Galaxy shape statistics in the effective field theory

Intrinsic galaxy alignments yield an important contribution to the observed statistics of galaxy shapes. The general bias expansion for galaxy sizes and shapes in three dimensions has been recently described by Vlah, Chisari \& Schmidt using the general perturbative effective field theory (EFT) framework, in analogy to the clustering of galaxies. In this work, we present a formalism that uses the properties of spherical tensors to project galaxy shapes onto the observed sky in the flat-sky approximation and compute the two-point functions at next-to-leading order as well as the leading-order three-point functions of galaxy shapes and number counts. The resulting expressions are given in forms that are convenient for efficient numerical implementation. For a source redshift distribution typical of Stage IV surveys, we find that that nonlinear intrinsic alignment contributions to galaxy shape correlations become relevant at angular wavenumbers $l \gtrsim 100$

The dependence of intrinsic alignment of galaxies on wavelength using KiDS and GAMA

The outer regions of galaxies are more susceptible to the tidal interactions that lead to intrinsic alignments of galaxies. The resulting alignment signal may therefore depend on the passband if the colours of galaxies vary spatially. To quantify this, we measured the shapes of galaxies with spectroscopic redshifts from the GAMA survey using deep gri imaging data from the KiloDegree Survey. The performance of the moment-based shape measurement algorithm DEIMOS was assessed using dedicated image simulations, which showed that the ellipticities could be determined with an accuracy better than 1% in all bands. Additional tests for potential systematic errors did not reveal any issues. We measure a significant difference of the alignment signal between the g,r and i-band observations. This difference exceeds the amplitude of the linear alignment model on scales below 2 Mpc/h. Separating the sample into central/satellite and red/blue galaxies, we find that that the difference is dominated by red satellite galaxies.Comment: 16 pages, 13 figures, accepted, to appear in A&

The halo model as a versatile tool to predict intrinsic alignments

Intrinsic alignments (IAs) of galaxies are an important contaminant for cosmic shear studies, but the modelling is complicated by the dependence of the signal on the source galaxy sample. In this paper, we use the halo model formalism to capture this diversity and examine its implications for Stage-III and Stage-IV cosmic shear surveys. We account for the different IA signatures at large and small scales, as well as for the different contributions from central/satellite and red/blue galaxies, and we use realistic mocks to account for the characteristics of the galaxy populations as a function of redshift. We inform our model using the most recent observational findings: we include a luminosity dependence at both large and small scales and a radial dependence of the signal within the halo. We predict the impact of the total IA signal on the lensing angular power spectra, including the current uncertainties from the IA best-fits to illustrate the range of possible impact on the lensing signal: the lack of constraints for fainter galaxies is the main source of uncertainty for our predictions of the IA signal. We investigate how well effective models with limited degrees of freedom can account for the complexity of the IA signal. Although these lead to negligible biases for Stage-III surveys, we find that, for Stage-IV surveys, it is essential to at least include an additional parameter to capture the redshift dependence

KiDS-450: tomographic cross-correlation of galaxy shear with Planck lensing

We present the tomographic cross-correlation between galaxy lensing measured in the Kilo Degree Survey (KiDS-450) with overlapping lensing measurements of the cosmic microwave background (CMB), as detected by Planck 2015. We compare our joint probe measurement to the theoretical expectation for a flat Λ cold dark matter cosmology, assuming the best-fitting cosmological parameters from the KiDS-450 cosmic shear and Planck CMB analyses. We find that our results are consistent within 1σ with the KiDS-450 cosmology, with an amplitude re-scaling parameter AKiDS = 0.86 ± 0.19. Adopting a Planck cosmology, we find our results are consistent within 2σ, with APlanck = 0.68 ± 0.15. We show that the agreement is improved in both cases when the contamination to the signal by intrinsic galaxy alignments is accounted for, increasing A by ∼0.1. This is the first tomographic analysis of the galaxy lensing – CMB lensing cross-correlation signal, and is based on five photometric redshift bins. We use this measurement as an independent validation of the multiplicative shear calibration and of the calibrated source redshift distribution at high redshifts. We find that constraints on these two quantities are strongly correlated when obtained from this technique, which should therefore not be considered as a stand-alone competitive calibration tool

The Schro¨\ddot{o}dinger-Poisson equations as the large-N limit of the Newtonian N-body system: applications to the large scale dark matter dynamics

In this paper it is argued how the dynamics of the classical Newtonian N-body system can be described in terms of the Schr$\ddot{o}$dinger-Poisson equations in the large $N$ limit. This result is based on the stochastic quantization introduced by Nelson, and on the Calogero conjecture. According to the Calogero conjecture, the emerging effective Planck constant is computed in terms of the parameters of the N-body system as $\hbar \sim M^{5/3} G^{1/2} (N/)^{1/6}$, where is $G$ the gravitational constant, $N$ and $M$ are the number and the mass of the bodies, and $$ is their average density. The relevance of this result in the context of large scale structure formation is discussed. In particular, this finding gives a further argument in support of the validity of the Schr$\ddot{o}$dinger method as numerical double of the N-body simulations of dark matter dynamics at large cosmological scales.Comment: Accepted for publication in the Euro. Phys. J.

