Journal Club Archive

LGRT 1033 Lecture Area

1. Luan Luan: “Fast galaxy bars continue to challenge standard cosmology” (Mahmood et al. 2021)

2. Joyce Caliendo: ALMA Measures Rapidly Depleted Molecular Gas Reservoirs in Massive Quiescent Galaxies at z~1.5” (Williams et al. 2021)

3. Sam Cutler: “The Milky Way’s bar and bulge revealed by APOGEE and Gaia EDR3” (Queiroz et al. 2020)

LGRT 1033 Lecture Area

1. Luan Luan: “Fast galaxy bars continue to challenge standard cosmology” (Mahmood et al. 2021)

2. Joyce Caliendo: ALMA Measures Rapidly Depleted Molecular Gas Reservoirs in Massive Quiescent Galaxies at z~1.5” (Williams et al. 2021)

3. Sam Cutler: “The Milky Way’s bar and bulge revealed by APOGEE and Gaia EDR3” (Queiroz et al. 2020)

LGRT 1033 Lecture Area

1. Luan Luan: “Fast galaxy bars continue to challenge standard cosmology” (Mahmood et al. 2021)

2. Joyce Caliendo: ALMA Measures Rapidly Depleted Molecular Gas Reservoirs in Massive Quiescent Galaxies at z~1.5” (Williams et al. 2021)

3. Sam Cutler: “The Milky Way’s bar and bulge revealed by APOGEE and Gaia EDR3” (Queiroz et al. 2020)

LGRT 1033 Lecture Area

The speakers will be reviewing papers that are directly connected to their own research projects, and will comment about how the selected papers are relevant to their graduate work.
 

1. Sarah Betti: “Possible evidence of ongoing planet formation in AB Aurigae: A showcase of the SPHERE/ALMA synergy.” (Boccaletti et al. 2020)

2. Yingjie Cheng: “The Single-cloud Star Formation Relation” (Pokhrel et al. 2021)

3. Lisiyuan Yang: “Column Density Profiles of Cold Clouds Driven by Galactic Outflow” (Cottle et al. 2018)

LGRT 1033 Lecture Area

The speakers will be reviewing papers that are directly connected to their own research projects, and will comment about how the selected papers are relevant to their graduate work.

1. Sandra Bustamante: “Black hole parameter estimation with synthetic very long baseline interferometry data from the ground and from space” (Roelofs et al. 2021)

2. Sophia Flury: “No strong dependence of Lyman continuum leakage on physical properties of star-forming galaxies at 3.1 < z < 3.5” (Saxena et al. 2021)

3. Zhiyuan Ji: “Rotation Curves in z~1-2 Star-Forming Disks: Evidence for Cored Dark Matter Distributions” (Genzel et al. 2020)

 

LGRT 1033 Lecture Area
4pm Zoom Meeting

Talk held during Colloquium time
 


 

LGRT 1033 Lecture Area
4pm Zoom Meeting

Talk held during Colloquium time
 


 

4pm Zoom Meeting

 

Talk held during journal club spot


 

LGRT 1033 Lecture Area

 

Remote - Zoom
5 graduate student talks of 10 minutes each:
 

Nat DeNigris: 
Wolf-Rayet Stars in the Antennae unveiled by MUSE https://arxiv.org/pdf/2010.09781.pdf

Zhiyuan Ji
"Cosmological Simulations with the aid of Machine Learning"
"Super-resolution emulator of cosmological simulations using deep physical models”— Kodi Ramanah et al. 2020 (https://arxiv.org/pdf/2001.05519.pdf)
"Learning neutrino effects in Cosmology with Convolutional Neural Networks"— Giusarma et al. 2019 (https://arxiv.org/pdf/1910.04255.pdf)
"The CAMELS project: Cosmology and Astrophysics with MachinE Learning Simulations" — Villaescusa-Navarro et al. 2020 (https://arxiv.org/pdf/2010.00619.pdf)
 
Alyssa Sokol
"Quantum Theories on Parallel Universe"
"New Fine-Tuning Argument for the Multiverse” https://link.springer.com/article/10.1007/s10701-019-00246-2
"Parallel Lives: A Local Realistic Interpretation of “nonlocal” Boxes”  https://arxiv.org/pdf/1709.10016.pdf
 
