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The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
- 2022
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.
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| 2. |
- Chen, C. T.J., et al.
(författare)
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The XMM-SERVS survey : New XMM-Newton point-source catalogue for the XMM-LSS field
- 2018
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 478:2, s. 2132-2163
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Tidskriftsartikel (refereegranskat)abstract
- We present an X-ray point-source catalogue from the XMM-Large Scale Structure (XMMLSS) survey region, one of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields. We target the XMM-LSS region with 1.3 Ms of new XMM-Newton AO-15 observations, transforming the archival X-ray coverage in this region into a 5.3 deg2 contiguous field with uniform X-ray coverage totaling 2.7 Ms of flare-filtered exposure, with a 46 ks median PN exposure time. We provide an X-ray catalogue of 5242 sources detected in the soft (0.5-2 keV), hard (2-10 keV), and/or full (0.5-10 keV) bands with a 1 per cent expected spurious fraction determined from simulations. A total of 2381 new X-ray sources are detected compared to previous source catalogues in the same area. Our survey has flux limits of 1.7 × 10-15, 1.3 × 10-14, and 6.5 × 10-15 erg cm-2 s-1 over 90 per cent of its area in the soft, hard, and full bands, respectively, which is comparable to those of the XMM-COSMOS survey. We identify multiwavelength counterpart candidates for 99.9 per cent of the X-ray sources, of which 93 per cent are considered as reliable based on their matching likelihood ratios. The reliabilities of these high-likelihood-ratio counterparts are further confirmed to be ≈97 per cent reliable based on deep Chandra coverage over ≈5 per cent of the XMM-LSS region. Results of multiwavelength identifications are also included in the source catalogue, along with basic optical-to-infrared photometry and spectroscopic redshifts from publicly available surveys. We compute photometric redshifts for X-ray sources in 4.5 deg2 of our field where forced-aperture multiband photometry is available; > 70 per cent of the X-ray sources in this subfield have either spectroscopic or high-quality photometric redshifts.
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| 3. |
- Vito, F., et al.
(författare)
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The deepest X-ray view of high-redshift galaxies : Constraints on low-rate black hole accretion
- 2016
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 463:1, s. 348-374
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Tidskriftsartikel (refereegranskat)abstract
- We exploit the 7 Ms Chandra observations in the Chandra Deep Field-South (CDF-S), the deepest X-ray survey to date, coupled with CANDELS/GOODS-S data, to measure the total X-ray emission arising from 2076 galaxies at 3.5 ≤ z < 6.5. This aim is achieved by stacking the Chandra data at the positions of optically selected galaxies, reaching effective exposure times of ≥109s.We detect significant (>3.7s) X-ray emission from massive galaxies at z ≈ 4. We also report the detection of massive galaxies at z ≈ 5 at a 99.7 per cent confidence level (2.7σ), the highest significance ever obtained for X-ray emission from galaxies at such high redshifts. No significant signal is detected from galaxies at even higher redshifts. The stacking results place constraints on theBHADassociated with the known high-redshift galaxy samples, as well as on the SFRD at high redshift, assuming a range of prescriptions for X-ray emission due to X- ray binaries.We find that the X-ray emission from our sample is likely dominated by processes related to star formation. Our results show that low-rate mass accretion on to SMBHs in individually X-ray-undetected galaxies is negligible, compared with the BHAD measured for samples of X-ray detected AGN, for cosmic SMBH mass assembly at high redshift. We also place, for the first time, constraints on the faint-end of the AGN X-ray luminosity function (logLX ~ 42) at z > 4, with evidence for fairly flat slopes. The implications of all of these findings are discussed in the context of the evolution of the AGN population at high redshift.
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| 4. |
- Dimitrievska, Mirjana, et al.
