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相关论文: The Temperature-Density Relation in the Intergalac…

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We present the study of CI/H$_2$ relative abundance in the diffuse cold neutral medium. Using the chemical and thermal balance model we calculated the dependence of CI/H$_2$ on the main parameters of the medium: hydrogen number density,…

星系天体物理 · 物理学 2024-02-02 Sergei Balashev , Daria Kosenko

The most important cooling lines of the neutral interstellar medium (ISM) lie in the far-infrared (FIR). We present measurements by the Infrared Space Observatory Long Wavelength Spectrometer of seven lines from neutral and ionized ISM of…

天体物理学 · 物理学 2008-12-18 S. Malhotra , M. J. Kaufman , D. Hollenbach , G. Helou , R. H. Rubin , J. Brauher , D. Dale , N. Y. Lu , S. Lord , G. Stacey , A. Contursi

We use the Gaussian-fit results of Paper I to investigate the properties of interstellar HI in the Solar neighborhood. The Warm and Cold Neutral Media (WNM and CNM) are physically distinct components. The CNM spin temperature histogram…

天体物理学 · 物理学 2010-04-06 Carl Heiles , T. H. Troland

An accurate value of the deuterium/hydrogen (D/H) ratio in the local interstellar medium (LISM) and a better understanding of the D/H variations with position in the Galactic disk can provide essential information on the primordial D/H…

天体物理学 · 物理学 2009-11-16 Jeffrey L. Linsky

We compute robust lower limits on the spin temperature, $T_{\rm S}$, of the $z=8.4$ intergalactic medium (IGM), implied by the upper limits on the 21-cm power spectrum recently measured by PAPER-64. Unlike previous studies which used a…

宇宙学与河外天体物理 · 物理学 2015-12-16 Bradley Greig , Andrei Mesinger , Jonathan C. Pober

We detect the neutral hydrogen (HI) radial brightness temperature profile in large-scale haloes by stacking 48,430 galaxies selected from the 2dFGRS catalogue onto a set of 21-cm intensity maps obtained with the Parkes radio telescope,…

宇宙学与河外天体物理 · 物理学 2020-10-14 Denis Tramonte , Yin-Zhe Ma

We use numerical hydrodynamical simulations of early structure formation in a LCDM universe to investigate the spin temperature and 21cm brightness of the diffuse intergalactic medium (IGM) prior to the epoch of cosmic reionization, at…

天体物理学 · 物理学 2009-11-13 Michael Kuhlen , Piero Madau , Ryan Montgomery

Analysis of interstellar absorption lines observed in high-resolution {\em HST} spectra of nearby stars provides temperatures, turbulent velocities, and kinetic properties of warm interstellar clouds. Previous studies identified 15 warm…

星系天体物理 · 物理学 2022-08-31 Jeffrey L. Linsky , Seth Redfield , Diana Ryder , Adina Chasan-Taber

In this paper, we investigate the conditions for the HI-to-H$_{2}$ transition in the solar neighborhood by analyzing HI emission and absorption measurements toward 58 Galactic lines of sight (LOSs) along with $^{12}$CO(1$-$0) (CO) and dust…

This is the first in a series of three papers describing a project with the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure abundances of the neutral interstellar medium (ISM) in a sample of 9 nearby star-forming…

星系天体物理 · 物理学 2015-06-22 Bethan L. James , Alessandra Aloisi , Timothy M. Heckman , Sangmo Tony Sohn , Michael A. Wolfe

We use the relationships between galactic HI mass and B-band luminosity determined by Rao & Briggs to recalculate the mass density of neutral gas at the present epoch based on more recent measures of the galaxy luminosity function than were…

天体物理学 · 物理学 2016-01-13 Priyamvada Natarajan , Max Pettini

We examine recent measurements of the z~2.5 intergalactic medium (IGM) which constrain the HI frequency distribution f(N) and the mean free path MFP to ionizing radiation. We argue that line-blending and the clustering of strong…

宇宙学与河外天体物理 · 物理学 2015-06-17 J. Xavier Prochaska , Piero Madau , John M. O'Meara , Michele Fumagalli

Interstellar reddening corrections are necessary to reconstruct the intrinsic spectral energy distributions (SEDs) of accreting protostellar systems. The stellar SED determines the heating and chemical processes that can occur in…

We estimate the mean dust-to-gas ratio of MgII absorbers as a function of rest equivalent width W_0 and redshift over the range 0.5<z<1.4. Using the expanded SDSS/HST sample of low-redshift Lyman-alpha absorbers we first show the existence…

天体物理学 · 物理学 2009-11-13 Brice Ménard , Doron Chelouche

We study the physical conditions in DLAs, using a sample of 33 systems toward 26 QSOs acquired for a recently completed survey of H_2 by Ledoux et al. (2003). We use the column densities of H_2 in different rotational levels, together with…

天体物理学 · 物理学 2009-11-13 Raghunathan Srianand , Patrick Petitjean , Cedric Ledoux , Gary Ferland , Gargi Shaw

When the neutral interstellar medium is exposed to EUV and soft X ray radiation, the argon atoms in it are far more susceptible to being ionized than the hydrogen atoms. We make use of this fact to determine the level of ionization in the…

星系天体物理 · 物理学 2013-01-29 Edward B. Jenkins

We analyse the formation of broad absorption troughs in the spectra of high-redshift sources in the redshift range $5 \le z \le 15$ for two observationally motivated reionization histories inferred from distant galaxy spectra and CMB…

宇宙学与河外天体物理 · 物理学 2026-04-08 Anguohao Yang , Bohdan Novosyadlyj , Pavlo Kopach , Bohdan Melekh , Gennadii Milinevsky

Recent observations suggest that hydrogen reionization ends late ($z \simeq 6$) and proceeds quickly. We present here a new model of the meta-galactic UV/X-ray background (UVB) that is consistent with this. It adopts the most recent…

星系天体物理 · 物理学 2019-01-30 Ewald Puchwein , Francesco Haardt , Martin G. Haehnelt , Piero Madau

The hot gas in galaxy halos may account for a significant fraction of missing baryons in galaxies, and some of these gases can be traced by high ionization absorption systems in QSO UV spectra. Using high S/N ratio $ HST$/COS spectra, we…

星系天体物理 · 物理学 2016-12-14 Zhijie Qu , Joel N. Bregman

The HI 21cm absorption optical depth and the N(HI) derived from Lya absorption can be combined to yield the spin temperature (Ts) of DLAs. Although Ts measurements exist for samples of DLAs with z <0.6 and z >1.7, the intermediate redshift…

宇宙学与河外天体物理 · 物理学 2015-06-05 Sara L. Ellison , Nissim Kanekar , J. Xavier Prochaska , Emmanuel Momjian , Gabor Worseck