541 research outputs found

    Extracting Hα\alpha flux from photometric data in the J-PLUS survey

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    We present the main steps that will be taken to extract Hα\alpha emission flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric data. For galaxies with z0.015z\lesssim0.015, the Hα\alpha+[NII] emission is covered by the J-PLUS narrow-band filter F660F660. We explore three different methods to extract the Hα\alpha + [NII] flux from J-PLUS photometric data: a combination of a broad-band and a narrow-band filter (rr' and F660F660), two broad-band and a narrow-band one (rr', ii' and F660F660), and a SED-fitting based method using 8 photometric points. To test these methodologies, we simulated J-PLUS data from a sample of 7511 SDSS spectra with measured Hα\alpha flux. Based on the same sample, we derive two empirical relations to correct the derived Hα\alpha+[NII] flux from dust extinction and [NII] contamination. We find that the only unbiased method is the SED fitting based one. The combination of two filters underestimates the measurements of the Hα\alpha + [NII] flux by a 28%, while the three filters method by a 9%. We study the error budget of the SED-fitting based method and find that, in addition to the photometric error, our measurements have a systematic uncertainty of a 4.3%. Several sources contribute to this uncertainty: differences between our measurement procedure and the one used to derive the spectroscopic values, the use of simple stellar populations as templates, and the intrinsic errors of the spectra, which were not taken into account. Apart from that, the empirical corrections for dust extinction and [NII] contamination add an extra uncertainty of 14%. Given the J-PLUS photometric system, the best methodology to extract Hα\alpha + [NII] flux is the SED-fitting based one. Using this method, we are able to recover reliable Hα\alpha fluxes for thousands of nearby galaxies in a robust and homogeneous way.Comment: 11 pages, 14 figures. Minor changes to match the published versio

    Dynamic Infrared Thermography of Nanoheaters Embedded in Skin-Equivalent Phantoms

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    Nanoheaters are promising tools for localized photothermal therapy (PTT) of malignant cells. The anisotropic AuNPs present tunable surface plasmon resonances (SPR) with ideal NIR optical response to be applied as theranostic agents. To this purpose, nanoparticles with branches are suitable because of the electromagnetic field concentrated at their vertices. We standardized a protocol to synthesize multibranched gold nanoparticles (MB-AuNPs) by the seed-growth method and found a size-seed dependence tunability on the hierarchy of branching. Once the optical response is evaluated, we tested the temporal stability as nanoheaters of the MB-AuNPs immersed in skin-equivalent phantoms by dynamic infrared thermography (DIRT). The most suited sample presents a concentration of 5.2×108 MB-AuNPs/mL showing good thermal stability with ΔT = 4.5°C, during 3 cycles of 10 min at 785 nm laser irradiation with power of 0.15 W. According to these results, the MB-AuNPs are suitable nanoheaters to be tested for PTT in more complex models

    The ALHAMBRA survey: Accurate merger fractions by PDF analysis of photometric close pairs

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    Our goal is to develop and test a novel methodology to compute accurate close pair fractions with photometric redshifts. We improve the current methodologies to estimate the merger fraction f_m from photometric redshifts by (i) using the full probability distribution functions (PDFs) of the sources in redshift space, (ii) including the variation in the luminosity of the sources with z in both the selection of the samples and in the luminosity ratio constrain, and (iii) splitting individual PDFs into red and blue spectral templates to deal robustly with colour selections. We test the performance of our new methodology with the PDFs provided by the ALHAMBRA photometric survey. The merger fractions and rates from the ALHAMBRA survey are in excellent agreement with those from spectroscopic work, both for the general population and for red and blue galaxies. With the merger rate of bright (M_B <= -20 - 1.1z) galaxies evolving as (1+z)^n, the power-law index n is larger for blue galaxies (n = 2.7 +- 0.5) than for red galaxies (n = 1.3 +- 0.4), confirming previous results. Integrating the merger rate over cosmic time, we find that the average number of mergers per galaxy since z = 1 is N_m = 0.57 +- 0.05 for red galaxies and N_m = 0.26 +- 0.02 for blue galaxies. Our new methodology exploits statistically all the available information provided by photometric redshift codes and provides accurate measurements of the merger fraction by close pairs only using photometric redshifts. Current and future photometric surveys will benefit of this new methodology.Comment: Submitted to A&A, 15 pages, 15 figures, 6 tables. Comments are welcome. Close pair systems available at https://cloud.iaa.csic.es/alhambra/catalogues/ClosePairs

