Measuring PAH Emission in Ultradeep<i>Spitzer</i>IRS Spectroscopy of High‐Redshift IR‐Luminous Galaxies

Teplitz, Harry I.; Desai, Vandana; Armus, L.; Chary, R.-R.; Marshall, J. A.; Colbert, James; Frayer, David; Pope, Alexandra; Blain, A.; Spoon, H. W. W.; Charmandaris, V.; Scott, D.

doi:10.1086/512802

Cited by 64 publications

(75 citation statements)

References 48 publications

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“…For example, SUBGs and non-SUBGs show on average S 8.0 /S 4.5 = 0.8 and no SUBG was found to be located above the Pope et al (2008) AGN criterion of 2.0. Finally, the Teplitz et al (2007) Spitzer IRS spectrum (source 2 in their Fig. 5) of the galaxy in the NPPS sample with the strongest 2175 Å feature, a K20 galaxy at z = 1.097, indicates a typical, star-formationdominated, luminous infrared galaxy.…”

Section: Fig 14mentioning

confidence: 96%

GMASS ultradeep spectroscopy of galaxies at z ~ 2

Noll

Pierini

Cimatti

et al. 2009

A&A

114

175

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Aims. The properties of dust attenuation at rest-frame UV wavelengths are inferred from very high-quality FORS 2 spectra of 78 galaxies from the GMASS survey at redshift 1 < z < 2.5. These objects complement a previously investigated sample of 108 UV-luminous, intermediate-mass (i.e., with stellar masses ∼10 10 −10 11 M ) galaxies at similar redshifts, selected from the FDF spectroscopic survey, the K20 survey, and the GDDS. Detection of the broad absorption feature centred on about 2175 Å ("UV bump") implies that the average UV extinction curve of a galaxy more closely resembles that of the Milky Way (MW) or the Large Magellanic Cloud (LMC), and differs from that of the Small Magellanic Cloud (SMC). Methods. The shape of the UV extinction curve is constrained by a parametric description of the rest-frame UV continuum with the support of a suite of models combining radiative transfer and stellar population synthesis. The UV bump is further characterised by fitting Lorentzian-like profiles. Results. Spectra exhibit a significant 2175 Å feature in at least 30% of the cases, especially those suffering from substantial reddening. If attenuation is dominated by dust ejected from the galaxy main body via galactic winds or more localised superwinds, UV extinction curves in-between those of the SMC and LMC characterise UV-luminous, intermediate-mass galaxies at 1 < z < 2.5. The fraction of galaxies with extinction curves differing from the SMC one increases, if more dust resides in the galactic plane or dust attenuation depends on stellar age. On average, the width of the manifested UV bumps is about 60% of the values typically measured along sightlines in the LMC and MW. This suggests the presence of dust similar to that found in the "supergiant" shell of ionised filaments LMC 2, close to 30 Dor. The presence of the carriers of the UV bump (probably organic carbon and amorphous silicates) at 1 < z < 2.5 argues for outflows from asymptotic giant branch (AGB) stars being copious then. Consistent with their higher star-formation rates, the GMASS galaxies with a manifested UV bump are more luminous at rest-frame 8 μm, where the emission is dominated by polycyclic aromatic hydrocarbons (also products of AGB stars). In addition, they exhibit larger equivalent widths for prominent UV (metal) absorption features, mostly of interstellar origin, which indicates overall more evolved stellar populations. Conclusions. We conclude that diversification of the small-size dust component (responsible for the differential extinction at UV wavelengths and the emission at mid-IR wavelengths) has already started in the most evolved star-forming systems at 1 < z < 2.5.

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Section: Fig 14mentioning

confidence: 96%

GMASS ultradeep spectroscopy of galaxies at z ~ 2

Noll

Pierini

Cimatti

et al. 2009

A&A

114

175

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“…We have compared our photometric redshifts against objects with a known spectroscopic redshift that is taken from the literature (Vanzella et al 2005(Vanzella et al , 2006(Vanzella et al , 2008Mignoli et al 2005;Szokoly et al 2004;Le Fèvre et al 2004;Doherty et al 2005;Wolf et al 2004;Daddi et al 2005;Cristiani et al 2000;Strolger et al 2004;van der Wel et al 2005;Roche et al 2006;Ravikumar et al 2007;Teplitz et al 2007;Xu et al 2007;Gronwall et al 2007;Nilsson et al 2007;Hathi et al 2008;Finkelstein et al 2008;Yang et al 2008;Popesso et al 2009). …”

