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Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-16T19:37:30Z No. of bitstreams: 1 GIVAL PORDEUS DA SILVA NETO – DISSERTAÇÃO (PPGFísica) 2015.pdf: 4886479 bytes, checksum: 8589cc7f91d5dab59210f3bf9b9a3d97 (MD5) / Made available in DSpace on 2018-10-16T19:37:30Z (GMT). No. of bitstreams: 1 GIVAL PORDEUS DA SILVA NETO – DISSERTAÇÃO (PPGFísica) 2015.pdf: 4886479 bytes, checksum: 8589cc7f91d5dab59210f3bf9b9a3d97 (MD5) Previous issue date: 2015-05-08 / Capes / A constante de Hubble (H0) é considerada fundamental na cosmologia. Ela é crucial para qualquer modelo cosmológico moderno, pois está relacionada com diversas grandezas cosmológicas, portanto, é de extrema importância a determinação mais restritiva e acurada possível do seu valor. A mais recente estimativa de H0 a partir de métodos locais (z 1), H0 = 73:8 2; 4 kms􀀀1Mpc􀀀1, e a partir de redshifts muito altos (z ' 1070), H0 = 67; 3 1; 2 kms􀀀1Mpc􀀀1, são discrepantes em um nível de con fiança de 2; 4 . Dentro deste contexto, Lima e Cunha (LC), a m de lançar alguma luz sobre este problema, derivou uma nova determinação de H0 utilizando quatro testes cosmológicos em redshifts intermediários (z 1), com base no chamado modelo CDM Plano. Eles obtiveram H0 = 74; 1 2; 2 kms􀀀1Mpc􀀀1, em pleno acordo com as medições locais. Neste trabalho, exploramos a robustez do resultado de LC, procurando por erros sistemáticos e a sua dependência com o modelo cosmológico usado. Nós constatamos que o valor H0 a partir desta análise conjunta é muito fracamente dependente de modelos cosmológico, mas a morfologia adotada para inferir o raio central dos aglomerados de galáxias, altera o resultado, sendo a principal fonte de erros sistemáticos. Concluímos que uma melhor compreensão da morfologia dos aglomerados é fundamental para transformar esse método em um poderoso estimador de H0. / The Hubble constant (H0) is considered a fundamental constant of cosmology. It is crucial for any modern cosmological model, it is related to various cosmological quantities, so it is extremely important a restrictive and accurate determination of its value. The most recent estimate of H0 from local observations (z 1), H0 = 73:8 2; 4 kms􀀀�1Mpc􀀀�1, and from high redshifts (z ' 1070), H0 = 67; 3 1; 2 kms􀀀�1Mpc􀀀�1, are discrepant in a con dence level of 2; 4 . Within this context, Cunha and Lima (LC), in order to shed some light on this problem, derived a new determination of H0 using four cosmological tests at intermediate redshifts (z 1), based on the model called Flat CDM. They obtained H0 = 74; 1 2; 2 kms􀀀�1Mpc􀀀�1, in full agreement with local measurements. In this work, we explore the robustness of the result LC looking for systematic errors and its dependence on the cosmological model used. We found that the H0 value from this combined analysis is very weakly dependent on the underlying cosmological model, but the morphology adopted to infer the core radius of galaxy clusters, changes the estimates being the main source of systematic errors. Hence, we conclude that a better understanding of the morphology of the clusters is essential to transform this method in a powerful cross-check to H0.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-11-07T20:16:04Z No. of bitstreams: 1 FELIPE SÉRVULO MACIEL COSTA – DISSERTAÇÃO (PPGFísica) 2017.pdf: 4976980 bytes, checksum: eb50b091cd9c69ef0ba3d67fba7d69bb (MD5) / Made available in DSpace on 2018-11-07T20:16:04Z (GMT). No. of bitstreams: 1 FELIPE SÉRVULO MACIEL COSTA – DISSERTAÇÃO (PPGFísica) 2017.pdf: 4976980 bytes, checksum: eb50b091cd9c69ef0ba3d67fba7d69bb (MD5) Previous issue date: 2017-11 / Capes / Há cerca de vinte anos, dois grupos de pesquisadores estudaram o brilho aparente das super novas do tipo Ia(SNe Ia) e, de forma independente, descobriram que a expansão atual do universo é acelerada. Esta descoberta lançou a astronomia para a era da energia escura, componente energética que, dentro da teoria da relatividade geral,é a responsável pela aceleração cósmica. Porém, a presença de uma opacidade cósmica nos dados de super novas pode imitar o comportamento de uma componente escura. Hoje em dia, embora a aceleração cósmica seja sustentada por outras observações astronômicas, uma possível presença de opacidade nos dados das SNe Ia pode levar a erros nas estimativas de parâmetros cosmológicos. Assim, vários trabalhos na literatura tem investigado a hipótese da transparência do Universo utilizando medidas de distâncias de luminosidade de velas-padrão, como supernovas do tipo Ia (SNeIa) e gamma raybursts (GRBs),e de distâncias obtidas pela taxa de