4,195 research outputs found
Cavityless self-organization of ultracold atoms due to the feedback-induced phase transition
Feedback is a general idea of modifying system behaviour depending on the
measurement outcomes. It spreads from natural sciences, engineering, and
artificial intelligence to contemporary classical and rock music. Recently,
feedback has been suggested as a tool to induce phase transitions beyond the
dissipative ones and tune their universality class. Here, we propose and
theoretically investigate a system possessing such a feedback-induced phase
transition. The system contains a Bose-Einstein condensate placed in an optical
potential with the depth that is feedback-controlled according to the intensity
of the Bragg-reflected probe light. We show that there is a critical value of
the feedback gain where the uniform gas distribution loses its stability and
the ordered periodic density distribution emerges. Due to the external
feedback, the presence of a cavity is not necessary for this type of atomic
self-organization. We analyze the dynamics after a sudden change of the
feedback control parameter. The feedback time constant is shown to determine
the relaxation above the critical point. We show as well that the control
algorithm with the derivative of the measured signal dramatically decreases the
transient time
The miniJPAS survey: Identification and characterization of the emission line galaxies down to in the AEGIS field
The Javalambre-Physics of the Accelerating Universe Astrophysical Survey
(J-PAS) is expected to map thousands of square degrees of the northern sky with
56 narrowband filters in the upcoming years. This will make J-PAS a very
competitive and unbiased emission line survey compared to spectroscopic or
narrowband surveys with fewer filters. The miniJPAS survey covered 1 deg,
and it used the same photometric system as J-PAS, but the observations were
carried out with the pathfinder J-PAS camera. In this work, we identify and
characterize the sample of emission line galaxies (ELGs) from miniJPAS with a
redshift lower than . Using a method based on artificial neural networks,
we detect the ELG population and measure the equivalent width and flux of the
, , [OIII], and [NII] emission lines. We explore the
ionization mechanism using the diagrams [OIII]/H versus [NII]/H
(BPT) and EW(H) versus [NII]/H (WHAN). We identify 1787 ELGs
(%) from the parent sample (2154 galaxies) in the AEGIS field. For the
galaxies with reliable EW values that can be placed in the WHAN diagram (2000
galaxies in total), we obtained that %, % , and
% are star-forming (SF), active galactic nucleus (Seyfert), and
quiescent galaxies, respectively. Based on the flux of we find that
the star formation main sequence is described as SFR and has an intrinsic scatter of . The cosmic evolution of the SFR density ()
is derived at three redshift bins: , , and
, which agrees with previous results that were based on
measurements of the emission line.Comment: 22 pages, 19 figure
The miniJPAS survey: clusters and galaxy groups detection with AMICO
Samples of galaxy clusters allow us to better understand the physics at play
in galaxy formation and to constrain cosmological models once their mass,
position (for clustering studies) and redshift are known. In this context,
large optical data sets play a crucial role. We investigate the capabilities of
the Javalambre-Physics of the Accelerating Universe Astrophysical Survey
(J-PAS) in detecting and characterizing galaxy groups and clusters. We analyze
the data of the miniJPAS survey, obtained with the JPAS-Pathfinder camera and
covering deg centered on the AEGIS field to the same depths and with
the same 54 narrow band plus 2 broader band near-UV and near-IR filters
anticipated for the full J-PAS survey. We use the Adaptive Matched Identifier
of Clustered Objects (AMICO) to detect and characterize groups and clusters of
galaxies down to in the redshift range . We detect 80, 30
and 11 systems with signal-to-noise ratio larger than 2.5, 3.0 and 3.5,
respectively, down to . We derive mass-proxy scaling
relations based on Chandra and XMM-Newton X-ray data for the signal amplitude
returned by AMICO, the intrinsic richness and a new proxy that incorporates the
galaxies' stellar masses. The latter proxy is made possible thanks to the J-PAS
filters and shows a smaller scatter with respect to the richness. We fully
characterize the sample and use AMICO to derive a probabilistic membership
association of galaxies to the detected groups that we test against
spectroscopy. We further show how the narrow band filters of J-PAS provide a
gain of up to 100% in signal-to-noise ratio in detection and an uncertainty on
the redshift of clusters of only placing J-PAS in
between broadband photometric and spectroscopic surveys. The performances of
AMICO and J-PAS with respect to mass sensitivity, mass-proxies qualityComment: 15 pages, 12 figures, 3 tables, submitted to A&
TOPz: Photometric redshifts for J-PAS
The importance of photometric galaxy redshift estimation is rapidly
increasing with the development of specialised powerful observational
facilities. We develop a new photometric redshift estimation workflow TOPz to
provide reliable and efficient redshift estimations for the upcoming
large-scale survey J-PAS which will observe 8500 deg2 of the northern sky
through 54 narrow-band filters. TOPz relies on template-based photo-z
estimation with some added J-PAS specific features and possibilities. We
present TOPz performance on data from the miniJPAS survey, a precursor to the
J-PAS survey with an identical filter system. First, we generated spectral
templates based on the miniJPAS sources using the synthetic galaxy spectrum
generation software CIGALE. Then we applied corrections to the input photometry
by minimising systematic offsets from the template flux in each filter. To
assess the accuracy of the redshift estimation, we used spectroscopic redshifts
from the DEEP2, DEEP3, and SDSS surveys, available for 1989 miniJPAS galaxies
with r < 22 magAB. We also tested how the choice and number of input templates,
photo-z priors, and photometric corrections affect the TOPz redshift accuracy.
The general performance of the combination of miniJPAS data and the TOPz
workflow fulfills the expectations for J-PAS redshift accuracy. Similarly to
previous estimates, we find that 38.6% of galaxies with r < 22 mag reach the
J-PAS redshift accuracy goal of dz/(1 + z) < 0.003. Limiting the number of
spectra in the template set improves the redshift accuracy up to 5%, especially
for fainter, noise-dominated sources. Further improvements will be possible
once the actual J-PAS data become available.Comment: 20 pages, 24 figure
Precise measurement of the W-boson mass with the CDF II detector
We have measured the W-boson mass MW using data corresponding to 2.2/fb of
integrated luminosity collected in proton-antiproton collisions at 1.96 TeV
with the CDF II detector at the Fermilab Tevatron collider. Samples consisting
of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement
MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most
precise measurement of the W-boson mass to date and significantly exceeds the
precision of all previous measurements combined
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