Neste trabalho investigamos os efeitos de choques (induzidos por supernovas) e de turbulência magneto-hidrodinâmica no processo de formação estelar. Primeiramente, considerando o impacto de um remanescente de supernova (RSN) com uma nuvem neutra magnetizada derivamos analiticamente um conjunto de condições através das quais estas interações podem levar à formação de estruturas densas capazes de tornarem-se gravitacionalmente instáveis e formar estrelas. Usando estas condições, construímos diagramas do raio do RSN, $R_$, versus a densidade inicial da nuvem, $n_c$, os quais delimitam um domínio no espaço paramétrico onde a formação estelar é permitida. Estes diagramas foram testados através de simulações numéricas magneto-hidrodinâmicas tridimensionais (3D MHD) onde seguimos a evolução espaço-temporal da interação de um RSN com uma nuvem auto-gravitante. Verificamos que a análise numérica está de acordo com os resultados previstos pelos diagramas. Observamos ainda que a presença de um campo magnético fraco, $\\sim 1 \\; \\mu$G, inicialmente homogêneo e perpendicular à velocidade de impacto do RSN, resulta em uma pequena diminuição da região permitida para formação estelar nos diagramas quando comparado a diagramas para nuvens não magnetizadas. Já um campo magnético mais intenso ($\\sim 10\\;\\mu$G) causa um encolhimento significativo nestas, como esperado. Embora derivados de considerações analíticas simples estes diagramas fornecem uma ferramenta útil para identificar locais onde a formação estelar pode ter sido induzida pelo impacto de uma onda de choque de SN. Aplicações a algumas regiões de nossa Galáxia (como a Grande Concha de CO na direção de Escorpião e a Nuvem Periférica 2 na direção da constelação de Cassiopeia) mostram que a formação estelar nestes locais pode ter sido induzida por uma onda de choque de um RSN em passado recente, quando se consideram valores específicos para as condições iniciais das nuvens impactadas.%, para valores específicos de raio do RSN e uma faixa de densidades iniciais possíveis para estas nuvens. Avaliamos também a eficiência de formação estelar efetiva para estas interações e encontramos que esta é geralmente menor do que os valores observados para a nossa Galáxia (sfe $\\sim$ 0.01$-$0.3). Este resultado é consistente com outros trabalhos da literatura e também sugere que este mecanismo, embora poderoso para induzir a formação de estruturas, turbulência supersônica e eventualmente formação estelar local, não parece ser suficiente para induzir a formação estelar global em galáxia normais, nem mesmo quando o campo magnético é desprezado. Além do estudo acima, exploramos ainda a formação estelar considerando a injeção prévia de turbulência (por um mecanismo físico arbitrário) em nuvens magnetizadas. Para uma nuvem ou glóbulo de nuvem molecular formar estrelas deve haver transporte de fluxo magnético das regiões internas mais densas para as regiões externas menos densas da nuvem, de outra forma o colapso poderá ser impedido pela força magnética. Consideramos aqui um novo mecanismo. Reconexão magnética rápida, a qual ocorre em presença de turbulência, pode induzir um processo de difusão eficiente dos campos magnéticos. Neste trabalho investigamos esse processo por meio de simulações numéricas 3D MHD e suas implicações para a formação estelar, estendendo um estudo prévio realizado para nuvens de simetria cilíndrica e sem auto-gravidade (Santos-Lima et al. 2010). Aqui consideramos nuvens mais realistas com potenciais gravitacionais esféricos (devido a estrelas embebidas) e também levando em conta os efeitos da auto-gravidade do gás. Determinamos, pela primeira vez, quais as condições em que o transporte do campo magnético devido à difusão por reconexão turbulenta leva uma nuvem inicialmente subcrítica a tornar-se super-crítica e capaz de colapsar para formar estrelas. Nossos resultados indicam que a formação de um núcleo supercrítico é resultado de uma complexa interação entre gravidade, auto-gravidade, intensidade do campo magnético e turbulência aproximadamente trans-sônica e trans-Alfvénica. Em particular, a auto-gravidade favorece a difusão do campo magnético por reconexão turbulenta e, como resultado, seu desacoplamento do gás colapsante torna-se mais eficiente do que quando apenas um campo gravitacional externo está presente. Demonstramos que a difusão por reconexão turbulenta é capaz de remover fluxo magnético da maior parte das nuvens investigadas, porém somente uma minoria desenvolve núcleos aproximadamente críticos