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[Fizinfo] Csillagda szeminariuma

Chronological Thread 
  • From: ilka AT (Kalman Belane)
  • To: fizinfo AT
  • Cc:
  • Subject: [Fizinfo] Csillagda szeminariuma
  • Date: Thu, 10 Nov 2005 14:06:18 +0100 (MET)
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  • List-id: ELFT HÍRADÓ <>

az MTA KTM Csillagászati Kutatóintézete


Eloado: G.M. Williger, (Univ. Kentucky)

Cim: "The Low-Redshift Lyman Alpha Forest toward PKS 0405-123"

We present STIS 7km/s resolution data of the Ly-a forest toward
PKS0405-123 (z=0.574). We make two samples. The strong sample (60 systems)
has column density logNHI>13.3 over 0.002<z<0.423, and the weak sample
(44) has logNHI>13.1 at 0.020<z<0.234; 7 absorbers show metals, all with
OVI, but often offset in velocity from HI. The strong sample Doppler
parameters show <b>=47+-22km/s; for the weak, <b>=44+-21km/s. Line

blending and s/n effects likely inflate b. The redshift density dN/dz is

consistent with previous, lower resolution results for logNHI>14.0. For

13.1<logNHI<14.0, we find a dN/dz overdensity of ~0.2-0.3 dex at

0.127<z<0.234, which we believe arises from cosmic variance. We find Ly-a

clustering over Delta v<250km/s for logNHI>13.3, consistent with a

numerical model. There is a void in the strong sample at 0.0320<z<0.0814.

We detect radial velocity correlations for Delta v<250km/s between Ly-a

absorbers and 39 galaxies in a 10' field. The correlation grows with

minimum NHI, peaking for logNHI ~> 13.5-14.0. The strength is similar to

that of the galaxy-galaxy correlation for our sample, implying that such

Ly-a systems have mass log M/Msun= 11.3+1.0-0.6. Including lower column

density systems in the sample shows correlations only out to Delta v

<125km/s, as would be expected for smaller density perturbations. Galaxy

counts and local HI column density appear correlated, peaking at ~5000km/s.

We also give column densities for Galactic species. (Abridged)

A szeminárium idõpontja: 2005. november 15, kedd 11 óra

Helye: MTA Konkoly Thege Miklós Csillagászati Kutatóintézete
1121 Budapest, Konkoly Thege Miklós út 13-17

Patkós László s.k.

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