Section: Redshift Selectionmentioning

confidence: 99%

Properties ofz~ 3–6 Lyman break galaxies

Barros

Schaerer

Stark

2014

A&A

156

205

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Context. To gain insight on the mass assembly and place constraints on the star formation history (SFH) of Lyman break galaxies (LBGs), it is important to accurately determine their properties. Aims. We estimate how nebular emission and different SFHs affect parameter estimation of LBGs.Methods. We present a homogeneous, detailed analysis of the spectral energy distribution (SED) of ∼1700 LBGs from the GOODS-MUSIC catalogue with deep multi-wavelength photometry from the U band to 8 μm to determine stellar mass, age, dust attenuation, and star formation rate. Using our SED fitting tool, which takes into account nebular emission, we explore a wide parameter space. We also explore a set of different star formation histories. Results. Nebular emission is found to significantly affect the determination of the physical parameters for the majority of z ∼ 3−6 LBGs. We identify two populations of galaxies by determining the importance of the contribution of emission lines to broadband fluxes. We find that ∼65% of LBGs show detectable signs of emission lines, whereas ∼35% show weak or no emission lines. This distribution is found over the entire redshift range. We interpret these groups as actively star-forming and more quiescent LBGs, respectively. We find that it is necessary to considerer SED fits with very young ages (<50 Myr) to reproduce some colours affected by strong emission lines. Other arguments favouring episodic star formation and relatively short star formation timescales are also discussed. Considering nebular emission generally leads to a younger age, lower stellar mass, higher dust attenuation, higher star formation rate, and a large scatter in the SFR-M relation. Our analysis yields a trend of increasing specific star formation rate with redshift, as predicted by recent galaxy evolution models. Conclusions. The physical parameters of approximately two thirds of high redshift galaxies are significantly modified when we account for nebular emission. The SED models, which include nebular emission shed new light on the properties of LBGs with numerous important implications.

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“…Genzel et al 1998;Rigopoulou et al 1999;Tran et al 2001) used the presence and strengths of spectral features attributed to PAHs in comparison to ionic line and continuum emission to disentangle the relative contributions of starburst and active nuclei to the overall luminosity in samples of ultraluminous IRAS galaxies (ULIRGs). Later, with the low resolution spectroscopy afforded by the Spitzer Space Telescope, it became not only possible to use the PAH emission features to estimate redshifts to infrared (IR) bright galaxies to at least z ∼ 2 but also to perform more detailed studies of those galaxies, thereby placing constraints on the contribution of star formation and active galactic nuclei (AGN) to the cosmic IR background (Schweitzer et al 2006;Spoon et al 2007;Teplitz et al 2007;Valiante et al 2007;Yan et al 2007).…”

Section: Introductionmentioning

confidence: 99%

3.3μm PAH observations of the central kiloparsecs of Centaurus A

Tacconi-Garman¹,

Sturm²

2013

A&A

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Aims. The aim of this work is to further investigate the nature of polycyclic aromatic hydrocarbon (PAH) excitation and emission especially in the context of tracing star formation in a variety of extragalactic environments. Here we turn our attention to the energetic environment of the closest active galactic nucleus (AGN) in our sample, Centaurus A. Methods. Using ISAAC on the ESO VLT UT1 (Antu) we have made high spatial resolution 3.3 µm imaging observations of the central kiloparsec of CenA. These observations have been compared with star formation tracers in the near-and mid-infrared, as well as with mid-infrared tracers of nuclear activity. Results. The nucleus is not devoid of PAH emission, implying that the PAH particles are not destroyed in the nucleus as might be expected for such a harsh environment. However, we see the feature to continuum ratio decrease towards the AGN. As well, the 3.3 µm PAH feature emission generally traces the sites of star formation in Cen A, but in detail there are spatial offsets, consistent with an earlier study of the starburst galaxies NGC 253 and NGC 1808. However, the feature-to-continuum ratio does not drop at the positions of star formation as was previously seen in that earlier study. The cause for this difference remains uncertain. Finally, our data reveal possible evidence for a nearly face-on, circular or spiral, dust structure surrounding the nucleus.

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Measuring PAH Emission in UltradeepSpitzerIRS Spectroscopy of High‐Redshift IR‐Luminous Galaxies

Cited by 64 publications

References 48 publications

GMASS ultradeep spectroscopy of galaxies at z ~ 2

GMASS ultradeep spectroscopy of galaxies at z ~ 2

Properties ofz~ 3–6 Lyman break galaxies

3.3μm PAH observations of the central kiloparsecs of Centaurus A

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