expansão de Hubble H(z), sendo estas últimas independentes da hipótese de transparência cósmica. Nesta dissertação, nós fazemos uma revisão bibliográ fica sobre estes trabalhos, nos quais foram usados dados de SNeIa, GRBse H(z). Novos limites sobre a opacidade foram colocados com os mais recentes dados de GRBse H(z) no contexto do modelo padrão da cosmologia. Os resultados obtidos mostraram que a hipótese da transparência cósmica está em acordo com os dados, porém, os resultados vindos das observações de GRBs, que alcançam z > 9, onde z é o redshift, não excluem a presença de alguma fonte de opacidade com alto grau de con fiança estatística. / About twenty years ago, two groups of researchers studying the apparent brightness of type Ia super nova e (SNe Ia), independently discovered that the current expansion of the universe is accelerated. This discovery launched astronomy in to the dark energy era, an energy component that, with in the theory of general relativity, is responsible for the cosmic acceleration. However, the presence of a cosmic opacity in SNe Ia data may mimicthe behavior of a dark component. Now a days, although the cosmic acceleration is supported by other astronomical observations, a possible presence of opacity in the SNe Ia data can lead to errors in the cosmological parameter estimates. Thus, several works in the literature have investigated the universe's transparency hypothesis using measurement so fluminosity distances of standard candles, suchas SNe Ia and gamma ray bursts (GRBs), and distances obtained of the cosmic expansion rate H(z). These last ones being independent of the cosmic transparency hypothesis. In this dissertation, we make a bibliographical review on these works and new limits on opacity were placed with the latest data of GRB sand H(z) in the context of the standard model. We have found that the cosmic transparency hypothesis is in agreement with the data, but the results from the observations of GRBs, which reach z > 9, where z is the it red shift, do not exclude the presence of some source of opacity with a high degree of statistical con dence.

Répondre aux questions fondamentales concernant notre compréhension de l’Univers, comme la cause de son expansion accélérée ou la nature de la matière noire, requiert de confronter les théories aux observations. Dans ce contexte, les amas de galaxies peuvent être utilisés comme de puissantes sondes observationnelles. Cependant, à l’heure actuelle, leur utilisation est limitée par des incertitudes et des effets systématiques, qui affectent notamment la mesure de leur masse, que l’on présume dominée par la matière noire. Les amas de galaxies peuvent être étudiés à différentes longueurs d’onde : le gaz chaud qui compose le milieu intra-amas (ICM en anglais) émet des rayons X et est observable dans le domaine millimétrique via l’effet Sunyaev Zel’dovich (SZ), alors que les galaxies rayonnent principalement en optique et infrarouge. Combiner et comparer ces observables permet de réduire les incertitudes et les effets systématiques des contraintes cosmologiques issues des amas. Dans ce contexte, cette thèse a pour but de préparer les grands relevés observationnels du futur comme Euclid et le Large Synoptic Survey Telescope (LSST). Elle présente les analyses multi-longueurs d’onde d’un échantillon d’amas détectés en X dans le relevé XXL, couvrant une large gamme de masses et de redshifts. La première partie de cette thèse introduit le contexte cosmologique et présente les propriétés observationnelles des galaxies et amas de galaxies, ainsi que les ingrédients pour construire des échantillons cosmologiques d’amas. La deuxième partie traite de la caractérisation optique des amas XXL et des propriétés de leurs galaxies membres. Nous commençons par la présentation de XXL et du Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), un relevé optique associé. Ensuite, nous nous concentrons sur la caractérisation de la qualité des redshifts photométriques du CFHTLS et sur leur utilisation pour construire les fonctions de luminosité (LF en anglais) optiques des galaxies d’amas XXL. Il apparaît que la LF des galaxies satellites dépend légèrement de la richesse des amas, le principal proxy de masse en optique, mais ne montre pas d’évolution significative avec le redshift. Ensuite, nous entreprenons l’étude de la couleur et de la fraction de galaxies à noyaux actifs (AGN en anglais) dans les galaxies d’amas XXL et montrons que la masse joue un rôle clé dans la régulation de l’activité de formation stellaire dans les amas. Pour finir, l’algorithme de détection d’amas WaZP est utilisé pour étudier