Jed McKinney
"Spatially Resolved Star Formation and Fueling in Galaxy Interactions", Moreno et al., 2020, https://ui.adsabs.harvard.edu/abs/2020MNRAS.tmp.2894M/abstract
LGRT 1033 Lecture Area
4pm Zoom Meeting

5 student talks of 10 minutes each

Sarah Betti
"Single magnetic white dwarfs with Balmer emission lines: A small class with consistent physical characteristics as possible signposts for close-in planetary companions"
Gänsicke 2020
 
Shuiyao Huang
"Evidence of runaway gas cooling in the absence of supermassive black hole feedback at the epoch of cluster formation
 
Patrick Kamieneski
"Searching for Gravitational Waves with Strongly Lensed Repeating Fast Radio Bursts.” 
Pearson et al. 2020
 
Michael McCrackan
"Associations of dwarf galaxies in a ΛCDM Universe”
Yaryura et al. 2020.
 
Each student will give a 10-12 minute talk followed by 3-5 minutes for questions. We will use a google doc to collect questions and the host will read the questions after each talk.
 
LGRT 1033 Lecture Area
4pm Zoom Meeting

Join Professor Grant Wilson in a discusson on building a professonal webpage. In preparation, Professor Wilson will ask students to consider the importance of a professional website. This will be the first of several breakout room discussions.
LGRT 1033 Lecture Area

 

Zoom

Graduate Student Yingjie Cheng: Quantifying starburst feedback via X-ray spectroscopy of 30 Doradus

X-ray observations provide a potentially powerful tool to study the starburst feedback and its impact on the surrounding medium. So far, the analysis and interpretation of such observations remain challenging, due to various complications including the non-isothermality of the X-ray-emitting hot plasma, and the inhomogeneity of the foreground absorption. To illustrate such complications and mitigate their effects, we present a spatially resolved X-ray spectroscopic study of 30 Doradus in the Large Magellanic Cloud (LMC), based on a 100 ks Suzaku
observation. The high sensitivity and spectral resolution of this observation, together with the proximity of this starburst region, enable us to measure the thermal and chemical properties of the diffuse hot plasma, and to quantitatively confront them with the feedback expected from embedded massive stars. Spectral analysis shows that the plasma temperature varies spatially in the range of 2.5x10^6 K, indicating that it is significantly non-isothermal. We thus characterize the temperature distribution of the plasma emission measure with a log-normal model, which improves the fits to the data. The metal abundances of the plasma are typically 1-2 times higher than the average values of the host galaxy, and the total mass of the plasma is derived as 1-2x10^4 Msun From these estimates, the total metal enrichment is consistent with the expected ejection from the central stellar cluster with two age components of 2 Myr and 4 Myr and that ~62% of the plasma is mass-loaded from the ambient medium. We further conclude that our spatially resolved measurements can be reasonably well reproduced by a global modeling of 30 Doradus with a log-normal temperature distribution and log-normal differential foreground absorption. This log-normal distribution model may be suitable for the X-ray spectral modeling of other giant HII regions, especially for which spatially resolved spectroscopy is not practical. Finally, our spectral analysis shows tentative evidence for a diffuse
non-thermal X-ray component, which most likely arises from inverse Compton scattering of strong radiation in the nebula.

Zoom
4pm Zoom Meeting

Sophia Flury

TITLE: The Low-Redshift Lyman Continuum Survey I. First Insights into LyC Diagnostics

ABSTRACT

The origin of cosmic reionization remains unknown. Because we cannot detect ionizing photons from reionization-era galaxies, we must turn to indirect diagnostics calibrated at low redshift to provide a foundation for future high redshift observations. We present the Low-Redshift Lyman Continuum Survey (LzLCS), which aims to establish these indirect diagnostics while providing insight into the conditions which facilitate the escape of ionizing or “Lyman continuum (LyC)” radiation. While line-of-sight orientation effects produce substantial scatter in all proposed diagnostics, we find compelling evidence for several key relationships. Properties such as star formation rate surface density and Lyα escape are not only useful diagnostics but also offer insight into the nature of the leaking Lyman continuum. LyC emission appears most consistent with an optically-thick ISM, suggesting a porous, orientation-dependent escape scenario. We find LyC leakers are most commonly compact, low-mass galaxies with highly concentrated star formation.

