scholarly journals Correlations in the three-dimensional Lyman-alpha forest contaminated by high column density absorbers

2018 ◽  
Vol 476 (3) ◽  
pp. 3716-3728 ◽  
Author(s):  
Keir K Rogers ◽  
Simeon Bird ◽  
Hiranya V Peiris ◽  
Andrew Pontzen ◽  
Andreu Font-Ribera ◽  
...  
Keyword(s):  
Column Density ◽  
Three Dimensional ◽  
Lyman Alpha ◽  
Lyman Alpha Forest ◽  
High Column

scholarly journals On the Origin of Metallicity in Lyman-Alpha Forest Systems

2002 ◽  
Vol 187 ◽  
pp. 123-127
Author(s):  
M. Chiba ◽  
B. B. Nath
Keyword(s):  
High Resolution ◽  
Column Density ◽  
Large Fraction ◽  
The Other ◽  
Absorption Lines ◽  
Lyman Alpha ◽  
Other Hand ◽  
Lyman Alpha Forest

Several recent observations indicate that even the low H I column density Lyα absorption lines may not be primordial, as they were previously thought to be. High-resolution observations using the Keck telescope (Cowie et al. 1995; Tytler et al 1995.; Songaila & Cowie 1996) have revealed that a large fraction of Lyα absorption lines with H I column density as low as NHI ~ 1014 cm−2 at redshift z ~ 3 are associated with metal lines (C IV). This fraction, hereafter denoted as fm, is estimated as 0.5-0.75. On the other hand, there is an indication that at low z a large fraction of Lyα absorption lines are directly associated with halos of visible galaxies. This fraction is hereafter denoted as fg. Lanzetta et al. (1995, hereafter LBTW) claimed fg ~ 0.6 at z ≲ 1 (see also Bowen, Pettini & Boyle 1997).

scholarly journals The stratified disc wind of MCG-03-58-007

2020 ◽  
Vol 500 (1) ◽  
pp. 291-300
Author(s):  
V Braito ◽  
J N Reeves ◽  
P Severgnini ◽  
R Della Ceca ◽  
L Ballo ◽  
...  
Keyword(s):  
Absorption Line ◽  
Velocity Component ◽  
Column Density ◽  
Accretion Disc ◽  
Line Profiles ◽  
Lower Velocity ◽  
Multiple Observations ◽  
Two Phases ◽  
The One ◽  
High Column

ABSTRACT Past Suzaku, XMM–Newton, and NuSTAR observations of the nearby (z = 0.03233) bright Seyfert 2 galaxy MCG-03-58-007 revealed the presence of two deep and blue-shifted iron K-shell absorption line profiles. These could be explained with the presence of two phases of a highly ionized, high column density accretion disc wind outflowing with vout1 ∼ −0.1c and vout2 ∼ −0.2c. Here we present two new observations of MCG-03-58-007: one was carried out in 2016 with Chandra and one in 2018 with Swift. Both caught MCG-03-58-007 in a brighter state ($F_{{\mathrm{2}-10\, keV}} \sim 4 \times 10^{-12}$ erg cm−2 s−1) confirming the presence of the fast disc wind. The multi-epoch observations of MCG-03-58-007 covering the period from 2010 to 2018 were then analysed. These data show that the lower velocity component outflowing with vout1 ∼ −0.072 ± 0.002c is persistent and detected in all the observations, although it is variable in column density in the range NH ∼ 3–8 × 1023 cm−2. In the 2016 Swift observation we detected again the second faster component outflowing with vout2 ∼ −0.2c, with a column density ($N_{\mbox{H}}=7.0^{+5.6}_{-4.1}\times 10^{23}$ cm−2), similar to that seen during the Suzaku observation. However during the Chandra observation 2 yr earlier, this zone was not present (NH < 1.5 × 1023 cm−2), suggesting that this faster zone is intermittent. Overall the multi-epochs observations show that the disc wind in MCG-03-58-007 is not only powerful, but also extremely variable, hence placing MCG-03-58-007 among unique disc winds such as the one seen in the famous QSO PDS456. One of the main results of this investigation is the consideration that these winds could be extremely variable, sometime appearing and sometime disappearing; thus to reach solid and firm conclusions about their energetics multiple observations are mandatory.

scholarly journals The lyman alpha forest in hierarchical cosmologies

1999 ◽  
Author(s):  
M. Machacek ◽  
G. L. Bryan ◽  
P. Anninos ◽  
A. Meiksin ◽  
M. L. Norman ◽  
...  
Keyword(s):  
Lyman Alpha ◽  
Lyman Alpha Forest
Sign in / Sign up

Export Citation Format

Share Document