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Anomalies in the abundance measurements of short lived radionuclides in meteorites indicate that the protosolar nebulae was irradiated by a large number of energetic particles ($E\gtrsim10\,$MeV), often called solar cosmic rays. The…

太阳与恒星天体物理 · 物理学 2020-01-22 Ch. Rab , M. Padovani , M. Güdel , I. Kamp , W. -F. Thi , P. Woitke

(abridged)The focus of this work is to study mid-infrared point sources and the diffuse interstellar medium (ISM) in the low-metallicity (~0.2 solar) giant HII region N66 using the Spitzer Space Telescope's Infrared Spectrograph. We study…

We present three-dimensional radiation-hydrodynamical simulations of the impact of stellar winds, photoelectric heating, photodissociating and photoionising radiation, and supernovae on the chemical composition and star formation in a…

During reionization, a fraction of galactic Ly$\alpha$ emission is scattered in the intergalactic medium (IGM) and appears as a diffuse light extending megaparsecs from the source. We investigate how to probe the properties of the early…

Upcoming 21 cm intensity mapping experiments like the Square Kilometer Array (SKA) hold significant potential to constrain the properties of dark matter. In this work, we model neutral hydrogen (HI) distributions using high-resolution…

宇宙学与河外天体物理 · 物理学 2024-01-02 Tibor Dome , Rumail Azhar , Anastasia Fialkov

If enough of their Lyman limit continuum escapes, star-forming galaxies could be significant contributors to the cosmic background of ionizing photons. To investigate this possibility, we obtained the first deep imaging in the far…

天体物理学 · 物理学 2009-11-10 Matthew Malkan , Wayne Webb , Quinn Konopacky

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

We present a study of the cold atomic hydrogen (HI) content of molecular clouds simulated within the SILCC-Zoom project. We produce synthetic observations of HI at 21 cm including HI self-absorption (HISA) and observational effects. We find…

星系天体物理 · 物理学 2022-03-14 D. Seifried , H. Beuther , S. Walch , J. Syed , J. D. Soler , P. Girichidis , R. Wünsch

We use the Galaxies-Intergalactic Medium Interaction Calculation (GIMIC) cosmological hydrodynamic simulation at z=0 to study the distribution and environmental dependence of neutral hydrogen (HI) gas in the outskirts of simulated galaxies.…

宇宙学与河外天体物理 · 物理学 2015-06-18 D. Cunnama , S. Andrianomena , C. M. Cress , A. Faltenbacher , B. K. Gibson , T. Theuns

We present a detailed study of an estimator of the HI column density, based on a combination of HI 21cm absorption and HI 21cm emission spectroscopy. This "isothermal" estimate is given by $N_{\rm HI,ISO} = 1.823 \times 10^{18} \int \left[…

星系天体物理 · 物理学 2014-07-30 Jayaram N. Chengalur , Nissim Kanekar , Nirupam Roy

The 21-cm signal in the vicinity of the first stars is expected to reflect properties of the first stars. In this study we pay special attention to tracing the time evolution of the ionizing photons' escape fraction, which affects the…

星系天体物理 · 物理学 2018-08-08 Toshiyuki Tanaka , Kenji Hasegawa , Hidenobu Yajima , Masato I. N. Kobayashi , Naoshi Sugiyama

Using Green Bank Telescope radio recombination line (RRL) data, we analyze the role of leaking radiation from HII regions in maintaining the ionization of the interstellar medium. We observed a sample of eight Galactic HII regions of…

星系天体物理 · 物理学 2019-02-27 Matteo Luisi , L. D. Anderson , Bin Liu , D. Anish Roshi , Ed Churchwell

O VI absorption is observed in a wide range of astrophysical environments, including the Local ISM, the disk and halo of the Milky Way, high-velocity clouds, the Magellanic clouds, starburst galaxies, the intergalactic medium, damped…

宇宙学与河外天体物理 · 物理学 2015-05-27 Andrew J. Fox

We calculate the column density distribution of damped Lyman alpha systems, modeled as spherical isothermal gaseous halos ionized by the external cosmic background. The effects of self-shielding introduce a hump in this distribution, at a…

天体物理学 · 物理学 2009-11-07 Zheng Zheng , Jordi Miralda-Escude

The observed high covering fractions of neutral hydrogen (HI) with column densities above $\sim 10^{17} \rm{cm}^{-2}$ around Lyman-Break Galaxies (LBGs) and bright quasars at redshifts z ~ 2-3 has been identified as a challenge for…

宇宙学与河外天体物理 · 物理学 2016-02-25 Alireza Rahmati , Joop Schaye , Richard G. Bower , Robert A. Crain , Michelle Furlong , Matthieu Schaller , Tom Theuns

This work is the continuation of a series attempting to characterize the local warm ionized medium through both static and time dependent simulations. We build upon our three dimensional, observationally-derived simulation of the local…

星系天体物理 · 物理学 2025-06-24 Lewis McCallum , Kenneth Wood , Robert Benjamin , Dhanesh Krishnarao , Anna F. McLeod

For the low density filamentary and sheet-like structures in the warm ($\sim 10^4$ to $\sim 10^6$ K) IGM predicted by numerical simulations the resonant line scattering of X-ray background (XRB) photons by He and H-like ions of heavy…

天体物理学 · 物理学 2009-10-31 E. Churazov , M. Haehnelt , O. Kotov , R. Sunyaev

Motivated by recent evidence that the epoch of reionization of hydrogen may have ended at a redshift as low as z~6 we consider the detectability of the sources responsible for this reionization. The main idea is that reionization places…

天体物理学 · 物理学 2009-11-10 M. Stiavelli , S. M. Fall , N. Panagia

The boundary conditions of the heliosphere are set by the ionization, density and composition of inflowing interstellar matter. Constraining the properties of the Local Interstellar Cloud (LIC) at the heliosphere requires radiative transfer…

天体物理学 · 物理学 2009-11-13 Jonathan D. Slavin , Priscilla C. Frisch

The HI and CO components of the interstellar medium (ISM) are usually used to derive the dynamical mass M_dyn of nearby galaxies. Both components become too faint to be used as a tracer in observations of high-redshift galaxies. In those…