4pm Zoom Meeting
Data challenge competition for ‘best plot’

4pm Zoom Meeting
Grad-student lead discussion of feedback from Department Culture Survey.

4pm Zoom Meeting

Students are encouraged to bring ideas, tips, and tricks for making compelling science plots. A competition for the best plot is scheduled for Monday, Sept 7th.


 

LGRT 1033 Lecture Area
LGRT 1033 Lecture Area
LGRT 1033 Lecture Area
LGRT 1033 Lecture Area
LGRT 1033 Lecture Area

Group Photo

LGRT 1033 Lecture Area
LGRT 1033 Lecture Area
LGRT 1033 Lecture Area
LGRT 1033 Lecture Area

5-Minute Research Talks

LGRT 1033 Lecture Area

Spring Break

LGRT 1033 Lecture Area
LGRT 533
LGRT 533 Lecture Area

Open to everyone

postponed from 12/2 to 12/12 due to snow day

Title: The Pre-Shipment Status of TolTEC: A New Multiwavelength Imaging Polarimeter for the LMT

Abstract: TolTEC is an upcoming millimeter-wave imaging polarimeter designed to fill the focal plane of the 50-m diameter Large Millimeter Telescope (LMT). Combined with the LMT, TolTEC will offer high angular resolution (5”-10”) for simultaneous, polarization-sensitive observations in three wavelength bands: 1.1, 1.4, and 2.0 mm. Additionally, TolTEC will feature mapping speeds greater than 2 deg^2/mJy^2/hr enabling wider surveys of large-scale structure, galaxy evolution, and star formation than is currently possible at these resolutions. We intend to commission TolTEC at the LMT in Winter 2020. In this talk, I will provide an update on TolTEC’s in-lab testing occurring at UMass Amherst in preparation for installation at the LMT. The improvements that TolTEC will offer are only possible through the integration of three separate focal planes totalling approximately 7000 low-noise, high-responsivity superconducting Lumped Element Kinetic Inductance Detectors (LEKIDs). As of November 2019, we have integrated and tested two of the three detector arrays (1.1 mm and 2.0 mm) to determine their responsivity and, where possible, their bandpasses. I will conclude my talk with some of the novel galaxy cluster physics I hope to study with TolTEC using the Sunyaev-Zel’dovich Effect. 

LGRT 1033

Open to everyone

Title: The Gas Physics of Interacting Galaxies: Feedback and Ram Pressure in NGC4631 and NGC4319

Abstract: We present a panchromatic study of two spiral galaxies (NGC4631 and NGC4319) that are involved in galaxy-galaxy interactions and provide unique constraints on the roles played by gas and dust in merger-driven galaxy evolution. NGC4631, the 'Whale Galaxy', is an edge-on spiral undergoing a merger and starburst. Above the midplane in the hot, x-ray emitting halo, O VI emission indicates that there is a kiloparsec-scale outflow originating from the disk. The ratio of far-ultraviolet to 24um emission shows dramatic changes along and perpendicular to the midplane of NGC4631; we suggest that multiple 'chimneys' are present in the disk, including a nuclear outflow that has evacuated the center and is the likely source of the hot gas seen in X-rays.  To investigate the origin of the O VI emission, we compare the O VI brightness at several positions above the midplane to the star formation properties of the underlying disk. NGC4319 is a face-on spiral with prominent tidal features that is also going through a merger. We find a large spatial offset between the 21cm and 24um emission, indicative of removal of the atomic gas from the galaxy due to ram-pressure stripping by intragroup gas. This is corroborated by an extraordinarily high molecular gas fraction in the disk (albeit with low overall column density), which is measured through detection of molecular hydrogen absorption lines along the line of sight to a background quasar. However, FCRAO 14m observations indicate that the molecular gas emission is probably centered on the 24um emission. We use the CO,  21cm, and 24um emission to study how the regions of molecular gas and star formation can be physically separated from the H I gas reservoir in galaxy interactions. We discuss the importance of molecular gas in these processes and how observations of CO rotational emission can provide the missing link for understanding the physics of interacting systems like NGC4319.