GAMA plus KiDS: Alignment of galaxies in galaxy groups and its dependence on galaxy scale

Intrinsic galaxy alignments are a source of bias for weak lensing measurements as well as a tool for understanding galaxy formation and evolution. In this work, we measure the alignment of shapes of satellite galaxies, in galaxy groups, with respect to the brightest group galaxy (BGG), as well as alignments of the BGG shape with the satellite positions, using the highly complete Galaxy And Mass Assembly (GAMA) spectroscopic survey and deep imaging from the Kilo Degree Survey. We control systematic errors with dedicated image simulations and measure accurate shapes using the DEIMOS shape measurement method. We find a significant satellite radial alignment signal, which vanishes at large separations from the BGG. We do not identify any strong trends of the signal with galaxy absolute magnitude or group mass. The alignment signal is dominated by red satellites. We also find that the outer regions of galaxies are aligned more strongly than their inner regions, by varying the radial weight employed during the shape measurement process. This behaviour is evident for both red and blue satellites. BGGs are also found to be aligned with satellite positions, with this alignment being stronger when considering the innermost satellites, using red BGGs and the shape of the outer region of the BGG. Lastly, we measure the global intrinsic alignment signal in the GAMA sample for two different radial weight functions and find no significant difference

Meteorological Investigation Of High Pm10 Concentration In Istanbul Kağithane Region

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2016Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2016Hava kirliliği, artan sanayi ve şehirleşme etkilerinden dolayı tüm dünyada önemli bir sorun haline gelmiştir. Yıllardır ülkemizde ve dünyada hava kirliliğine bağlı olarak çevresel ve sağlık sorunları ortaya çıkmaktadır. 1952 yılında İngiltere’de meydana gelen hava kirliliğinden dolayı 5.000 kişi hayatını kaybetmiştir. 2013 yılında Çin’de meydana gelen hava kirliliği vakasında ise şehirde görüş oldukça azalmış, kirlilik nedeniyle gelen sisten dolayı bir hafta boyunca olan kaza sayısı 70’ e çıkmış ve bir çok astım hastası ve alerjisi olan kişiler de durumdan olumsuz etkilenmiştir. Hava kirliliğinin meydana gelmesi, hava kalitesinin düşmesine neden olmaktadır. Dünya’da da diğer ülkeler hava kirliliğine ve hava kalitesine oldukça önem vermektedir. Özellikle Çin hem sanayi faaliyetlerinin çok fazla olması hem de nüfus yoğunluğu nedeniyle düşük hava kalitesi koşullarına sahiptir. Çin’de yapılan çalışmalar genellikle partiküler kirliliğin sağlık üzerindeki etkileri üzerinedir. Hava kirliliği turizm sektörünü de etkilemektedir ve bu nedenle İspanya’da da PM10 kirliliğinin turizme olan etkileri araştırılmıştır. Avrupa’da da partiküler madde kirliliğinin kaynakları ve partiküler maddenin uzak ve yakın kıta taşınımları üzerine çalışmalar yapılmaktadır. Türkiye’ de ise hava kirliliği çalışmaları yaklaşık olarak 1960’ lı yıllarda başlamıştır. İlk önce çalışmalara Ankara’da başlanmış, daha sonra kirliliğin diğer şehirlerde de yaygınlaşmasıyla konuyla ilgili analizler artmıştır. Ancak genel olarak şehrin coğrafi konumundan, etkisinde olduğu iklimsel faktörler açısından, batılı ve güneyli rüzgarlara maruz kalması faktöründen, nüfus yoğunluğuna bağlı olarak artan endüstriyel faaliyet, konutsal ısınma ve motorlu araç emisyonlarından, Boğazdan geçen gemilerin neden olduğu emisyonlardan dolayı artan hava kirliliği sorunu nedeniyle yapılan çalışmalar İstanbul üzerinde yoğunlaşmıştır. İstanbul baz alınarak yapılan spesifik çalışmalar da genellikle trafiğin yoğun olarak görüldüğü bölgeler üzerinde olmuştur. Hava kirliliği sanayi emisyonlarından, konutsal ısıtma sistemlerinden, organik kaynaklardan (volkanik küller, çöl tozları, çiçek polenleri, vs.), atmosferde meydana gelen bazı kimyasal tepkimeler sonucunda ya da yakın/uzak kıta partiküler madde taşınımından dolayı meydana gelebilmektedir. Hava kirliliğinin ortaya çıkmasında atmosferde bulunan partiküllerin yanı sıra o anki meteorolojik şartlar da oldukça önemlidir. Yüksek basınç, sakin rüzgarlar, yağışın olmaması atmosferde bulunan partiküler maddenin konsantrasyonunu ve atmosferde kalış süresini oldukça etkilemektedir. İstanbul yaklaşık olarak 15 milyon kişinin yaşadığı mega şehirlerden biridir ve gün geçtikçe nüfus daha da artmaktadır. Nüfus artışına bağlı olarak, motorlu araç sayısı ve konut sayısı da artmaktadır ki bu durumda da araçlardan ve kentsel ısınmadan dolayı olan emisyonlar da aynı hızla yükselişe geçmektedir. İstanbul aynı zamanda Avrupa’dan batılı rüzgarlar ile taşınan partiküler madde kirliliğine da maruz kalmaktadır ve özellikle güneyli rüzgarların da etkisiyle Afrika’dan Sahra çölü üzerinden genellikle son bahar ve ilk bahar aylarında toz taşınımı görülmektedir. Bu toz taşınımından Türkiye’nin güney kıyıları ve İstanbul önemli derecede etkilenmektedir. Dolayısıyla tüm bu etkenler İstanbul’daki kirliliği arttırıcı rol oynamaktadır. Bu yüksek lisans bitirme tez çalışmasında İstanbul’ da yer alan Kağıthane bölgesi çalışma alanı olarak seçilmiştir. Kağıthane bölgesi bir vadi özelliği göstermektedir ki bölgenin bu özelliğinden dolayı düşük dispersiyon koşulları gözlenmektedir. Yüksek basıncın etkili olduğu ve rüzgar hızının da düşük olduğu zamanlarda kirletici oranları da yüksek olarak ölçüldüğünde, bölgede hava kirliliği ortaya çıkmakta ve hava kalitesi oldukça düşmektedir. Bu amaçla bölgede PM10 ölçümlerini yapmak ve kaynaklarını belirlemek hem çevresel hem de sağlık açısından oldukça önemlidir. Daha önce yapılan çalışmalarda İstanbul’ daki PM10 konsantrasyonlarının günlük ve yıllık bazda EU limit değerlerinin üzerinde olduğu saptanmıştır. Çalışmada 2012-2014 yılları arası PM10 konsantrasyonları düzenli olarak ölçülmüş ve günlük, aylık, mevsimlik bazda istatistiksel incelemesi yapılmıştır. Bu incelemeler sonucunda episod gününe karar verilmiştir ve episod gününde yüksek olarak ölçülen PM10 konsantrasyonunun kaynağı belirlenmeye çalışılmıştır. Bu amaçla meteorolojik analizler yapılmış, yüksek seviye kartları incelenmiştir. Meteorolojik analizler sonucunda episod gününde yerde yüksek basıncın etkili olmasıyla, rüzgar hızının da sakin olmasıyla ve enverziyonun da görülmesiyle birlikte PM10 bölge üzerinde çökmüştür. WRF modeli çalıştırılarak yer ve yukarı seviyelerdeki yatay rüzgar hızı değerleri incelenmiştir. Bunlara ek olarak, uzak ve yakın kıta PM10 taşınımlarının o gün üzerine olan etkisini belirlemek amacıyla HYSPLIT modeli çalıştırılarak geriye dönük yörünge analizi yapılmış ve taşınımın kısa dönem içerisinde Doğu Avrupa üzerinden ve uzun dönem içerisinde de Sahra çölü üzerinden geldiği ortaya konulmuştur. Yer seviyesindeki taşınımı ortaya koymak açısından SODAR cihazıyla episod günü ölçülen yatay ve düşey rüzgar bileşenleri incelenmiş ve düşeyde taşınımın aşağı yönde olduğu ve enverziyonun olduğu da SODAR ölçümleriyle desteklenerek ortaya konulmuştur.Air pollution has become an important problem in the world because of industrialization and urbanization. For years, in our country and the world, there are health and environmental issues connected with the air pollution. In 1952, nearly 5.000 people lost their lives because of the effect of air pollution in England. In 2013 in China, visibility decreased due to the fog event causing from air pollution, the number of traffic accident rose to 70 and lots of allergic and asthma people were affected from this pollution. Occurrence of air pollution decreases the air quality in the atmosphere. In the world, the other countries attach quite importance to air pollution and air quality. Especially China has lower air quality conditions due to its high population density and higher industrial activities. Studies done in China are generally about effects of particulate pollution on health effects. Air pollution affects the tourism sector so that in Spain PM10 pollution