ou super-críticos, o que é consistente com as observações. A formação destes é restrita ao seguinte intervalo de condições iniciais para as nuvens: razão pressão térmica-pressão magnética, $\\beta \\sim 1$ a $3$, razões entre a energia turbulenta e a energia magnética $E_/E_\\sim 1.62$ a $2.96$, e densidades $50 < n < 140$ cm$^$, quando consideramos massas estelares M$_{\\star}\\sim 25$M$_{\\odot}$, implicando uma massa total da nuvem (gás + estrelas) M$_\\lesssim 120$M$_{\\odot}$. / In this work, we have investigated the effects of shocks (induced by supernovae) and magnetohydrodynamical turbulence in the process of star formation. Considering first, the impact of a supernova remnant (SNR) with a neutral magnetized cloud we derived analytically a set of conditions through which these interactions can lead to the formation of dense structures able to become gravitationally unstable and form stars. Using these conditions, we have built diagrams of the SNR radius, $R_{SNR}$, versus the initial cloud density, $n_c$, that constrain a domain in the parameter space where star formation is allowed. These diagrams have been also tested by means of three-dimensional magneto-hydrodynamical (3D MHD) numerical simulations where the space-time evolution of a SNR interacting with a self-gravitating cloud is followed. We find that the numerical analysis is in agreement with the results predicted by the diagrams. We have also found that the effects of a weak homogeneous magnetic field ($\\sim 1 \\; \\mu$G) approximately perpendicular to the impact velocity of the SNR results only a small decrease of the allowed zone for star formation in the diagrams when compared with the diagrams with non-magnetized clouds. A larger magnetic field ($\\sim 10\\;\\mu$G) on the other hand, causes a significant shrinking of the star formation zone, as one should expect. Although derived from simple analytical considerations, these diagrams provide a useful tool for identifying sites where star formation could be triggered by the impact of a SN blast wave. Applications of them to a few regions of our own Galaxy (e.g., the large CO shell in the direction of Scorpious, and the Edge Cloud 2 in the direction of the Cassiopeia constellation) have revealed that star formation in those sites could have been triggered by shock waves from SNRs in a recent past, when considering specific values of the SNR radius and the initial conditions in the neutral clouds. We have also evaluated the effective star formation efficiency for this sort of interaction and found that it is generally smaller than the observed values in our Galaxy (sfe $\\sim$ 0.01$-$0.3). This result is consistent with previous work in the literature and also suggests that the mechanism presently investigated, though very powerful to drive structure formation, supersonic turbulence and eventually, local star formation, does not seem to be sufficient to drive $global$ star formation in normal star forming galaxies, not even when the magnetic field is neglected. Besides the study above, we have also explored star formation considering a priori injection of turbulence (by an arbitrary physical mechanism) in magnetized clouds. For a molecular cloud clump to form stars some transport of magnetic flux may be required from the denser, inner regions to the outer regions of the cloud, otherwise this can prevent the gravitational collapse. We have considered here a new mechanism. Fast magnetic reconnection which takes place in the presence of turbulence can induce a process of reconnection diffusion of the magnetic field. In this work, we have investigated this process by means of 3D MHD numerical simulations considering its implications on star formation. We have extended a previous study which considered clouds with cylindrical geometry and no self-gravity (Santos-Lima et al. 2010). Here, we considered more realistic clouds with spherical gravitational potentials (from embedded stars) and also accounted for the effects of the gas self-gravity. We demonstrated that reconnection diffusion takes place. We have also, for the first time, determined the conditions under which reconnection diffusion is efficient enough to make an initially subcritical cloud clump to become supercritical and collapse. Our results indicate that the formation of a supercritical core is regulated by a complex interplay between gravity, self-gravity, magnetic field strength and nearly transonic and trans-Alfvénic turbulence. In particular, self-gravity helps