LGRT 1033, 4:00pm

Title: Measuring the Heating and Cooling of the Interstellar Medium at High Redshift : PAH and [C II] Observations of the Same Star Forming Galaxies at z ~ 2

Abstract: Star formation depends critically on cooling mechanisms in the interstellar medium (ISM); however, thermal properties of gas in galaxies at the peak epoch of star formation (z ∼ 2) remain poorly understood. In this talk, I will compare low- and  high-redshift observations of [C II] emission, a principal cooling channel, with observations of Polycyclic Aromatic Hydrocarbons (PAHs), a measure of photoelectric heating in photodissociation regions (PDRs). I will discuss the diagnostic power of combining these tracers in the same dusty, star forming galaxies at z ~ 2, and how they may be used to study cosmological trends in galaxy evolution. In particular, changes in the [C II]/PAH ratio with redshift can trace evolution in the physical PDR conditions with implications for the star-formation efficiency. Finally, I will summarize ongoing and future projects that aim to characterize PDRs in nearby and z ~ 2 galaxies. 
LGRT 1033

Wednesday 11/13 is on a Monday schedule
Open to all

Title: The Role of Environment in Core Evolution: Predictions for the TolTEC Clouds to Cores Legacy Survey

Abstract: Using magnetohydrodynamical simulations of star forming gas with stellar feedback and sink particles (proxies for young stellar objects (YSOs)), we present predictions of synthetic 1.1 mm continuum observations at differing distances (150 - 1000 pc) and ages (0.49 - 1.27 Myr). We characterize how core properties, including mass and size, change with distance, cloud evolution, and the presence of YSOs. We find a clear separation between the size of cores with and without YSOs suggesting evolutionary difference in cores that host YSOs but find little to no temperature dependence on core properties. This separation increases by ∼ 16% with increasing age as cores with YSOs decrease in mass and size. We also find that the atmospheric filtering and core segmentation treatments have distance dependent impacts on the resulting core properties for D < 300 pc and characterize these in detail. These predictions and systematic characterizations will help guide analysis of cores for the upcoming TolTEC Clouds to Cores Legacy Survey on the LMT. 

LGRT 533

Open to graduate students

LGRT 533

Open to graduate students

LGRT 533 Lecture Area

Open to graduate students

LGRT 533

Tuesday 10/15 is on a Monday Schedule
Open to graduate students

Zhiyuan Ji:

Title: Hubble tension between the Early and the Late Universe

Abstract: Predictions made by the Lambda-CDM paradigm has been extensively shown to be consistent with many aspects of modern observational cosmology. The corresponding basic cosmological parameters are being measured with unprecedented precision. Discrepancies between observations in the Early and the Late Universe, however, seem to be confirmed with high significance, which might indicates the requirement of an expansion of the standard cosmological model. In my talk, I will review the different observational technologies of measuring the Hubble constant, both in the Early and the Late Universe, including potential systematics behind different measures. I will also briefly describe the ongoing/near future efforts that astronomers and physics are trying to make to ‘’solve’’ this tension.

Patrick Kamieneski:

Title: The effect of galaxy mergers on star formation rates from z=0-4 The effect of galaxy mergers on star formation rates from z=0-4

Abstract: Galaxy mergers and interactions play a crucial role in our current conception of galaxy evolution and hierarchical structure in the Universe. In the case of some of the most extreme objects yet observed, including Ultra-luminous Infrared Galaxies (ULIRGs) and Dusty Star-forming Galaxies (DSFGs), mergers are often assumed to be at least partially responsible for elevated star formation rates. However, it has been difficult to quantify by how much merger activity typically amplifies star formation. Studying the statistical effect of galaxy mergers on the build-up of stellar mass is fundamental to understanding the growth and evolution of galaxies across cosmic time. In addressing this question, I will present recent results from Pearson et al. 2019, including the use of convolutional neural networks to identify mergers in the SDSS, KiDS, and CANDELS surveys, spanning a redshift range of 0 to 4.

