European Southern Observatory

About: European Southern Observatory is a facility organization based out in Garching bei München, Germany. It is known for research contribution in the topics: Galaxy & Stars. The organization has 3594 authors who have published 16157 publications receiving 823095 citations. The organization is also known as: The European Southern Observatory，ESO & ESO.

The evolving relations between size, mass, surface density, and star formation in 3x10^4 galaxies since z=2

Abstract: The presence of massive, compact, quiescent galaxies at z>2 presents a major challenge for theoretical models of galaxy formation and evolution. Using one of the deepest large public near-IR surveys to date, we investigate in detail the correlations between star formation and galaxy structural parameters (size, stellar mass, and surface density) from z = 2 to the present. At all redshifts, massive quiescent galaxies (i.e., those with little or no star formation) occupy the extreme high end of the surface density distribution and follow a tight mass-size correlation, while star-forming galaxies show a broad range of both densities and sizes. Conversely, galaxies with the highest surface densities comprise a nearly homogeneous population with little or no ongoing star formation, while less dense galaxies exhibit high star formation rates and varying levels of dust obscuration. Both the sizes and surface densities of quiescent galaxies evolve strongly from z = 2-0; we parameterize this evolution for both populations with simple power-law functions and present best-fit parameters for comparison to future theoretical models. Higher-mass quiescent galaxies undergo faster structural evolution, consistent with previous results. Interestingly, star-forming galaxies' sizes and densities evolve at rates similar to those of quiescent galaxies. It is therefore possible that the same physical processes drive the structural evolution of both populations, suggesting that dry mergers may not be the sole culprit in this size evolution.

The extended Chandra deep field-south survey: Chandra point-source catalogs

Abstract: We present Chandra point‐source catalogs for the Extended Chandra Deep Field–South (E‐CDF‐S) survey. The E‐CDF‐S consists of four contiguous 250 ks Chandra observations covering an approximately square region of total solid angle ≈0.3 deg2, which flank the existing ≈1 Ms Chandra Deep Field–South (CDF‐S). The survey reaches sensitivity limits of ≈ and ≈ ergs cm−2 s−1 for the 0.5–2.0 and 2–8 keV bands, respectively. We detect 762 distinct X‐ray point sources within the E‐CDF‐S exposure; 589 of these sources are new (i.e., not previously detected in the ≈1 Ms CDF‐S). This brings the total number of X‐ray point sources detected in the E‐CDF‐S region to 915 (via the E‐CDF‐S and ≈1 Ms CDF‐S observations). Source positions are determined using matched‐filter and centroiding techniques; the median positional uncertainty is ≈035. The basic X‐ray and optical properties of these sources indicate a variety of source types, although absorbed active galactic nuclei (AGNs) seem to dominate. In addition to our main Chandra catalog, we constructed a supplementary source catalog containing 33 lower significance X‐ray point sources that have bright optical counterparts (R < 23). These sources generally have X‐ray–to–optical flux ratios expected for normal and starburst galaxies, which lack a strong AGN component. We present basic number‐count results for our main Chandra catalog and find good agreement with the ≈1 Ms CDF‐S for sources with 0.5–2.0 and 2–8 keV fluxes greater than and ergs cm−2 s−1, respectively. Furthermore, three extended sources are detected in the 0.5–2.0 keV band, which are found to be likely associated with galaxy groups or poor clusters at ; these have typical rest‐frame 0.5–2.0 keV luminosities of ergs s−1.

The fifteenth data release of the Sloan Digital Sky Surveys: First release of MaNGA-derived quantities, data visualization tools, and stellar library

Abstract: Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July–2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA—we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020–2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.

The star formation history of Seyfert 2 nuclei

Abstract: We present a study of the stellar populations in the central ∼200 pc of a large and homogeneous sample comprising 79 nearby galaxies, most of which are Seyfert 2s. The star formation history of these nuclei is reconstructed by means of state-of-the-art population synthesis modelling of their spectra in the 3500‐5200 A interval. A quasar-like featureless continuum (FC) is added to the models to account for possible scattered light from a hidden active galactic nucleus (AGN). We find the following. (1) The star formation history of Seyfert 2 nuclei is remarkably heterogeneous: young starbursts, intermediate-age and old stellar populations all appear in significant and widely varying proportions. (2) A significant fraction of the nuclei show a strong FC component, but this FC is not always an indication of a hidden AGN: it can also betray the presence of a young, dusty starburst. (3) We detect weak broad Hβ emission in several Seyfert 2s after cleaning the observed spectrum by subtracting the synthesis model. These are most likely the weak scattered lines from the hidden broad-line region envisaged in the unified model, given that in most of these cases independent spectropolarimetry data find a hidden Seyfert 1. (4) The FC strengths obtained by the spectral decomposition are substantially larger for the Seyfert 2s which present evidence of broad lines, implying that the scattered nonstellar continuum is also detected. (5) There is no correlation between the star formation in the nucleus and either the central or overall morphology of the parent galaxies. Ke yw ords: galaxies: active ‐ galaxies: Seyfert ‐ galaxies: statistics ‐ galaxies: stellar content.