scholarly journals Dissecting cold gas in a high-redshift galaxy using a lensed background quasar

2018 ◽  
Vol 619 ◽  
pp. A142 ◽  
Author(s):  
J.-K. Krogager ◽  
P. Noterdaeme ◽  
J. M. O’Meara ◽  
M. Fumagalli ◽  
J. P. U. Fynbo ◽  
...  
Keyword(s):  
High Redshift ◽  
Gas Absorption ◽  
Line Of Sight ◽  
Lens Model ◽  
Physical Separation ◽  
Redshift Galaxy ◽  
Solar Metallicity ◽  
The Individual ◽  
Relative Excitation ◽  
Cold Gas

We present a study of cold gas absorption from a damped Lyman-α absorber (DLA) at redshift zabs = 1.946 toward two lensed images of the quasar J144254.78+405535.5 at redshift zQSO = 2.590. The physical separation of the two lines of sight at the absorber redshift is dabs = 0.7 kpc according to our lens model. We observe absorption lines from neutral carbon and H2 along both lines of sight, indicating that cold gas is present on scales larger than dabs. We measure the column densities of H I to be log N(HI) = 20.27 ± 0.02 and 20.34 ± 0.05 and those of H2 to be log N(H2) = 19.7 ± 0.1 and 19.9 ± 0.2. The metallicity inferred from sulphur is consistent with solar metallicity for both sightlines: [S/H]A = 0.0 ± 0.1 and [S/H]B = −0.1 ± 0.1. Based on the excitation of low rotational levels of H2, we constrain the temperature of the cold gas phase to be T = 109 ± 20 and T = 89 ± 25 K for the two lines of sight. From the relative excitation of fine-structure levels of C I, we constrain the hydrogen volumetric densities to lie in the range of 40 − 110 cm−3. Based on the ratio of observed column density and volumetric density, we infer the average individual “cloud” size along the line of sight to be l ≈ 0.1 pc. Using the transverse line-of-sight separation of 0.7 kpc together with the individual cloud size, we are able to place an upper limit to the volume filling factor of cold gas of fvol < 0.1%. Nonetheless, the projected covering fraction of cold gas must be large (close to unity) over scales of a few kpc in order to explain the presence of cold gas in both lines of sight. Compared to the typical extent of DLAs (∼10 − 30 kpc), this is consistent with the relative incidence rate of C I absorbers and DLAs.

scholarly journals Radio Line and Continuum Observations of Quasar-Galaxy Pairs and the Origin of Low Redshift Quasar Absorption Line Systems

1990 ◽  
Vol 124 ◽  
pp. 473-477
Author(s):  
C.L. Carilli ◽  
J.H. van Gorkom ◽  
E.M. Hauxthausen ◽  
J.T. Stocke ◽  
J. Salzer
Keyword(s):  
Absorption Line ◽  
Alternative Hypothesis ◽  
High Redshift ◽  
Gravitational Interaction ◽  
Optical Disk ◽  
Line Of Sight ◽  
Radio Line ◽  
Redshift Galaxy ◽  
Interacting Systems ◽  
Companion Galaxy

There are a number of known quasars for which our line of sight to the high redshift quasar passes within a few Holmberg radii of a low redshift galaxy. In a few of these cases, spectra of the quasar reveal absorption by gas associated with the low redshift galaxy. A number of these pairs imply absorption by gas which lies well outside the optical disk of the associated galaxy, leading to models of galaxies with ‘halos’ or ‘disks’ of gas extending to large radii. We present observations of 4 such pairs. In three of the four cases, we find that the associated galaxy is highly disturbed, typically due to a gravitational interaction with a companion galaxy, while in the fourth case the absorption can be explained by clouds in the optical disk of the associated galaxy. We are led to an alternative hypothesis concerning the origin of the low redshift absorption line systems: the absorption is by gas clouds which have been gravitationally stripped from the associated galaxy. These galaxies are rapidly evolving, and should not be used as examples of absorption by clouds in halos of field spirals. We conclude by considering the role extended gas in interacting systems plays in the origin of higher redshift quasar absorption line systems.

scholarly journals Filamentary infall of cold gas and escape of Lyα and hydrogen ionizing radiation from an interacting high-redshift galaxy★

2011 ◽  
Vol 418 (2) ◽  
pp. 1115-1126 ◽  
Author(s):  
Michael Rauch ◽  
George D. Becker ◽  
Martin G. Haehnelt ◽  
Jean-Rene Gauthier ◽  
Swara Ravindranath ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
High Redshift ◽  
Redshift Galaxy ◽  
Cold Gas

The Distribution of High‐Redshift Galaxy Colors: Line‐of‐Sight Variations in Neutral Hydrogen Absorption

1999 ◽  
Vol 518 (1) ◽  
pp. 103-116 ◽  
Author(s):  
Matthew A. Bershady ◽  
Jane C. Charlton ◽  
Janet M. Geoffroy
Keyword(s):  
Hydrogen Absorption ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Line Of Sight ◽  
Redshift Galaxy

scholarly journals Modeling the statistics of the cold neutral medium in absorption-selected high-redshift galaxies