LGRT 533

Open to graduate students

LGRT 1033 Lecture Area

Open to everyone

 

 

 

Luan Luan
 
Titie: STATISTICAL CHARACTERIZATION OF THE X-RAY INTENSITY DISTRIBUTION IN GALAXY CLUSTERS OUTSKIRTS
 
Abstract: Hot gas halo is the major baryon component of galaxy clusters and galaxy groups, which impacts and reveals the evolution of the universe, from galaxy scale to the cosmos scale. Due to the limited sensitivity of X-ray telescope, this kind of research mostly is from the stacking analysis of clusters (e.g. Eckert 2012, Anderson et al. 2015)and groups or from very nearby and massive clusters (e.g. Bautz et al. 2009). However, Hot gas halos are very extending and we always observe the 3-dimension on the 2-dimension sky, this introduce very strong projection e ect when we did the stacking analysis, especially for the faint outskirt of hot gas halo and poor clusters and groups. In this work, we used ROSAT All-sky Survey data and analysis the X-ray emission from all group halos discovered by SDSS, 2MRS, 6dF and 2dF. Compared to stacking analysis, we developed a simultaneous fitting method to solve the problem about the overlapping between groups halos. We shows that the intrinsic profile of hot gas halo is steeper than we knew previously from stacking analysis. And this kind of method is also necessary for the future research about the properties of hot gas halo outskirt.
LGRT 1033 Lecture Area

Open to everyone

Speaker: Dooseok Jung

Title: Investigation into the Star Formation Laws for Starbusting Centers, Disks of Nearby Spiral Galaxies and Starbusts Galaxies

Abstract: We have conducted an analysis of the correlation between surface density of star formation rate (SFR), hydrogen molecular gas mass density and surface density of total gas in a sample of 13 nearby spiral galaxies within 15 Mpc to focus on centers of the galaxies. We measure depletion time in binned regions throughout each galaxy. The goal of this project is to quantify depletion time in the starbursting central regions (SB centers) of several nearby galaxies and compare its values with those of the more quiescent galaxy disks. We use the multiwavelength data in the far-ultraviolet (FUV) from the Galaxy Evolution Explorer (GALEX), mid-Infrared (mid-IR) 24 micron-m from Spitzer Space Telescope Infrared Nearby Galaxies Survey (SINGS), HI from The HI Nearby Galaxy Survey (THINGS) and CO from HERA CO-Line Extragalactic Survey (HERACLES). In the Kennicutt-Schmidt (KS) law plot, the power-law indices are N = 1.134 with molecular gas and N = 2.153 with total gas. We set the standard to identify SB centers which is the ratio between depletion time of each center to the mean value of depletion time in disks for molecular gas of each galaxy is lower than 1/3 and we find six SB galaxies in our sample. The SB centers do not have a strong offset as starburst galaxies (SBGs) do in the universal KS plane for molecular gas, although all of the six SB centers are above the fitted line by data from disks. The SB stars do not show clear evidence for behaving as universal SBGs.

 

Speaker: Ben Gregg

Title: Quantifying the Molecular Gas in a z=1.75 Galaxy Cluster

Abstract: We present VLA observations of one of the most robustly detected massive galaxy clusters at high redshift, with z=1.75. We characterize this cluster's molecular gas contents by quantifying the strength of CO(1-0) emission within its central regions. We detect one significant CO emission source with a spatial signal-to-noise ratio of 5.29, which is offset from a photometrically determined cluster member galaxy by 2.5 arcseconds (21.5 kpc at z=1.75). We also place 3 sigma upper limits on undetected candidate cluster member galaxies within the half power of our VLA beam. Assuming the association to be accurate, we find that our CO detected galaxy is forming stars at rates that are consistent or below field galaxies with similar stellar mass and molecular gas mass, and that it has significant levels of offset molecular gas with a gas fraction that is consistent with field galaxies at similar redshift. We find our 3 sigma upper limits to indicate that on average the undetected cluster member galaxies are forming stars either on or likely  below  the  main  sequence,  are  consistent with  a  normal  star formation efficiency,  and  have  gas  fractions  that are similar or likely below that of field galaxies at similar redshift. As a result, we find that our cluster has low molecular gas reservoirs and that its galaxies have low star formation rates and thus we find that our cluster is undergoing the process of quenching. We find our results to be consistent with other blind CO(1-0) surveys of high redshift galaxy clusters, concluding that cluster members galaxies detected in CO have properties resembling that  of  a  star-forming  field  galaxy  with  similar stellar mass, gas mass, and redshift.

