29 research outputs found
Learning to Be Human by Pretending to Be Elves, Dwarves, and Mages: A Phenomenological Aesthetic of Video Games
Thesis advisor: Eileen SweeneyThis paper combines principles from aesthetic cognitivism with phenomenological embodiment as explained by Maurice Merleau-Ponty in order to construct both an argument for video games as a form of art as well as a method for appreciating them. I argue that the unique status of video games as interactive fictions warrants an adjusted set of aesthetic criteria. My proposed method of examination involves the concept of "fictional embodiment" in which an appreciator imaginatively undergoes the experiences of the video game character. After establishing this framework the paper applies it to narrative and emotion in video games before moving on to extended examples.Thesis (BA) — Boston College, 2014.Submitted to: Boston College. College of Arts and Sciences.Discipline: College Honors Program.Discipline: Philosophy
The Evolution of the Fractions of Quiescent and Star-forming Galaxies as a Function of Stellar Mass Since z=3: Increasing Importance of Massive, Dusty Star-forming Galaxies in the Early Universe
Using the UltraVISTA DR1 and 3D-HST catalogs, we construct a
stellar-mass-complete sample, unique for its combination of surveyed volume and
depth, to study the evolution of the fractions of quiescent galaxies,
moderately unobscured star-forming galaxies, and dusty star-forming galaxies as
a function of stellar mass over the redshift interval . We
show that the role of dusty star-forming galaxies within the overall galaxy
population becomes more important with increasing stellar mass, and grows
rapidly with increasing redshift. Specifically, dusty star-forming galaxies
dominate the galaxy population with at . The ratio of dusty and non-dusty star-forming galaxies as
a function of stellar mass changes little with redshift. Dusty star-forming
galaxies dominate the star-forming population at , being a factor of 3-5 more common,
while unobscured star-forming galaxies dominate at . At , red
galaxies dominate the galaxy population at all redshift , either because
they are quiescent (at late times) or dusty star-forming (in the early
universe).Comment: 7 pages, 4 figures, 1 table. Accepted by Astrophysical Journal
Letters after minor revisio
Stellar and Dust Properties of a Complete Sample of Massive Dusty Galaxies at from MAGPHYS Modeling of UltraVISTA DR3 and Herschel Photometry
We investigate the stellar and dust properties of massive (log) and dusty () galaxies at by modeling
their spectral energy distributions (SEDs) obtained from the combination of
UltraVISTA DR3 photometry and \textit{Herschel} PACS-SPIRE data using MAGPHYS.
Although the rest-frame U-V vs V-J (UVJ) diagram traces well the star-formation
rates (SFR) and dust obscuration (A) out to , 15-20\% of
the sample surprisingly resides in the quiescent region of the UVJ diagram,
while \% at fall in the unobscured star-forming region. The
median SED of massive dusty galaxies exhibits weaker MIR and UV emission, and
redder UV slopes with increasing cosmic time. The IR emission for our sample
has a significant contribution () from dust heated by evolved stellar
populations rather than star formation, demonstrating the need for panchromatic
SED modeling. The local relation between dust mass and SFR is followed only by
a sub-sample with cooler dust temperatures, while warmer objects have reduced
dust masses at a given SFR. Most star-forming galaxies in our sample do not
follow local IRX- relations, though IRX does strongly correlate with
A. Our sample follows local relations, albeit with large scatter, between
ISM diagnostics and sSFR. We show that FIR-detected sources represent the
extreme of a continuous population of dusty galaxies rather than a
fundamentally different population. Finally, using commonly adopted relations
to derive SFRs from the combination of the rest-frame UV and the observed
24m is found to overestimate the SFR by a factor of 3-5 for the galaxies
in our sample.Comment: Accpeted for publication in Ap
HFF-DeepSpace photometric catalogs of the 12 Hubble frontier fields, clusters, and parallels : photometry, photometric redshifts, and stellar masses
We present Hubble multi-wavelength photometric catalogs, including (up to) 17 filters with the Advanced Camera for Surveys and Wide Field Camera 3 from the ultra-violet to near-infrared for the Hubble Frontier Fields and associated parallels. We have constructed homogeneous photometric catalogs for all six clusters and their parallels. To further expand these data catalogs, we have added ultra-deep KS-band imaging at 2.2. mu m from the Very Large Telescope HAWK-I and Keck-I MOSFIRE instruments. We also add post-cryogenic Spitzer imaging at 3.6 and 4.5. mu m with the Infrared Array Camera (IRAC), as well as archival IRAC 5.8 and 8.0. mu m imaging when available. We introduce the public release of the multi-wavelength (0.2-8 mu m) photometric catalogs, and we describe the unique steps applied for the construction of these catalogs. Particular emphasis is given to the source detection band, the contamination of light from the bright cluster galaxies (bCGs), and intra-cluster light (ICL). In addition to the photometric catalogs, we provide catalogs of photometric redshifts and stellar population properties. Furthermore, this includes all the images used in the construction of the catalogs, including the combined models of bCGs and ICL, the residual images, segmentation maps, and more. These catalogs are a robust data set of the Hubble Frontier Fields and will be an important aid in designing future surveys, as well as planning follow-up programs with current and future observatories to answer key questions remaining about first light, reionization, the assembly of galaxies, and many more topics, most notably by identifying high-redshift sources to target
Beyond UVJ: Color Selection of Galaxies in the JWST Era
We present a new rest-frame color-color selection method using "synthetic
and '', colors to identify star-forming and
quiescent galaxies. Our method is similar to the widely-used versus
() diagram. However, suffers known systematics. Spectroscopic
campaigns have shown that -selected quiescent samples at
include contamination from galaxies with dust-obscured star