la contrepartie optique des amas XXL. La troisième partie de cette thèse est consacrée au projet observationnel dédié à la cartographie du signal SZ de trois amas XXL distants, avec la camera à haute résolution angulaire NIKA2. La préparation du projet est discutée, en se servant des données optiques et X afin de prédire le signal SZ attendu. Ensuite, nous présentons la procédure d’observation au télescope et la réduction des données, dédiée à la production des cartes SZ étalonnées. Le projet est en cours et un amas, XLSSC102, à z = 0.97, a été observé partiellement. Nous développons ensuite une méthode de détection en aveugle des potentielles galaxies qui peuvent contaminer le signal SZ, permettant la découverte fortuite de galaxies poussiéreuses à haut taux de formation stellaire dans le champ de XLSSC102. La morphologie et l’état dynamique de XLSSC102 sont ensuite caractérisés grâce à la combinaison des données optiques, SZ et X et les profils radiaux de masse et de propriétés thermodynamiques de l’ICM sont mesurés en associant les données X et SZ. Cela permet de montrer que XLSSC102 est un amas en coalescence avec une masse de ∼ 3 × 10^14 Msol et est compatible avec le scénario d’évolution standard de la formation des amas. / Addressing fundamental questions regarding our understanding of the Universe, such as the cause of its accelerated expansion or the nature of dark matter, requires to confront theories and observations. In this context, galaxy clusters can be used as powerful observational probes. However, their current utilisation is limited by uncertainties and systematic effects, notably affecting the measurement of their mass, which is presumably dominated by dark matter.Galaxy clusters can be studied at different wavelengths: the hot gas composing the Intra Cluster Medium (ICM) shines in X-ray and is observable at millimetre wavelengths via the Sunyaev-Zel’dovich (SZ) effect, whereas galaxies emit principally in the optical and infrared. Combining and comparing these observables allows us to reduce the uncertainties and systematics in the cosmological constraints obtained from clusters. In this context, this thesis aims at paving the way of future large surveys such as Euclid and the Large Synoptic Survey Telescope. It presents the multi-wavelengths analyses of a sample of clusters detected in X-ray in the XXL survey, spanning a wide range of masses and redshifts. The first part of the thesis introduces the cosmological context and presents the observational properties of galaxies and clusters, and the ingredients to build cosmological cluster samples. The second part concentrates on the optical characterisation of XXL clusters and the properties of their member galaxies. It starts by presenting XXL and the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), an optical counterpart survey. Then, it focuses on the characterisation of the CFHTLS photometric redshifts quality and their use to construct the optical galaxy luminosity functions (LF) of XXL clusters. The LF of satellite galaxies is found to slightly depend on cluster richness, the main optical mass proxy, but no significant redshift evolution is observed. Then, the study of the colour and active galactic nuclei (AGN) fraction in XXL cluster galaxies is performed, finding that the mass plays a key role in shaping AGN and star formation activity in clusters. Finally, the WaZP optical cluster finder algorithm is used to investigate the optical counterparts of XXL clusters. The third part of this thesis is dedicated to the observational project dedicated to the mapping of the SZ signal in three distant XXL clusters, with the high angular resolution NIKA2 camera. The preparation of the project is discussed, making use of the X-ray and optical data to predict the expected SZ signal. Then, the observation procedure at the telescope and the data reduction, dedicated to produce calibrated SZ maps, are presented. The project is still ongoing and one cluster, XLSSC102, at z = 0.97, has been partially observed. The development of the blind detection of galaxies potentially contaminating the SZ signal is developed, allowing for the serendipitous discovery of dusty star forming galaxies in the field of XLSSC102. The morphology and dynamical state of XLSSC102 are then characterised using optical, SZ and X-ray data and the radial ICM thermodynamics and mass profiles are measured combining SZ and X-ray data. This allows us to show that XLSSC102 is a merging cluster with a mass ∼ 3 × 10 14 M, and is compatible with the standard evolution scenario of cluster formation.

No description available.