LGRT 1033 Lecture Area
LGRT 1033 Lecture Area

TBD

LGRT-B 1033 Lecture Area

TBD

LGRT-B 1033 Lecture Area

Zhiyuan Ji & Dooseok Jung

Please note: Wednesday 4/17/19 will follow a UMass Monday schedule

LGRT 1033 Lecture Area

Karl Haislmaier & Yvonne Ban

LGRT-B 1033 Lecture Area

Michael McCrackan & Jed McKinney

LGRT-B 1033 Lecture Area

Shuiyao Huang & Natalie DeNigris

CANCELED

SPRING BREAK - NO JOURNAL CLUB

CANCELED

NO JOURNAL CLUB
Please Note: AP students will meet at a different time

LGRT-B 1033 Lecture Area

Seunghwan Lim & Sarah Betti

LGRT-B 1033 Lecture Area

 

Alyssa Sokol discusses faculty biases towards students: https://www.pnas.org/content/pnas/109/41/16474.full.pdfSupplemental info: https://www.pnas.org/content/pnas/suppl/2012/09/16/1211286109.DC
Supplemental/pnas.201211286SI.pdf?targetid=nameddest%3DSTXT

Luan Luan discusses scientific literacy in ungergraduate students:
https://www.researchgate.net/profile/S_Buxner/publication/258569236_Non-...

Please note: Tuesday 2/19/19 will follow a UMass Monday schedule

LGRT-B 1033 Lecture Area

Patrick Kamienski & Ben Gregg

LGRT 1033 Lecture Area

Sandy Peterson (Guest Presenter): Multi-Institutional Study of GRE Scores as Predictors of STEM PhD Degree Completion

Abstract: 

The process of selecting students likely to complete science, technology, engineering and mathematics (STEM) doctoral programs has not changed greatly over the last few decades and still relies heavily on Graduate Record Examination (GRE) scores in most U.S. universities. It has been long debated whether the GRE is an appropriate selection tool and whether overreliance on GRE scores may compromise admission of students historically underrepresented in STEM. Despite many concerns about the test, there are few studies examining the efficacy of the GRE in predicting PhD completion and even fewer examining this question in STEM fields. For the present study, we took advantage of a long-lived collaboration among institutions in the Northeast Alliance for Graduate Education and the Professoriate (NEAGEP) to gather comparable data on GRE scores and PhD completion for 1805 U.S./Permanent Resident STEM doctoral students in four state flagship institutions. We found that GRE Verbal (GRE V) and GRE Quantitative (GRE Q) scores were similar for women who completed STEM PhD degrees and those who left programs. Remarkably, GRE scores were significantly higher for men who left than counterparts who completed STEM PhD degrees. In fact, men in the lower quartiles of GRE V or Q scores finished degrees more often than those in the highest quartile. This pattern held for each of the four institutions in the study and for the cohort of male engineering students across institutions. GRE scores also failed to predict time to degree or to identify students who would leave during the first year of their programs. Our results suggests that GRE scores are not an effective tool for identifying students who will be successful in completing STEM doctoral programs. Considering the high cost of attrition from PhD programs and its impact on future leadership for the U.S. STEM workforce, we suggest that it is time to develop more effective and inclusive admissions strategies. Full article: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0206570
LGRT-B 1033 Lecture Area

