51 research outputs found
Photometric Selection of Unobscured QSOs in the Ecliptic Poles: KMTNet in the South Field and Pan-STARRS in the North Field
We search for quasi-stellar objects (QSOs) in a wide area of the south
ecliptic pole (SEP) field, which has been and will continue to be intensively
explored through various space missions. For this purpose, we obtain deep
broadband optical images of the SEP field covering an area of
deg with the Korea Microlensing Telescope Network.
The 5 detection limits for point sources in the bands are
estimated to be 22.59, 22.60, 22.98, and 21.85 mag, respectively.
Utilizing data from Wide-field Infrared Survey Explorer, unobscured QSO
candidates are selected among the optically point-like sources using the
mid-infrared (MIR) and optical-MIR colors. To further refine our selection and
eliminate any contamination not adequately removed by the color-based
selection, we perform the spectral energy distribution fitting with archival
photometric data ranging from optical to MIR. As a result, we identify a total
of 2,383 unobscured QSO candidates in the SEP field. We also apply a similar
method to the north ecliptic pole field using the Pan-STARRS data and obtain a
similar result of identifying 2,427 candidates. The differential number count
per area of our QSO candidates is in good agreement with those measured from
spectroscopically confirmed ones in other fields. Finally, we compare the
results with the literature and discuss how this work will be implicated in
future studies, especially with the upcoming space missions.Comment: 14 pages, 9 figures, accepted for publication in ApJ
Search for the Sagittarius Tidal Stream of Axion Dark Matter around 4.55 eV
We report the first search for the Sagittarius tidal stream of axion dark
matter around 4.55 eV using CAPP-12TB haloscope data acquired in March of
2022. Our result excluded the Sagittarius tidal stream of
Dine-Fischler-Srednicki-Zhitnitskii and Kim-Shifman-Vainshtein-Zakharov axion
dark matter densities of and GeV/cm,
respectively, over a mass range from 4.51 to 4.59 eV at a 90% confidence
level.Comment: 6 pages, 7 Figures, PRD Letter accepte
Extensive search for axion dark matter over 1\,GHz with CAPP's Main Axion eXperiment
We report an extensive high-sensitivity search for axion dark matter above
1\,GHz at the Center for Axion and Precision Physics Research (CAPP). The
cavity resonant search, exploiting the coupling between axions and photons,
explored the frequency (mass) range of 1.025\,GHz (4.24\,eV) to 1.185\,GHz
(4.91\,eV). We have introduced a number of innovations in this field,
demonstrating the practical approach of optimizing all the relevant parameters
of axion haloscopes, extending presently available technology. The CAPP 12\,T
magnet with an aperture of 320\,mm made of NbSn and NbTi superconductors
surrounding a 37-liter ultralight-weight copper cavity is expected to convert
DFSZ axions into approximately microwave photons per second. A powerful
dilution refrigerator, capable of keeping the core system below 40\,mK,
combined with quantum-noise limited readout electronics, achieved a total
system noise of about 200\,mK or below, which corresponds to a background of
roughly photons per second within the axion bandwidth. The
combination of all those improvements provides unprecedented search
performance, imposing the most stringent exclusion limits on axion--photon
coupling in this frequency range to date. These results also suggest an
experimental capability suitable for highly-sensitive searches for axion dark
matter above 1\,GHz.Comment: A detailed axion dark matter article with 27 pages, 22 figure
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