| 1. |
- Abolfathi, Bela, et al.
(författare)
-
The Fourteenth Data Release of the Sloan Digital Sky Survey : First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
- 2018
-
Ingår i: Astrophysical Journal Supplement Series. - : IOP Publishing Ltd. - 0067-0049 .- 1538-4365. ; 235:2
-
Tidskriftsartikel (refereegranskat)abstract
- The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
|
|
| 2. |
- Dong, Chenze, et al.
(författare)
-
Observational Evidence for Large-scale Gas Heating in a Galaxy Protocluster at z = 2.30
- 2023
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 945:2
-
Tidskriftsartikel (refereegranskat)abstract
- We report a z = 2.30 galaxy protocluster (COSTCO-I) in the COSMOS field, where the Lyα forest as seen in the CLAMATO IGM tomography survey does not show significant absorption. This departs from the transmission–density relationship (often dubbed the fluctuating Gunn–Peterson approximation; FGPA) usually expected to hold at this epoch, which would lead one to predict strong Lyα absorption at the overdensity. For comparison, we generate mock Lyα forest maps by applying the FGPA to constrained simulations of the COSMOS density field and create mocks that incorporate the effects of finite sight-line sampling, pixel noise, and Wiener filtering. Averaged over r = 15 h−1 Mpc around the protocluster, the observed Lyα forest is consistently more transparent in the real data than in the mocks, indicating a rejection of the null hypothesis that the gas in COSTCO-I follows the FGPA (p = 0.0026, or 2.79σ significance). It suggests that the large-scale gas associated with COSTCO-I is being heated above the expectations of the FGPA, which might be due to either large-scale AGN jet feedback or early gravitational shock heating. COSTCO-I is the first known large-scale region of the IGM that is observed to be transitioning from the optically thin photoionized regime at cosmic noon to eventually coalesce into an intracluster medium (ICM) by z = 0. Future observations of similar structures will shed light on the growth of the ICM and allow constraints on AGN feedback mechanisms.
|
|
| 3. |
- Lee, Khee-Gan, et al.
(författare)
-
The FRB 20190520B Sight Line Intersects Foreground Galaxy Clusters
- 2023
-
Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 954:1
-
Tidskriftsartikel (refereegranskat)abstract
- The repeating fast radio burst FRB 20190520B is an anomaly of the FRB population thanks to its high dispersion measure (DM = 1205 pc cm(-3)) despite its low redshift of z(frb) = 0.241. This excess has been attributed to a large host contribution of DMhost approximate to 900 pc cm(-3), far larger than any other known FRB. In this paper, we describe spectroscopic observations of the FRB 20190520B field obtained as part of the FLIMFLAM survey, which yielded 701 galaxy redshifts in the field. We find multiple foreground galaxy groups and clusters, for which we then estimated halo masses by comparing their richness with numerical simulations. We discover two separate M-halo > 1014M(circle dot) galaxy clusters at z = 0.1867 and 0.2170 that are directly intersected by the FRB sight line within their characteristic halo radius r(200). Subtracting off their estimated DM contributions, as well that of the diffuse intergalactic medium, we estimate a host contribution of DMhost = 430(-220)(+ 140) or 280(-170)(+140) pc cm(-3) (observed frame), depending on whether we assume that the halo gas extends to r(200) or 2 x r(200). This significantly smaller DMhost-no longer the largest known value-is now consistent with H-alpha emission measures of the host galaxy without invoking unusually high gas temperatures. Combined with the observed FRB scattering timescale, we estimate the turbulent fluctuation and geometric amplification factor of the scattering layer to be (F) over tildeG approximate to 4.5-11(pc(2) km)(-1/3), suggesting that most of the gas is close to the FRB host. This result illustrates the importance of incorporating foreground data for FRB analyses both for understanding the nature of FRBs and to realize their potential as a cosmological probe.
|
|
| 4. |
-
The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
- 2022
-
Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
-
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.
|
|
| 5. |
- Vardanyan, Valeri, et al.
(författare)
-
Revisiting tests of Lorentz invariance with gamma-ray bursts : Effects of intrinsic lags
- 2023
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 108:12
-
Forskningsöversikt (refereegranskat)abstract
- Due to their cosmological distances high-energy astrophysical sources allow for unprecedented tests of fundamental physics. Gamma-ray bursts (GRBs) comprise among the most sensitive laboratories for exploring the violation of the central physics principle of Lorentz invariance (LIV), by exploiting the spectral time lag of arriving photons. It has been believed that GRB spectral lags are inherently related with their luminosities, and intrinsic source contributions, which remain poorly understood, could significantly impact the LIV results. Using a combined sample of 49 long and short GRBs observed by the Swift telescope, we perform a stacked spectral lag search for LIV effects. We set novel limits on LIV, including limits on quadratic effects, and systematically explore for the first time the impacts of the intrinsic GRB lag-luminosity relation. We find that source contributions can strongly impact resulting LIV tests, modifying their limits by up to a factor of a few. We discuss constraints coming from GRB 221009A.
|
|
| 6. |
- Västhagen, Maja, et al.
(författare)
-
Refugee parents’ experiences of coming to Sweden : A qualitative study
- 2022
-
Ingår i: International Journal of Intercultural Relations. - : Elsevier. - 0147-1767 .- 1873-7552. ; 91, s. 97-109
-
Tidskriftsartikel (refereegranskat)abstract
- Each year, millions of people worldwide are forced to leave their homes. Many of those affected are families. There are already a considerable number of initiatives designed to support refugees who are resettling in new countries and cultures. However, few are promotive interventions aiming to support parents and thereby their children through the extraordinary challenges they face. To develop a culturally adaptive intervention, more knowledge about how refugee parents from different countries perceive and handle these challenges is needed. This study explores refugee parents’ own perspectives on the obstacles, challenges and opportunities they faced during their first years in Sweden to guide the future development of promotive interventions for refugee parents. Interviews were conducted with Arabic, Kurdish, and Somali-speaking refugee parents (n = 28; 19 mothers, 9 fathers). The interviews were examined using content analysis. One overarching theme emerged; “The new language is the key for entering social networks and society, and for helping your child in a new country”. The new language was viewed as a key to integration, and to mastering parenthood in the new context. This theme consisted of four categories; “parents’ motivation and hope as driving forces,” “navigating among past and present culture and values”, “loneliness as a risk factor” and “a new way of being a parent and relating to an acculturation gap”. These findings may help guide the development of parenting interventions for refugees, to promote integration and well-being among parents and their children.
|
|