(författare)
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Structural and Dynamical Properties of Potassium Dodecahydro-monocarba-closo-dodecaborate: KCB11H12
- 2020
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:33, s. 17992-18002
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Tidskriftsartikel (refereegranskat)abstract
- MCB11H12 (M: Li, Na) dodecahydro-monocarba-closo-dodecaborate salt compounds are known to have stellar superionic Li+ and Na+ conductivities in their high-temperature disordered phases, making them potentially appealing electrolytes in all-solid-state batteries. Nonetheless, it is of keen interest to search for other related materials with similar conductivities while at the same time exhibiting even lower (more device-relevant) disordering temperatures, a key challenge for this class of materials. With this in mind, the unknown structural and dynamical properties of the heavier KCB11H12 congener were investigated in detail by X-ray powder diffraction, differential scanning calorimetry, neutron vibrational spectroscopy, nuclear magnetic resonance, quasielastic neutron scattering, and AC impedance measurements. This salt indeed undergoes an entropy-driven, reversible, order-disorder transformation and with a lower onset temperature (348 K upon heating and 340 K upon cooling) in comparison to the lighter LiCB11H12 and NaCB11H12 analogues. The K+ cations in both the low-T ordered monoclinic (P2(1)/c) and high-T disordered cubic (Fm (3) over barm) structures occupy octahedral interstices formed by CB11H12- anions. In the low-T structure, the anions orient themselves so as to avoid close proximity between their highly electropositive C-H vertices and the neighboring K+ cations. In the high-T structure, the anions are orientationally disordered, although to best avoid the K+ cations, the anions likely orient themselves so that their C-H axes are aligned in one of eight possible directions along the body diagonals of the cubic unit cell. Across the transition, anion reorientational jump rates change from 6.2 x 10(6) s(-1) in the low-T phase (332 K) to 2.6 x 10(10) s(-1) in the high-T phase (341 K). In tandem, K+ conductivity increases by about 30-fold across the transition, yielding a high-T phase value of 3.2 x 10(-4 )S cm(-1 )at 361 K. However, this is still about 1 to 2 orders of magnitude lower than that observed for LiCB(11)H(12 )and NaCB11H12, suggesting that the relatively larger K+ cation is much more sterically hindered than Li+ and Na+ from diffusing through the anion lattice via the network of smaller interstitial sites.
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| 6. |
- Grinderslev, Jakob B., et al.
(författare)
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Neutron Scattering Investigations of the Global and Local Structures of Ammine Yttrium Borohydrides
- 2021
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:28, s. 15415-15423
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Tidskriftsartikel (refereegranskat)abstract
- Complex metal hydrides are a fascinating and continuously expanding class of materials with many properties relevant for solid-state hydrogen and ammonia storage and solid-state electrolytes. The crystal structures are often investigated using powder X-ray diffraction (PXD), which can be ambiguous. Here, we revisit the crystal structure of Y(11BD4)3·3ND3 with the use of neutron diffraction, which, in comparison to previous PXD studies, provides accurate information about the D positions in the compound. Upon cooling to 10 K, the compound underwent a polymorphic transition, and a new monoclinic low-temperature polymorph denoted as α-Y(11BD4)3·3ND3 was discovered. Furthermore, the series of Y(11BH4)3·xNH3 (x = 0, 3, and 7) were also investigated with inelastic neutron scattering and infrared spectroscopy techniques, which provided information of the local coordination environment of the 11BH4- and NH3 groups and unique insights into the hydrogen dynamics. Partial deuteration using ND3 in Y(11BH4)3·xND3 (x = 3 and 7) allowed for an unambiguous assignment of the vibrational bands corresponding to the NH3 and 11BH4- in Y(11BH4)3·xNH3, due to the much larger neutron scattering cross section of H compared to D. The vibrational spectra of Y(11BH4)3·xNH3 could roughly be divided into three regions: (i) below 55 meV, containing mainly 11BH4- librational motions, (ii) 55-130 meV, containing mainly NH3 librational motions, and (iii) above 130 meV, containing 11B-H and N-H bending and stretching motions.
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