152 research outputs found
Probing the near infrared stellar population of Seyfert galaxies
We employ IRTF SpeX NIR (0.8-2.4 microns) spectra to investigate the stellar
population (SP), active galactic nuclei (AGN) featureless continuum (FC) and
hot dust properties in 9 Sy 1 and 15 Sy 2 galaxies. Both the starlight code and
the hot dust as an additional base element were used for the first time in this
spectral range. We found evidence of correlation among the equivalent widths
(W) Si I 1.59 microns x Mg I 1.58 microns, equally for both kinds of activity.
Part of the W{Na I 2.21 microns} and W {CO 2.3 microns} strengths may be
related to galaxy inclination. Our synthesis shows significant differences
between Sy 1 and Sy 2 galaxies: the hot dust component is required to fit the
K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2;
about 50 % of the Sy 2 galaxies require a component contribution >20%,
while this fraction increases to 60% in the Sy 1; also, in about 50 % of the
Sy2, the combined FC and young components contribute with more than 20%, while
this occurs in 90% of the Sy1, suggesting recent star formation in the central
region. The central few hundred parsecs of our galaxy sample contain a
substantial fraction of intermediate-age SPs with a mean metallicity near
solar. Our SP synthesis confirms that the 1.1 micron CN band can be used as a
tracer of intermediate-age SPs. The simultaneous fitting of SP, FC and hot dust
components increased in ~150% the number of AGNs with hot dust detected and the
mass estimated. The NIR emerges as an excellent window to study the stellar
population of Sy 1 galaxies, as opposed to the usually heavily attenuated
optical range. Our approach opens a new way to investigate and quantify the
individual contribution of the three most important NIR continuum components
observed in AGNs.Comment: The paper contains 14 figures and 5 tables. Accepted for publication
in MNRA
Sub-National Revenue Mobilization in Latin America and Caribbean Countries: The Case of Venezuela
A Political Economy Model of the Vertical Fiscal Gap and Vertical Fiscal Imbalances in a Federation
Barriers to Non-Formal Professional Training in Spain in Periods of Economic Growth and Crisis. An Analysis with Special Attention to the Effect of the Previous Human Capital of Workers
The Distribution of Skills Among the European Adult Population and Unemployment: A Comparative Approach
Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
We report the first measurement of charged particle elliptic flow in Pb-Pb
collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron
Collider. The measurement is performed in the central pseudorapidity region
(||<0.8) and transverse momentum range 0.2< < 5.0 GeV/. The
elliptic flow signal v, measured using the 4-particle correlation method,
averaged over transverse momentum and pseudorapidity is 0.087 0.002
(stat) 0.004 (syst) in the 40-50% centrality class. The differential
elliptic flow v reaches a maximum of 0.2 near = 3
GeV/. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow
increases by about 30%. Some hydrodynamic model predictions which include
viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/389
Tax Professionals' View of the Spanish Tax System: Efficiency, Equity and Tax Planning
Evaluating Landsat Thematic Mapper spectral indices for estimating burn severity of the 2007 Peloponnese wildfires in Greece
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