    The ALHAMBRA survey : Estimation of the clustering signal encoded in the cosmic variance

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    The relative cosmic variance (σv\sigma_v) is a fundamental source of uncertainty in pencil-beam surveys and, as a particular case of count-in-cell statistics, can be used to estimate the bias between galaxies and their underlying dark-matter distribution. Our goal is to test the significance of the clustering information encoded in the σv\sigma_v measured in the ALHAMBRA survey. We measure the cosmic variance of several galaxy populations selected with BB-band luminosity at 0.35z<1.050.35 \leq z < 1.05 as the intrinsic dispersion in the number density distribution derived from the 48 ALHAMBRA subfields. We compare the observational σv\sigma_v with the cosmic variance of the dark matter expected from the theory, σv,dm\sigma_{v,{\rm dm}}. This provides an estimation of the galaxy bias bb. The galaxy bias from the cosmic variance is in excellent agreement with the bias estimated by two-point correlation function analysis in ALHAMBRA. This holds for different redshift bins, for red and blue subsamples, and for several BB-band luminosity selections. We find that bb increases with the BB-band luminosity and the redshift, as expected from previous work. Moreover, red galaxies have a larger bias than blue galaxies, with a relative bias of brel=1.4±0.2b_{\rm rel} = 1.4 \pm 0.2. Our results demonstrate that the cosmic variance measured in ALHAMBRA is due to the clustering of galaxies and can be used to characterise the σv\sigma_v affecting pencil-beam surveys. In addition, it can also be used to estimate the galaxy bias bb from a method independent of correlation functions.Comment: Astronomy and Astrophysics, in press. 9 pages, 4 figures, 3 table

    The ALHAMBRA survey : BB-band luminosity function of quiescent and star-forming galaxies at 0.2z<10.2 \leq z < 1 by PDF analysis

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    Our goal is to study the evolution of the BB-band luminosity function (LF) since z=1z=1 using ALHAMBRA data. We used the photometric redshift and the II-band selection magnitude probability distribution functions (PDFs) of those ALHAMBRA galaxies with I24I\leq24 mag to compute the posterior LF. We statistically studied quiescent and star-forming galaxies using the template information encoded in the PDFs. The LF covariance matrix in redshift-magnitude-galaxy type space was computed, including the cosmic variance. That was estimated from the intrinsic dispersion of the LF measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the photometric redshift prior is also included in our analysis. We modelled the LF with a redshift-dependent Schechter function affected by the same selection effects than the data. The measured ALHAMBRA LF at 0.2z<10.2\leq z<1 and the evolving Schechter parameters both for quiescent and star-forming galaxies agree with previous results in the literature. The estimated redshift evolution of MBQzM_B^* \propto Qz is QSF=1.03±0.08Q_{\rm SF}=-1.03\pm0.08 and QQ=0.80±0.08Q_{\rm Q}=-0.80\pm0.08, and of logϕPz\log \phi^* \propto Pz is PSF=0.01±0.03P_{\rm SF}=-0.01\pm0.03 and PQ=0.41±0.05P_{\rm Q}=-0.41\pm0.05. The measured faint-end slopes are αSF=1.29±0.02\alpha_{\rm SF}=-1.29\pm0.02 and αQ=0.53±0.04\alpha_{\rm Q}=-0.53\pm0.04. We find a significant population of faint quiescent galaxies, modelled by a second Schechter function with slope β=1.31±0.11\beta=-1.31\pm0.11. We find a factor 2.55±0.142.55\pm0.14 decrease in the luminosity density jBj_B of star-forming galaxies, and a factor 1.25±0.161.25\pm0.16 increase in the jBj_B of quiescent ones since z=1z=1, confirming the continuous build-up of the quiescent population with cosmic time. The contribution of the faint quiescent population to jBj_B increases from 3% at z=1z=1 to 6% at z=0z=0. The developed methodology will be applied to future multi-filter surveys such as J-PAS.Comment: Accepted for publication in Astronomy and Astrophysics. 25 pages, 20 figures, 7 table

