J/ApJ/780/76 SII energy levels and transition line strengths (Kisielius+, 2014)
Atomic data for S II--Toward better diagnostics of chemical evolution in
high-redshift galaxies.
Kisielius R., Kulkarni V.P., Ferland G.J., Bogdanovich P., Lykins M.L.
<Astrophys. J., 780, 76 (2014)>
=2014ApJ...780...76K 2014ApJ...780...76K
ADC_Keywords: Atomic physics
Keywords: atomic data - atomic processes - galaxies: abundances -
ISM: abundances - quasars: absorption lines
Abstract:
Absorption-line spectroscopy is a powerful tool used to estimate
element abundances in both the nearby and distant universe. The
accuracy of the abundances thus derived is naturally limited by the
accuracy of the atomic data assumed for the spectral lines. We have
recently started a project to perform new extensive atomic data
calculations used for optical/UV spectral lines in the plasma modeling
code Cloudy using state of the art quantal calculations. Here, we
demonstrate our approach by focussing on S II, an ion used to estimate
metallicities for Milky Way interstellar clouds as well as distant
damped Lyman-alpha (DLA) and sub-DLA absorber galaxies detected in the
spectra of quasars and gamma-ray bursts. We report new extensive
calculations of a large number of energy levels of S II, and the line
strengths of the resulting radiative transitions. Our calculations are
based on the configuration interaction approach within a numerical
Hartree-Fock framework, and utilize both non-relativistic and
quasirelativistic one-electron radial orbitals. The results of these
new atomic calculations are then incorporated into Cloudy and applied
to a lab plasma, and a typical DLA, for illustrative purposes. The new
results imply relatively modest changes (~0.04dex) to the
metallicities estimated from SII in past studies. These results will
be readily applicable to other studies of SII in the Milky Way and
other galaxies.
Description:
We report new extensive calculations of a large number of energy
levels of SII, and the line strengths of the resulting radiative
transitions. One of our main tasks is to assess the accuracy of the
spectroscopic data used in modeling the SII emission or absorption
spectra.
Our calculations are based on the configuration interaction approach
within a numerical Hartree-Fock framework, and utilize both
non-relativistic and quasirelativistic one-electron radial orbitals.
Table 1 presents the energy levels of SII. The results of our
calculations obtained with two methods (the CIHF+TRO and the
CIQR+TRO approximations) are compared with the experimental data and
with the values calculated by Froese Fischer et al.
(2006ADNDT..92..607F 2006ADNDT..92..607F) and Tayal & Zatsarinny 2010 (cat.
J/ApJS/188/32). Table 3 lists the calculated transition line
strengths.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 50 Comparison of calculated SII energy levels
with experimental data
table3.dat 20 870 Transition line strengths S (in a.u.) for SII
determined in the CIHF+TRO approximation
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See also:
J/ApJS/188/32 : Breit-Pauli transition probabilities for SII (Tayal+, 2010)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- MSD Indicates that the data provided at the bottom of
the table are the Mean-Square Deviation (MSD)
values
5- 6 I2 --- Index [1/49]? Level index
8- 19 A12 --- State Configuration
21- 23 F3.1 --- J [0.5/4.5]? The J value
25- 30 I6 cm-1 E1 [0/154834] Our SII energy level value obtained in
the CIHF+TRO approximation (1)
32- 37 I6 cm-1 E2 [0/155791] Our SII energy level value obtained in
the CIQR+TRO approximation (2)
39- 44 I6 cm-1 Exp [0/151652]? Experimental value of SII energy level
46- 51 I6 cm-1 E3 [0/153365] SII energy level value calculated by
Froese Fischer et al. (2006ADNDT..92..607F 2006ADNDT..92..607F) with a
MultiConfiguration Hartree-Fock (MCHF) method (3)
53- 58 I6 cm-1 E4 [0/151745] SII energy level value of SII computed
by Tayal & Zatsarinny 2010 (cat. J/ApJS/188/32)
with a MultiConfiguration Hartree-Fock (MCHF)
method with Term-Dependant (TD) non-orthogonal
orbital (4)
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Note (1): Using non-orthogonal spline Configuration Interaction (CI),
multiconfiguration Hartree-Fock (HF) method, and Transformed Radial
Orbital (TRO). Please see Section 2 in the paper for all the details
about the CIHF+TRO approximation.
Note (2): Using non-orthogonal spline Configuration Interaction (CI),
QuasiRelativistic (QR) radial orbital, and Transformed Radial Orbital
(TRO). See Section 2 for additional details about the CIQR+TRO method.
Note (3): Froese Fischer et al. (2006ADNDT..92..607F 2006ADNDT..92..607F) considered energy levels,
lifetimes, and transition probabilities for several sequences, including
the SII ion as a member of the P-like sequence. See Section 2 in the paper
for further informations about the MCHF06 calculation.
Note (4): Tayal & Zatsarinny 2010 (cat. J/ApJS/188/32) reported new calculations
for transition probabilities and electron impact collision strengths for
the astrophysically important lines in SII. The MCHF method with
term-dependent (MCHFTD) non-orthogonal orbitals was employed for accurate
representation of the target wavefunctions. Please refer to Section 2 in
the paper for more details about the MCHFTD method.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Data [S] Transition data type (S=line strength S)
3- 4 A2 --- Type Transition line type (E1, E2, E3, or M1)
6- 7 I2 --- Ilow [1/44] Lower level index
10- 11 I2 --- Iup [2/49] Upper level index
13- 20 E8.3 --- S [3e-10/567] Transition line strength in atomic
units
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 28-Jan-2015