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- All Subjects: Millimeter-Wave Astronomy
- Creators: Scannapieco, Evan
- Creators: Windhorst, Rogier
Description
This work examines star formation in the debris associated with collisions of dwarf and spiral galaxies. While the spectacular displays of major mergers are famous (e.g., NGC 4038/9, ``The Antennae''), equal mass galaxy mergers are relatively rare compared to minor mergers (mass ratio <0.3) Minor mergers are less energetic than major mergers, but more common in the observable universe and, thus, likely played a pivotal role in the formation of most large galaxies. Centers of mergers host vigorous star formation from high gas density and turbulence and are surveyed over cosmological distances. However, the tidal debris resulting from these mergers have not been well studied. Such regions have large reservoirs of gaseous material that can be used as fuel for subsequent star formation but also have lower gas density. Tracers of star formation at the local and global scale have been examined for three tidal tails in two minor merger systems. These tracers include young star cluster populations, H-alpha, and [CII] emission. The rate of apparent star formation derived from these tracers is compared to the gas available to estimate the star formation efficiency (SFE). The Western tail of NGC 2782 formed isolated star clusters while massive star cluster complexes are found in the UGC 10214 (``The Tadpole'') and Eastern tail of NGC 2782. Due to the lack of both observable CO and [CII] emission, the observed star formation in the Western tail of NGC 2782 may have a low carbon abundance and represent only the first round of local star formation. While the Western tail has a normal SFE, the Eastern tail in the same galaxy has an low observed SFE. In contrast, the Tadpole tidal tail has a high observed star formation rate and a corresponding high SFE. The low SFE observed in the Eastern tail of NGC 2782 may be due to its origin as a splash region where localized gas heating is important. However, the other tails may be tidally formed regions where gravitational compression likely dominates and enhances the local star formation.
ContributorsKnierman, Karen A (Author) / Scowen, Paul (Thesis advisor) / Groppi, Christopher (Thesis advisor) / Mauskopf, Philip (Committee member) / Windhorst, Rogier (Committee member) / Jansen, Rolf (Committee member) / Arizona State University (Publisher)
Created2013
ContributorsPowell, Devon (Author) / Gardner, Carl (Thesis director) / Scannapieco, Evan (Committee member) / Windhorst, Rogier (Committee member) / Barrett, The Honors College (Contributor)
Created2012-05
Description
Millimeter astronomy unlocks a window to the earliest produced light in the universe, called the Cosmic Microwave Background (CMB). Through analysis of the CMB, overarching features about the universe's evolution and structure can be better understood. Modern millimeter-wave instruments are constantly seeking improvements to sensitivity in the effort to further constrain small CMB anisotropies in both temperature and polarization. As a result, detailed investigations into lesser-known processes of the universe are now becoming possible.
Here I present work on the millimeter-wavelength analysis of z ≈ 1 quiescent galaxy samples, whose conspicuous quenching of star formation is likely the result of active galactic nuclei (AGN) accretion onto supermassive black holes. Such AGN feedback would heat up a galaxy's surrounding circumgalactic medium (CGM). Obscured by signal from cold dust, I isolate the thermal Sunyaev-Zel'dovich effect, a CMB temperature anisotropy produced by hot ionized gas, to measure the CGM's average thermal energy and differentiate between AGN accretion models. I find a median thermal energy that best corresponds with moderate to high levels of AGN feedback. In addition, the radial profile of cold dust associated with the galaxy samples appears to be consistent with large-scale clustering of the universe.
In the endeavor of increasingly efficient millimeter-wave detectors, I also describe the design process for novel multichroic dual-polarization antennas. Paired with extended hemispherical lenslets, simulations of these superconducting antennas show the potential to match or exceed performance compared to similar designs already in use. A prototype detector array, with dual-bowtie and hybrid trapezoidal antennas coupled to microwave kinetic inductance detectors (MKIDs) has been made and is under preparation to be tested in the near future.
Finally, I also present my contributions to the cryogenic readout design of the Ali CMB Polarization Telescope (AliCPT), a large-scale CMB telescope geared towards searching the Northern Hemisphere sky for a unique `B-mode' polarization expected to be produced by primordial gravitational waves. Cryogenic readout is responsible for successful interfacing between room temperature electronics and sensitive detectors operating on AliCPT's sub-Kelvin temperature focal plane. The development of millimeter-wave instruments and future endeavors show great potential for the overall scientific community.
ContributorsMeinke, Jeremy (Author) / Mauskopf, Philip (Thesis advisor) / Alarcon, Ricardo (Committee member) / Scannapieco, Evan (Committee member) / Trichopoulos, Georgios (Committee member) / Arizona State University (Publisher)
Created2023
Description
TolTEC is a three-band millimeter-wave, imaging polarimeter installed on the 50 m diameter Large Millimeter Telescope (LMT) in Mexico. This camera simultaneously images the focal plane at three wavebands centered at 1.1 mm (270 GHz), 1.4 mm (214 GHz), and 2.0 mm (150 GHz). TolTEC combines polarization-sensitive kinetic inductance detectors (KIDs) with the LMT to produce high resolution images of the sky in both total intensity and polarization. I present an overview of the TolTEC camera’s optical system and my contributions to the optomechanical design and characterization of the instrument. As part of my work with TolTEC, I designed the mounting structures for the cold optics within the cryostat accounting for thermal contraction to ensure the silicon lenses do not fracture when cooled. I also designed the large warm optics that re-image the light from the telescope, requiring me to perform static and vibration analyses to ensure the mounts correctly supported the mirrors. I discuss the various methods used to align the optics and the cryostat in the telescope. I discuss the Zemax optical model of TolTEC and compare it with measurements of the instrument to help with characterization. Finally, I present the results of stacking galaxies on data from the Atacama Cosmology Telescope (ACT) to measure the Sunyaev-Zel’dovich (SZ) effect and estimate the thermal energy in the gas around high red-shift, quiescent galaxies as an example of science that could be done with TolTEC data. Since the camera combines high angular resolution with images at three wavelengths near distinct SZ features, TolTEC will provide precise measurements to learn more about these types of galaxies.
ContributorsLunde, Emily Louise (Author) / Mauskopf, Philip (Thesis advisor) / Groppi, Christopher (Committee member) / Scannapieco, Evan (Committee member) / Noble, Allison (Committee member) / Bryan, Sean (Committee member) / Arizona State University (Publisher)
Created2023