2020 ◽  
Vol 644 ◽  
pp. L6
Author(s):  
Jens-Kristian Krogager ◽  
Pasquier Noterdaeme
Keyword(s):  
High Redshift ◽  
Gas Absorption ◽  
Neutral Medium ◽  
Selection Function ◽  
Two Phase ◽  
High Redshift Galaxies ◽  
Physical Conditions ◽  
Neutral Gas ◽  
Total Incidence ◽  
Cold Gas

We present a statistical model of the selection function of cold neutral gas in high-redshift (z = 2.5) absorption systems. The model is based on the canonical two-phase model of the neutral gas in the interstellar medium and contains only one parameter for which we do not have direct observational priors: namely the central pressure of an L* halo at z = 2.5, P*. Using observations of the fraction of cold gas absorption in strong H I-selected absorbers, we were able to constrain P*. The model simultaneously reproduces the column density distributions of H I and H2, and we derived an expected total incidence of cold gas at z ∼ 2.5 of lCNM = 12 × 10−3. Compared to recent measurements of the incidence of C I-selected absorbers (EWλ 1560 >  0.4 Å), the value of lCNM from our model indicates that only 15% of the total cold gas would lead to strong C I absorption (EW > 0.4 Å). Nevertheless, C I lines are extremely useful probes of the cold gas as they are relatively easy to detect and provide direct constraints on the physical conditions. Lastly, our model self-consistently reproduces the fraction of cold gas absorbers as a function of NH I.

scholarly journals Free-form Lens Model and Mass Estimation of the High-redshift Galaxy Cluster ACT-CL J0102-4915, “El Gordo”

2020 ◽  
Vol 904 (2) ◽  
pp. 106
Author(s):  
Jose M. Diego ◽  
S. M. Molnar ◽  
C. Cerny ◽  
T. Broadhurst ◽  
R. Windhorst ◽  
...  
Keyword(s):  
High Redshift ◽  
Galaxy Cluster ◽  
Free Form ◽  
Lens Model ◽  
Mass Estimation ◽  
Redshift Galaxy

scholarly journals The impact of line-of-sight structures on measuring H0 with strong lensing time delays

2021 ◽  
Vol 504 (2) ◽  
pp. 2224-2234
Author(s):  
Nan Li ◽  
Christoph Becker ◽  
Simon Dye
Keyword(s):  
Time Delays ◽  
Line Of Sight ◽  
Lens Model ◽  
Local Universe ◽  
Significant Discrepancy ◽  
Turn On ◽  
Strong Lensing ◽  
Systematic Effects ◽  
The Impact ◽  
Realistic Line

ABSTRACT Measurements of the Hubble–Lemaitre constant from early- and local-Universe observations show a significant discrepancy. In an attempt to understand the origin of this mismatch, independent techniques to measure H0 are required. One such technique, strong lensing time delays, is set to become a leading contender amongst the myriad methods due to forthcoming large strong lens samples. It is therefore critical to understand the systematic effects inherent in this method. In this paper, we quantify the influence of additional structures along the line of sight by adopting realistic light-cones derived from the cosmoDC2 semi-analytical extragalactic catalogue. Using multiple-lens plane ray tracing to create a set of simulated strong lensing systems, we have investigated the impact of line-of-sight structures on time-delay measurements and in turn, on the inferred value of H0. We have also tested the reliability of existing procedures for correcting for line-of-sight effects. We find that if the integrated contribution of the line-of-sight structures is close to a uniform mass sheet, the bias in H0 can be adequately corrected by including a constant external convergence κext in the lens model. However, for realistic line-of-sight structures comprising many galaxies at different redshifts, this simple correction overestimates the bias by an amount that depends linearly on the median external convergence. We therefore conclude that lens modelling must incorporate multiple-lens planes to account for line-of-sight structures for accurate and precise inference of H0.

scholarly journals Kinematics of a high-redshift galaxy: A case study

2000 ◽  
pp. 5-8
Author(s):  
M.M. Cirkovic
Keyword(s):  
Interstellar Medium ◽  
Absorption Spectroscopy ◽  
High Redshift ◽  
Redshift Galaxy

A kinematics of a z = 2.81 galaxy toward bright QSO 0528-250, as inferred from the absorption spectroscopy is discussed. There are sufficient arguments for a far-reaching conclusion that we are observing an older, uninvolved version of the local Galactic interstellar medium.

scholarly journals Doppler Shift of Radio Signals Transmitted between Orbiting Satellites

1982 ◽  
Vol 35 (2) ◽  
pp. 155 ◽  
Author(s):  
PL Dyson ◽  
JA Bennett
Keyword(s):  
Electron Concentration ◽  
Doppler Shift ◽  
Rate Of Change ◽  
Line Of Sight ◽  
Concentration Gradients ◽  
Mean Velocity ◽  
Radio Signals ◽  
The Mean ◽  
The Moment ◽  
The Individual

A general expression, applicable at VHF and above, is derived for the Doppler shift of radio signals transmitted between two satellites embedded in the ionosphere. The Doppler shift is made up of several contributions which depend on (a) the rate of change of the free space path between the satellites, (b) the components, perpendicular to the line of sight between the satellites, of both the mean velocity of the satellites and the electron concentration gradients, (c) the moment of the perpendicular electron concentration gradients and the deviations from the mean of the individual satellite perpendicular velocities, (d) the velocity components along the line of sight between the satellites, and the electron concentration values at each satellite, and (e) changes occurring in the ionosphere with time.

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