TY - JOUR A1 - Abeysekara, A. U. A1 - Archer, A. A1 - Benbow, Wystan A1 - Bird, Ralph A1 - Brill, A. A1 - Brose, Robert A1 - Buckley, J. H. A1 - Christiansen, Jessie L. A1 - Chromey, A. J. A1 - Daniel, M. K. A1 - Falcone, A. A1 - Feng, Qi A1 - Finley, John P. A1 - Fortson, L. A1 - Furniss, Amy A1 - Gillanders, Gerard H. A1 - Gueta, O. A1 - Hanna, David A1 - Hervet, O. A1 - Holder, J. A1 - Hughes, G. A1 - Humensky, T. B. A1 - Johnson, Caitlin A. A1 - Kaaret, Philip A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Kieda, David A1 - Krause, Maria A1 - Krennrich, F. A1 - Lang, M. J. A1 - Moriarty, P. A1 - Mukherjee, Reshmi A1 - Ong, R. A. A1 - Otte, A. N. A1 - Park, N. A1 - Petrashyk, A. A1 - Pohl, Martin A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, Gregory T. A1 - Roache, E. A1 - Rulten, C. A1 - Sadeh, I. A1 - Santander, Marcos A1 - Scott, S. S. A1 - Sembroski, G. H. A1 - Shahinyan, Karlen A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Wells, R. M. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Williamson, T. J. A1 - Zitzer, B. A1 - Kaur, A. T1 - VERITAS Observations of the BL Lac Object TXS 0506+056 JF - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters N2 - On 2017 September 22, the IceCube Neutrino Observatory reported the detection of the high-energy neutrino event IC 170922A, of potential astrophysical origin. It was soon determined that the neutrino direction was consistent with the location of the gamma-ray blazar TXS 0506+056. (3FGL J0509.4+ 0541), which was in an elevated gamma-ray emission state as measured by the Fermi satellite. Very Energetic Radiation Imaging Telescope Array System (VERITAS) observations of the neutrino/blazar region started on 2017 September 23 in response to the neutrino alert and continued through 2018 February 6. While no significant very-high-energy (VHE; E > 100 GeV) emission was observed from the blazar by VERITAS in the two-week period immediately following the IceCube alert, TXS 0506+ 056 was detected by VERITAS with a significance of 5.8 standard deviations (sigma) in the full 35 hr data set. The average photon flux of the source during this period was (8.9 +/- 1.6). x. 10(-12) cm(-2) s(-1), or 1.6% of the Crab Nebula flux, above an energy threshold of 110 GeV, with a soft spectral index of 4.8. +/-. 1.3. KW - astroparticle physics KW - BL Lacertae objects: individual (TXS 0506+056, VER J0509+057) KW - gamma rays: galaxies KW - quasars: general KW - neutrinos Y1 - 2018 U6 - https://doi.org/10.3847/2041-8213/aad053 SN - 2041-8205 SN - 2041-8213 VL - 861 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Johnson, Sean D. A1 - Chen, Hsiao-Wen A1 - Straka, Lorrie A1 - Schaye, Joop A1 - Cantalupo, Sebastiano A1 - Wendt, Martin A1 - Muzahid, Sowgat A1 - Bouché, Nicolas A1 - Herenz, Edmund Christian A1 - Kollatschny, Wolfram A1 - Mulchaey, John S. A1 - Marino, Raffaella A. A1 - Maseda, Michael A1 - Wisotzki, Lutz T1 - Galaxy and quasar fueling caught in the act from the intragroup to the interstellar medium JF - The astrophysical journal : Part 2, Letters N2 - We report the discovery of six spatially extended (10-100 kpc) line-emitting nebulae in the z approximate to 0.57 galaxy group hosting PKS 0405-123, one of the most luminous quasars at z < 1. The discovery is enabled by the Multi Unit Spectroscopic Explorer and provides tantalizing evidence connecting large-scale gas streams with nuclear activity on scales of <10 proper kpc (pkpc). One of the nebulae exhibits a narrow, filamentary morphology extending over 50 pkpc toward the quasar with narrow internal velocity dispersion (50 km s(-1)) and is not associated with any detected galaxies, consistent with a cool intragroup medium filament. Two of the nebulae are 10 pkpc north and south of the quasar with tidal-arm-like morphologies. These two nebulae, along with a continuum-emitting arm extending 60 pkpc from the quasar, are signatures of interactions that are expected to redistribute angular momentum in the host interstellar medium (ISM) to facilitate star formation and quasar fueling in the nucleus. The three remaining nebulae are among the largest and most luminous [O III] emitting "blobs" known (1400-2400 pkpc(2)) and correspond both kinematically and morphologically to interacting galaxy pairs in the quasar host group, consistent with arising from stripped ISM rather than large-scale quasar outflows. The presence of these large- and small-scale nebulae in the vicinity of a luminous quasar bears significantly on the effect of large-scale environment on galaxy and black hole fueling, providing a natural explanation for the previously known correlation between quasar luminosity and cool circumgalactic medium. KW - galaxies: interactions KW - intergalactic medium KW - quasars: general KW - quasars: individual (PKS 0405-123) Y1 - 2018 U6 - https://doi.org/10.3847/2041-8213/aaf1cf SN - 2041-8205 SN - 2041-8213 VL - 869 IS - 1 PB - IOP Publishing Ltd. (Bristol) CY - Bristol ER - TY - JOUR A1 - Marino, Raffaella Anna A1 - Cantalupo, Sebastiano A1 - Lilly, Simon J. A1 - Gallego, Sofia G. A1 - Straka, Lorrie A. A1 - Borisova, Elena A1 - Pezzulli, Gabriele A1 - Bacon, Roland A1 - Brinchmann, Jarle A1 - Carollo, C. Marcella A1 - Caruana, Joseph A1 - Conseil, Simon A1 - Contini, Thierry A1 - Diener, Catrina A1 - Finley, Hayley A1 - Inami, Hanae A1 - Leclercq, Floriane A1 - Muzahid, Sowgat A1 - Richard, Johan A1 - Schaye, Joop A1 - Wendt, Martin A1 - Wisotzki, Lutz T1 - Dark Galaxy Candidates at Redshift similar to 3.5 Detected with MUSE JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - Recent theoretical models suggest that the early phase of galaxy formation could involve an epoch when galaxies are gas rich but inefficient at forming stars: a "dark galaxy" phase. Here, we report the results of our Multi-Unit Spectroscopic Explorer (MUSE) survey for dark galaxies fluorescently illuminated by quasars at z > 3. Compared to previous studies which are based on deep narrowband (NB) imaging, our integral field survey provides a nearly uniform sensitivity coverage over a large volume in redshift space around the quasars as well as full spectral information at each location. Thanks to these unique features, we are able to build control samples at large redshift distances from the quasars using the same data taken under the same conditions. By comparing the rest-frame equivalent width (EW0) distributions of the Ly alpha sources detected in proximity to the quasars and in control samples, we detect a clear correlation between the locations of high-EW0 objects and the quasars. This correlation is not seen in other properties, such as Ly alpha luminosities or volume overdensities, suggesting the possible fluorescent nature of at least some of these objects. Among these, we find six sources without continuum counterparts and EW0 limits larger than 240 angstrom that are the best candidates for dark galaxies in our survey at z > 3.5. The volume densities and properties, including inferred gas masses and star formation efficiencies, of these dark galaxy candidates are similar to those of previously detected candidates at z approximate to 2.4 in NB surveys. Moreover, if the most distant of these are fluorescently illuminated by the quasar, our results also provide a lower limit of t - 60 Myr on the quasar lifetime. KW - galaxies: formation KW - galaxies: high-redshift KW - galaxies: star formation KW - intergalactic medium KW - quasars: emission lines KW - quasars: general Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aab6aa SN - 0004-637X SN - 1538-4357 VL - 859 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Schmidt, Tobias M. A1 - Hennawi, Joseph F. A1 - Worseck, Gabor A1 - Davies, Frederick B. A1 - Lukic, Zarija A1 - Oñorbe, Jose T1 - Modeling the HeII transverse proximity effect BT - constraints on quasar lifetime and obscuration JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - The He II transverse proximity effect-enhanced He II Ly alpha transmission in a background sightline caused by the ionizing radiation of a foreground quasar-offers a unique opportunity to probe the emission properties of quasars, in particular the emission geometry (obscuration, beaming) and the quasar lifetime. Building on the foreground quasar survey published in Schmidt et al., we present a detailed model of the He II transverse proximity effect, specifically designed to include light travel time effects, finite quasar ages, and quasar obscuration. We postprocess outputs from a cosmological hydrodynamical simulation with a fluctuating He II ultraviolet background model, with the added effect of the radiation from a single bright foreground quasar. We vary the age t(age) and obscured sky fractions Omega(obsc) of the foreground quasar, and explore the resulting effect on the He II transverse proximity effect signal. Fluctuations in intergalactic medium density and the ultraviolet background, as well as the unknown orientation of the foreground quasar, result in a large variance of the He II Ly alpha transmission along the background sightline. We develop a fully Bayesian statistical formalism to compare far-ultraviolet He II Ly alpha transmission spectra of the background quasars to our models, and extract joint constraints on t(age) and Omega(obsc) for the six Schmidt et al. foreground quasars with the highest implied He II photoionization rates. Our analysis suggests a bimodal distribution of quasar emission properties, whereby one foreground quasar, associated with a strong He II transmission spike, is relatively old (22 Myr) and unobscured (Omega(obsc) < 35%), whereas three others are either younger than 10 Myr or highly obscured (Omega(obsc) > 70%). KW - dark ages, reionization, first stars KW - intergalactic medium KW - quasars: general Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aac8e4 SN - 0004-637X SN - 1538-4357 VL - 861 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER -