The Young and the Dustless: Interpreting Radio Observations of Ultraviolet‐Luminous Galaxies

Basu-Zych, Antara; Schiminovich, David; Johnson, Benjamin D.; Hoopes, Charles G.; Overzier, Roderik; Treyer, Marie; Heckman, Timothy M.; Barlow, Tom A.; Bianchi, Luciana; Conrow, T.; Donas, J.; Forster, Karl; Friedman, Peter G.; Lee, Young-Wook; Madore, Barry F.; Martin, D. Christopher; Milliard, B.; Morrissey, Patrick; Neff, Susan G.; Rich, R. Michael; Salim, Samir; Seibert, Mark; Small, Todd; Szalay, Alexander S.; Wyder, Ted K.; Yi, Sukyoung K.

doi:10.1086/521146

Cited by 43 publications

(41 citation statements)

References 51 publications

(77 reference statements)

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“…These rare local objects are very similar to high-z Lyman Break galaxies in all their properties studied to date Hoopes et al 2007;Basu-Zych et al 2007Goncalves et al 2010;Overzier et al 2009, O09;Overzier et al 2008Overzier et al , 2010Overzier et al , 2011. We have compared these rare objects to a sample of 15 typical UV-bright local starbursts.…”

Section: Summary and Implicationsmentioning

confidence: 79%

“…These LBAs are a very rare population of local galaxies that strongly resemble the high-z Lyman Break galaxies Hoopes et al 2007;Overzier at al. 2008Basu-Zych et al 2007. They are defined to have a range in far-UV luminosity (>2×10 10 L ) and far-UV effective surface brightness (>10 9 L kpc −2 ) that are similar to typical Lyman Break galaxies.…”

Section: Introductionmentioning

confidence: 99%

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Extreme Feedback and the Epoch of Reionization: Clues in the Local Universe

Heckman

Borthakur

Overzier

et al. 2011

ApJ

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288

405

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The source responsible for reionizing the universe at z > 6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough fraction of their ionizing radiation can escape into the intergalactic medium. Attempts to measure this escape fraction in intensely star-forming galaxies at lower redshifts have largely yielded upper limits. In this paper, we present new Hubble Space Telescope Cosmic Origins Spectrograph and archival Far-Ultraviolet Spectroscopic Explorer (FUSE) far-UV spectroscopy of a sample of 11 Lyman Break Analogs (LBAs), a rare population of local galaxies that strongly resemble the high-z Lyman Break galaxies. We combine these data with Sloan Digital Sky Survey optical spectra and Spitzer photometry. We also analyze archival FUSE observations of 15 typical UV-bright local starbursts. We find evidence of small covering factors for optically thick neutral gas in three cases. This is based on two independent pieces of evidence: a significant residual intensity in the cores of the strongest interstellar absorption-lines tracing neutral gas and a small ratio of extinction-corrected Hα to UV plus far-IR luminosities. These objects represent three of the four LBAs that contain a young, very compact (∼10 2 pc), and highly massive (∼10 9 M ) dominant central object (DCO). These three objects also differ from the other galaxies in showing a significant amount of blueshifted Lyα emission, which may be related to the low covering factor of neutral gas. All four LBAs with DCOs in our sample show extremely high velocity outflows of interstellar gas, with line centroids blueshifted by about 700 km s −1 and maximum outflow velocities reaching at least 1500 km s −1 . We show that these properties are consistent with an outflow driven by a powerful starburst that is exceptionally compact. We speculate that such extreme feedback may be required to enable the escape of ionizing radiation from star-forming galaxies.

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Section: Summary and Implicationsmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Extreme Feedback and the Epoch of Reionization: Clues in the Local Universe

Heckman

Borthakur

Overzier

et al. 2011

ApJ

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288

405

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“…These were selected as super-compact UV luminous galaxies by Heckman et al (2005) and Hoopes et al (2007) in order to isolate Lyman break analogues (LBAs) of distant Lyman break galaxies (LBGs). LBAs appear to be very rare locally (Heckman et al 2005) and indeed share many similarities with distant LBGs, such as their (stellar or dynamical) masses, UV luminosities, sizes, star formation rates, dust attenuation or gas metallicities (Heckman et al 2005;Basu-Zych et al 2007;Hoopes et al 2007). High-resolution images from the HST revealed UV morphologies similar to those of LBGs, once degraded to similar depth and spatial resolution (Overzier et al 2008(Overzier et al , 2010.…”

Section: Interactions As a Driver For Clump Formationmentioning

confidence: 99%

Clumpy galaxies at z∼0.6: kinematics, stability and comparison with analogues at other redshifts