effects on tourism were investigated. Also, in Europe studies and analyzes include particulate matter sources and particulate matter’s transboundary transportations over continentals. In Turkey, studies about air pollution had begun in 1960’s and at first, studies were done in Ankara then with the increase of air pollution problems in other cities, studies and analysis became widespread. Studies were generally focused on Istanbul because of increasing air pollution due to the city’s geographical location, climate conditions, factor of westerly and southerly winds, domestic heating and motor vehicle emissions, ships emissions passing over Bosphorus. The other specific studies based on Istanbul were done over the regions, which have high traffic density. Industrial emissions, domestic heating, organic sources (volcanic ashes, desert dusts, pollens, etc.) and chemical reactions in the atmosphere or transboundary particulate matter transportation cause air pollution in the atmosphere. Meteorological conditions are also have important effects on occurrence of air pollution besides particulates in the atmosphere. Especially high pressure, calm winds and no precipitation conditions increase the particulate matter concentration and duration in the air. İstanbul is one of the megacities with approximately 15 million people living in and population density increases rapidly day by day. The number of residences increases along with the increment of the population and usage of motor vehicles and at the same time, emissions due to domestic heating and vehicles are expected to be risen. Also, İstanbul is exposed to particulate matter pollution carried with westerly winds coming from Europe and affected by southerly winds where there is dust transportation from Africa over Saharan Desert at the spring and fall seasons. Turkey’s south regions and İstanbul are affected from this dust transportation significantly. Therefore, all these factors play a role in enhancing pollution in İstanbul. In this study, Kağıthane region in İstanbul were selected as study area. Kağıthane region is a creek valley and due to this topographical structure, low dispersion conditions are obtained. When high-pressure system and low wind speed conditions occur and high pollutant concentrations are measured, air pollution and air quality decreases dramatically. For this purpose, it is important to do PM10 measurements and determine the sources for environmental and health issues. In other studies, it was put forward that PM10 concentrations exceeded the European Union (EU) limits on daily and monthly bases. In our study, PM10 concentrations were measured regularly in between 2012 and 2014 years and some statistical analysis were done for daily, monthly, seasonally PM10 concentration. In 2012, mean PM10 concentration value was calculated as 80.77 μg/m3 and maximum concentration values were found as 195.2 μg/m3. In 2013, mean PM10 concentration value was calculated as 86.83 μg/m3 and maximum concentration values was found as 329.9 μg/m3 and In 2014, mean PM10 concentration value was calculated as 79.66 μg/m3 and maximum concentration values was found as 265.2 μg/m3. To test the homogeneity of the data some quality control and quality assurance tests were done. According to results of homogeneity test, PM10 concentration data belonging to 2014 year were selected as study data. After these analyses, episodic period were determined in between 5 December 2015 and 25 December 2015 because PM10 concentration increases gradually from December 5 to December 25. For this day the sources of PM10 concentration were determined. Meteorological analyses were done and upper level air charts were examined. According to meteorological analysis results, on the episode day, there was a high-pressure system over Turkey and PM10 was sunk over Kağıthane Creek Valley because of calm winds and the inversion effect. Wind speed and direction is obtained by using Weather Research and Forecast model (WRF) and analyses for the episode day were done. With WRF outputs 850hPa temperature, height and wind speed values were visualized for inner (10x10km) and outer (3.3x3.3km) domain. 700hPa and 500hPa upper air maps were plotted to see the upper air particulate matter transportation with higher wind speed. According to these maps, with the effects of low-pressure system over Iceland and approaching high-pressure system over Aegean and Mediterranean to Istanbul on December 15th 2014, there was particulate matter transportation over Eastern Europe to Istanbul by westerly winds from 4500m and 6000m heights in the atmosphere. There was no precipitation on episode day due to the high-pressure system. The effects of transboundary PM10 transportation on episode day were searched with back trajectory analysis with Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT). According to this trajectory analysis, PM10 transportation were started from eastern Europe at 4500m and 6000m height two days before episode day and PM10 transported from Africa over Saharan Desert with southerly winds at 1500m nearly six days before. These transportations from different locations was caused to measure high level PM10 concentrations. In addition to these analyses, horizontal and vertical wind speed was measured with SODAR instrument over study area. These measurements were done at different elevations from surface level. In every 30 minutes at different elevations (30, 50, 70, …, 410m) wind data were recorded. Horizontal wind speed component was measured approximately 2 m/s over surface and there was a decrease in wind speed magnitude at 50m level. From surface to 50m heights, there was an inversion layer on December 15 at 00UTC. After 50m heights, wind speed increases with height. Because of the low wind speed effect, there was not a significant PM10 transportation over surface. Vertical wind speed component was measured and due to the inversion, the motion of air was toward from surface to the 50m height. Vertical wind speed component was measured with negative sign at 00UTC time period. With the effect of vertical wind speed, there is a vertical PM10 transportation over study area and these situations caused PM10 sank. Altogether, meteorological, topographical and human effects caused the higher PM10 concentration measurements over Kağıthane Valley regionYüksek LisansM.Sc

Multitracing anisotropic non-Gaussianity with galaxy shapes

Correlations between intrinsic galaxy shapes on large scales arise due to the effect of the tidal field of the large-scale structure. Anisotropic primordial non-Gaussianity induces a distinct scale-dependent imprint in these tidal alignments on large scales. Motivated by the observational finding that the alignment strength of luminous red galaxies depends on how galaxy shapes are measured, we study the use of two different shape estimators as a multitracer probe of intrinsic alignments. We show, by means of a Fisher analysis, that this technique promises a significant improvement on anisotropic non-Gaussianity constraints over a singletracer method. For future weak lensing surveys, the uncertainty in the anisotropic non-Gaussianity parameter, A 2 , is forecast to be σ(A 2 ) ≈ 50, ∼40% smaller than currently available constraints from the bispectrum of the cosmic microwave background. This corresponds to an improvement of a factor of 4-5 over the uncertainty from a single-tracer analysis

Caught in the rhythm: how satellites settle into a plane around their central galaxy

Using the cosmological hydrodynamics simulation Horizon-AGN, we investigate the spatial distribution of satellite galaxies relative to their central counterpart in the redshift range between 0.3 and 0.8. We find that, on average, these satellites tend to be located on the galactic plane of the central object. This effect is detected for central galaxies with a stellar mass larger than 10^10 solar masses and found to be strongest for red passive galaxies, while blue galaxies exhibit a weaker trend. For galaxies with a minor axis parallel to the direction of the nearest filament, we find that the coplanarity is stronger in the vicinity of the central galaxy, and decreases when moving towards the outskirts of the host halo. By contrast, the spatial distribution of satellite galaxies relative to their closest filament follows the opposite trend: their tendency to align with them dominates at large distances from the central galaxy, and fades away in its vicinity. Relying on mock catalogs of galaxies in that redshift range, we show that massive red centrals with a spin perpendicular to their filament also have corotating satellites well aligned with both the galactic plane and the filament. On the other hand, lower-mass blue centrals with a spin parallel to their filament have satellites flowing straight along this filament, and hence orthogonally to their galactic plane. The orbit of these satellites is then progressively bent towards a better alignment with the galactic plane as they penetrate the central region of their host halo. The kinematics previously described are consistent with satellite infall and spin build-up via quasi-polar flows, followed by a re-orientation of the spin of massive red galaxies through mergers

Caught in the rhythm: how satellites settle into a plane around their central galaxy

Using the cosmological hydrodynamics simulation Horizon-AGN, we investigate the spatial distribution of satellite galaxies relative to their central counterpart in the redshift range between 0.3 and 0.8. We find that, on average, these satellites tend to be located on the galactic plane of the central object. This effect is detected for central galaxies with a stellar mass larger than 10^10 solar masses and found to be strongest for red passive galaxies, while blue galaxies exhibit a weaker trend. For galaxies with a minor axis parallel to the direction of the nearest filament, we find that the coplanarity is stronger in the vicinity of the central galaxy, and decreases when moving towards the outskirts of the host halo. By contrast, the spatial distribution of satellite galaxies relative to their closest filament follows the opposite trend: their tendency to align with them dominates at large distances from the central galaxy, and fades away in its vicinity. Relying on mock catalogs of galaxies in that redshift range, we show that massive red centrals with a spin perpendicular to their filament also have corotating satellites well aligned with both the galactic plane and the filament. On the other hand, lower-mass blue centrals with a spin parallel to their filament have satellites flowing straight along this filament, and hence orthogonally to their galactic plane. The orbit of these satellites is then progressively bent towards a better alignment with the galactic plane as they penetrate the central region of their host halo. The kinematics previously described are consistent with satellite infall and spin build-up via quasi-polar flows, followed by a re-orientation of the spin of massive red galaxies through mergers