<p>Galaxies live in extended, non-luminous haloes of dark matter. How dark matter haloes are affected by environment has been examined using cosmological simulations, and resulting predictions tested for isolated and cluster galaxies. However, predictions have have yet to be tested in the intermediate density environment of galaxy groups. We present a weak galaxy-galaxy lensing analysis of galaxies in groups, with the aim of examining how the group environment affects the dark matter haloes of member galaxies. In particular, we address three questions: 1) whether the dark matter haloes of galaxies in groups are truncated relative to galaxies in the field, 2) how dark matter is distributed within the group environment and 3) whether the halo-to-stellar mass ratio is different between field and group galaxies. We use a basic stacking method and a maximum likelihood technique to parameterize the dark matter haloes of group and field galaxies. Our samples of intermediate redshift group and field galaxies were identified by the Group Environment and Evolution Collaboration in the CNOC2 Redshift Survey. For these data, we measure the average radial extent of a group galaxy dark matter halo to be $s_* = 54^{+114}_{-39}$ kpc, which hints at the possible truncation of galaxy haloes in the group environment. We develop a method of examining the distribution of dark matter within the galaxy group itself, but obtain inconclusive results. Our preliminary analysis of star formation efficiency (halo-to-stellar mass ratio) indicates group galaxies may be less efficient at forming stars compared to galaxies in the field. Larger data samples are required in order to conduct a more rigorous analysis.</p> / Master of Science (MSc)

This thesis presents spectroscopic observations of z ≥ 7 galaxy candidates in the Hubble Ultra Deep Field, which were selected with HST WFC3 imaging, using the Lyman-Break technique. Four z-band (z ≈ 7) dropout galaxies were targeted with Gemini/GNIRS, one z-band dropout galaxy and three Y -band (z ≈ 8 − 9) dropout galaxies with VLT/XSHOOTER, and 22 z-band dropouts with VLT/FORS2, where 15 of the latter are strong candidates. No evidence of Lyman-α emission is found, and the upper limits on the Lyman-α flux and the broad-band magnitudes are used to constrain the rest-frame equivalent widths for this line emission. Amongst the targeted objects, observations were made of HUDF.YD3, a relatively bright Y -band dropout galaxy likely to be at z ≈ 8 − 9 on the basis of its colours in the HST ACS and WFC3 images. Lehnert et al. (2010) observed this galaxy using the VLT/SINFONI integral field spectrograph and claim that it exhibits Lyman-α emission at z = 8.55. In observations of this object described in this thesis, which were made with VLT/XSHOOTER and Subaru/MOIRCS, this line was not reproduced despite the expected signal in the combined MOIRCS & XSHOOTER data being 5σ. Hence it appears unlikely that the reported Lyman-α line emission at z > 8 is real. Accounting for incomplete spectral coverage, in total (across all spectro- graphs) 9.63 z-band dropouts and 1.15 Y -band dropouts are surveyed to a Lyman-α rest-frame Equivalent Width better than 75 ̊A. A model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z = 3−6.5 is inconsistent with these non-detections at z = 7−9 at a confidence level of ∼ 91%, which may indicate that a significant neutral HI fraction (χHI) in the intergalactic medium suppresses the Lyman-α line at z > 7. In particular, the lack of detection of Lyman-α emission in this spectroscopy is compared with results at lower redshift by Stark et al. (2010), who derive a mapping between Lyman-α fractions and χHI based on radiative transfer simulations by McQuinn et al. (2007). These results suggest a lower limit of χHI ~ 0.5.

