Integrated spectra extraction based on signal-to-noise optimization using integral field spectroscopy

Rosales-Ortega, F. F.; Arribas, S.; Colina, L.

doi:10.1051/0004-6361/201117774

Cited by 19 publications

(9 citation statements)

References 24 publications

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“…From the lFS data cubes, we generated a spatially integrated spectrum per galaxy via the S/N optimization method proposed by Rosales-Ortega et al (2012), using the pingsoft tool (Rosales-Ortega 2011). Before integration, the spectra were corrected from the general stellar velocity pattern.…”

Section: Discussionmentioning

confidence: 99%

Neutral gas outflows in nearby [U]LIRGs via optical NaD feature

Cazzoli

Arribas

Maiolino

et al. 2016

A&A

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We studied the properties of the neutral gas in a sample of 38 local luminous and ultra luminous infrared galaxies ([U]LIRGs, 51 individual galaxies at z ≤ 0.09), which mainly covers the less explored LIRG luminosity range. This study is based on the analysis of the spatially integrated and spatially resolved spectra of the NaDλλ 5890, 5896 Å feature obtained with the integral field unit (IFU) of VIMOS at the Very Large Telescope. Analyzing spatially integrated spectra, we find that the contribution of the stars to the observed NaD equivalent width is small (<35%) for about half of the sample, and therefore this feature is dominated by inter stellar medium (ISM) absorption. After subtracting the stellar contribution, we find that the pure-ISM integrated spectra generally show blueshifted NaD profiles, indicating neutral gas outflow velocities, V, in the range 65−260 km s −1 . Excluding the galaxies with powerful AGNs, V shows a dependency with the star formation rate (SFR) of the type V ∝ SFR 0.15 , which is in rather good agreement with previous results. The spatially resolved analysis could be performed for 40 galaxies, 22 of which have neutral gas velocity fields dominated by noncircular motions with signatures of cone-like winds. However, a large number of targets (11/40) show disk rotation signatures. Based on a simple model, we found that the wind masses are in the range 0.4−7.5 × 10 8 M , reaching up to ∼3% of the dynamical mass of the host. The mass rates are typically only ∼0.2−0.4 times the corresponding global SFR indicating that, in general, the mass loss is too small to slow down the star formation significantly. In the majority of cases, the velocity of the outflowing gas is not sufficient to escape the host potential well and, therefore, most of the gas rains back into the galaxy disk. On average V/v esc is higher in less massive galaxies, confirming that the galaxy mass has a primary role in shaping the recycling of gas and metals. The comparison between the wind power and kinetic power of the starburst associated with SNe indicates that only the starburst could drive the outflows in nearly all the [U]LIRGs galaxies, as the wind power is generally lower than 20% of the kinetic power supplied by the starburst. The contribution of an active galactic nuclei (AGN) is, in principle, significant in two cases.

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Section: Discussionmentioning

confidence: 99%

Neutral gas outflows in nearby [U]LIRGs via optical NaD feature

Cazzoli

Arribas

Maiolino

et al. 2016

A&A

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“…In this manner the integrated spectra are not affected by the broadening due to the large-scale velocity field, and have increased S/N. We reject individual spectra with low S/N, following the procedure for an optimal extraction of IFS spectra proposed by Rosales-Ortega et al (2012). As a consequence the final spectra have in general very high S/N (i.e.,>100), which facilitates the line fitting (see Appendix A1).…”

