Simple Models of Metal-Line Absorption and Emission From Cool Gas Outflows

Prochaska, J. Xavier; Kasen, Daniel; Rubin, Kate H. R.

doi:10.1088/0004-637x/734/1/24

Cited by 155 publications

(355 citation statements)

References 71 publications

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“…The different degrees of blueshift for different lines were also suggested by Prochaska et al (2011) and were observed in the Keck spectra of SFGs by Erb et al (2012) and Kornei et al (2013) and in the VLT spectra by Tang et al (2014). Erb et al (2012, see also Kornei et al 2013) also found a variety of Mg II profiles in their individual spectra, and suggested some emission might originate from H II regions.…”

Section: Discussionmentioning

confidence: 54%

“…For the eBOSS ELGs, the mean spectral resolution is about 2000 ~(60-70 km s 1 -) and the mean redshift precision is about 20 km s 1 -at redshift z ∼ 0.8. Our model is in principle similar to the one introduced by Scarlata & Panagia (2015, see also Rubin et al 2011Prochaska et al 2011), which the authors used as the basis in their radiative transfer simulations to interpret space-based observations in the FUV, though here we emphasize the statistical aspect of our model. Considering the sample size and S/N of our current data, we cannot yet place strong constraints on the model details, such as the functional form of the profiles or the parameters.…”

Section: Basics Of the Gas Outflow Modelmentioning

confidence: 93%

“…Scarlata & Panagia (2015, see also Prochaska et al 2011) included an excellent discussion of the general radiative transfer processes involved in a galactic outflow, and Prochaska et al (2011) also pioneered theoretical considerations of the NUV transitions. We refer the reader to those papers for more details.…”

Section: General Radiative Transfer Processesmentioning

confidence: 99%

“…These non-resonant emission lines are likely caused by scattered fluorescent photons after the occurrence of resonant absorption. As the non-resonant emission lines in the FUV (e.g., Shapley et al 2003;Jones et al 2012), they have provided a new means to study the radiative transfer physics in the complex baryon processes in galaxy evolution (e.g., Rubin et al 2011;Prochaska et al 2011;Scarlata & Panagia 2015).…”

Section: Introductionmentioning

confidence: 99%

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NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

Zhu

Comparat

Kneib

et al. 2015

ApJ

104

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We present rest-frame near-ultraviolet (NUV) spectroscopy of star-forming galaxies (SFGs) at 0.6 < z < 1.2 from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) in SDSS-IV. One of the eBOSS programs is to obtain 2″ (about 15 kpc) fiber spectra of about 200,000 emission-line galaxies (ELGs) at redshift z  0.6. We use the data from the pilot observations of this program, including 8620 spectra of SFGs at 0.6 < z < 1.2. The median composite spectra of these SFGs at 2200 Å < λ < 4000 Å feature asymmetric, preferentially blueshifted nonresonant emission, Fe II * , and blueshifted resonant absorption, e.g., Fe II and Mg II, indicating ubiquitous outflows driven by star formation at these redshifts. For the absorption lines, we find a variety of velocity profiles with different degrees of blueshift. Comparing our new observations with the literature, we do not observe the nonresonant emission in the small-aperture (<40 pc) spectra of local star-forming regions with the Hubble Space Telescope, and find the observed line ratios in the SFG spectra to be different from those in the spectra of local starforming regions, as well as those of quasar absorption-line systems in the same redshift range. We introduce an outflow model that can simultaneously explain the multiple observed properties and suggest that the variety of absorption velocity profiles and the line ratio differences are caused by scattered fluorescent emission filling in on top of the absorption in the large-aperture eBOSS spectra. We develop an observation-driven, model-independent method to correct the emission infill to reveal the true absorption profiles. Finally, we show that the strengths of both the non-resonant emission and the emission-corrected resonant absorption increase with [O II] λλ3727, 3730 rest equivalent width and luminosity, with a slightly larger dependence on the former. Our results show that the eBOSS and future dark-energy surveys (e.g., Dark Energy Spectroscopic Instrument survey and Prime Focus Spectrograph survey) will provide rich data sets of rest-frame NUV spectroscopy for astrophysical applications.

