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An extreme metallicity, large-scale outflow from a star-forming galaxy ATz∼ 0.4


Muzahid, Sowgat; Kacprzak, Glenn G; Churchill, Christopher W; Charlton, Jane C; Nielsen, Nikole M; Mathes, Nigel L; Trujillo-Gomez, Sebastian (2015). An extreme metallicity, large-scale outflow from a star-forming galaxy ATz∼ 0.4. The Astrophysical Journal, 811(2):132.

Abstract

We present a detailed analysis of a large-scale galactic outflow in the CGM of a massive (M_h ~ 10^12.5 Msun), star-forming (6.9 Msun/yr), sub-L* (0.5 L_B*) galaxy at z=0.39853 that exhibits a wealth of metal-line absorption in the spectra of the background quasar Q 0122-003 at an impact parameter of 163 kpc. The galaxy inclination angle (i=63 degree) and the azimuthal angle (Phi=73 degree) imply that the QSO sightline is passing through the projected minor-axis of the galaxy. The absorption system shows a multiphase, multicomponent structure with ultra-strong, wide velocity spread OVI (logN = 15.16\pm0.04, V_{90} = 419 km/s) and NV (logN = 14.69\pm0.07, V_{90} = 285 km/s) lines that are extremely rare in the literature. The highly ionized absorption components are well explained as arising in a low density (10^{-4.2} cm^{-3}), diffuse (10 kpc), cool (10^4 K) photoionized gas with a super-solar metallicity ([X/H] > 0.3). From the observed narrowness of the Lyb profile, the non-detection of SIV absorption, and the presence of strong CIV absorption we rule out equilibrium/non-equilibrium collisional ionization models. The low-ionization photoionized gas with a density of 10^{-2.5} cm^{-3} and a metallicity of [X/H] > -1.4 is possibly tracing recycled halo gas. We estimate an outflow mass of ~2x10^{10} Msun, a mass-flow rate of ~54 Msun/yr, a kinetic luminosity of ~9x10^{41} erg/s, and a mass loading factor of ~8 for the outflowing high-ionization gas. These are consistent with the properties of "down-the-barrel" outflows from infrared-luminous starbursts as studied by Rupke et al. Such powerful, large-scale, metal-rich outflows are the primary means of sufficient mechanical and chemical feedback as invoked in theoretical models of galaxy formation and evolution.

Abstract

We present a detailed analysis of a large-scale galactic outflow in the CGM of a massive (M_h ~ 10^12.5 Msun), star-forming (6.9 Msun/yr), sub-L* (0.5 L_B*) galaxy at z=0.39853 that exhibits a wealth of metal-line absorption in the spectra of the background quasar Q 0122-003 at an impact parameter of 163 kpc. The galaxy inclination angle (i=63 degree) and the azimuthal angle (Phi=73 degree) imply that the QSO sightline is passing through the projected minor-axis of the galaxy. The absorption system shows a multiphase, multicomponent structure with ultra-strong, wide velocity spread OVI (logN = 15.16\pm0.04, V_{90} = 419 km/s) and NV (logN = 14.69\pm0.07, V_{90} = 285 km/s) lines that are extremely rare in the literature. The highly ionized absorption components are well explained as arising in a low density (10^{-4.2} cm^{-3}), diffuse (10 kpc), cool (10^4 K) photoionized gas with a super-solar metallicity ([X/H] > 0.3). From the observed narrowness of the Lyb profile, the non-detection of SIV absorption, and the presence of strong CIV absorption we rule out equilibrium/non-equilibrium collisional ionization models. The low-ionization photoionized gas with a density of 10^{-2.5} cm^{-3} and a metallicity of [X/H] > -1.4 is possibly tracing recycled halo gas. We estimate an outflow mass of ~2x10^{10} Msun, a mass-flow rate of ~54 Msun/yr, a kinetic luminosity of ~9x10^{41} erg/s, and a mass loading factor of ~8 for the outflowing high-ionization gas. These are consistent with the properties of "down-the-barrel" outflows from infrared-luminous starbursts as studied by Rupke et al. Such powerful, large-scale, metal-rich outflows are the primary means of sufficient mechanical and chemical feedback as invoked in theoretical models of galaxy formation and evolution.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:August 2015
Deposited On:23 Feb 2016 07:55
Last Modified:08 Dec 2017 18:37
Publisher:IOP Publishing
ISSN:1538-4357
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1088/0004-637X/811/2/132
Other Identification Number:arXiv:1506.01028v2

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