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Related papers: Are Compact High-Velocity Clouds Extragalactic Obj…

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The consortium for Galactic studies with the Arecibo L-band Feed Array (ALFA) is conducting a neutral hydrogen (HI) survey of the whole Arecibo sky (declination range from -1 to 38 degrees), with high angular (3.5') and velocity resolution…

We model the kinematics of the high- and intermediate- velocity clouds (HVCs and IVCs) observed in absorption towards a sample of 55 Galactic halo stars with accurate distance measurements. We employ a simple model of a thick disc whose…

Astrophysics of Galaxies · Physics 2022-05-25 A. Marasco , F. Fraternali , N. Lehner , J. C. Howk

We report five Local Volume dwarf galaxies (two of which are presented here for the first time) uncovered during a comprehensive archival search for optical counterparts to ultra-compact high velocity clouds (UCHVCs). The UCHVC population…

It has been suggested that high velocity clouds may be distributed throughout the Local Group and are therefore not in general associated with the Milky Way galaxy. With the aim of testing this hypothesis, we have made observations in the…

Astrophysics · Physics 2009-11-07 S. L. Tufte , J. D. Wilson , G. J. Madsen , L. M. Haffner , R. J. Reynolds

We report the detection of extremely broad emission toward two molecular clumps in the Galactic central molecular zone. We have mapped the Sagittarius C complex ($-0^\circ.61 < l < -0^\circ.27$, $-0^\circ.29 < b < 0^\circ.04$) in the HCN…

Astrophysics of Galaxies · Physics 2015-06-18 Kunihiko Tanaka , Tomoharu Oka , Shinji Matsumura , Makoto Nagai , Kazuhisa Kamegai

We report ultraviolet spectra of Galactic high-velocity clouds (HVCs) in Complex C, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), together with new 21-cm spectra from the Green Bank Telescope. The wide…

Astrophysics of Galaxies · Physics 2015-05-28 Michael Shull , Matthew Stevans , Charles Danforth , Steven Penton , Felix J. Lockman , Nahum Arav

We present a precise estimate of the bulk virial scaling relation of halos formed via hierarchical clustering in an ensemble of simulated cold dark matter cosmologies. The result is insensitive to cosmological parameters, the presence of a…

We show 21-cm line profiles in the direction of stars and extragalactic objects, lying projected on high- and intermediate-velocity clouds (HVCs and IVCs). About half of these are from new data obtained with the Effelsberg 100-m telescope,…

Astrophysics · Physics 2009-11-06 B. P. Wakker , P. M. W. Kalberla , H. van Woerden , K. S. de Boer , M. E. Putman

We analyze the physical conditions of the cool, photoionized (T $\sim 10^4$ K) circumgalactic medium (CGM) using the COS-Halos suite of gas column density measurements for 44 gaseous halos within 160 kpc of $L \sim L^*$ galaxies at $z \sim…

The ROSAT mission gave us the unique possibility to study the galactic interstellar medium by ``shadowing'' observations on arcmin angular resolution level. The high sensitivity of the ROSAT PSPC in combination with the large field of view…

Astrophysics · Physics 2007-05-23 J. Kerp , P. M. W. Kalberla , M. J. Freyberg , Dap Hartmann , W. B. Burton

We show that the ionization of dense molecular clouds can be used to set strong constraints on dark matter models producing UV/X-ray photons in their annihilation or decay. We place robust and competitive constraints on various dark matter…

High Energy Physics - Phenomenology · Physics 2026-03-24 Pedro De la Torre Luque , Pierluca Carenza , Thong T. Q. Nguyen

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)…

Astrophysics · Physics 2015-06-24 Harald Riffert , Pawan Kumar , W. K. Huchtmeier

In this contribution the current state of knowledge about the high-velocity clouds (HVCs) is summarized. Recent progress has shown that the HVCs are a diverse phenomenon. The intermediate-velocity clouds (IVCs) are likely to be part of a…

Astrophysics · Physics 2007-05-23 B. P. Wakker

Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of the 21-cm HI column densities, along with estimates of the local dust abundances, we measure the volume densities of a sample of actively star-forming giant molecular…

Astrophysics · Physics 2009-11-13 Jonathan S. Heiner , Ronald J. Allen , O. Ivy Wong , Pieter C. van der Kruit

Recent, high sensitivity, HI observations of nearby spiral galaxies show that their thin `cold' disks are surrounded by thick layers (halos) of neutral gas with anomalous kinematics. We present results for three galaxies viewed at different…

Astrophysics · Physics 2007-05-23 Filippo Fraternali , Tom Oosterloo , Rense Boomsma , Rob Swaters , Renzo Sancisi

We present search results of 22 high latitude (b > 25 deg.) sightlines for OH 18-cm emission using the 305-m radio telescope at the Arecibo Observatory. These sightlines appear in neutral hydrogen emission at intermediate velocities (V_lsr…

Astrophysics of Galaxies · Physics 2023-05-10 Allison Smith , D. Anish Roshi

A table is presented that summarizes published absorption line measurements for the high- and intermediate velocity clouds (HVCs and IVCs). New values are derived for N(HI) in the direction of observed probes, in order to arrive at reliable…

Astrophysics · Physics 2009-11-06 B. P. Wakker

By comparing sensitive Spitzer Space Telescope (SST) infrared and Green Bank Telescope 21 cm observations, we are able to report the first detection of dust emission in Complex C, the largest High Velocity Cloud in the sky. Dust in the…

Astrophysics · Physics 2009-11-11 M. -A. Miville-Deschenes , F. Boulanger , W. T. Reach , A. Noreiga-Crespo

We examine the baryon content of low-mass {\Lambda}CDM halos $(10^8<M_{200}/{\rm M_\odot}<5\times 10^{9})$ using the APOSTLE cosmological hydrodynamical simulations. Most of these systems are free of stars and have a gaseous content set by…

We present a proof-of-concept study of a method to estimate the inclination angle of compact high velocity clouds (CHVCs), i.e. the angle between a CHVC's trajectory and the line-of-sight. The inclination angle is derived from the CHVC's…

Astrophysics of Galaxies · Physics 2016-07-27 F. Heitsch , B. Bartell , S. E. Clark , J. E. G. Peek , D. Cheng , M. Putman