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Section: Discussionmentioning

confidence: 54%

Section: Basics Of the Gas Outflow Modelmentioning

confidence: 93%

Section: General Radiative Transfer Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

Zhu

Comparat

Kneib

et al. 2015

ApJ

104

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“…This can create a diffuse, low surface brightness emission component. Prochaska et al (2011) model the effect of reemitted light and conclude that in the extreme case that all of this light eventually escapes and is caught within the aperture, it can significantly reduce the observed equivalent width. We expect this effect to be very small in our analysis, however, since we are looking only at narrow slits and apertures that are small compared to the galaxies (1.5 arcsec corresponds to roughly 0.6 kpc in Haro 11 and just 0.3 kpc in ESO 338-IG04).…”

Section: Possible Stellar Contamination Of Na Dmentioning

confidence: 99%

Neutral gas in Lyman-alpha emitting galaxies Haro 11 and ESO 338-IG04 measured through sodium absorption

Sandberg

Östlin

Hayes

et al. 2013

A&A

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Context. The Lyman alpha emission line of neutral hydrogen is an important tool for finding galaxies at high redshift, thus for probing the structure of the early universe. However, the resonance nature of the line and its sensitivity to dust and neutral gas is still not fully understood.Aims. We present measurements of the velocity, covering fraction and optical depth of neutral gas in front of two well-known, local blue compact galaxies that show Lyman alpha in emission: ESO 338-IG 04 and Haro 11. We thus observationally test the hypothesis that Lyman alpha can escape through neutral gas by being Doppler shifted out of resonance. Methods. We present integral field spectroscopy, obtained with the GIRAFFE/Argus spectrograph at VLT/FLAMES in Paranal, Chile. The excellent wavelength resolution allowed us to accurately measure the velocity of the ionized and neutral gas through the Hα emission and Na D absorption, which trace the ionized medium and cold interstellar gas, respectively. We also present independent measurements from the VLT/X-shooter spectrograph that confirm our results. Results. For ESO 338-IG04 we measure no significant shift of neutral gas: the best fit velocity offset is −15 ± 16 km s −1 . For Haro 11, we see an outflow from knot B at 44 ± 13 km s −1 , and infalling gas towards knot C with 32 ± 12 km s −1 . Based on the relative strength of the Na D absorption lines, we estimate low covering fractions of neutral gas (down to 10%) in all three cases. Conclusions. The Na D absorption most likely occurs in dense clumps with higher column densities than the medium in which the bulk of the Ly α scattering takes place. Still, we find no strong correlation between outflowing neutral gas and strong Ly α emission. The Ly α photons from these two galaxies are therefore likely to be escaping due to a low column density and/or covering fraction.

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A Dynamical Model of Supernova Feedback: Gas Outflows from the Interstellar Medium

Lagos

2013

Springer Theses

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We present a dynamical model of supernova feedback which follows the evolution of pressurised bubbles driven by supernovae in a multi-phase interstellar medium (ISM). The bubbles are followed until the point of break-out into the halo, starting from an initial adiabatic phase to a radiative phase. We show that a key property which sets the fate of bubbles in the ISM is the gas surface density, through the work done by the expansion of bubbles and its role in setting the gas scaleheight. The multi-phase description of the ISM is essential, and neglecting it leads to order of magnitude differences in the predicted outflow rates. We compare our predicted mass loading and outflow velocities to observations of local and high-redshift galaxies and find good agreement over a wide range of stellar masses and velocities. With the aim of analysing the dependence of the mass loading of the outflow, β (i.e. the ratio between the outflow and star formation rates), on galaxy properties, we embed our model in the galaxy formation simulation, GALFORM, set in the ΛCDM framework. We find that a dependence of β solely on the circular velocity, as is widely assumed in the literature, is actually a poor description of the outflow rate, as large variations with redshift and galaxy properties are obtained. Moreover, we find that below a circular velocity of ≈ 80 km s −1 the mass loading saturates. A more fundamental relation is that between β and the gas scaleheight of the disk, h g , and the gas fraction, f gas , as β ∝ h 1.1 g f 0.4 gas , or the gas surface density, Σ g , and the gas fraction, as β ∝ Σ −0.6 g f 0.8 gas . We find that using the new mass loading model leads to a shallower faint-end slope in the predicted optical and near-IR galaxy luminosity functions.

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Simple Models of Metal-Line Absorption and Emission From Cool Gas Outflows

Cited by 155 publications

References 71 publications

NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

Neutral gas in Lyman-alpha emitting galaxies Haro 11 and ESO 338-IG04 measured through sodium absorption

A Dynamical Model of Supernova Feedback: Gas Outflows from the Interstellar Medium

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