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Kinematic Confirmation of a Remarkable Linear Trail of Galaxies in the NGC 1052 Field, Consistent with Formation in a High-speed Bullet Dwarf Collision
Get PDFA unique linear trail of diffuse galaxies was recently identified in the NGC 1052 field. This trail includes the remarkable, ultradiffuse galaxies DF2 and DF4, which lack dark matter and host unusually luminous globular clusters. It has been proposed that the trail formed via a high-speed collision between two gas-rich dwarf galaxies. This scenario predicts that the trail galaxies are kinematically connected and follow a specific trend in radial velocity as a function of position, based on the known velocities and positions of DF2 and DF4. To test this hypothesis, we measured radial velocities for seven additional galaxies on the trail. While the galaxies’ low surface brightnesses presented observational challenges, we employ several methods to obtain measurements for galaxies with effective surface brightnesses up to 28.6 mag arcsec−2, including a narrow slit placed over globular clusters and a novel wide slit mode on Keck/Low Resolution Imaging Spectrometer (LRIS), as well as a “light bucket” mode on Keck/Keck Cosmic Web Imager (KCWI). We find that five of our seven targets follow the precise velocity trend predicted by DF2 and DF4, to a degree with just a 2% chance of randomly occurring. Moreover, the trail galaxies’ radial velocities are significantly higher than those of the NGC 1052 group, setting it apart as a separate, kinematically connected system. Our findings support the theory that this trail of galaxies, including DF2 and DF4, formed together in a single event. A “bullet dwarf” collision remains the only known explanation for all the unusual properties of DF2, DF4, and the associated trail of galaxies
Dynamic Mode Decomposition of Geostrophically Balanced Motions From SWOT Cal/Val in the Separated Gulf Stream
Get PDFThe decomposition of oceanic flow into its geostrophically balanced and unbalanced motions carries theoretical and practical significance for the oceanographic community. These two motions have distinct dynamical characteristics and affect the transport of tracers differently from one another. The launch of the Surface Water and Ocean Topography (SWOT) satellite provides a prime opportunity to diagnose the surface balanced and unbalanced motions on a global scale at an unprecedented spatial resolution. Here, we apply dynamic-mode decomposition (DMD), a linear-algebraic data-driven method, to tidally-forced idealized and realistic numerical simulations at submesoscale-permitting resolution and one-day-repeat SWOT observations of sea-surface height (SSH) in the Gulf Stream downstream of Cape Hatteras, a region commonly referred to as the separated Gulf Stream. DMD is able to separate out the spatial modes associated with sub-inertial periods from super-inertial periods. The sub-inertial modes of DMD can be used to extract geostrophically balanced motions from SSH fields, which have an imprint of internal gravity waves, so long as the data extends long enough in time. We utilize the statistical relation between relative vorticity and strain rate as the metric to gauge the extraction of geostrophy
Radial velocities and stellar populations for a sample of MATLAS survey dwarfs
Get PDFSpectroscopic observations are essential for confirming associations, measuring kinematics, and determining stellar populations in dwarf galaxies. Here, we present Keck Cosmic Web Imager spectra for 12 MATLAS survey dwarfs. For 9, we confirm recession velocities consistent with their literature-assumed host galaxies. We propose revisions of the host galaxy associations for MATLAS-631, 1494, and 1938. For MATLAS-1494, our measured redshift reclassifies it from an ultra-diffuse galaxy candidate to a dwarf galaxy that is of smaller physical size and places it in the field. It also appears old and passive, providing a challenge to models that invoke quenching by tidal effects. Additionally, we measure stellar population estimates for 7 of the 12 galaxies, finding a ‘mixed bag’ of old quenched galaxies and those that are currently forming stars. Compared to the literature we find generally younger ages and higher metallicities. This result may help reconcile the observed offset of MATLAS survey dwarf galaxies from the universal stellar mass-metallicity relationship reported by Heesters et al. (2023)