    Tetrahydropyrazolo[1,5-a]Pyrimidine-3-Carboxamide and N-Benzyl-6′,7′-Dihydrospiro[Piperidine-4,4′-Thieno[3,2-c]Pyran] analogues with bactericidal efficacy against Mycobacterium tuberculosis targeting MmpL3

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    Mycobacterium tuberculosis is a major human pathogen and the causative agent for the pulmonary disease, tuberculosis (TB). Current treatment programs to combat TB are under threat due to the emergence of multi-drug and extensively-drug resistant TB. As part of our efforts towards the discovery of new anti-tubercular leads, a number of potent tetrahydropyrazolo[1,5-a]pyrimidine-3-ca​rboxamide(THPP) and N-benzyl-6′,7′-dihydrospiro[piperidine-4,​4′-thieno[3,2-c]pyran](Spiro) analogues were recently identified against Mycobacterium tuberculosis and Mycobacterium bovis BCG through a high-throughput whole-cell screening campaign. Herein, we describe the attractive in vitro and in vivo anti-tubercular profiles of both lead series. The generation of M. tuberculosis spontaneous mutants and subsequent whole genome sequencing of several resistant mutants identified single mutations in the essential mmpL3 gene. This ‘genetic phenotype’ was further confirmed by a ‘chemical phenotype’, whereby M. bovis BCG treated with both the THPP and Spiro series resulted in the accumulation of trehalose monomycolate. In vivo efficacy evaluation of two optimized THPP and Spiro leads showed how the compounds were able to reduce >2 logs bacterial cfu counts in the lungs of infected mice

    An accurate cluster selection function for the J-PAS narrow-band wide-field survey

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    The impending Javalambre Physics of the accelerating Universe Astrophysical Survey (J-PAS) will be the first wide-field survey of ≳ 8500 deg^2 to reach the ‘stage IV’ category. Because of the redshift resolution afforded by 54 narrow-band filters, J-PAS is particularly suitable for cluster detection in the range z80 per cent completeness and purity is M_h ∼ 5 × 10^(13) M_⊙ up to z ∼ 0.7. We also model the optical observable, M^∗_(CL)–halo mass relation, finding a non-evolution with redshift and main scatter of σM^∗_(CL)|M_h∼0.14dex down to a factor 2 lower in mass than other planned broad-band stage IV surveys, at least. For the M_h ∼ 1 × 10^(14) M_⊙ Planck mass limit, J-PAS will arrive up to z ∼ 0.85 with a σM^∗_(CL)|M_h∼0.12dex. Therefore, J-PAS will provide the largest sample of clusters and groups up to z ∼ 0.8 with a mass calibration accuracy comparable to X-ray data

    The miniJPAS survey: Optical detection of galaxy clusters with PZWav

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    Galaxy clusters are an essential tool to understand and constrain the cosmological parameters of our Universe. Thanks to its multi-band design, J-PAS offers a unique group and cluster detection window using precise photometric redshifts and sufficient depths. We produce galaxy cluster catalogues from the miniJPAS, which is a pathfinder survey for the wider J-PAS survey, using the PZWav algorithm. Relying only on photometric information, we provide optical mass tracers for the identified clusters, including richness, optical luminosity, and stellar mass. By reanalysing the Chandra mosaic of the AEGIS field, alongside the overlapping XMM-Newton observations, we produce an X-ray catalogue. The analysis reveals the possible presence of structures with masses of 4×1013\times 10^{13} M_\odot at redshift 0.75, highlighting the depth of the survey. Comparing results with those from two other cluster catalogues, provided by AMICO and VT, we find 4343 common clusters with cluster centre offsets of 100±\pm60 kpc and redshift differences below 0.001. We provide a comparison of the cluster catalogues with a catalogue of massive galaxies and report on the significance of cluster selection. In general, we are able to recover approximately 75%\% of the galaxies with M>M^{\star} >2×1011\times 10^{11} M_\odot. This study emphasises the potential of the J-PAS survey and the employed techniques down to the group scales.Comment: 15 pages, 11 figures, 5 tables. Submitted to A&A in December 19, 202