Riwaj Pokhrel & Aleks Popstefanija

LGRT 1033 Lecture Area

Speakers: Ben Gregg and Karl Haislmaier

LGRT 1033 Lecture Area

Speaker: Aleks Popstefanija

LGRT 1033 Lecture Area

Speaker: Bingqing Sun

LGRT 1033 Lecture Area

Speakers: Dooseok Jung and Riwaj Pokhrel

LGRT 1033 Lecture Area

Speakers: Seunghwan Lim and Luan Luan

LGRT 1033 Lecture Area

Speakers: Michael McCrackan and Yvonne Ban

LGRT 1033 Lecture Area

Speaker: Alyssa Sokol

CANCELED

LGRT 1033 Lecture Area

Speakers: Patrick Kamieneski and Yuping Tang

LGRT 1033 Lecture Area

Speakers: Jed McKinney and Natalie DeNigris

LGRT 1033 Lecture Area

Speakers: Sarah Betti and Tazkera Haque

LGRT 1033 Lecture Area

Speaker: Zhiyuan Ji

LGRT 1033 Lecture Area

Riwaj Pokhrel

Title: A HERSCHEL-SPIRE SURVEY OF THE MON R2 GIANT MOLECULAR CLOUD Abstract: We present a far-IR survey of the entire Mon R2 GMC covering 4.30 deg by 4.36 deg, obtained with SPIRE and cross-calibrated with Planck-HFI data for absolute off- set and zero point correction. As the best representation of cold dusty molecular clouds, we fit the far-IR SEDs of each pixel with modified blackbody function. We fixed the dust emissivity, \beta, across all fits with the help of the flux ratio plot and found the most optimal value as 1.8. We studied the nature of distribution of column densities. We found that below 7 × 10^{20} cm^{&#8722;2} , the distribution is log-normal in nature whereas above this value, the distribution takes the power-law form. We performed an algorithmic extraction of nested structures from the col- umn density map using the python software package, astrodendro, and found the presence of structures with a variety of aspect ratios. We examined the impact of different fundamental gas configurations (sphere, sheet, filament) on the critical mass and free-fall times derived from our data. We studied the radial profile of filaments and found that the outer density profile takes a power-law form with a shallower slope than for an isothermal filament in equilibrium, suggesting that these filaments are unstable to further collapse.

LGRT 1033 Lecture Area
 

Brandt Gaches

Title: ASTROCHEMICAL CORRELATIONS IN MOLECULAR CLOUDS Abstract: We investigate the spectral correlations between different species used to observe molecular clouds. We use hydrodynamic simulations and a full chemical network to study the abundances of over 150 species in typical Milky Way molecular clouds. We perform synthetic observations in order to produce emission maps of a subset of these tracers. We study the effects of different lines of sight and spatial resolution on the emission distribution and perform a robust quantitative comparison of the species to each other. We use the Spectral Correlation Function (SCF), which quantifies the root mean squared difference between spectra separated by some length scale, to characterize the structure of the simulated cloud in position-position-velocity (PPV) space. We predict the observed SCF for a broad range of observational tracers, and thus, identify homologous species. In particular, we show that the pairs C and CO, C+ and CN, NH3 and H2CS have very similar SCFs. We measure the SCF slope variation as a function of beam size for all species and demonstrate that the beam size has a distinct effect on different species emission. However, for beams of up to 10”, placing the cloud at 1 kpc, the change is not large enough to move the SCF slopes into different regions of parameter space. The results from this study provide observational guidance for choosing the best tracer to probe various cloud length scales.

LGRT 1033 Lecture Area

Joe Burchett

Quenching of Star Formation in SDSS Groups: Centrals, Satellites and Galactic Conformity

LGRT 1033 Lecture Area

The dark side of galaxy colour: evidence from new SDSS measurements of galaxy clustering and lensing

 

 

LGRT 1033 Lecture Area

Shawn Roberts

Internal properties and environments of dark matter haloes

Michael Petersen

Connecting the cosmic web to the spin of dark haloes: implications for galaxy formation

LGRT 1033 Lecture Area

Kathryn Grasha

Are Dusty Galaxies Blue? Insights On UV Attenuation From Dust-Selected Galaxies

Shuiyao Huang

GIZMO: A New Class of Accurate, Mesh-Free Hydrodynamic Simulation Methods

LGRT 1033 Lecture Area

Bomee Lee

How dead are dead galaxies? MID-Infrared fluxes of quiescent galaxies at redshift 0.3<z<2.5: Implication for star-formation rates and dust heating.

Ryan Cybulski

The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). IV: The role of the cluster environment on galaxy evolution.