Comparing self-construal scales: Cultural implications for the United States, East Asia, Southeast Asia, Latin America, and the Middle East
Get PDFContemporary self-construal research indicates that people define themselves either as independent or interdependent. We review self-construal scales across the United States, East Asia, Southeast Asia, Latin America, and the Middle East to compare/contrast their operationalizations of interdependence (or independence). Taken together, this body of research suggests that, consistent with findings on American and East Asian selves, Southeast Asian cultures also exhibit interdependent self-construal. Latin Americans, however, display independent self-construal despite their long-standing characterization as a collectivist culture, while Arabs display both independence and interdependence. Future directions—including the improved validity of multidimensional measures of the self over dichotomous scales, cultural differences on distinctiveness, research on bicultural individuals, within-cultural comparisons, and the role of polyculturalism—are discussed
An Unexplained Origin for the Unusual Globular Cluster System in the Ultradiffuse Galaxy FCC 224
No full textWe study the quiescent ultradiffuse galaxy FCC 224 in the Fornax cluster using Hubble Space Telescope (HST) imaging, motivated by peculiar properties of its globular cluster (GC) system revealed in shallower imaging. The surface brightness fluctuation distance of FCC 224 measured from HST is 18.6 ± 2.7 Mpc, consistent with the Fornax cluster distance. We use Prospector to infer the stellar population from a combination of multiwavelength photometry (HST, ground-based, Wide-field Infrared Survey Explorer) and Keck Cosmic Web Imager spectroscopy. The galaxy has a mass-weighted age of ∼10 Gyr, metallicity [M/H] of ∼−1.25 dex, and a very short formation e-folding time of τ ∼ 0.3 Gyr. Its 12 candidate GCs exhibit highly homogeneous g475 − I814 colors, merely 0.04 mag bluer than the diffuse starlight, which supports a single-burst formation scenario for this galaxy. We confirm a top-heavy GC luminosity function, similar to the two dark matter deficient galaxies NGC 1052-DF2 and DF4. However, FCC 224 differs from those galaxies with relatively small GC sizes of ∼3 pc (∼35% smaller than typical for other dwarfs), and with radial mass segregation in its GC system. We are not yet able to identify a formation scenario to explain all of the GC properties in FCC 224. Follow-up measurements of the dark matter content in FCC 224 will be crucial because of the mix of similarities and differences among FCC 224, DF2, and DF4
A Review of Social, Behavioral, and Ethical Considerations for Smart Life Engineering
Get PDFSmart Life (SL) systems do not exist in a technological vacuum; they are embedded in a social ecosystem and have rich and complex interactions with their surroundings. It is important to recognize that their design and implementation will have an impact on the individuals and communities around them. This chapter examines the social, behavioral, and ethical issues to be considered in a holistic systems approach to SL engineering, to help practitioners and stakeholders to design the strategies needed for successful SL deployments. It addresses these topics from several disciplinary viewpoints and provides a comprehensive set of references for those requiring further detailed information
Is drainage reorganization a plausible explanation for late Cenozoic incision of Yosemite Valley and within the Kings and Kaweah watersheds (Sierra Nevada, California)?
Get PDFIncreases in the rates of river incision can be driven by a variety of causes, such as tectonic uplift, changes in sediment supply, changes in climate, and drainage reorganization. Here, I evaluate whether drainage reorganization may have driven late Cenozoic episodes of accelerated river incision in the Sierra Nevada (California) that have previously been attributed to uplift. I propose several lines of evidence useful for distinguishing between these two potential drivers of incision and apply them at three sites with well-documented histories of late Cenozoic incision: Yosemite Valley and Tenaya Canyon, along the South Fork Kings River, and in the Kaweah River watershed. These lines of evidence include the spatial patterns of knickpoints and relief, the presence of paleochannels, the morphologies of alluvial fans, and results from numerical modeling. The analyses suggest that a river draining a Miocene–Pliocene volcanic edifice along the crest of the northern Sierra Nevada temporarily extended into Tenaya Creek, greatly increasing the latter’s erosive power and incising Tenaya Canyon and Yosemite Valley. This hypothesis explains previously unsolved issues, such as the presence of voluminous andesitic volcaniclastic deposits in the Merced River paleofan, despite their absence in the Merced watershed, and the discrepancy in relief between Tenaya Canyon and neighboring Little Yosemite Valley. Results for the Kings River drainage show that deep incision since the mid-Pliocene has been confined to the upper portion of its watershed and that it occurred in a rapid pulse, consistent with an episode of stream piracy. Albeit limited, the geomorphic evidence for drainage reorganization in the Kaweah watershed includes a 1800-m-high convex knickpoint on a trunk stream and an anomalously large alluvial fan. This study demonstrates the importance of considering drainage reorganization as an alternative to uplift when investigating abrupt and short-lived increases in river incision rates
The Impact of Early Life Experiences on Math Confidence
Get PDFStudents form beliefs about their academic abilities through a combination of emotional experiences and early learning environments. While prior research has documented how math anxiety can undermine performance and how early experiences with math-typed activities can foster positive attitudes, less is known about how these factors collectively influence students’ math confidence. The present study investigates how math anxiety, engagement in childhood math-typed activities, and perceived support for math-related learning contribute to college students’ confidence in their math abilities. Participants (N = 102) completed self-report measures assessing each of these constructs. A multiple regression analysis revealed that the three predictors collectively accounted for 63% of the variance in math confidence. Math anxiety was the strongest predictor, showing a robust negative association with math confidence. Childhood math-typed activities were also significantly and positively associated with math confidence, while perceived support was not a significant unique predictor in the model. Exploratory results suggest that gender is marginally associated with math confidence. These findings suggest that emotional barriers and early informal experiences may be more central to math confidence than generalized perceptions of support, and they highlight the value of addressing math anxiety and early engagement to promote long-term confidence in quantitative domains. Keywords: math confidence, math anxiety, childhood activities, perceived suppor
The Relationship Between Hindrance Demands and Work Engagement: The Moderating Role of Resilience
Get PDFThe coronavirus pandemic decreased work engagement globally due to increased hindrance demands. Many organizations were motivated to increase work engagement, which is positively correlated with beneficial organizational outcomes. The intention of this study is to examine if personal resources like resilience moderate the relationship between hindrance demands and work engagement. Hindrance demands are refined from job demands and hindrance stressors, which are stressors that impede progress in employees. Resilience is a personal resource correlated with pro-social behavior, internal locus of control, and higher levels of empathy. Resilience as a personal resource has mainly been studied as a predictor of work engagement, not as a moderator of the relationship between job demands and work engagement. The study was conducted with through an online survey with 90 participants. The results showed resilience did not moderate the relationship between hindrance demands and work engagement. However, results showed that hindrance demands were negatively associated with work engagement, while resilience had a positive relationship with work engagement. Organizations can boost work engagement by investing in resilience-based interventions to boost resilience in employees and reducing hindrance demands
Living in the Hyphen: Creating Puentes through Encuentros and Pláticas with Latinx Cross-Cultural Kids
No full textLatinx cross-cultural kids, or children of immigrants, are often faced with a feeling of not belonging to mainstream American culture nor their parents’ home culture(s) of origin. As such, they are viewed through a deficit lens and forced to negotiate their sense of identity and belonging through language and culture to fit in. By embracing the concept of educación, using culturally responsive methods of encuentros and pláticas with cross-cultural kids and their families, this study intends to find ways to foster a sense of belonging for this population in schools through participants’ testimonies. It aims to find ways to bridge the educación at home with the formal academic education in schools to find a place where both languages and cultures unite to strengthen the bond between the two environments. Through critical race theory and community cultural wealth, this study intends to shift the narrative from a deficit lens where Latinx cross-cultural students are seen as not belonging to either culture to an asset-based narrative where they are seen as belonging to both. My hope is that Latinx cross-cultural kids and their families are recognized and appreciated for what they bring to any educational setting instead of what they lack and find a sense of belonging in all spaces where it once failed to exist