reconnection diffusion and, as a result, the magnetic field decoupling from the collapsing gas becomes more efficient than in the case when only an external gravitational field is present. We have demonstrated that reconnection diffusion is able to remove magnetic flux from most of the collapsing clumps analysed, but only a few of them develop nearly critical or supercritical cores, which is consistent with the observations. Their formation is restricted to a range of initial conditions for the clouds as follows: thermal to magnetic pressure ratios $\\beta \\sim$ 1 to 3, turbulent to magnetic energy ratios $E_{turb}/E_{mag}\\sim 1.62$ to $2.96$, and densities $50 < n < 140$ cm$^{-3}$, when considering stellar masses M$_{\\star}\\sim 25$M$_{\\odot}$, implying total (gas+stellar) masses M$_{tot} \\lesssim 120$M$_{\\odot}$.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21565号 / 理博第4472号 / 新制||理||1642(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 細川 隆史, 教授 田中 貴浩, 教授 井岡 邦仁 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Les galaxies amplifiées par lentillage gravitationnel fort offrent une opportunité exceptionnelle pour caractériser la formation stellaire intense au sein des galaxies poussiéreuses les plus distantes. Dans les cas les plus favorables, il est possible d'étudier les mécanismes qui régissent la formation stellaire jusqu'aux échelles des régions de formation d'étoiles individuelles. Les alignements fortuits entre ces galaxies actives et des structures d'avant-plan produisant des facteurs d'amplification par lentillage gravitationnel >> 10 restent néanmoins très rares. L'échantillon des Planck's Dusty GEMS (Gravitationally Enhanced subMillimeter Sources), découvert par le relevé de ciel complet du satellite Planck dans le domaine sub-millimétrique, contient onze galaxies à haut décalage spectral extrêmement brillantes. Leurs densités de flux à 350 microns se situent entre 300 et 1000 mJy, au-delà de la plupart des sources lentillées précédemment découvertes par les relevés en infrarouge lointain et sub-millimétrique. Six d'entre elles dépassent la limite en complétude à 90% du catalogue de sources ponctuelles détectées par Planck (PCCS), indiquant qu'elles sont parmi les plus brillantes sources lointaines sélectionnées par leur formation stellaire intense. Cette thèse s'intègre dans le suivi multi-longueur d'onde de cet échantillon exceptionnel, destiné à sonder les propriétés globales des sources d'arrière-plan et à contraindre les configurations de lentillage. Premièrement, j'utilise de l'imagerie et de la spectroscopie en visible et en infrarouge proche et moyen pour caractériser les structures formant la lentille et pour construire des modèles de lentillage gravitationnel complets. J'en déduis que les onze GEMS sont effectivement alignées avec des surdensités de matière en avant-plan, soit des galaxies massives et isolées, soit des groupes ou amas de galaxies. Ces objets amplifiants contiennent des populations d'étoiles évoluées et âgées de plusieurs milliards d'années, indiquant qu'il s'agit de galaxies précoces. De plus, la modélisation détaillée de l'effet de lentillage vers les GEMS suggère que les amplifications atteignent systématiquement des facteurs > 10, et > 20 pour certaines lignes de visée. Deuxièmement, nous observons dans les domaines infrarouge lointain et millimétrique pour caractériser les sources d'arrière-plan. Les données en interférométrie de l'IRAM et du SMA à des résolutions inférieures à la seconde d'arc montrent que les GEMS ont des morphologies très déformées, preuve de fortes distorsions gravitationnelles. J'obtiens des températures de poussières de 33 à 50 K et des luminosités atteignant 2x10^14 luminosités solaires en infrarouge lointain, sans corriger du facteur d'amplification. La relation entre températures de poussières et luminosités infrarouge confirme également que, pour une température donnée, les GEMS sont plus brillantes que les galaxies similaires non lentillées. Je conclus qu'à ces longueurs d'onde, le chauffage des poussières semble être dominé par l'activité de formation stellaire avec une contamination par d'éventuels noyaux actifs systématiquement inférieure à 30%. Nous trouvons des décalages vers le rouge compris entre 2.2 et 3.6 grâce à la détection d'au moins deux raies d'émission du gaz atomique ou moléculaire par source. Finalement, je cible les trois sources lentillées de l'échantillon ayant les propriétés les plus remarquables. En particulier, la plus brillante d'entre elles