Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy \u1d6fe rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different \u1d6fe-ray instruments

Observation of the Gamma-Ray Binary HESS J0632+057 with the HESS, MAGIC, and VERITAS Telescopes

The results of gamma-ray observations of the binary system HESS J0632 + 057 collected during 450 hr over 15 yr, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these observations were accompanied by measurements of the H alpha emission line. A significant detection of the modulation of the very high-energy gamma-ray fluxes with a period of 316.7 +/- 4.4 days is reported, consistent with the period of 317.3 +/- 0.7 days obtained with a refined analysis of X-ray data. The analysis of data from four orbital cycles with dense observational coverage reveals short-timescale variability, with flux-decay timescales of less than 20 days at very high energies. Flux variations observed over a timescale of several years indicate orbit-to-orbit variability. The analysis confirms the previously reported correlation of X-ray and gamma-ray emission from the system at very high significance, but cannot find any correlation of optical H alpha parameters with fluxes at X-ray or gamma-ray energies in simultaneous observations. The key finding is that the emission of HESS J0632 + 057 in the X-ray and gamma-ray energy bands is highly variable on different timescales. The ratio of gamma-ray to X-ray flux shows the equality or even dominance of the gamma-ray energy range. This wealth of new data is interpreted taking into account the insufficient knowledge of the ephemeris of the system, and discussed in the context of results reported on other gamma-ray binary systems

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

Reimagining engineering diversity : a study of institutional perspectives on socioeconomic status

While calls to transform engineering education often revolve around pedagogy, curriculum, and student learning (1–4), there is a concomitant need to consider diversity given demographic shifts (5). However, despite various diversity initiatives enacted in the past fifty years, participation and completion by women and minorities in engineering has improved only modestly (6). As a result, some have questioned the almost exclusive focus on gender and ethnicity/race, increasingly turning toward social class as an additional area for exploration (7–10) and another way to consider the field’s “cultural competence” (11). Exploring social class in undergraduate engineering is important and promising in two ways. First, it expands traditional diversity efforts focused on historically underrepresented groups (i.e., women, African-Americans, Latina/os, and Native Americans). Although there is no data presenting low- versus higher-SES student outcomes in engineering, previous research shows that socioeconomic status is an important predictor for achievement (8,12). Social class disadvantages, like high school poverty level, are highly correlated to ethnicity/race (13), but exert a different force based on group membership and institution enrolled (14,15). Thus, more work that examines social class as a relevant component of diversity in engineering is needed. Second, by exploring social class, engineering stakeholders will have a more nuanced understanding of the range of socio-demographic backgrounds (7,8). Social class is often measured by a proxy, socioeconomic status (SES), an index of parent’s level of education, occupation, and income. The typically dichotomous way SES is characterized (e.g., “low SES” versus “high SES”) can contribute to simplistic conceptions of social class disadvantage (16), and potentially inefficient retention efforts. For example, institutional strategies related to financial aid (17) or information-sharing (18,19) seek to address economic challenges and deficits in college-knowledge, respectively. However, there is notable evidence that financial aid alone is not sufficient to overcome attrition risk factors (20,21), and furthermore institutional resources are not equally or properly accessed by all undergraduates (19,22). Social class theory may help explain why conceptions of diversity in engineering should be expanded, and why many engineering students are stifled when it comes to appropriating and manipulating institutional resources to fuel their academic success

Using high school and district economic variables to predict engineering persistence

Prior research has shown that Peer Economic Status (PES), a socioeconomic indicator based on a school’s free lunch participation, is predictive of enrollment in engineering, first-year GPA, and engineering degree completion. In that study, PES was calculated as an average over the entire time period (1987-2004). To further explore the utility of this variable two new time-variant forms will be used, computed at the school-level and the district-level. Academic variables are drawn from the Multiple Institution Database for Investigation of Engineering Longitudinal Development (MIDFIELD) database and high school codes are used to link data from the National Center for Education Statistics (NCES). The time-variant PES is calculated from the four years each student is expected to have been in high school. Additionally, a new algorithm for the treatment of missing values is utilized. The district economic status (DES) is computed in a similar fashion. A series of logistic regression models is used to determine the impact of school- and district-level economic status variables on six-year degree completion. Results show that the time-averaged measures are stronger indicators of engineering persistence than the time-variant measures and that school-level variables are better predictors than district-level variables. Additionally the importance of context in interpreting socioeconomic variables is highlighted

