The far-ultraviolet spectra of early-type galaxies

Burstein, David; Bertola, F.; Buson, L. M.; Faber, S. M.; Lauer, Tod R.

doi:10.1086/166304

Cited by 309 publications

(453 citation statements)

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“…Besides AGN, there is one further effect which can mimic young stars in the near-UV. Extremely old stellar populations can give rise to the UV upturn phenomenon in some early-type galaxies 32,33 . We choose the NUV-r colour of one of the strongest UV upturn galaxies NGC 4552 33 to be the boundary between galaxies with no young component on the one hand and those that are so blue they must have some young stars in them.…”

Section: The Rsf Criterionmentioning

confidence: 99%

“…Extremely old stellar populations can give rise to the UV upturn phenomenon in some early-type galaxies 32,33 . We choose the NUV-r colour of one of the strongest UV upturn galaxies NGC 4552 33 to be the boundary between galaxies with no young component on the one hand and those that are so blue they must have some young stars in them. Although still quite limited, theoretical population synthesis models which are supported by empirical data (Lee et al 34 ) also suggest that the NUV-r of passively evolving ETGs could not be much bluer than 5.4.…”

Section: The Rsf Criterionmentioning

confidence: 99%

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Suppression of star formation in early-type galaxies by feedback from supermassive black holes

Schawinski¹,

Khochfar²,

Kaviraj³

et al. 2006

Nature

147

157

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Detailed high resolution observations of the innermost central parts of nearby galaxies have revealed the presence of supermassive black holes 1-4 . These black holes may interact with 1 their host galaxies by means of 'feedback' in the form of energy and material jets; this feedback affects the evolution of the host and gives rise to the observed relations between the black hole and the host 5 . Here we report observations of the ultraviolet emissions of massive early-type galaxies. We derive an empirical relation for a critical black-hole mass (as a function of velocity dispersion) above which the outflows from these black holes suppress star formation in their hosts by heating and expelling all available cold gas. Supermassive black holes are negligible in mass compared to their hosts but nevertheless seem to play a critical role in the star formation history of galaxies.The near-UV (NUV) detector of the Galaxy Evolution Explorer satellite GALEX 6 covers a range in wavelength between 1771 and 2831Å and is extremely sensitive to young stellar populations. With it, we can detect small mass fractions of 1-3% of young stars formed within the last billion years 7, 8 . This high sensitivity allows us to trace ongoing residual star formation in present day early-type galaxies (ETGs). We select a volume-limited sample of visually inspected ETGs from the Sloan Digital Sky Survey 9 that have been observed by GALEX. We remove active galactic nucleus (AGN) candidates from our sample to avoid confusion between the observed UV emissions from the AGN and from young stars 1 .We use NUV − r colour as a probe of small amounts of recent star formation (RSF) and find that the fraction of ETGs that show signs of RSF is strongly correlated with the stellar velocity dispersion σ, (hereafter "RSF-σ relation"), but not with the luminosity of the galaxy (see Figure 1). The correlation with σ cannot be explained by a systematic trend of σ with internal extinction, 2 because such a trend would be exact opposite 11 to that observed.We use a semi-analytic model of galaxy evolution in the ΛCDM paradigm to interpret these results 2, 3, 14 (for model details see Supplements). Our simulation includes all the systematic processes that affect galaxy evolution and takes into account the different merger and star formation histories of galaxies 15 . When we run this simulation and investigate the predicted amount of recent star formation in low redshift ETGs, we find that all galaxies underwent enough star formation within the last billion years to be detected by the extremely sensitive GALEX NUV detector. Massive galaxies continued to gain cold gas as fuel for star formation from mergers with satellites and through the cooling of hot gas present in those galaxies.This overproduction of stars in massive galaxies is a known problem in models of galaxy evolution. In order to prevent star formation, a shutdown mechanism is required: cold gas must be heated up and expelled to prevent it from turning into stars. Feedback from supernovae (SNe) was o...

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Section: The Rsf Criterionmentioning

confidence: 99%

Section: The Rsf Criterionmentioning

confidence: 99%

Suppression of star formation in early-type galaxies by feedback from supermassive black holes

Schawinski¹,

Khochfar²,

Kaviraj³

et al. 2006

Nature

147

157

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“…More specifically, our own SAURON stellar absorption-line measurements indicate a nearly Solar value of [Fe/H] ∼ −0.2 for the average metallicity of the nuclear stars of M31, in line with what found in the centers of low mass early-type galaxies (e.g., as in SAURON survey; Kuntschner et al 2006), whereas the optical regions of M32 display stellar metallicity values around [Fe/H] ∼ −0.5, well below Solar standards and closer to what observed in the outskirts of more typical early-type galaxies (see, e.g., Weijmans et al 2009). At the same time, is has long been known since the first low-resolution UV spectroscopic observations of Burstein et al (1988) with the International Ultraviolet Explorer (IUE) that M31 shows stronger far-UV fluxes than M32 (within their central ∼ 20 ).…”

Section: Connection With the Parent Stellar Populationmentioning

confidence: 99%

The central planetary nebulae populations of external galaxies with SAURON

Sarzi

2011

Proc. IAU

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Abstract. Thanks to SAURON integral-field observations we uncovered the planetary nebulae (PNe) populations inhabiting the central and nuclear regions of our galactic neighbours M32 and M31, respectively, and discuss the significant differences between their corresponding PNe luminosity functions in light of the properties of their parent stellar populations. In particular, we conclude that the lack of bright PNe in the nuclear regions of M31 is likely linked to the nearly Solar value for the stellar metallicity, consistent with previous suggestions that a larger metallicity would bias the horizontal-branch (HB) populations toward bluer colors, leading to fewer red HB stars capable of producing PNe and more blue HB stars that instead could contribute to the far-UV flux observed in metal-rich early-type galaxies and, incidentally, in the nucleus of M31.

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“…As stressed above its "oval" (10 × 20 ) shape is photometrically equivalent to a 7 radius circular aperture (cf. Burstein et al 1988), i.e. ∼0.5 r e NGC 3610 (Idiart et al 2003).…”

Section: Uv Observationsmentioning

confidence: 99%

The mid-UV population of the nucleus and the bulk of the post-merger NGC 3610

Buson

2010

A&A

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Context. The very center (r r e ) of NGC 3610, a clearly disturbed giant elliptical that is generally assumed to be a post-merger remnant, appears dominated in the mid-UV (2500−3200 Å spectral region) by a stellar population that is markedly different from that dominating the bulk of its stellar body. Aims. We make use of the mid-UV spectra of NGC 3610 as seen through tiny (∼1 ) and large (10 × 20 ) apertures as a diagnostic population tool. Methods. We compare archive IUE/LWP large aperture and HST/FOS UV data of NGC 3610.Results. The strength of mid-UV triplet (dominated by the turnoff population) shows a remarkable drop when switching from the galaxy central arcsec (FOS aperture) to an aperture size comparable to ∼0.5 r e (IUE). Conclusions. The sub-arsec (mid)-UV properties of this galaxy involved in a past merger reveal a central metal enrichment which left the bulk of its pre-existing population intact.

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The far-ultraviolet spectra of early-type galaxies

Cited by 309 publications

References 0 publications

Suppression of star formation in early-type galaxies by feedback from supermassive black holes

Suppression of star formation in early-type galaxies by feedback from supermassive black holes

The central planetary nebulae populations of external galaxies with SAURON

The mid-UV population of the nucleus and the bulk of the post-merger NGC 3610

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