Search Publications
The Baryon Content of Dark Matter Halos: Empirical Constraints from Mg II Absorbers
Chen, Hsiao-Wen; Tinker, Jeremy L.
We study the extent and covering fraction of cool baryons around galaxies of different luminosity and mass, based on a survey of Mg II λλ2796, 2803 absorption features near known galaxies. The initial sample consists of 13 galaxy and absorber pairs and 10 galaxies that do not produce Mg II absorption lines to within sensitive upper limits. The red…
GMASS ultradeep spectroscopy of galaxies at z ∼2. III. The emergence of the color bimodality at z ∼2
Berta, S.; Cimatti, A.; Daddi, E. +12 more
Aims: The aim of this work is to study the evolution of the rest-frame color distribution of galaxies with the redshift, in particular in the critical interval 1.4<z<3.
Methods: We combined ultradeep spectroscopy from the GMASS project (Galaxy Mass Assembly ultradeep Spectroscopic Survey) with GOODS multi-band photometry (from optical to…
Hinode Observations of Magnetic Elements in Internetwork Areas
Lites, B. W.; Ishikawa, R.; Tarbell, T. D. +3 more
We use sequences of images and magnetograms from Hinode to study magnetic elements in internetwork parts of the quiet solar photosphere. Visual inspection shows the existence of many long-lived (several hours) structures that interact frequently and may migrate over distances of ~7 Mm over a period of a few hours. About a fifth of the elements hav…
X-MAS2: Study Systematics on the ICM Metallicity Measurements
Rasia, E.; Bourdin, H.; Mazzotta, P. +5 more
X-ray measurements of the intracluster medium metallicity are becoming more and more frequent due to the availability of powerful X-ray telescopes with excellent spatial and spectral resolutions. The information that can be extracted from measurements of the α-elements, such as oxygen, magnesium, and silicon, with respect to the iron abundance is …
The End of Amnesia: A New Method for Measuring the Metallicity of Type Ia Supernova Progenitors Using Manganese Lines in Supernova Remnants
Hughes, John P.; Badenes, Carles; Bravo, Eduardo
We propose a new method to measure the metallicity of Type Ia supernova progenitors using Mn and Cr lines in the X-ray spectra of young supernova remnants. We show that the Mn-to-Cr mass ratio in Type Ia supernova ejecta is tightly correlated with the initial metallicity of the progenitor, as determined by the neutron excess of the white dwarf mat…
Spectroscopic Detection of Turbulence in Post-CME Current Sheets
Bemporad, A.
Plasma in post-CME current sheets (CSs) is expected to be highly turbulent because of the tearing and coalescence instability and/or local microscopic instabilities. For this reason, in the last decade the inconsistency between the observed (~104-105 km) and the expected (~1-10 m) CS thickness has been tentatively explained i…
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. VII. Time delays and the Hubble constant from WFI J2033-4723
Magain, P.; Kochanek, C. S.; Meylan, G. +10 more
Gravitationally lensed quasars can be used to map the mass distribution in lensing galaxies and to estimate the Hubble constant H0 by measuring the time delays between the quasar images. Here we report the measurement of two independent time delays in the quadruply imaged quasar WFI J2033-4723 (z = 1.66). Our data consist of R-band imag…
Chandra observation of the edge-on spiral NGC 5775: probing the hot galactic disc/halo connection
Wang, Q. Daniel; Li, Zhiyuan; Li, Jiang-Tao +2 more
We study the edge-on galaxy NGC 5775, utilizing a 58.2 ks Chandra ACIS-S observation together with complementary Hubble Space Telescope (HST) ACS, Spitzer IRAC and other multi-wavelength data sets. This edge-on galaxy, with its disc-wide active star formation, is particularly well suited for studying the disc/halo interaction on subgalactic scales…
Comparison of Distances from RR Lyrae Stars, the Tip of the Red Giant Branch, and Classical Cepheids
Sandage, Allan; Tammann, G. A.; Reindl, B.
The extragalactic distance scale relies heavily on Cepheids. However, it has become clear from observations and pulsation models that the slope and zero point of their P-L relations differ from galaxy to galaxy. This makes the determination of Cepheid distances complex and calls for an independent test of their differences. The test is provided by…
Plasma Flows Guided by Strong Magnetic Fields in the Solar Corona
Tian, Hui; Marsch, Eckart; Sun, Jian +2 more
In this study new results are presented regarding the relationships between the coronal magnetic field and the intensities and Doppler shifts of ultraviolet emission lines. This combination of magnetic field and spectroscopic data is used here to study material flows in association with the coronal field. We introduce the term "coronal circulation…