Les observations des supernovae, du fond diffus cosmologique, et plus récemment la mesure des oscillations acoustiques des baryons et des effets de lentilles gravitationnelles faibles, favorisent le modèle cosmologique LambdaCDM pour lequel l'expansion de l'Univers est actuellement en accélération. Ce modèle fait appel à deux composants insaisissables, la matière sombre et l'énergie sombre. Deux approches semblent particulièrement prometteuses pour sonder à la fois la géométrie de l'Univers et la croissance des structures de matière noire, l'analyse des distorsions faibles des galaxies lointaines par cisaillement gravitationnel et l'étude des oscillations acoustiques des baryons. Ces deux méthodes demandent de très grands relevés du ciel, de plusieurs milliers de degrés carrés, en imagerie et en spectroscopie. Dans le contexte du relevé spectroscopique de la mission spatiale EUCLID, dédiée à l'étude des composantes sombres de l'univers, j'ai réalisé des simulations pixels permettant l'analyse des performances instrumentales. La méthode proposée peut se résumer en trois étapes. La première étape est de simuler les observables, c'est à dire principalement les sources du ciel. Pour cela j'ai développé une nouvelle méthode, adapté à la spectroscopie, qui permet d'imiter un relevé existant, en s'assurant que la distribution des propriétés spectrales des galaxies soit représentative des observations actuelles, en particulier la distribution des raies d'émission. La seconde étape est de simuler l'instrument et de produire des images équivalentes aux images réelles attendues. / The observations of the supernovae, the cosmic microwave background, and more recently the measurement of baryon acoustic oscillations and the weak lensing effects, converge to a LambdaCDM model, with an accelerating expansion of the today Universe. This model need two dark components to fit the observations, the dark matter and the dark energy. Two approaches seem particularly promising to measure both geometry of the Universe and growth of dark matter structures, the analysis of the weak distortions of distant galaxies by gravitational lensing and the study of the baryon acoustic oscillations. Both methods required a very large sky surveys of several thousand square degrees. In the context of the spectroscopic survey of the space mission EUCLID, dedicated to the study of the dark side of the universe, I developed a pixel simulation tool for analyzing instrumental performances. The proposed method can be summarized in three steps.The first step is to simulate the observables, ie mainly the sources of the sky. I work up a new method, adapted for spectroscopic simulations, which allows to mock an existing survey of galaxies in ensuring that the distribution of the spectral properties of galaxies are representative of current observations, in particular the distribution of the emission lines. The second step is to simulate the instrument and produce images which are equivalent to the expected real images. Based on the pixel simulator of the HST, I developed a new tool to compute the images of the spectroscopic channel of EUCLID. The new simulator have the particularity to be able to simulate PSF with various energy distributions and detectors which have different pixels

The principal observational contribution of this thesis is an innovative technique, using spatially resolved spectroscopy of highly magnified, gravitationally lensed galaxies, to study their internal structure and kinematics at redshift, z≥1 on sub-galactic scales. The scientific objective is to measure the important, but poorly understood, role of star formation and associated feedback on galaxy evolution. With Gemini GMOS-IFU observations of CFRS03+1077, a lensed galaxy at z=2.94, we determined surface brightness and integration time requirements for spatially resolved kinematics with spectra in the visible region (< 1 micron). For reasonable exposure times the presence of a strong emission line is key, limiting the redshift range to < 1.5 for [OII]3727Å. To tackle the lack of suitable lenses for such studies, we designed a lens search algorithm suitable for multi-color photometric data (with a minimum of 2 colors). Our method uses a two-step approach, first automatically identifying galaxy clusters and groups as high likelihood lensing regions, followed by a dedicated visual search for lensed arcs in pseudo-color images of sub-regions centered on these candidates. By using the color-position clustering of elliptical galaxies in high density environments, the algorithm efficiently isolates candidates with a completeness ≥ 80% for z ≤ 0.6 in Monte-Carlo simulations. Implemented on the CFHT Legacy Survey-Wide fields with available g, r and i photometry, the present yield is 9 lenses (8 new and 1 previously known) from 104 deg². With Gemini GMOS, we confirmed two lensed galaxies with strong [OII]3727Å emission suitable for IFU spectroscopy. The follow-up of both systems, the confirmation of remaining lenses and the application of the lens detector to the remaining 91 square degrees of CFHTLS-Wide are ongoing. In a complementary project, we aim to understand non-linear structure formation within the Λ-CDM framework by characterizing the mass distributions and mass/light ratios of