    The intrinsic shape of galaxy bulges

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    The knowledge of the intrinsic three-dimensional (3D) structure of galaxy components provides crucial information about the physical processes driving their formation and evolution. In this paper I discuss the main developments and results in the quest to better understand the 3D shape of galaxy bulges. I start by establishing the basic geometrical description of the problem. Our understanding of the intrinsic shape of elliptical galaxies and galaxy discs is then presented in a historical context, in order to place the role that the 3D structure of bulges play in the broader picture of galaxy evolution. Our current view on the 3D shape of the Milky Way bulge and future prospects in the field are also depicted.Comment: Invited Review to appear in "Galactic Bulges" Editors: Laurikainen E., Peletier R., Gadotti D. Springer Publishing. 24 pages, 7 figure

    The mini-JPAS: A study of the wavelength dependence of the photon response nonuniformity of the JPAS-pathfinder camera

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    Understanding the origins of small-scale flats of CCDs and their wavelength-dependent variations plays an important role in high-precision photometric, astrometric, and shape measurements of astronomical objects. Based on the unique flat data of 47 narrowband filters provided by JPAS-Pathfinder, we analyze the variations of small-scale flats as a function of wavelength. We find moderate variations (from about 1.0% at 390 nm to 0.3% at 890 nm) of small-scale flats among different filters, increasing toward shorter wavelengths. Small-scale flats of two filters close in central wavelengths are strongly correlated. We then use a simple physical model to reproduce the observed variations to a precision of about ±0.14% by considering the variations of charge collection efficiencies, effective areas, and thicknesses between CCD pixels. We find that the wavelength-dependent variations of the small-scale flats of the JPAS-Pathfinder camera originate from inhomogeneities of the quantum efficiency (particularly charge collection efficiency), as well as the effective area and thickness of CCD pixels. The former dominates the variations in short wavelengths, while the latter two dominate at longer wavelengths. The effects on proper flat-fielding, as well as on photometric/flux calibrations for photometric/slitless spectroscopic surveys, are discussed, particularly in blue filters/wavelengths. We also find that different model parameters are sensitive to flats of different wavelengths, depending on the relations between the electron absorption depth, photon absorption length, and CCD thickness. In order to model the wavelength-dependent variations of small-scale flats, a small number (around 10) of small-scale flats with well-selected wavelengths are sufficient to reconstruct small-scale flats in other wavelengths. © 2021. The American Astronomical Society. All rights reserved.he PRNU model adopted in this work was developed as part of Mr. Baocun Chen's undergraduate thesis work under the supervision of H.Z. This work is supported by the National Natural Science Foundation of China through projects NSFC 12173007 and 11603002, the National Key Basic R&D Program of China via 2019YFA0405503, and Beijing Normal University grant No. 310232102. We acknowledge the science research grants from the China Manned Space Project with Nos. CMS-CSST-2021-A08 and CMS-CSST2021-A09. Based on observations made with the JST/T250 telescope and JPCam at the Observatorio Astrofisico de Javalambre (OAJ) in Teruel, owned, managed, and operated by the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA). We acknowledge the OAJ Data Processing and Archiving Unit (UPAD) for reducing and calibrating the OAJ data used in this work. Funding for the JPAS Project has been provided by the Governments of Spain and Aragon through the Fondo de Inversion de Teruel, European FEDER funding, and the Spanish Ministry of Science, Innovation and Universities, as well as by the Brazilian agencies FINEP, FAPESP, and FAPERJ and the National Observatory of Brazil. Additional funding was also provided by the Tartu Observatory and the JPAS Chinese Astronomical Consortium. With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709
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