Section: Integrated and Clumps Spectra Setsmentioning

confidence: 99%

Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies

Arribas¹,

Colina²,

Bellocchi³

et al. 2014

Proc. IAU

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We study the kinematic properties of the ionised gas outflows and ambient interstellar medium (ISM) in a large and representative sample of local luminous and ultra-luminous infrared galaxies (U/LIRGs) (58 systems, 75 galaxies) at galactic and sub-galactic (i.e., star-forming clumps) scales, thanks to integral field spectroscopy (IFS)-based high signal-to-noise integrated spectra. The velocity dispersion of the ionized ISM in U/LIRGs (<σ> ∼ 70 kms −1 ) is larger than in lower luminosity local star-forming galaxies (<σ> ∼ 25 kms −1 ). While for isolated disc LIRGs star formation appears to sustain turbulence, gravitational energy release associated with interactions and mergers plays an important role in driving σ in the U/LIRG range. We find that σ has a dependency on the star formation rate density (Σ S FR ), which is weaker than expected if it were driven by the energy released by the starburst. The relatively small role of star formation (SF) driving the σ in U/LIRGs is reinforced by the lack of an increase in σ associated with high luminosity SF clumps. We also find that the impact of an active galactic nucleus (AGN) in ULIRGs is strong, increasing on average σ by a factor 1.5. Low-z U/LIRGs cover a range of velocity dispersion (σ ∼ 30 to 100 km s −1 ) and star formation rate density (Σ S FR ∼ 0.1 to 20 M ⊙ yr −1 kpc −2 ) similar to those of SFGs. Moreover, the observed weak dependency of σ on Σ S FR for local U/LIRGs (σ ∝ Σ +0.06 S FR ) is in very good agreement with that measured in some high-z samples. The presence of ionized gas outflows in U/LIRGs seems universal based on the detection of a broad, usually blueshifted, Hα line. The observed dependency of the maximum velocity of the outflow (V max ) on the star formation rate (SFR) is of the type V max (non−AGN) ∝ S FR(L IR ) +0.24 . We find that AGNs in U/LIRGs are able to generate faster (∼ × 2) and more massive (∼ × 1.4) ionized gas outflows than pure starbursts. The derived ionized mass loading factors (η) are in general below 1, with only a few AGNs above this limit. The escaping gas fraction is low with only less massive (log(M dyn /M ⊙ ) < 10.4) U/LIRGs having outflowing terminal velocities higher than their escape velocities, and more massive galaxies retaining the gas, even if they host an AGN. The observed average outflow properties in U/LIRGs are similar to high-z galaxies of comparable SFR. However, while high-z galaxies seem to require Σ S FR > 1 M ⊙ yr −1 kpc −2 for launching strong outflows, this threshold is not observed in low-z U/LIRGs even after correcting for the differential fraction of the gas content. In the bright SF clumps found in LIRGs, ionized gas outflows appear to be very common (detection rate over 80%). Their observed properties are less extreme than those associated with the entire galaxy. The clumps in LIRGs follow the general size-L-σ scaling relations found for low-and high-z clumps, though they are in general smaller, less luminous, and are characterized by lower σ than at high-z. For a given observed (no internal extin...

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“…The IFS analysis of NGC 628, the largest spectroscopic mosaic on a single galaxy, was taken as an example of the new methodology and analysis that could be performed with a large spectroscopic database for a single object. The contribution of PINGS also resides in defining a self-consistent methodology in terms of observation, data reduction and analysis for present and future IFS surveys of the kind, as well as a whole new set of visualization and analysis software that has been made public to the community (e.g., [51,52]). Despite all the complexities involved in the observations, data reduction, and analysis, PINGS proved to be feasible.…”

Section: Discussionmentioning

confidence: 99%

The Study of Nebular Emission on Nearby Spiral Galaxies in the IFU Era

Rosales-Ortega

2013

Advances in Astronomy

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A new generation of wide-field emission-line surveys based on integral field units (IFU) is allowing us to obtain spatially resolved information of the gas-phase emission in nearby late-type galaxies, based on large samples of HII regions and full two-dimensional coverage. These observations are allowing us to discover and characterise abundance differentials between galactic substructures and new scaling relations with global physical properties. Here I review some highlights of our current studies employing this technique: (1) the case study of NGC 628, the largest galaxy ever sampled with an IFU; (2) a statistical approach to the abundance gradients of spiral galaxies, which indicates a universal radial gradient for oxygen abundance; and (3) the discovery of a new scaling relation of HII regions in spiral galaxies, the local mass-metallicity relation of star-forming galaxies. The observational properties and constrains found in local galaxies using this new technique will allow us to interpret the gas-phase abundance of analogue high-z systems.

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Integrated spectra extraction based on signal-to-noise optimization using integral field spectroscopy

Cited by 19 publications

References 24 publications

Neutral gas outflows in nearby [U]LIRGs via optical NaD feature

Neutral gas outflows in nearby [U]LIRGs via optical NaD feature

Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies

The Study of Nebular Emission on Nearby Spiral Galaxies in the IFU Era

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