formation and strong emission lines. Moreover, at , colors are
extrapolated because the rest-frame J-band shifts beyond the coverage of the
deepest bandpasses at (typically /IRAC 4.5 or
future /NIRCam observations). We demonstrate that offers
improvements to at , and can be applied to galaxies in the
era. We apply selection to galaxies at from the (observed)
3D-HST and UltraVISTA catalogs, and to the (simulated) JAGUAR catalogs. We show
that extrapolation can affect color by up to 1 magnitude, but changes
color by 0.2 mag, even at . While
-selected quiescent samples are comparable to in completeness
(both achieve 85-90% at ), reduces contamination in
quiescent samples by nearly a factor of two, from 35% to 17% at
, and from 60% to 33% at . This leads to
improvements in the true-to-false-positive ratio (TP/FP), where we find TP/FP
2.2 for at , compared to TP/FP 1 for
-selected samples. This indicates that contaminants will outnumber true
quiescent galaxies in at these redshifts, while will provide
higher-fidelity samples.Comment: Submitted to Ap
A First Look at Spatially Resolved Balmer Decrements at from JWST NIRISS Slitless Spectroscopy
We present the first results on the spatial distribution of dust attenuation
at traced by the Balmer Decrement, H/H, in
emission-line galaxies using deep JWST NIRISS slitless spectroscopy from the
CAnadian NIRISS Unbiased Cluster Survey (CANUCS). H and H
emission line maps of emission-line galaxies are extracted and stacked in bins
of stellar mass for two grism redshift bins, and
. Surface brightness profiles for the Balmer Decrement are
measured and radial profiles of the dust attenuation towards H,
, are derived. In both redshift bins, the integrated
Balmer Decrement increases with stellar mass. Lower mass
(Log(/M)) galaxies have centrally
concentrated, negative dust attenuation profiles whereas higher mass galaxies
(Log(/M)) have flat dust attenuation
profiles. The total dust obscuration is mild, with on average and
mag in the low and high redshift bins respectively. We model the
typical light profiles of star-forming galaxies at these redshifts and stellar
masses with GALFIT and apply both uniform and radially varying dust attenuation
corrections based on our integrated Balmer Decrements and radial dust
attenuation profiles. If these galaxies were observed with typical JWST NIRSpec
slit spectroscopy ( shutters), on average,
H star formation rates (SFRs) measured after slit-loss corrections
assuming uniform dust attenuation will overestimate the total SFR by and at and
respectively.Comment: 7 pages, 5 figures, submitted to ApJ
CDM not dead yet: massive high-z Balmer break galaxies are less common than previously reported
Early JWST observations that targeted so-called double-break sources
(attributed to Lyman and Balmer breaks at ), reported a previously unknown
population of very massive, evolved high-redshift galaxies. This surprising
discovery led to a flurry of attempts to explain these objects' unexpected
existence including invoking alternatives to the standard CDM
cosmological paradigm. To test these early results, we adopted the same
double-break candidate galaxy selection criteria to search for such objects in
the JWST images of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS), and
found a sample of 19 sources over five independent CANUCS fields that cover a
total effective area of arcmin at . However, (1) our SED
fits do not yield exceptionally high stellar masses for our candidates, while
(2) spectroscopy of five of the candidates shows that while all five are at
high redshifts, their red colours are due to high-EW emission lines in
star-forming galaxies rather than Balmer breaks in massive, evolved systems.
Additionally, (3) field-to-field variance leads to differences of
dex in the maximum stellar masses measured in the different fields, suggesting
that the early single-field JWST observations may have suffered from cosmic
variance and/or sample bias. Finally, (4) we show that the presence of even a
single massive outlier can dominate conclusions from small samples such as
those in early JWST observations. In conclusion, we find that the double-break
sources in CANUCS are not sufficiently massive or numerous to warrant
questioning the standard CDM paradigm.Comment: V2: correction of display problem of Fig.1 in Chrome browser.
Submitted to MNRAS, 10 pages (+4 in Appendix), 5 figures (+4), 1 table (+1
The Sparkler: Evolved High-Redshift Globular Clusters Captured by JWST
Using data from JWST, we analyze the compact sources ("sparkles") located
around a remarkable galaxy (the "Sparkler") that is
strongly gravitationally lensed by the galaxy cluster SMACS
J0723.3-7327. Several of these compact sources can be cross-identified in
multiple images, making it clear that they are associated with the host galaxy.
Combining data from JWST's {\em Near-Infrared Camera} (NIRCam) with archival
data from the {\em Hubble Space Telescope} (HST), we perform 0.4-4.4m
photometry on these objects, finding several of them to be very red and
consistent with the colors of quenched, old stellar systems. Morphological fits
confirm that these red sources are spatially unresolved even in strongly
magnified JWST/NIRCam images, while JWST/NIRISS spectra show [OIII]5007
emission in the body of the Sparkler but no indication of star formation in the
red compact sparkles. The most natural interpretation of these compact red
companions to the Sparkler is that they are evolved globular clusters seen at
. Applying \textsc{Dense Basis} SED-fitting to the sample, we infer
formation redshifts of for these globular cluster
candidates, corresponding to ages of Gyr at the epoch of
observation and a formation time just 0.5~Gyr after the Big Bang. If
confirmed with additional spectroscopy, these red, compact "sparkles" represent
the first evolved globular clusters found at high redshift, could be amongst
the earliest observed objects to have quenched their star formation in the
Universe, and may open a new window into understanding globular cluster
formation. Data and code to reproduce our results will be made available at
\faGithub\href{https://niriss.github.io/sparkler.html}{http://canucs-jwst.com/sparkler.html}.Comment: Submitted to ApJL. Comments are welcome. Data and code to reproduce
our results will be made available at niriss.github.io/sparkler.htm