s'avère être un sursaut présentant des densités de formation stellaire proches de la limite d'Eddington, et permet de sonder la naissance des étoiles dans ses phases les plus extrêmes. / Strongly gravitationally lensed galaxies offer an outstanding opportunity to characterize the most intensely star-forming galaxies in the high-redshift universe. In the most extreme cases, one can probe the mechanisms that underlie the intense star formation on the scales of individual star-forming regions. This requires very fortuitous gravitational lensing configurations offering magnification factors >> 10, which are particularly rare toward the high-redshift dusty star-forming galaxies. The Planck's Dusty GEMS (Gravitationally Enhanced subMillimeter Sources) sample contains eleven of the brightest high-redshift galaxies discovered with the Planck sub-millimeter all-sky survey, with flux densities between 300 and 1000 mJy at 350 microns, factors of a few brighter than the majority of lensed sources previously discovered with other surveys. Six of them are above the 90% completeness limit of the Planck Catalog of Compact Sources (PCCS), suggesting that they are among the brightest high-redshift sources on the sky selected by their active star formation. This thesis comes within the framework of the extensive multi-wavelength follow-up programme designed to determine the overall properties of the high-redshift sources and to probe the lensing configurations. Firstly, to characterize the intervening lensing structures and calculate lensing models, I use optical and near/mid-infrared imaging and spectroscopy. I deduce that our eleven GEMS are aligned with intervening matter overdensities at intermediate redshift, either massive isolated galaxies or galaxy groups and clusters. The foreground sources exhibit evolved stellar populations of a few giga years, characteristic of early-type galaxies. Moreover, the first detailed models of the light deflection toward the GEMS suggest magnification factors systematically > 10, and > 20 for some lines-of-sight. Secondly, we observe the GEMS in the far-infrared and sub-millimeter domains in order to characterize the background sources. The sub-arcsec resolution IRAM and SMA interferometry shows distorded morphologies which definitively confirm that the eleven sources are strongly lensed. I obtain dust temperatures between 33 and 50 K, and outstanding far-infrared luminosities of up to 2x10^14 solar luminosities before correcting for the gravitational magnification. The relationship between dust temperatures and far-infrared luminosities also confirms that the GEMS are brighter than field galaxies at a given dust temperature. I conclude that dust heating seems to be strongly dominated by the star formation activity with an AGN contamination systematically below 30%. We find secure spectroscopic redshifts between 2.2 and 3.6 for the eleven targets thanks to the detection of at least two CO emission lines per source. Finally, I focus on the three gravitationally lensed sources showing the most remarkable properties including the brightest GEMS, a maximal starburst with star formation surface densities near the Eddington limit.

Massive stars are powerful energetic sources shaping their surrounding interstellar medium, which is often swept up into a cold dense shell. If the shell fragments and forms a new generation of massive stars, the stars may form new shells, and this sequence repeats recursively leading to propagating star formation. Using three dimensional hydrodynamic simulations, we investigate fragmentation of the shell in order to estimate masses of stars formed in the shell. We develop a new numerical method to calculate the gravitational potential, which enables us to approximate a part of the shell with a plane-parallel layer. Our main results are as follows. Firstly, we compare our numerical calculations to several analytical theories for shell fragmentation, constrain the parameter space of their validity, and discuss the origin of their limitations. Secondly, we report a new qualita- tively different mode of fragmentation - the coalescence driven collapse. While layers with low pressure confinement form monolithically collapsing fragments, layers with high pressure confinement firstly break into stable fragments, which subsequently coalesce. And thirdly, we study whether layers tend to self-organise and form regular patterns as was suggested in literature, and we find no evidence for this conjecture. Based on our...