Viewing access and persistence in engineering through a socioeconomic lens

“Education, then, beyond all other devices of human origin, is a great equalizer of conditions of man—the balance wheel of the social machinery. . . . It does better than to disarm the poor of their hostility toward the rich; it prevents being poor.” In contrast to Horace Mann’s inspirational words (1848, p. 669), writers from such varying perspectives as Bourdieu and Passeron (1977), Bowles and Gintis (1976), Bernstein (1990), Livingstone (1987), and Giroux (1983) describe various processes by which social class reproduces through the process of education. In this work, we explore the forces promoting social class reproduction by limiting access to and success in college. Because engineering promises high earnings and the first professional degree is the bachelor’s, access to and success in an engineering degree are of particular interest.Graduation rates of engineering students are discussed as they are related to pre-college measures, institution, race/ethnicity, gender, and socioeconomic status (SES). Researchers often have difficulty identifying the contributions of race and ethnicity to degree attainment and separately the role of family background and income (e.g., Corbett, Hill, & St, Rose, 2008; Tinto, 2006). As we look at the dynamics of access and success for students from all backgrounds, there is an urgent need to identify the relationship between economic conditions, gender, and race/ethnicity both to understand and improve engineering student success. With the economic crisis of 2008 and a shift in the past decade from need-based to merit-based aid, financial challenges to low SES students may be even greater, increasing the urgency of this research.This work expands on the research of Ohland and others (e.g., Ohland et al., 2008) using the Multiple-Institution Database for Investigating Engineering Longitudinal Development (MIDFIELD). MIDFIELD includes student data from 12 engineering colleges, including seven of the 50 largest US undergraduate engineering programs (American Society for Engineering Education, 2010). This discussion will center on social justice and the equality of opportunity, especially for minorities and students attending high-poverty high schools. A socioeconomic lens will be defined in terms of SES, “a measure of an individual or family’s relative economic and social ranking” (Donaldson, Lichtenstein, & Sheppard, 2008). While socioeconomic status was borne through the early work of Marx by identifying social classes via property ownership, notions of class also take Bourdieuian form in their attention to power and culture (Collins, 1994), accounting for economic, but also human, cultural, and social capital. While not considered synonymous, SES is often used as a proxy for social class status, although sociologists agree that notions of class have largely gone unresolved (Lareau & Conley, 2008). In social theory, education is both seen as a “great equalizer” and simultaneously as a location for promoting social stratification. That is, individuals from higher social classes will have relatively higher economic, human, cultural, and social capital that will be rewarded in schools, resulting in higher achievement. In educationalresearch, SES is often operationalized as a composite measure of parent education levels, parent occupations, and family income or wealth. In this study, we define our socioeconomic lens in terms of eligibility for free lunch (Harwell & LeBeau, 2010), which is thefourth most common measure for SES, after parental education, occupation, and income (Sirin, 2005). Free lunch eligibility, which is granted if family income is at or less than 130% of the poverty line, is used as a proxy for economic and social ranking. That is, we assume that free lunch eligibility is indirectly related to family income, but directly related to housing and schooling patterns, and accordingly the socioeconomic background of students in particular high schools. From our database, we plan to show the relationship between a student’s socioeconomic background, gender, and race/ethnicity as it relates to college access and graduation rates in our sample of engineering undergraduates

Gaining access or losing ground? : Socioeconomically disadvantaged students in undergraduate engineering, 1994-2003

Expanding access to engineering for underrepresented groups has by and large focused on ethnicity/race and gender, with little understanding of socioeconomic disadvantages. In this study, we use economic, human, and cultural capital theories to frame and then describe access to undergraduate engineering degree programs and bachelor’s degrees. Using individual student-level data from 10 universities from the Multiple-Institution Database for Investigating Engineering Longitudinal Development (MIDFIELD) and aggregate school-level data (i.e., free-lunch status) from the Common Core of Data between 1994 and 2003, we first describe students who enter engineering programs by peer economic status (PES) with attention to gender, ethnicity/race, and SAT Math score. Second, a subset of the data is analyzed to describe access to bachelor’s degrees in engineering by PES using graduation rates. The findings show an increase in access to engineering degree programs by disadvantaged students, but that access to engineering bachelor’s degrees may be constrained, and especially for underrepresented ethnic/racial groups. The data highlight variable PES differences that accrue in engineering at entry and upon graduation (6 years later) across ethnic/racial groups; these differences have implications for broadening participation. Recommendations for future research and improving engineering access at the secondary and postsecondary levels are discussed

A Culture of Success: Black Alumnae Discussions of the Assets-Based Approach at Spelman College

Some campuses are exemplars for best practices for racial inclusion in higher education, and they offer a vital opportunity to understand how to better include Black students. This critical life story analysis of Black college alumnae who graduate from a historically Black, women’s institution, Spelman College, demonstrates the importance of fostering success throughout a student’s college experience. The findings suggest that Spelman offered a deliberate and systematic culture of success from the beginning to the end of the women’s experiences offering lessons that could be adapted within other institutional types in order to foster the success of Black students