Search results for "GAL"
showing 10 items of 9260 documents
Euclid preparation : XX. The Complete Calibration of the Color–Redshift Relation survey : LBT observations and data release
2022
The Complete Calibration of the Color–Redshift Relation survey (C3R2) is a spectroscopic program designed to empirically calibrate the galaxy color–redshift relation to the Euclid depth (IE = 24.5), a key ingredient for the success of Stage IV dark energy projects based on weak lensing cosmology. A spectroscopic calibration sample that is as representative as possible of the galaxies in the Euclid weak lensing sample is being collected, selecting galaxies from a self-organizing map (SOM) representation of the galaxy color space. Here, we present the results of a near-infrared H- and K-band spectroscopic campaign carried out using the LUCI instruments at the LBT. For a total of 251 galaxies,…
Sinbiotiska produkta iegūšana, veicot no piena permeāta iegūta galaktooligosaharīdu (GOS) maisījuma selektīvu fermentāciju ar probiotiskiem celmiem
2022
Piena permeāts un tajā esošā laktoze kā substrāts var tikt izmantots ogļhidrātu biokonversijas pētījumos, kā arī dažādu mikroorganismu kultivēšanā, lai veidotu produktus ar pievienoto vērtību. Darba mērķis bija izvērtēt iespēju iegūt galaktooligosaharīdu (GOS) un pienskābo baktēriju saturošu sinbiotisku produktu, veicot selektīvu fermentāciju maisījumā, kas iegūts fermentatīvās GOS biosintēzes laikā no piena permeāta. Veicot fermentatīvu sintēzi ar ß-galaktozidāzēm, tika iegūts un aprakstīts GOS saturošs maisījums, kurā vēlāk tika veikta selektīva fermentācija ar probiotiskajiem Lactobacillus spp. celmiem, izvērtējot šo celmu ogļhidrātu preferences un izdzīvotību. Veicot fermentatīvu sintēz…
Latviju apmeklējušo tūristu viedoklis un attieksme
2018
Bakalaura darba tēma “Latviju apmeklējušo tūristu viedoklis un attieksme.” Darba mērķis ir noskaidrot ārzemju tūristu viedokli un attieksmi par Latviju. Faktorus, kuru rezultātā ārzemju tūristi ir izvēlējušies Latviju kā galamērķi. Teorētiskajā daļā tiek apskatīts tūrisms un tā attīstības faktori, motivācijas aspekti tūrismā. Tāpat tiek apskatīta teorija par galamērķa izvēli un komunikācijas kanāliem. Teorijas pamats ļauj izprast tūrisma nozares darbību, aplūkojot tās pozitīvās un negatīvās puses. Lai nostiprinātu teoriju un papildinātu darbu pētījuma daļā, tiek veikta strukturētā intervija, kas ļauj noskaidrot tūrisma nozares speciālistu viedokli. Bakalaura darbs ir uzrakstīts latviešu val…
Tūrista uzvedības izvērtējums un ietekmējamība elektroniskajos resursos: Siguldas novada piemērs
2016
Pētījuma mērķis ir izpētīt tūrista uzvedību, motivāciju un ietekmējamību, izvēloties Siguldas novadu kā ceļojuma galamērķi un kā informācijas avotu izmantojot elektroniskos resursus. Globalizācija, pasaules iedzīvotāju pieaugums un dzīvesveida attīstība aizvien palielina tūrisma nozares apjomus, savukārt cilvēka izziņas un uzvedības pētījumi, kas veikti, izmantojot globālo tīmekli, var dot lielu ieguldījumu tūrisma attīstībā un plānošanā. Pētījumā konstatēts, ka cilvēki savus ceļojumu plānošanas paradumus pārsvarā balsta uz draugu un paziņu ieteikumiem un nopietni ņem vērā to sniegtos viedokļus. Drauga vai paziņas sociālās saziņas vietnē publicēts ceļojuma attēls vai attēlu galerija nereti …
High-energy monitoring of NGC 4593 II. Broad-band spectral analysis: testing the two-corona model
2019
It is widely believed that the primary X-ray emission of AGN is due to the Comptonisation of optical-UV photons from a hot electron corona, while the origin of the 'soft-excess' is still uncertain and matter of debate. A second Comptonisation component, called warm corona, was therefore proposed to account for the soft-excess, and found in agreement with the optical-UV to X-ray emission of a sample of Seyfert galaxies. In this context, we exploit the broadband XMM-Newton and NuSTAR simultaneous observations of the Seyfert galaxy NGC 4593 to further test the so called "two corona model". The NGC 4593 spectra are well reproduced by the model, from the optical/UV to the hard X-rays. Moreover, …
