POLYCYCLIC AROMATIC HYDROCARBONS IN GALAXIES AT<i>z</i>∼ 0.1: THE EFFECT OF STAR FORMATION AND ACTIVE GALACTIC NUCLEI

O’Dowd, Matthew; Schiminovich, David; Johnson, Benjamin D.; Treyer, Marie; Martin, Christopher; Wyder, Ted K.; Charlot, S.; Heckman, Timothy M.; Martins, Lucimara P.; Seibert, Mark; Hulst, van der Thijs

doi:10.1088/0004-637x/705/1/885

Cited by 77 publications

(141 citation statements)

References 20 publications

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“…The Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS; PI: D. Schiminovich) contains 101 local (0.03 < z < 0.21) galaxies overlapping the Lockman Hole region (O'Dowd et al 2009;Treyer et al 2010;O'Dowd et al 2011). This sample is augmented by the Spitzer SDSS Spectroscopic Survey (S5; PI: D. Schiminovich), increasing the sample size of local (in this case, 0.05 < z < 0.1) star-forming galaxies to 300 (B. Bertincourt et al, in preparation).…”

Section: Sample Selectionmentioning

confidence: 99%

“…SFRs have consequently been calibrated on PAH luminosities (e.g., Farrah et al 2007). However, the PAH luminosity may be affected by AGN activity, and the effect may be different for the different PAH features (e.g., O'Dowd et al 2009;Treyer et al 2010;. In this analysis, we consider the sum of the PAH luminosities at 7.7 μm, 11.3 μm, and 17 μm (L ΣPAH 7.7,11.3,17 μm ).…”

Section: Ir Sfr Diagnostics: Neon Emission Lines and Pah Luminositiesmentioning

confidence: 99%

“…Disentangling the contribution from the AGN versus star formation then becomes a necessary intermediate step in using continuum IR emission as a tracer of star formation in active galaxies, and such a process can be plagued with uncertainties. Previous studies have indicated that emission from PAHs tends to be suppressed in galaxies hosting an active nucleus, which is sometimes attributed to the harsh radiation field produced by the AGN accretion disk destroying PAHs (e.g., Voit 1992;O'Dowd et al 2009;Treyer et al 2010;LaMassa et al 2010;.…”

Section: Introductionmentioning

confidence: 99%

“…An anti-correlation between ionization field hardness and the ratio of PAH features at 7.7 μm and 11.3 μm has been reported and is interpreted as due to an increasing contribution to the mid-IR continuum emission by AGN-heated dust. The selective destruction of smaller PAH grains may also play a role (e.g., Smith et al 2007b;O'Dowd et al 2009;Treyer et al 2010;Wu et al 2010), and so the flux ratios of the different PAH features can then also potentially trace the relative contribution of AGNs and star formation in active galaxies.…”

Section: Introductionmentioning

confidence: 99%

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Exploring the Connection Between Star Formation and Active Galactic Nucleus Activity in the Local Universe

LaMassa

Heckman

Ptak

et al. 2012

ApJ

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We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from the Sloan Digital Sky Survey (SDSS) and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic contributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [Ne ii] 12.8 μm emission line is well correlated with the star formation rate measured from the SDSS spectra, and this holds for the star-forming, composite, and AGN-dominated systems. AGNs show a clear excess of [Ne iii] 15.6 μm emission relative to star-forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including the mid-IR spectral slope, the ratio of the [Ne v] 14.3 μm to [Ne ii] μm 12.8 fluxes, the equivalent widths of the 7.7 μm, 11.3 μm, and 17 μm polycyclic aromatic hydrocarbon (PAH) features, and the optical "D" parameter which measures the distance at which a source lies from the locus of star-forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN dominance. We find that the PAH 11.3 μm feature is significantly suppressed in the most AGN-dominated systems.

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Section: Sample Selectionmentioning

confidence: 99%

Section: Ir Sfr Diagnostics: Neon Emission Lines and Pah Luminositiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exploring the Connection Between Star Formation and Active Galactic Nucleus Activity in the Local Universe

LaMassa

Heckman

Ptak

et al. 2012

ApJ

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“…Hence, the H 2 gas that comprises the bulk of the molecular interstellar medium (ISM) is commonly believed to be too cold to be visible. And yet, despite these observational disadvantages, the advent of the Infrared Space Observatory and in particular Spitzer's Infrared Spectrograph (IRS, Houck et al 2004) revealed pure rotational H 2 emission from a rich variety of extragalactic sources, including normal star-forming galaxies (Roussel et al 2007), ultraluminous and luminous infrared galaxies (U/LIRGs Lutz et al 2003;Veilleux et al 2009;PereiraSantaella et al 2010;Stierwalt et al 2014), galaxy mergers (Appleton et al 2006), radio-loud active galactic nuclei (AGNs) (Ocaña Flaquer et al 2010), UV-selected galaxies (O'Dowd et al 2009), quasar hosts (Evans et al 2001), cooling-flow cluster systems (Egami et al 2006), sources with extreme shockdominated energetics (Ogle et al 2010), and even star-forming sources at redshifts 2 ).…”