galaxy groups; these structures (where 60% of all galaxies reside), have masses representative of the critical break between cluster and field galaxy mass scales. We use strong gravitational lensing to constrain the mass in the inner core, with velocity dispersion measurements from MOS spectroscopy to map the mass distribution up to the scale of the virial radius. The formalism supporting this approach as well as the tools for analysis (including an efficient B-spline based method for flat fielding and sky subtraction of sky limited spectra) are presented in this thesis. The deflectors of 6 lenses in our catalog resemble galaxy groups suitable for this study. One group, for which the observations are complete, is compatible with either NFW or Hernquist profile; these results will be corroborated with observations of other candidates in forthcoming observing programs. The objective is to amalgamate our results with mass measurements from weak lensing and X-ray observations from our Strong Lensing Legacy Survey (SL2S) collaborators to build a comprehensive picture of the dark matter profile and thus constrain theoretical predictions of mass assembly in galaxy groups.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-18T17:24:51Z No. of bitstreams: 1 LEONARDO RIBEIRO COLAÇO – DISSERTAÇÃO (PPGFísica) 2016.pdf: 3372949 bytes, checksum: 8387f15d435a4dd929618ecca701927e (MD5) / Made available in DSpace on 2018-10-18T17:24:51Z (GMT). No. of bitstreams: 1 LEONARDO RIBEIRO COLAÇO – DISSERTAÇÃO (PPGFísica) 2016.pdf: 3372949 bytes, checksum: 8387f15d435a4dd929618ecca701927e (MD5) Previous issue date: 2018 / Capes / As teorias cosmológicas mais comumente aceitas são baseadas no pressuposto de que as constantes fundamentais da natureza, como a constante gravitacional G, a constante de estrutura fina α, entre outras, são de fato constantes. Sendo assim, a suposição de que essas constantes não variam no espaço-tempo é apenas uma hipótese, precisando então ser comprovada a partir de dados experimentais. Neste trabalho, propomos um novo método, independente de modelo cosmológico, capaz de investigar uma possível variação como redshift da constante de estrutura fina, α=е2 /hc, onde é a carga elementar, h é a constante de Planck dividida por 2 π e c é a velocidade da luz. Para tal fim, mostramos também que a técnica combinada do Efeito Sunyaev-Zel'dovich (ESZ) como Brilho Superficial em raios-X (SX) para se medir Distância de Diâmetro Angular (DDA) dos Aglomerados de Galáxias (AG) é dependente da constante de estrutura fina. Mais precisamente,se = 0 (z), argumentamos que os dados atuais dessa técnica fornecem DobsA (z) = 2(z)DA(z), onde DA(z) é a verdadeira DDA para o aglomerado de galáxias e (z) é o campo escalar Dilaton que governa uma possível variação em α. Considerando uma amostra de 25 medidas de DobsA (z), feitas por De Filippis et al. (2005),via ESZ/SX na faixa de redshift 0; 023 < zAG < 0; 784 e estimando medidas de DA(z) do assim chamado Union 2.1 Compilation de Super nova e tipoIa (SNeIa), onde o redshift das SNeIa foram cuidadosamente selecionados para coincidir como redshift do aglomerado de galáxias associado com a maior diferença de redshift obedece a jzAG 􀀀 zSNej < 0; 005. Portanto, foi possível atribuir algumas restrições sobre uma possível variação de α para uma classe de Modelos Dilaton Run away, (z) =1􀀀 ln (1+ z). Nossas análises mostraram que = 􀀀0; 037 0; 157 em 1 , ou seja, nossas análises são compatíveis com uma não variação da constante de estrutura fina. / The most common accepted cosmological theories are base don the assumption that the fundamental constants of nature, suchas the gravitational constant G, the new structure constant α, and others, are infact constant. Thus, the assumption that these constants do not vary with time or space is only a hypothesis, then it needs to be confirmed from experimental data. In this paper, we propose a new method, independent of cosmological models, which is cap able to investigate a possible variation with redshift of the new structure constant, α = e2=hc, where e is the elementary charge, h is Planck's constant over 2π and c is the speed of light. For that purpose, we also show that the combined technique between Sunyaev-Zel'doviche effect (SZE) and X-ray surface brightness (SX) to measure Angular Diameter Distance (ADD) of Galaxy Clusters (GC), dependents on the new structure constant. More precisely, if α = α0 (z) we argue that the current data of this technique gives DobsA (z) = 2(z)DA(z), where DA(z) is the true ADD for galaxy clustersand (z) is the dilatons calareld that governs a possible variation of α. We considere da sample of 25 measurements of Dobs A (z), made by De Filipp is e tal. (2005),via ESZ/SX in the range of redshift 0:023 < zGC < 0:784 and we also estimated DA(z) from the so-called Union 2.1 Super novaeIa(SNEIa) Compilation,where the SNeIa redshifts were carefully selected to match the one soft he as sociated galaxy cluster with the larger redshiftd iαe rencefollows jzGC 􀀀� zSNej < 0:005. There for e,it was possible to put some constraints on a possible variation of α for a class of Dilaton Run a way Model, (z) =1 􀀀� ln (1+ z). We obtained = 􀀀�0; 037 0; 157 in1 , i.e.,our analysis is compatible with an on variation of the new structure constant.