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相关论文: A Very Sensitive 21cm Survey for Galactic High-Vel…

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We report a deep Giant Metrewave Radio Telescope (GMRT) search for Galactic H{\sc i} 21cm absorption towards the quasar B0438$-$436, yielding the detection of wide, weak H{\sc i} 21cm absorption, with a velocity-integrated H{\sc i} 21cm…

Dark gas in the interstellar medium (ISM) is believed to not be detectable either in CO or Hi radio emission, but it is detected by other means including gamma-rays, dust emission and extinction traced outside the Galactic plane at |b|>5…

星系天体物理 · 物理学 2015-06-19 Y. Fukui , K. Torii , T. Onishi , H. Yamamoto , R. Okamoto , T. Hayakawa , K. Tachihara , H. Sano

A large fraction of baryons predicted from the standard cosmology has been missing observationally. Although previous numerical simulations have indicated that most of the missing baryons reside in large-scale filaments in the form of Warm…

宇宙学与河外天体物理 · 物理学 2017-09-20 Toshihiro Horii , Shinsuke Asaba , Kenji Hasegawa , Hiroyuki Tashiro

Radio spectroscopy at 323 MHz using the Arecibo Telescope and the VLA has produced a tentative detection of the 21cm line of neutral hydrogen at Z_abs=3.38716+-0.00007 in absorption against the radio continuum of the QSO MG0201+113 (Z_em =…

天体物理学 · 物理学 2009-10-30 F. H. Briggs , E. Brinks , A. M. Wolfe

Sensitive 21cm HI line observations were performed for 23 dwarf members and possible members of the nearby M81 group of galaxies, including five objects of a clustering of extremely low-surface brightness objects of unknown nature. With the…

天体物理学 · 物理学 2007-05-23 W. van Driel , R. C. Kraan-Korteweg , B. Binggeli , W. K. Huchtmeier

Neutral Hydrogen (HI) provides a very important fuel for star formation, but is difficult to detect at high redshift due to weak emission, limited sensitivity of modern instruments, and terrestrial radio frequency interference (RFI) at low…

星系天体物理 · 物理学 2016-07-20 Lucas R. Hunt , D. J. Pisano , Stanislav S. Edel

We present methods and results from "21-cm Spectral Line Observations of Neutral Gas with the EVLA" (21-SPONGE), a large survey for Galactic neutral hydrogen (HI) absorption with the Karl G. Jansky Very Large Array (VLA). With the upgraded…

We derived the dust-to-HI ratio of the intermediate-velocity clouds (IVCs), the high-velocity clouds (HVCs), and the local HI gas, by carrying out a multiple-regression analysis of the 21cm HI emission combined with the sub-mm dust optical…

星系天体物理 · 物理学 2024-01-24 Takahiro Hayakawa , Yasuo Fukui

The GMRT HI 21cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ~23 Mpc, is a loose group of \~200 galaxies. The group extends more than 10 Mpc in projection. The velocity dispersion…

天体物理学 · 物理学 2009-11-10 A. Omar , K. S. Dwarakanath

We measure the properties of optical emission lines in multiple locations across the Large Magellanic Cloud (LMC) using the Australian National University 2.3-metre telescope and the WiFeS integral field spectrograph. From these…

星系天体物理 · 物理学 2024-03-05 Philip Lah , Matthew Colless , Francesco D'Eugenio , Brent Groves , Joseph D. Gelfand

We have mapped two molecular clouds at (l, b) = (3.2 degrees, + 0.3 degrees) and (l, b) = (5.4 degrees, -0.5 degrees) in 21-cm line and continuum emission. These clouds show unusually large velocity dispersions of more than 100 km/s (FWHM)…

天体物理学 · 物理学 2015-06-24 Harald Riffert , Pawan Kumar , W. K. Huchtmeier

We have determined column densities of H I and/or H_2 for sight lines in the Magellanic Clouds from archival HST and FUSE spectra of H I Lyman-alpha and H_2 Lyman-band absorption. Together with some similar data from the literature, we now…

星系天体物理 · 物理学 2015-06-03 Daniel E. Welty , Rui Xue , Tony Wong

Previous HST and FUSE observations have revealed highly ionized high-velocity clouds (HVCs) or more generally low HI column HVCs along extragalactic sightlines over 70-90% of the sky. The distances of these HVCs have remained largely…

星系天体物理 · 物理学 2015-05-14 N. Lehner , J. C. Howk

We have used the Westerbork array to carry out an unbiased wide-field survey for HI emission features, achieving an RMS sensitivity of about 18 mJy/Beam at a velocity resolution of 17 km/s over 1800 deg^2 and between -1000 < V_Hel<+6500…

天体物理学 · 物理学 2016-08-30 Robert Braun , David Thilker , Rene Walterbos

Galactic HI emission profiles in an area where several large-scale filaments at velocities ranging from -46 km/s to 0 km/s overlap were decomposed into Gaussian components. Eighteen families of components defined by similarities of center…

星系天体物理 · 物理学 2015-06-15 Gerrit L Verschuur

We investigate the possible presence of neutral hydrogen (HI) in intergalactic filaments at very low redshift ($z\sim 0.08$), by stacking a set of 274,712 2dFGRS galaxy pairs over 21-cm maps obtained with dedicated observations conducted…

宇宙学与河外天体物理 · 物理学 2019-08-14 Denis Tramonte , Yin-Zhe Ma , Yi-Chao Li , Lister Staveley-Smith

We probe the neutral circumgalactic medium (CGM) along the major axes of NGC891 and NGC4565 in 21-cm emission out to $\gtrsim 100$kpc using the Green Bank Telescope (GBT), extending our previous minor axes observations. We achieve an…

Searching the HI Parkes All-Sky Survey (HIPASS) and its northern extension, we detected a population of very compact high-velocity clouds (HVCs) with similar velocities in the Galactic standard-of-rest frame which appear to be arranged in…

天体物理学 · 物理学 2009-11-13 T. Westmeier , B. S. Koribalski

We report the discovery of 15 stars in the H3 survey that lie, in projection, near the tip of the trailing gaseous Magellanic Stream (MS). The stars have Galactocentric velocities $< -155$ km s$^{-1}$, Galactocentric distances of $\approx…

We present recent results from our searches of 21-cm absorption using GBT, GMRT, VLBA and WSRT to trace the evolution of cold gas in galaxies. Using ~130 sight lines with 21-cm absorption measurements, we find that within the measurement…

星系天体物理 · 物理学 2014-02-24 N. Gupta , R. Srianand , P. Petitjean , P. Noterdaeme , E. Momjian