Testing warm Comptonization models for the origin of the soft X-ray excess in AGNs
2018
The X-ray spectra of many active galactic nuclei (AGN) show a soft X-ray excess below 1-2 keV on top of the extrapolated high- energy power law. The origin of this component is uncertain. It could be a signature of relativistically blurred, ionized reflection, or the high-energy tail of thermal Comptonization in a warm (kT $\sim$ 1 keV), optically thick ($\tau\simeq$ 10-20) corona producing the optical/UV to soft X-ray emission. The purpose of the present paper is to test the warm corona model on a statistically significant sample of unabsorbed, radio-quiet AGN with XMM-newton archival data, providing simultaneous optical/UV and X-ray coverage. The sample has 22 objects and 100 observations…
The XMM Cluster Outskirts Project (X-COP): Thermodynamic properties of the Intracluster Medium out to $R_{200}$ in Abell 2319
2018
We present the joint analysis of the X-ray and SZ signals in A2319, the galaxy cluster with the highest signal-to-noise ratio in Planck maps and that has been surveyed within our XMM Cluster Outskirts Project (X-COP). We recover the thermodynamical profiles by the geometrical deprojection of the X-ray surface brightness, of the SZ comptonization parameter, and an accurate and robust spectroscopic measurements of the temperature. We resolve the clumpiness of the density to be below 20 per cent demonstrating that most of this clumpiness originates from the ongoing merger and can be associated to large-scale inhomogeneities. This analysis is done in azimuthally averaged radial bins and in eigh…
Mass-Metallicity Relation from Cosmological Hydrodynamical Simulations and X-ray Observations of Galaxy Groups and Clusters
2018
Recent X-ray observations of galaxy clusters show that the distribution of intra-cluster medium (ICM) metallicity is remarkably uniform in space and time. In this paper, we analyse a large sample of simulated objects, from poor groups to rich clusters, to study the dependence of the metallicity and related quantities on the mass of the systems. The simulations are performed with an improved version of the Smoothed-Particle-Hydrodynamics \texttt{GADGET-3} code and consider various astrophysical processes including radiative cooling, metal enrichment and feedback from stars and active galactic nuclei (AGN). The scaling between the metallicity and the temperature obtained in the simulations ag…
The origin of ICM enrichment in the outskirts of present-day galaxy clusters from cosmological hydrodynamical simulations
2018
The uniformity of the intra-cluster medium (ICM) enrichment level in the outskirts of nearby galaxy clusters suggests that chemical elements were deposited and widely spread into the intergalactic medium before the cluster formation. This observational evidence is supported by numerical findings from cosmological hydrodynamical simulations, as presented in Biffi et al. (2017), including the effect of thermal feedback from active galactic nuclei. Here, we further investigate this picture, by tracing back in time the spatial origin and metallicity evolution of the gas residing at z=0 in the outskirts of simulated galaxy clusters. In these regions, we find a large distribution of iron abundanc…
Cosmological hydrodynamical simulations of galaxy clusters: X-ray scaling relations and their evolution
2018
We analyse cosmological hydrodynamical simulations of galaxy clusters to study the X-ray scaling relations between total masses and observable quantities such as X-ray luminosity, gas mass, X-ray temperature, and $Y_{X}$. Three sets of simulations are performed with an improved version of the smoothed particle hydrodynamics GADGET-3 code. These consider the following: non-radiative gas, star formation and stellar feedback, and the addition of feedback by active galactic nuclei (AGN). We select clusters with $M_{500} > 10^{14} M_{\odot} E(z)^{-1}$, mimicking the typical selection of Sunyaev-Zeldovich samples. This permits to have a mass range large enough to enable robust fitting of the r…