LGRT 1033 Lecture Area

Zhon Butcher

Galaxy And Mass Assembly (GAMA): The dependence of the galaxy luminosity function on environment, redshift and colour.

LGRT 1033 Lecture Area

Seunghwan Lim

Title : The Nearest Stellar Factory : Suzaku X-ray study on 30 Doradus Abstract : We explored the general properties of the diffuse plasma in the 30 Doradus, using Suzaku observations. Exploiting high spectral resolution and a low and stable instrumental background of Suzaku, we were able to do more reliable investigations on 30 Dor. We found that the four seperate wing-like regions of 30 Dor can be modeled as diffuse thin thermal plasma of ~5*10^6K and share quite similar temperatures and chemical enrichments, which could be originating from one of the stellar population at the center of 30Dor. We also found that, because of different column densities of the regions, the overall properties of the whole region as a single spectra should be explored with a more flexible model. This implies that when we observe a distant diffuse object not to be spatially resolved, the spatial mix of the regions is likely to require more careful modeling in order to constrain the parameters such as abundances properly. We also report energy crisis in 30 Dor and possible flatter powerlaw component around the central region.

Chris Thibodeau

Title: The Effect of Clustering on Recovering Sources in Millimeter Surveys Abstract: Surveys of galaxies in millimeter and submillimeter wavelengths probe the dust emission from star-forming galaxies at redshifts 1 < z < 8, and so allow the study of galaxy formation and evolution across cosmic time. However, galaxy clustering can complicate source identification. In this study, we have created and analysed 0.7-by-0.7-degree simulated maps at 1100 microns convolved with an 8-arcsec telescope beam (AzTEC on the 32m Large Millimeter Telescope). The map is populated using a differential counts model by Béthermin et al. (2011). We find that in the case of strong clustering between the source positions, the 60% and 80% completeness limits are about a factor of two higher in flux than the case where sources are positioned randomly (no clustering). We also find an increase in artificial flux boosting of the sources for a given completeness percent that is about a factor of two higher in the strong clustering case than the no-clustering case. This analysis is useful because it allows us to anticipate confusion and flux boosting as a function of detected source flux of AzTEC at a 32m LMT aperture and correct for them in surveys as appropriate. Lastly, we suggest that these results are robust for maps greater than about 0.16 square degrees.

LGRT 1033 Lecture Area

Andrew Battisti

Continuous Mid-Infrared Star Formation Rate Indicators

Karl Haislmaier

Metal-line absorption around z~2.4 star-forming galaxies

LGRT 1033 Lecture Area

Zhankui Lu

Assembly of Galaxies in Dark Matter Halos

LGRT 1033 Lecture Area

Seunghwan Lim

Discovery of the Recombining Plasma In the South of the Galactic Center: A Relic of the Past Galactic Center Activity?

Bomee Lee

Intrinsic characteristics of galaxies at 1≤z≤3.5 in the SFR-M* plane

LGRT 1033 Lecture Area

Chris Thibodeau

Outflow from the Cosmic Eyelash

Allison Kirkpatrick

What Lies Beneath: Probing Dust Obscured Star Formation and Black Hole Growth through Spectral Energy Distributions

LGRT 1033 Lecture Area
 

Mihwa Han

The Nature of Starbursts. III. The Spatial Distribution of Star Formation

Riwaj Pokhrel

Filamentary accretion flows in the embedded Serpens South protocluster.

 

 

LGRT 1033 Lecture Area

Yuping Tang

Dust emissivity in Submillimeter Galaxies

Hansung Gim

The Green Valley is a Red Herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early- and late-type galaxies

LGRT 1033 Lecture Area

Ryan Cybulski

From voids to Coma: the prevalence of pre-processing in the local Universe

LGRT 1033 Lecture Area

Michael Petersen

The Formation and Evolution of Bars as Drivers of Galactic Structure

LGRT 1033 Lecture Area

Shawn Roberts

Galaxies on FIRE (Feedback in Realistic Environments): Stellar Feedback Explains Cosmologically Inefficient Star Formation

Joe Burchett

The Baryon Cycle of Dwarf Galaxies: Dark, Bursty, Gas-Rich Polluters