Puech¹

2010

Monthly Notices of the Royal Astronomical Society

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Distant clumpy galaxies are thought to be Jeans‐unstable discs and an important channel for the formation of local galaxies, as suggested by recent spatially resolved kinematic observations of z∼ 2 galaxies. I study the kinematics of clumpy galaxies at z∼ 0.6 and compare their properties with those of counterparts at higher and lower redshifts. I selected a sample of 11 clumpy galaxies at z∼ 0.6 from the representative sample of emission‐line, intermediate‐mass galaxies IMAGES. Selection was based on rest‐frame UV morphology from Hubble Space Telescope/Advanced Camera for Surveys images, mimicking the selection criteria commonly used at higher redshifts. Their spatially resolved kinematics were derived in the frame of the IMAGES survey, using the Very Large Telescope/FLAMES‐GIRAFFE multi‐integral field spectrograph. For those showing large‐scale rotation, I derived the Toomre Q parameter, which characterizes the stability of their gaseous and stellar phases. I find that the fraction of UV‐selected clumpy galaxies at z∼ 0.6 is 20 ± 12 per cent. Roughly half of them (45 ± 30 per cent) have complex kinematics inconsistent with Jeans‐unstable discs, while those in the remaining half (55 ± 30 per cent) show large‐scale rotations. The latter reveal a stable gaseous phase, but the contribution of their stellar phase makes them globally unstable to clump formation. Clumpy galaxies appear to be less unstable at z∼ 0.6 than at z∼ 2, which could explain why the UV clumps tend to vanish in rest‐frame optical images of z∼ 0.6 clumpy galaxies, conversely to z∼ 2 clumpy galaxies, in which the stellar phase can substantially fragment. This suggests that the former correspond to patchy star formation regions superimposed on a smoother mass distribution. A possible and widespread scenario for driving clump formation relies on instabilities by cold streams penetrating the dark matter haloes where clumpy galaxies inhabit. While such a gas accretion process is predicted to be significant in massive, z∼ 2 haloes, it is also predicted to be strongly suppressed in similar, z∼ 0.6 haloes, which could explain why lowest z clumpy galaxies appear to be driven by a different mechanism. Instead, I found that interactions are probably the dominant driver leading to the formation of clumpy galaxies at z < 1. I argue that the nature of z > 1 clumpy galaxies remains more uncertain. While cold flows could be an important driver at z∼ 2, I also argue that the observed and cumulative merger fraction between z= 2 and z= 3 is large enough so that every z∼ 2 galaxy might be the result of a merger that occurred within their past 1 Gyr. I conclude that it is premature to rule out mergers as a universal driver for galaxy evolution from z∼ 2 down to z= 0.

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“…a UV SFR derived from the FUV luminosity (uncorrected for dust). Adapted from Basu-Zych et al (2007). b IR SFR derived from the bolometric dust luminosity (given in Table 5) and calculated using the formula log 10 L dust ¼ 9:75 þ log 10 SFR IR and assuming a 100 Myr old constant SFR model with Salpeter IMF as given in Takeuchi et al (2005).…”

Section: Archival Imaging Data Of Haro 11 and Vv 114mentioning

confidence: 99%

“…Interestingly, once selected according to these criteria, the UVLG sample proved to be similar to typical LBGs in all other measurable properties (see H05 and H07). Further details on the sample are given by Basu-Zych et al (2007), who investigated the radio to UV continuum properties of the sample and found that they follow the radioYfar-infrared correlation of normal star-forming galaxies but generally have less dust than other star-forming galaxies with such high specific SFRs. In this respect, they are similar to LBGs.…”

Section: Introductionmentioning

confidence: 99%

Hubble Space TelescopeMorphologies of Local Lyman Break Galaxy Analogs. I. Evidence for Starbursts Triggered by Merging

Overzier

Heckman

Kauffmann

et al. 2008

ApJ

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127

165

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Heckman and coworkers used the GALEX UV imaging survey to show that there exists a rare population of nearby compact UV-luminous galaxies (UVLGs) that closely resemble high-redshift Lyman break galaxies (LBGs). We present HST images in the UV, optical, and H and resimulate them at the depth and resolution of the GOODS/UDF fields to show that the morphologies of UVLGs are also similar to those of LBGs. Our sample of eight LBG analogs thus provides detailed insight into the connection between star formation and LBG morphology. Faint tidal features or companions can be seen in all of the rest-frame optical images, suggesting that the starbursts are the result of a merger or interaction. The UV/optical light is dominated by unresolved ($100Y300 pc) super starburst regions (SSBs). A detailed comparison with the galaxies Haro 11 and VV 114 at z ¼ 0:02 indicates that the SSBs themselves consist of diffuse stars and (super) star clusters. The structural features revealed by the new HST images occur on very small physical scales and are thus not detectable in images of high-redshift LBGs, except in a few cases where they are magnified by gravitational lensing. We propose, therefore, that LBGs are mergers of gas-rich, relatively low-mass (M Ã $ 10 10 M ) systems, and that the mergers trigger the formation of SSBs. If galaxies at high redshifts are dominated by SSBs, then the faint-end slope of the luminosity function is predicted to have slope $ 2. Our results are the most direct confirmation to date of models that predict that the main mode of star formation in the early universe was highly collisional.

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The Young and the Dustless: Interpreting Radio Observations of Ultraviolet‐Luminous Galaxies

Cited by 43 publications

References 51 publications

Extreme Feedback and the Epoch of Reionization: Clues in the Local Universe

Extreme Feedback and the Epoch of Reionization: Clues in the Local Universe

Clumpy galaxies at z∼0.6: kinematics, stability and comparison with analogues at other redshifts

Hubble Space TelescopeMorphologies of Local Lyman Break Galaxy Analogs. I. Evidence for Starbursts Triggered by Merging

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