Nebular and global properties of the gravitationally lensed galaxy “the 8 o’clock arc”

Home

All issues

Volume 533 (September 2011)

A&A, 533 (2011) A15

Full HTML

Free Access

Table 4

Physical properties derived for the 8 o’clock arc images A2 and A3.

	A2			A3
	Total	Main	Blob	Total	Reference

Magnification factor μ	5.0 ± 1.0	5.0 ± 1.0	11.7 ± 2.3	3.9 ± 0.8	Sect. 3.2
Half-light radius r_1/2 (kpc)	1.8 ± 0.2	1.8 ± 0.2	0.53 ± 0.05	1.8 ± 0.2	Sect. 3.2
E(B − V)_gas^a	0.30 ± 0.04	0.34 ± 0.10	0.23 ± 0.15	0.29 ± 0.09	Sect. 4.2
E(B − V)_β^b	0.23 ± 0.10			0.16 ± 0.10	Sect. 4.2
E(B − V)_stars^c^,^d			0.19 ± 0.04		Sect. 4.1
12 + log (O/H)_N2^e	8.35 ± 0.19	8.39 ± 0.19	8.22 ± 0.25	8.46 ± 0.19	Sect. 4.3
Z_N2/Z_⊙^f	0.46 ± 0.20	0.50 ± 0.22	0.34 ± 0.20	0.59 ± 0.26	Sect. 4.3
12 + log (O/H)_Ne3O2^g	>8.09	>8.09	>8.09	>8.18	Sect. 4.3
SFR_Hα (M_⊙ yr^-1)^h	279 ± 45	207 ± 80	33 ± 19	239 ± 99	Sect. 4.4
SFR_UV (M_⊙ yr^-1)ⁱ	156 ± 110			198 ± 140	Sect. 4.4
SFR_SED (M_⊙ yr^-1)^d					Sect. 4.1
W₀(Hα) (Å)^j	134 ± 67	89 ± 45	45 ± 23	139 ± 72	Sect. 4.5
W₀(Hα) (Å)^k	187 ± 124	139 ± 115	51 ± 49	187 ± 152	Sect. 4.5
W₀(Hβ) (Å)^j	30 ± 2	19 ± 3	11 ± 3	29 ± 3	Sect. 4.5
W₀(Hβ) (Å)^k	47 ± 14	35 ± 22	13 ± 12	44 ± 23	Sect. 4.5
W₀(Hα)_SED (Å)^d			255 ± 95		Sect. 4.1
Age (Myr)^d					Sect. 4.1
M_stars (10⁹ M_⊙)^d					Sect. 4.1
M_gas (10⁹ M_⊙)^l	20.9 ± 3.9	17.6 ± 5.6	2.2 ± 0.9	19.1 ± 6.4	Sect. 4.6.1
M_dyn,rot (10⁹ M_⊙)^m	16.0 ± 4.9	8.4 ± 2.7	1.1 ± 0.3	20.2 ± 15.9	Sect. 4.6.2
M_dyn,disp (10⁹ M_⊙)ⁿ	14.3 ± 4.5	12.6 ± 4.0	1.7 ± 0.5		Sect. 4.6.2

Notes. For A2 are listed the total values and the individual values corresponding to the main galaxy and the star-forming blob, as described in Sects. 3.2 and 3.3.

^(a)

Gas-phase (nebular) dust extinctions computed from the Hα/Hγ Balmer decrement.

^(b)

Stellar dust extinctions derived from the UV slopes, β, measured from the observed (V − I) colors (Table 1), following the prescriptions of Bouwens et al. (2009).

^(c)

Stellar dust extinction derived from the SED modeling and corrected for the Galactic dust extinction, E(B − V)^Gal = 0.056, at the position of the 8 o’clock arc (Schlegel et al. 1998).

^(d)

Combined SED modeling results obtained with and without the treatment of nebular emission (continuum plus lines) and scaled to the Chabrier (2003) IMF. The predicted W₀(Hα)_SED comes, of course, only from SED models including the nebular emission.

^(e)

Oxygen abundances derived from the N2 calibration from Pettini & Pagel (2004). The errors include the 0.18 dex systematic uncertainty in the N2 calibration zeropoint.

^(f)

Gas-phase metallicities relative to the solar value of 12 + log (O/H)_⊙ = 8.69 (Asplund et al. 2009).

^(g)

Oxygen abundances derived from the Ne3O2 calibration from Nagao et al. (2006).

^(h)

Star-formation rates computed from the Hα luminosity and corrected for dust extinction by E(B − V)_gas values and for gravitational lensing by the magnification factor μ.

⁽ⁱ⁾

Star-formation rates computed from the UV continuum luminosity at the rest-frame wavelength of 1600 Å and corrected for dust extinction by E(B − V)_stars values and for gravitational lensing by the magnification factor μ.

^(j)

Rest-frame equivalent widths computed from the observed Balmer line and local continuum fluxes, assuming that the same dust extinction applies to the nebular and stellar emission.

^(k)

Rest-frame equivalent widths computed from the dust-corrected Balmer line and local continuum fluxes, assuming that the gas-phase dust extinction, E(B − V)_gas, applies to the nebular emission and the stellar dust extinction, E(B − V)_stars, applies to the stellar continuum.

^(l)

Gas masses derived from the Hα star-formation rates, SFR_Hα, through the Schmidt-Kennicutt relation. The rest-frame UV star-formation rates, SFR_UV, corrected for dust extinction by E(B − V)_stars values, lead to smaller gas masses by a factor of up to ~1.4.

^(m)

Dynamical masses derived under the assumption of rotation-dominated kinematics.

⁽ⁿ⁾

Dynamical masses derived under the assumption of dispersion-dominated kinematics.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.