9,599 research outputs found

    Near-Infrared MOSFIRE Spectra of Dusty Star-Forming Galaxies at 0.2<z<4

    Get PDF
    We present near-infrared and optical spectroscopic observations of a sample of 450Ī¼\mum and 850Ī¼\mum-selected dusty star-forming galaxies (DSFGs) identified in a 400 arcmin2^2 area in the COSMOS field. Thirty-one sources of the 102 targets were spectroscopically confirmed at 0.2<z<40.2<z<4, identified primarily in the near-infrared with Keck MOSFIRE and some in the optical with Keck LRIS and DEIMOS. The low rate of confirmation is attributable both to high rest-frame optical obscuration in our targets and limited sensitivity to certain redshift ranges. The high-quality photometric redshifts available in the COSMOS field allow us to test the robustness of photometric redshifts for DSFGs. We find a subset (11/31ā‰ˆ35\approx35%) of DSFGs with inaccurate (Ī”z/(1+z)>0.2\Delta z/(1+z)>0.2) or non-existent photometric redshifts; these have very distinct spectral energy distributions from the remaining DSFGs, suggesting a decoupling of highly obscured and unobscured components. We present a composite rest-frame 4300--7300\AA\ spectrum for DSFGs, and find evidence of 200Ā±\pm30 km sāˆ’1^{-1} gas outflows. Nebular line emission for a sub-sample of our detections indicate that hard ionizing radiation fields are ubiquitous in high-z DSFGs, even more so than typical mass or UV-selected high-z galaxies. We also confirm the extreme level of dust obscuration in DSFGs, measuring very high Balmer decrements, and very high ratios of IR to UV and IR to HĪ±\alpha luminosities. This work demonstrates the need to broaden the use of wide bandwidth technology in the millimeter to the spectroscopic confirmations of large samples of high-z DSFGs, as the difficulty in confirming such sources at optical/near-infrared wavelengths is exceedingly challenging given their obscuration.Comment: 14 pages, 13 figures, ApJ accepted. Composite DSFG Halpha spectrum available at www.as.utexas.edu/~cmcasey/downloads.htm

    A massive, distant proto-cluster at z=2.47 caught in a phase of rapid formation?

    Get PDF
    Numerical simulations of cosmological structure formation show that the Universe's most massive clusters, and the galaxies living in those clusters, assemble rapidly at early times (2.5 < z < 4). While more than twenty proto-clusters have been observed at z > 2 based on associations of 5-40 galaxies around rare sources, the observational evidence for rapid cluster formation is weak. Here we report observations of an asymmetric, filamentary structure at z = 2.47 containing seven starbursting, submillimeter-luminous galaxies and five additional AGN within a comoving volume of 15000 Mpc3^{3}. As the expected lifetime of both the luminous AGN and starburst phase of a galaxy is ~100 Myr, we conclude that these sources were likely triggered in rapid succession by environmental factors, or, alternatively, the duration of these cosmologically rare phenomena is much longer than prior direct measurements suggest. The stellar mass already built up in the structure is āˆ¼1012MāŠ™\sim10^{12}M_{\odot} and we estimate that the cluster mass will exceed that of the Coma supercluster at zāˆ¼0z \sim 0. The filamentary structure is in line with hierarchical growth simulations which predict that the peak of cluster activity occurs rapidly at z > 2.Comment: 7 pages, 3 figures, 2 tables, accepted in ApJL (small revisions from previous version

    An Education System Built on the Pillars of White Supremacy and Anti-Blackness: A Collection of Autoethnographic Studies Depicting How Black Kids Never Had a Chance

    Get PDF
    In this collection of autoethnographic studies, a group of five women with differing racial identities takes us through each of their deeply personal journeys of social justice awareness and transformation. Using the theoretical frameworks of Critical Race Theory and Critical Whiteness Studies, these women share personal narratives of their lived experiences depicting how the education system in the United States is built on the pillars of White supremacy and anti-Blackness. Through their stories, we learn that schools are not meant for all students to succeed, and in actuality, Black students never had a chance. This collection of autoethnographic studies exposes how our school system perpetuates the larger agenda of White supremacy in our nation. The study concludes with implications of the work and suggestions for the future of multicultural education, hoping that one day we will have an education system that fosters the success of each student

    The Indian family on UK reality television: Convivial culture in salient contexts

    Get PDF
    This is the author's accepted manuscript. The final published article is available from the link below, copyright 2012 @ the author.This article demonstrates how The Family (2009), a fly-on-the wall UK reality series about a British Indian family, facilitates both current public service broadcasting requirements and mass audience appeal. From a critical cultural studies perspective, the author examines the journalistic and viewer responses to the series where authenticity, universality, and comedy emerge as major themes. Textual analysis of the racialized screen representations also helps locate the series within the contexts of contested multiculturalism, genre developments in reality television and public service broadcasting. Paul Gilroyā€™s concept of convivial culture is used as a frame in understanding how meanings of the series are produced within a South Asian popular representational space. The author suggests that the social comedy taxonomy is a prerequisite for the making of this particular observational documentary. Further, the popular (comedic) mode of conviviality on which the series depends is both expedient and necessary within the various sociopolitical contexts outlined

    Identification of a novel retroviral gene unique to human immunodeficiency virus type 2 and simian immunodeficiency virus SIVMAC

    Get PDF
    Human and simian immunodeficiency-associated retroviruses are extraordinarily complex, containing at least five genes, tat, art, sor, R, and 3' orf, in addition to the structural genes gag, pol, and env. Recently, nucleotide sequence analysis of human immunodeficiency virus type 2 (HIV-2) and simian immunodeficiency virus SIVMAC revealed the existence of still another open reading frame, termed X, which is highly conserved between these two viruses but absent from HIV-1. In this report, we demonstrate for the first time that the X open reading frame represents a functional retroviral gene in both HIV-2 and SIVMAC and that it encodes a virion-associated protein of 14 and 12 kilodaltons, respectively. We also describe the production of recombinant TrpE/X fusion proteins in Escherichia coli and show that sera from some HIV-2-infected individuals specifically recognize these proteins
    • ā€¦
    corecore