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The processes allowing the escape of ionizing photons from galaxies into the intergalactic medium are poorly known. To understand how Lyman continuum (LyC) photons escape galaxies, we constrain the HI covering fractions and column densities…

星系天体物理 · 物理学 2018-08-08 Simon Gazagnes , John Chisholm , Daniel Schaerer , Anne Verhamme , Jane R. Rigby , Matthew Bayliss

Ionized outflows in Active Galactic Nuclei (AGN) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our…

高能天体物理现象 · 物理学 2017-11-22 Junjie Mao , J. S. Kaastra , M. Mehdipour , A. J. J. Raassen , Liyi Gu , J. M. Miller

We report results from a FUSE survey of interstellar molecular hydrogen (H2) along 45 sight lines to AGN at high Galactic latitudes (|b| > 20 degrees). Most (39 of 45) of the sight lines show detectable Galactic H2 absorption from Lyman and…

天体物理学 · 物理学 2009-11-13 Kristen Gillmon , J. Michael Shull , Jason Tumlinson , Charles Danforth

In this white paper we describe the prospects for ASTRO-H for the study of outflows from active galactic nuclei. The most important breakthroughs in this field are expected to arise from the high spectral resolution and sensitivity in the…

Helium is a pivotal element in understanding multiple main sequences and extended horizontal branches observed in some globular clusters. Here we present a spectroscopic study of helium in the nearby globular cluster M4. We have obtained…

太阳与恒星天体物理 · 物理学 2015-08-06 Jay Strader , A. K. Dupree , Graeme H. Smith

As a complement to the HyGAL Stratospheric Observatory for Infrared Astronomy Legacy Program, we report the results of a ground-based absorption line survey of simple molecules in diffuse and translucent Galactic clouds. Using the Institut…

The observational counterparts of theoretically predicted first hydrostatic cores (FHSC) have been searched for in the interstellar medium for nearly two decades now. Distinguishing them from other types of more evolved but still embedded…

星系天体物理 · 物理学 2022-11-09 V. Wakelam , A. Coutens , P. Gratier , T. H G Vidal , N. Vaytet

High mass stars form in groups or clusters within massive cores in dense molecular clumps with sizes of 1pc and masses of 200Msun which are important laboratories for high-mass star formation in order to study the initial conditions. We…

星系天体物理 · 物理学 2018-12-12 Gozde Saral , Marc Audard , Yuan Wang

A density functional theory is used to investigate the instability arising in superfluid $^4$He as it flows at velocity u just above the Landau critical velocity of rotons v_c. Confirming an early theoretical prediction by one of us [JETP…

其他凝聚态物理 · 物理学 2009-11-10 F. Ancilotto , F. Dalfovo , L. P. Pitaevskii , F. Toigo

We have obtained Keck HIRES spectra of three images of the gravitationally lensed QSO 2237+0305 to study low ionization absorption systems and their differences in terms of projected velocity and column density across the lines of sight. We…

天体物理学 · 物理学 2009-11-07 M. Rauch , W. L. W. Sargent , T. A. Barlow , R. A. Simcoe

There is a robust polyatomic chemistry in diffuse, partially-molecular interstellar gas that is readily accessible in absorption at radio/mm/sub-mm wavelengths. Accurate column densities are derived owing to the weak internal excitation, so…

星系天体物理 · 物理学 2023-02-15 Harvey Liszt , Maryvonne Gerin

Aims: We searched for the molecular outflows from fifteen molecular clouds associated with ultra-compact and compact HII (UCHII/HII) regions and discussed possible gas heating mechanism. Methods: Mapping observations of CO $J=3-2$ and…

天体物理学 · 物理学 2009-11-13 Sheng-Li Qin , Jun-Jie Wang , Gang Zhao , Martin Miller , Jun-Hui Zhao

Several neutral species (MgI, SiI, CaI, FeI) have been detected in a weak MgII absorption line system (W_r(2796)~0.15 Angstroms) at z~0.45 along the sightline toward HE0001-2340. These observations require extreme physical conditions, as…

宇宙学与河外天体物理 · 物理学 2015-05-18 Therese M. Jones , Toru Misawa , Jane C. Charlton , Andrew C. Mshar , Gary J. Ferland

(Abridged) We have used the Far Ultraviolet Spectroscopic Explorer (FUSE) to search for H_2 absorption in five starburst galaxies: NGC 1705, NGC 3310, NGC 4214, M83 (NGC 5236), and NGC 5253. We tentatively detect weak absorption by H_2 in…

天体物理学 · 物理学 2009-11-10 C. G. Hoopes , K. R. Sembach , T. M. Heckman , G. R. Meurer , A. Aloisi , D. Calzetti , C. Leitherer , C. L. Martin

BL Lacertae (Lac) objects that are detected at very-high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties of the extragalactic background light and the…

For a detailed analysis of stellar chemical abundances, high-resolution spectra in the optical have mainly been used, while the development of near-infrared (NIR) spectrograph has opened new wavelength windows. Red giants have a large…

We have undertaken the largest survey for outflows within the Galactic Plane using simultaneously observed 13CO and C18O data. 325 out of a total of 919 ATLASGAL clumps have data suitable to identify outflows, and 225 (69+-3%) of them show…

星系天体物理 · 物理学 2018-09-05 Aiyuan Yang , Mark Thompson , James Urquhart , Wenwu Tian

Emission signatures from galactic winds provide an opportunity to directly map the outflowing gas, but this is traditionally challenging because of the low surface brightness. Using deep observations (27 hours) of the Hubble Deep Field…

We present a measurement of the HI column density distribution function, f(N), at the present epoch for column densities log N > 20 cm^-2. These high column densities compare to those measured in damped Ly alpha lines seen in absorption…

天体物理学 · 物理学 2015-06-24 Martin Zwaan , Marc Verheijen , Frank Briggs

We have used a numerical simulation of a turbulent cloud to synthesize maps of the thermal emission from dust at a variety of far-IR and sub-mm wavelengths. The average column density and external radiation field in the simulation is well…

天体物理学 · 物理学 2009-11-11 S. Schnee , T. Bethell , A. Goodman