We have identified 1027 star-forming complexes in a sample of 46 galaxies from the Spirals, Bridges, and Tails (SB&T) sample of interacting galaxies, and 693 star-forming complexes in a sample of 38 non-interacting spiral (NIS) galaxies in 8 μm observations from the Spitzer Infrared Array Camera. We have used archival multi-wavelength UV-to IR observations to fit the observed spectral energy distribution of our clumps with the Code Investigating GALaxy Emission using a double exponentially declined star formation history. We derive the star formation rates (SFRs), stellar masses, ages and fractions of the most recent burst, dust attenuation, and fractional emission due to an active galactic nucleus for these clumps. The resolved star formation main sequence holds on 2.5 kpc scales, although it does not hold on 1 kpc scales. We analyzed the relation between SFR, stellar mass, and age of the recent burst in the SB&T and NIS samples, and we found that the SFR per stellar mass is higher in the SB&T galaxies, and the clumps are younger in the galaxy pairs. We analyzed the SFR radial profile and found that the SFR is enhanced through the disk and in the tidal features relative to normal spirals.

Using archived data from the Chandra X-ray telescope, we have extracted the diffuse X-ray emission from 49 equal-mass interacting/merging galaxy pairs in a merger sequence, from widely separated pairs to merger remnants. After the removal of contributions from unresolved point sources, we compared the diffuse thermal X-ray luminosity from hot gas (L X(gas)) with the global star formation rate (SFR). After correction for absorption within the target galaxy, we do not see a strong trend of L X(gas)/SFR with the SFR or merger stage for galaxies with SFR > 1 Myr-1. For these galaxies, the median L X(gas)/SFR is 5.5 ×1039 ((erg s-1)/Myr-1)), similar to that of normal spiral galaxies. These results suggest that stellar feedback in star-forming galaxies reaches an approximately steady-state condition, in which a relatively constant fraction of about 2% of the total energy output from supernovae and stellar winds is converted into X-ray flux. Three late-stage merger remnants with low SFRs and high K-band luminosities (L K ) have enhanced L X(gas)/SFR; their UV/IR/optical colors suggest that they are post-starburst galaxies, perhaps in the process of becoming ellipticals. Systems with L K < 1010 L have lower L X(gas)/SFR ratios than the other galaxies in our sample, perhaps due to lower gravitational fields or lower metallicities. We see no relation between L X(gas)/SFR and Seyfert activity in this sample, suggesting that feedback from active galactic nuclei is not a major contributor to the hot gas in our sample galaxies.

Large observational surveys have compiled substantial galaxy samples with an array of different properties across cosmic time. While we have a broad understanding of how galaxies grow and build their observable properties, the details of galaxy growth and evolution pose a fundamental challenge to galaxy evolution theories. Nonetheless, galaxy evolution is ultimately regulated by the properties of the gas reservoir. In this thesis I use numerical simulations to answer key questions related to the galactic gas reservoir, and galaxy mergers: a major transformational process. In Chapter 2 I present an analysis of 28 simulated L* galaxies to understand the physical processes that shape the massive gas reservoir surrounding galaxies (i.e. the circum-galactic medium; CGM). I show that (1) the gas and metal content of the CGM is driven by galaxy growth and the strength/presence of feedback processes, and (2) the ionisation and internal structures of the CGM are shaped by galactic outflows, and active galactic nucleus luminosity. Albeit dependent on internal galactic properties and the physical processes that shape them, the CGM remains greatly diverse, thus posing a challenge for observational surveys. As a follow-up to my study of normal L* galaxy gas halos, in Chapter 3 I present a theoretical study of the effect of galaxy mergers on the CGM. I demonstrate that galaxy mergers can leave a strong imprint on the CGM's gas and metal content, metallicity, and size. The merger can increase (1) the CGM's metallicity by 0.2-0.3 dex within 0.5 Gyr post-merge, and (2) the metal covering fractions by factors of 2-3. In spite of the increase in the CGM's metal content, the hard ionising field during the merger can drive a decline in the covering fractions of commonly observed ions. In Chapter 4 I shift focus to star formation, particularly the effects of galaxy mergers on star formation. While the effects of galaxy mergers have been proven observationally, theoretical predictions are limited to small binary merger suites and cosmological zoom-in studies. I present a statistical study of 27,691 post-merger galaxies from IllustrisTNG to quantify the effect of galaxy mergers on galactic star formation. I report a dependence in the merger-induced star formation rate (SFR) on mass ratio, stellar mass, gas fraction, and galaxy SFR. I also track the evolution of the effects of galaxy mergers demonstrating their decay over ~500 Myr. In Chapter 6, I leverage galactic scaling relations to extend my work on the effects of galaxy mergers to resolved scales. However, before using the simulated resolved scaling relations, I first examine their existence and robustness. In Chapter 5, I demonstrate the emergence of the kpc-scale star forming main sequence (rSFMS) in the FIRE-2 simulations. Nonetheless, the slope of the rSFMS is dependent on the (1) star formation tracer's timescale, and (2) observed resolution, which I propose is caused by the clumpiness of star formation. I develop a toy model that quantitatively captures the effects of clumpy star formation. I then illustrate how the model can be used to characterise the mass of star-forming clumps. Having demonstrated the existence and robustness of known scaling relations in numerical simulations, I explore the effects of galaxy mergers on resolved scales in Chapter 6. I generate synthetic observations for 1,927 post-mergers in IllustrisTNG and examine the radially-dependent merger-driven SFR enhancement, and metallicity suppression in post-mergers. Galaxy mergers preferentially boost star formation in the centres and suppress metallicities globally. The effects of the merger depends on galaxy properties such as stellar mass, SFR, mass ratio, and gas fraction. / Graduate

abstract: This dissertation details the development of an open source, frequency domain multiplexed (FDM) readout for large-format arrays of superconducting lumped-element kinetic inductance detectors (LEKIDs). The system architecture is designed to meet the requirements of current and next generation balloon-borne and ground-based submillimeter (sub-mm), far-infrared (FIR) and millimeter-wave (mm-wave) astronomical cameras, whose science goals will soon drive the pixel counts of sub-mm detector arrays from the kilopixel to the megapixel regime. The in-flight performance of the readout system was verified during the summer, 2018 flight of ASI's OLIMPO balloon-borne telescope, from Svalbard, Norway. This was the first flight for both LEKID detectors and their associated readout electronics. In winter 2019/2020, the system will fly on NASA's long-duration Balloon Borne Large Aperture Submillimeter Telescope (BLAST-TNG), a sub-mm polarimeter which will map the polarized thermal emission from cosmic dust at 250, 350 and 500 microns (spatial resolution of 30", 41" and 59"). It is also a core system in several upcoming ground based mm-wave instruments which will soon observe at the 50 m Large Millimeter Telescope (e.g., TolTEC, SuperSpec, MUSCAT), at Sierra Negra, Mexico. The design and verification of the FPGA firmware, software and electronics which make up the system are described in detail. Primary system requirements are derived from the science objectives of BLAST-TNG, and discussed in the context of relevant size, weight, power and cost (SWaP-C) considerations for balloon platforms. The system was used to characterize the instrumental performance of the BLAST-TNG receiver and detector arrays in the lead-up to the 2019/2020 flight attempt from McMurdo Station, Antarctica. The results of this characterization are interpreted by applying a parametric software model of a LEKID detector to the measured data in order to estimate important system parameters, including the optical efficiency, optical passbands and sensitivity. The role that magnetic fields (B-fields) play in shaping structures on various scales in the interstellar medium is one of the central areas of research which is carried out by sub-mm/FIR observatories. The Davis-Chandrasekhar-Fermi Method (DCFM) is applied to a BLASTPol 2012 map (smoothed to 5') of the inner ~1.25 deg2 of the Carina Nebula Complex (CNC, NGC 3372) in order to estimate the strength of the B-field in the plane-of-the-sky (B-pos). The resulting map contains estimates of B-pos along several thousand sightlines through the CNC. This data analysis pipeline will be used to process maps of the CNC and other science targets which will be produced during the upcoming BLAST-TNG flight. A target selection survey of five nearby external galaxies which will be mapped during the flight is also presented. / Dissertation/Thesis / Doctoral Dissertation Astrophysics 2019

Star formation is a complex hierarchical process that witnesses the transfer of mass among a range of scales from large diffuse molecular clouds to crowded clumps and finally down to prestellar cores. The final stage of this process has prestellar cores actively accreting matter while undergoing gravitational collapse on their way to becoming main sequence stars. This thesis presents multi wavelength submillimeter observations of the Perseus molecular cloud using 160 μm, 250 μm, 350 μm, and 500 μm maps of thermal dust emission from the Herschel space observatory. Additionally C18O J = 3 → 2 spectral line emission is observed in four star forming clumps within Perseus using the James Clerk Maxwell Telescope. Spectral line emission allows for the separation of material along the line of sight. Prestellar core mass is derived from observational maps using various source finding algorithms. The mass is overestimated when compared to prestellar core mass found from spectral line data. This overestimation can be mitigated with careful selection of source finding algorithm and background removal. Further, the prestellar core mass derived from spectral line data was the closest match to the initial stellar mass function over dust maps. However, both the spectral line masses and dust map masses do not agree with the IMF confirming a star forming efficiency factor in the evolutionary step between prestellar core and main sequence star. Lastly, a filamentary analysis finds that high mass stars preferentially form in crowded regions close to, or contained within, filament structure. / Thesis / Master of Science (MSc) / Star formation is a complex hierarchical process that witnesses the transfer of mass among a range of scales from large diffuse molecular clouds to crowded clumps and finally down to prestellar cores. The final stage of this process has prestellar cores actively accreting matter while undergoing gravitational collapse on their way to becoming main sequence stars. This thesis presents multi wavelength submillimeter observations of the Perseus molecular cloud using 160 μm, 250 μm, 350 μm, and 500 μm maps of thermal dust emission from the Herschel space observatory. Additionally carbon monoxide spectral line emission is observed in four star forming clumps within Perseus using the James Clerk Maxwell Telescope. Spectral line emission allows for the separation of material along the line of sight. Prestellar core mass is derived from observational maps using various source finding algorithms. The mass is overestimated when compared to prestellar core mass found from spectral line data. This overestimation can be mitigated with careful selection of source finding algorithm and background removal. Further, the prestellar core mass derived from spectral line data was the closest match to the initial stellar mass function over dust maps. However, both the spectral line masses and dust map masses do not agree with the IMF confirming a star forming efficiency factor in the evolutionary step between prestellar core and main sequence star. Lastly, a filamentary analysis finds that high mass stars preferentially form in crowded regions close to, or contained within, filament structure.

I have identified 51 young stellar object candidates in N206, an H II complex in the nearby Large Magellanic Cloud galaxy. Using archival images from the Spitzer Space Telescope, supplemented with other infrared and optical images, I located point sources in this region. I distinguished possible young stellar objects based on their spectral energy distributions, morphologies, and locations in color-magnitude space. I classified the young stellar object candidates based on their likelihood of being young stellar objects and based on their apparent evolutionary stages. The spatial distribution of these candidates in N206 indicates that star formation is being triggered in a giant molecular cloud in the region.