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We are just starting to understand the physical processes driving the dramatic change in cosmic star-formation rate between $z\sim 2$ and the present day. A quantity directly linked to star formation is the molecular gas density, which…

We present the first detailed analysis of the rest-frame UV spectrum of the gravitationally lensed Lyman break galaxy (LBG), the `8 o'clock arc'. The spectrum of the 8 o'clock arc is rich in stellar and interstellar medium (ISM) features,…

宇宙学与河外天体物理 · 物理学 2015-05-14 M. Dessauges-Zavadsky , S. D'Odorico , D. Schaerer , A. Modigliani , C. Tapken , J. Vernet

In this article we discuss the importance of high-resolution absorption spectroscopy for our understanding of the distribution and physical nature of the gaseous circumgalactic medium (CGM) that surrounds the Milky Way. Observational and…

星系天体物理 · 物理学 2019-08-19 P. Richter , A. J. Fox , N. Ben Bekhti , M. T. Murphy , D. Bomans , S. Frank

We present measurements of the oxygen abundance of the Milky Way's ISM by observing the K-shell X-ray photoionization edge towards galaxy clusters. This effect is most easily observed towards objects with galactic columns (n_H) of a few…

天体物理学 · 物理学 2009-11-13 Wayne H. Baumgartner , Richard F. Mushotzky

We present a new investigation of the thermal history of the intergalactic medium (IGM) during and after reionization using the Lyman-$\alpha$ forest flux power spectrum at $4.0\lesssim z\lesssim5.2$. Using a sample of 15 high-resolution…

宇宙学与河外天体物理 · 物理学 2019-02-27 Elisa Boera , George D. Becker , James S. Bolton , Fahad Nasir

The damped Lyman alpha systems seen in the spectra of high redshift QSOs offer the means to determine element abundances in galaxies observed while still at an early stage of evolution. Such measurements, which have only recently come…

天体物理学 · 物理学 2016-08-30 Max Pettini , Keith Lipman , Richard W. Hunstead

The cooling transition temperature gas in the interstellar medium (ISM), traced by the high ions, Si IV, C IV, N V, and O VI, helps to constrain the flow of energy from the hot ISM with T >10^6 K to the warm ISM with T< 2x10^4 K. We…

星系天体物理 · 物理学 2015-05-20 N. Lehner , W. F. Zech , J. C. Howk , B. D. Savage

We perform the first measurement of the thermal and ionization state of the intergalactic medium (IGM) across 0.9 < z < 1.5 using 301 \lya absorption lines fitted from 12 HST STIS quasar spectra, with a total pathlength of \Delta z=2.1. We…

宇宙学与河外天体物理 · 物理学 2024-02-06 Teng Hu , Vikram Khaire , Joseph F. Hennawi , Todd M. Tripp , Jose Oñorbe , Michael Walther , Zarija Lukic

We study the composition of the Galactic interstellar medium (ISM) toward the Galactic center region (5 < |l| < 20 degree) by utilizing X-ray absorption features of three bright low-mass X-ray binaries (LMXBs), GX 13+1, GX 5-1, and GX…

天体物理学 · 物理学 2009-11-10 Yoshihiro Ueda , Kazuhisa Mitsuda , Hiroshi Murakami , Kyoko Matsushita

Strong constraints on possible variations in fundamental constants can be derived from HI 21-cm and molecular rotational absorption lines observed towards quasars. With the aim of forming a statistical sample of constraints we have begun a…

天体物理学 · 物理学 2016-08-16 S. J. Curran , J. K. Webb , M. T. Murphy , Y. M. Pihlström

Magnesium abundances of cool stars with different metallicities are important for understanding the galactic chemical evolution. This study tests atomic data used in stellar magnesium abundance analyses. We evaluate non-local…

太阳与恒星天体物理 · 物理学 2015-06-12 Lyudmila Mashonkina

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

The Lyman alpha absorption from intergalactic, once-ionized helium (HeII) has been measured with HST in four quasars over the last few years, over the redshift range 2.4 < z < 3.2. These observations have indicated that the HeII…

天体物理学 · 物理学 2009-10-31 Jordi Miralda-Escude

This report summarizes laboratory measurements of atomic wavelengths, energy levels, hyperfine and isotope structure, energy level lifetimes, and oscillator strengths. Theoretical calculations of lifetimes and oscillator strengths are also…

太阳与恒星天体物理 · 物理学 2012-11-08 Gillian Nave , Glenn M. Wahlgren , Jeffrey R. Fuhr

The interstellar medium (ISM) is a key ingredient in galaxy formation and evolution as it provides the molecular gas reservoir which fuels star formation and supermassive black hole accretion. Yet the ISM is one of the least studied aspects…

星系天体物理 · 物理学 2009-01-23 T. R. Greve

This review summarises what we have learnt in the last two decades based on HI 21-cm absorption observations about the cold interstellar medium (ISM) in the central regions of active galaxies and the interplay between this gas and the…

星系天体物理 · 物理学 2019-05-15 Raffaella Morganti , Tom Oosterloo

We characterize the multiphase circumgalactic medium and galaxy properties at z = 6.0-6.5 in four quasar fields from the James Webb Space Telescope A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE) program. We use the…

The Circum-Galactic Medium (CGM) can be probed through the analysis of absorbing systems in the line-of-sight to bright background quasars. We present measurements of the metallicity of a new sample of 15 sub-damped Lyman-$\alpha$ absorbers…

In order to search for metals in the Lyman alpha forest at redshifts z > 4, we have obtained spectra of high S/N and resolution of three QSOs at z > 5.4 discovered by the Sloan Digital Sky Survey. These data allow us to probe to metal…

天体物理学 · 物理学 2009-11-07 Max Pettini , Piero Madau , Michael Bolte , Jason X. Prochaska , Sara L. Ellison , Xiaohui Fan

In this work, we investigate the abundance and distribution of metals in the intergalactic medium (IGM) at $\langle z \rangle \simeq 2.8$ through the analysis of an ultra-high signal-to-noise ratio UVES spectrum of the quasar HE0940-1050.…