Section: Introductionmentioning

confidence: 99%

LIGHTING THE DARK MOLECULAR GAS: H₂ AS A DIRECT TRACER

Togi

Smith

2016

ApJ

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Robust knowledge of molecular gas mass is critical for understanding star formation in galaxies. The H 2 molecule does not emit efficiently in the cold interstellar medium, hence the molecular gas content of galaxies is typically inferred using indirect tracers. At low metallicity and in other extreme environments, these tracers can be subject to substantial biases. We present a new method of estimating total molecular gas mass in galaxies directly from pure mid-infrared rotational H 2 emission. By assuming a power-law distribution of H 2 rotational temperatures, we can accurately model H 2 excitation and reliably obtain warm (T100 K) H 2 gas masses by varying only the power law's slope. With sensitivities typical of Spitzer/IRS, we are able to directly probe the H 2 content via rotational emission down to ∼80 K, accounting for ∼15% of the total molecular gas mass in a galaxy. By extrapolating the fitted power-law temperature distributions to a calibrated single lower cutoff temperature, the model also recovers the total molecular content within a factor of ∼2.2 in a diverse sample of galaxies, and a subset of broken powerlaw models performs similarly well. In ULIRGs, the fraction of warm H 2 gas rises with dust temperature, with some dependency on α CO . In a sample of five low-metallicity galaxies ranging down to [ ] + = 12 log O H 7.8, the model yields molecular masses up to ∼100×larger than implied by CO, in good agreement with other methods based on dust mass and star formation depletion timescale. This technique offers real promise for assessing molecular content in the early universe where CO and dust-based methods may fail.

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AGN feedback and star formation in young and old radio galaxies

et al. 2016

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Powerful radio galaxies show evidence of ongoing active galactic nuclei (AGN) feedback, mainly in the form of fast, massive outflows. Yet, it is not clear how these outflows affect the star formation of their hosts. We investigated the different manifestations of AGN feedback in the evolved 3C 293 radio source, and in the young, reactivated 3C 236. Both sources harbor young star‐forming regions and fast outflows of H I and ionized gas. Due to the different evolution stages of these sources, they are expected to be at different phases of the AGNISM interaction process. Using high spatial resolution observations of CO lines taken with the IRAM Plateau de Bure interferometer, we studied the distribution and kinematics of the molecular gas in these sources, and compared the results with the dust and star‐formation images of the host. We searched for signatures of outflow motions in the CO kinematics, and derived the star formation rate (SFR) and star formation efficiency (SFE) of the host with all available SFR tracers. Based on the gas mass derived from our observations and on the SFR estimates, we compared the star‐formation efficiency of 3C 236 and 3C 293 against a sample of powerful radio galaxies. Our results suggest that the apparently low SFE of evolved radio galaxies is not necessarily due to AGN feedback, but may be caused by an underestimation of the SFR and/or an overestimation of the molecular gas densities in radio galaxies. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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POLYCYCLIC AROMATIC HYDROCARBONS IN GALAXIES ATz∼ 0.1: THE EFFECT OF STAR FORMATION AND ACTIVE GALACTIC NUCLEI

Cited by 77 publications

References 20 publications

Exploring the Connection Between Star Formation and Active Galactic Nucleus Activity in the Local Universe

Exploring the Connection Between Star Formation and Active Galactic Nucleus Activity in the Local Universe

LIGHTING THE DARK MOLECULAR GAS: H₂ AS A DIRECT TRACER

AGN feedback and star formation in young and old radio galaxies

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POLYCYCLIC AROMATIC HYDROCARBONS IN GALAXIES ATz∼ 0.1: THE EFFECT OF STAR FORMATION AND ACTIVE GALACTIC NUCLEI

Cited by 77 publications

References 20 publications

Exploring the Connection Between Star Formation and Active Galactic Nucleus Activity in the Local Universe

Exploring the Connection Between Star Formation and Active Galactic Nucleus Activity in the Local Universe

LIGHTING THE DARK MOLECULAR GAS: H2 AS A DIRECT TRACER

AGN feedback and star formation in young and old radio galaxies

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Product

Resources

About

LIGHTING THE DARK MOLECULAR GAS: H₂ AS A DIRECT TRACER