4,006 research outputs found
Distributions and Relations: A Hybrid Account
There is a deep divide amongst political philosophers of an egalitarian stripe. On the one hand, there are so-called distributive egalitarians, who hold that equality obtains within a political community when each of its members enjoys an equal share of the community’s resources. On the other hand, there are so-called social egalitarians, who instead hold that equality obtains within a political community when each of its members stands in certain relations to other members of the community, such non-domination and lack of oppression, for example. In this paper, we have three aims. Our first aim is to cast doubt on the helpfulness of characterizing the debate in this way. Our second aim is to reconstruct this debate in alternative and more precise terms, so that disagreements between advocates of either side are easier to evaluate. Our third aim is to advance a hybrid account that integrates element from both views
Extracting H flux from photometric data in the J-PLUS survey
We present the main steps that will be taken to extract H emission
flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric
data. For galaxies with , the H+[NII] emission is
covered by the J-PLUS narrow-band filter . We explore three different
methods to extract the H + [NII] flux from J-PLUS photometric data: a
combination of a broad-band and a narrow-band filter ( and ), two
broad-band and a narrow-band one (, and ), and a SED-fitting
based method using 8 photometric points. To test these methodologies, we
simulated J-PLUS data from a sample of 7511 SDSS spectra with measured
H flux. Based on the same sample, we derive two empirical relations to
correct the derived H+[NII] flux from dust extinction and [NII]
contamination. We find that the only unbiased method is the SED fitting based
one. The combination of two filters underestimates the measurements of the
H + [NII] flux by a 28%, while the three filters method by a 9%. We
study the error budget of the SED-fitting based method and find that, in
addition to the photometric error, our measurements have a systematic
uncertainty of a 4.3%. Several sources contribute to this uncertainty:
differences between our measurement procedure and the one used to derive the
spectroscopic values, the use of simple stellar populations as templates, and
the intrinsic errors of the spectra, which were not taken into account. Apart
from that, the empirical corrections for dust extinction and [NII]
contamination add an extra uncertainty of 14%. Given the J-PLUS photometric
system, the best methodology to extract H + [NII] flux is the
SED-fitting based one. Using this method, we are able to recover reliable
H fluxes for thousands of nearby galaxies in a robust and homogeneous
way.Comment: 11 pages, 14 figures. Minor changes to match the published versio
Star Forming Objects in the Tidal Tails of Compact Groups
A search for star forming objects belonging to tidal tails has been carried
out in a sample of deep Halpha images of 16 compact groups of galaxies. A total
of 36 objects with Halpha luminosity larger than 10^38 erg s-1 have been
detected in five groups. The fraction of the total Halpha luminosity of their
respective parent galaxies shown by the tidal objects is always below 5% except
for the tidal features of HCG95, whose Halpha luminosity amounts to 65% of the
total luminosity. Out of this 36 objects, 9 star forming tidal dwarf galaxy
candidates have been finally identified on the basis of their projected
distances to the nuclei of the parent galaxies and their total Halpha
luminosities. Overall, the observed properties of the candidates resemble those
previously reported for the so-called tidal dwarf galaxies.Comment: 5 gif figures. Accepted for publication in Astrophysical Journa
Quasars Clustering at z approx 3 on Scales less sim 10 h^{-1} Mpc
We test the hypothesis whether high redshift QSOs would preferentially appear
in small groups or pairs, and if they are associated with massive, young
clusters. We carried out a photometric search for \Ly emitters on scales
Mpc, in the fields of a sample of 47 known
QSOs. Wide and narrow band filter color-magnitude diagrams were generated for
each of the fields. A total of 13 non resolved objects with a
significant color excess were detected as QSO candidates at a redshift similar
to that of the target. All the candidates are significantly fainter than the
reference QSOs, with only 2 of them within 2 magnitudes of the central object.
Follow-up spectroscopic observations have shown that 5, i.e., about 40% of the
candidates, are QSOs at the same redshift of the target; 4 are QSOs at
different z (two of them probably being a lensed pair at z = 1.47); 2
candidates are unresolved HII galaxies at z0.3; one unclassified and one
candidate turned out to be a CCD flaw. These data indicate that at least 10% of
the QSOs at z3 do have companions.
We have also detected a number of resolved, rather bright \Ly Emitter
Candidates. Most probably a large fraction of them might be bright galaxies
with [OII] emission, at z 0.3. The fainter population of our
candidates corresponds to the current expectations. Thus, there are no strong
indication for the existence of an overdensity of \Ly galaxies brighter than m
25 around QSOs at 3.Comment: 29 pages, 8 figures, tar gzip LaTex file, accepted to appear in Ap
Periodic very high energy γ -Ray Emission from LS I +61◦303 Observed with the magic telescope
The MAGIC collaboration has recently reported the discovery of γ -ray emission from the binary system
LS I +61◦303 in the TeV energy region. Here we present new observational results on this source in the energy range
between 300 GeV and 3 TeV. In total, 112 hr of data were taken between 2006 September and December covering
four orbital cycles of this object. This large amount of data allowed us to produce an integral flux light curve covering
for the first time all orbital phases of LS I +61◦303. In addition, we also obtained a differential energy spectrum for
two orbital phase bins covering the phase range 0.5 < φ < 0.6 and 0.6 < φ < 0.7. The photon index in the two
phase bins is consistent within the errors with an average index Γ = 2.6±0.2stat ±0.2sys. LS I +61◦303 was found
to be variable at TeV energies on timescales of days. These new MAGIC measurements allowed us to search for
intranight variability of the very high energy emission; however, no evidence for flux variability on timescales down
to 30 min was found. To test for possible periodic structures in the light curve, we apply the formalism developed
by Lomb and Scargle to the LS I +61◦303 data taken in 2005 and 2006. We found the LS I +61◦303 data set to be
periodic with a period of (26.8 ± 0.2) days (with a post-trial chance probability of 10−7), close to the orbital period.Peer reviewe
How Dry Are Red Mergers?
The focus of current research in galaxy evolution has increasingly turned to
understanding the effect that mergers have on the evolution of systems on the
red sequence. For those interactions purported to occur dissipationlessly (so
called "dry mergers"), it would appear that the role of gas is minimal.
However, if these mergers are not completely dry, then even low levels of gas
may be detectable. The purpose of our study is to test whether early type
galaxies with HI in or around them, or "wet" ellipticals, would have been
selected as dry mergers by the criteria in van Dokkum (2005, AJ, 130, 2647). To
that end, we examine a sample of 20 early types from the HI Rogues Gallery with
neutral hydrogen in their immediate environs. Of these, the 15 brightest and
reddest galaxies match the optical dry merger criteria, but in each case, the
presence of HI means that they are not truly dry.Comment: 8 pages plus 1 table and 5 figures; accepted for publication in A
“Sobre el valor nutritivo de la almendra de albaricoque (prunus armeniaca). – I. Sobre la toxicidad en la rata de la almendra de albaricoque”
Este trabajo es un resumen de parte de la Tesis Doctoral
Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53
The spectral characteristics throughout the dwarf irregular galaxy DDO 53 are
studied. The results are very similar to those for other irregular galaxies:
high excitation and low values of the [SII]/Halpha ratio. The most likely
ionization source is photon leakage from the classical HII regions, without any
other source, although the interstellar medium of the galaxy is quite
perturbed. Moreover, the physical conditions throughout the galaxy do not
change very much because both the photon leakage percentage and the ionization
temperature are very similar. In addition, the determined metal content for two
HII regions indicates that DDO 53 is a low-metallicity galaxy.Comment: 32 pages, 9 figures, 7 tables. AJ, in pres
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