters per square degree, consistent with the detection of richness class 0 and higher clusters to z∼0.3. In addition, we demonstrate an effective photometric redshift estimator for our clusters.

Published
2001

7. Multiwavelength Monitoring of the BL Lacertae Object PKS 2155−304 in 1994 May. I. The Ground‐based Campaign

Author

Pesce, Joseph E., primary, Urry, C. Megan, additional, Maraschi, Laura, additional, Treves, Aldo, additional, Grandi, Paola, additional, Kollgaard, Ronald I., additional, Pian, Elena, additional, Smith, Paul S., additional, Aller, Hugh D., additional, Aller, Margo F., additional, Barth, Aaron J., additional, Buckley, David A. H., additional, Covino, Elvira, additional, Filippenko, Alexei V., additional, Hooper, Eric J., additional, Joner, Michael D., additional, Kedziora‐Chudczer, Lucyna, additional, Kilkenny, David, additional, Knee, Lewis B. G., additional, Kunkel, Michael, additional, Layden, Andrew C., additional, Magalhaes, Antonio Mario, additional, Marang, Fred, additional, Margoniner, Vera E., additional, Palma, Christopher, additional, Pereyra, Antonio, additional, Rodrigues, Claudia V., additional, Schutte, Andries, additional, Sitko, Michael L., additional, Tornikoski, Merja, additional, van der Walt, Johan, additional, van Wyk, Francois, additional, Whitelock, Patricia A., additional, and Wolk, Scott J., additional

Published
1997
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8. Multiwavelength Monitoring of the BL Lacertae Object PKS 2155-304 in 1994 May. I. The Ground-based Campaign

Author

Pesce, Joseph E., Urry, Megan, Maraschi, Laura, Treves, Aldo, Grandi, Paola, Kollgaard, Ronald I., Pian, Elena, Smith, Paul S., Aller, Hugh D., Aller, Margo F., Barth, Aaron J., H, David A., Covino, Elvira, Filippenko, Alexei V., Hooper, Eric J., Joner, Michael D., Kedziora, Lucyna, Kilkenny, David, G, Lewis B., Kunkel, Michael, Layden, Andrew C., Mario, Antonio, Marang, Fred, Margoniner, Vera E., Palma, Christopher, Pereyra, Antonio, Rodrigues, Claudia V., Schutte, Andries, Sitko, Michael L., Tornikoski, Merja, van, Johan, Walt, der, van, Francois, Whitelock, Patricia A., and Wolk, Scott J.

Abstract

Optical, near-infrared, and radio observations of the BL Lac object PKS 2155-304 were obtained simultaneously with a continuous UV/EUV/X-ray monitoring campaign in 1994 May. Further optical observations were gathered throughout most of 1994. The radio, millimeter, and near-infrared data show no strong correlations with the higher energies. The optical light curves exhibit flickering of 0.2-0.3 mag on timescales of 1-2 days, superposed on longer timescale variations. Rapid variations of ~0.01 mag minute-1, if real, are the fastest seen to date for any BL Lac object. Small (0.2-0.3 mag) increases in the V and R bands occur simultaneously with a flare seen at higher energies. All optical wave bands (UBVRI) track each other well over the period of observation, with no detectable delay. For most of the period the average colors remain relatively constant, although there is a tendency for the colors (in particular, B-V) to vary more when the source fades. In polarized light, PKS 2155-304 showed strong color dependence (polarization increases toward the blue, PU/PI = 1.31) and the highest optical polarization (U = 14.3%) ever observed for this source. The polarization variations trace the flares seen in the UV flux. For the fastest variability timescale observed, we estimate a central black hole mass of [?]1.5 x 109(d/10) M, consistent with UV and X-ray constraints and smaller than previously calculated for this object.

Published
1997

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