The Disappearance of Telecommunications

Saracco, Roberto; Harrow, Jeffrey R.; Weihmayer, Robert

doi:10.1109/9780470546567

Cited by 9 publications

(5 citation statements)

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“…Early-type galaxies (ETGs) are the most effective probes to investigate this topic, as they are the most massive and oldest galaxies in the local Universe and most likely those whose stars formed earliest. Observations have shown that a population of massive and passive galaxies is already in place at high redshift, when the Universe was only a few Gyr old (Cimatti et al 2004, Saracco et al 2005. So far, the main physical parameters ⋆ Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (program: 086.A-0088(A)) † E-mail: ilaria.lonoce@brera.inaf.it (OAB) related to their formation and assembly have been mainly estimated on local ETGs, and their ageing and evolution can mix up and confuse the original properties when the bulk of their mass formed and assembled.…”

Section: Introductionmentioning

confidence: 99%

Old age and supersolar metallicity in a massivez∼ 1.4 early-type galaxy from VLT/X-Shooter spectroscopy

Lonoce¹,

Longhetti²,

Maraston³

et al. 2015

Mon. Not. R. Astron. Soc.

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We present the first estimate of age, stellar metallicity and chemical abundance ratios, for an individual early-type galaxy at high-redshift (z = 1.426) in the COSMOS field. Our analysis is based on observations obtained with the X-Shooter instrument at the VLT, which cover the visual and near infrared spectrum at high (R > 5000) spectral resolution. We measure the values of several spectral absorptions tracing chemical species, in particular Magnesium and Iron, besides determining the agesensitive D4000 break. We compare the measured indices to stellar population models, finding good agreement. We find that our target is an old (t > 3 Gyr), high-metallicity ([Z/H] > 0.5) galaxy which formed its stars at z f orm > 5 within a short time scale ∼ 0.1 Gyr, as testified by the strong [α/Fe] ratio (> 0.4), and has passively evolved in the first > 3 − 4 Gyr of its life. We have verified that this result is robust against the choice and number of fitted spectral features, and stellar population model. The result of an old age and high-metallicity has important implications for galaxy formation and evolution confirming an early and rapid formation of the most massive galaxies in the Universe.

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Section: Introductionmentioning

confidence: 99%

Old age and supersolar metallicity in a massivez∼ 1.4 early-type galaxy from VLT/X-Shooter spectroscopy

Lonoce¹,

Longhetti²,

Maraston³

et al. 2015

Mon. Not. R. Astron. Soc.

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“…The measurement of the Mgb index and of the H δ and H γ strength in early-type galaxies up to z=0.83 has independently provided z>2 -3 as the redshift at which their stars formed (Ziegler & Bender 1997;Kelson et al 2001). Spectroscopy from the ground has made also possible to use a set of FeII, MgII and MgI lines in the rest-frame UV and identify massive early-type galaxies (M * > 10 11 M ⊙ ) up to z≃2.15 (Cimatti et al 2004;Glazebrook et al 2004;McCarthy et al 2004;Saracco et al 2005). In particular, Cimatti et al (2004) stacked together the rest-frame UV spectra of 4 early-type galaxies with 1.6 < z < 1.9 and compared the average with synthetic spectra of simple stellar populations to find a mean stellar age of about 1 Gyr for solar metallicity (or better 0.5 < age < 1.5 Gyr for 2.5 > Z/Z ⊙ > 0.4).…”

Section: Introductionmentioning

confidence: 99%

Early-Type Galaxies in the Pears Survey: Probing the Stellar Populations at Moderate Redshift

Ferreras

Pasquali

Malhotra

et al. 2009

ApJ

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Using HST/ACS slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample -extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z>0.4 -comprises 228 galaxies (i F775W < 24 mag, AB) out to z 1.3 over 320 arcmin 2 , with a median redshift z M =0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over ∼11 arcmin 2 ; Pasquali et al. 2006b). The grism data allow us to separate the sample into 'red' and 'blue' spectra, with the latter comprising 15% of the total. Three different grids of models parameterising the star formation history are used to fit the low-resolution spectra. Over the redshift range of the sample -corresponding to a cosmic age between 5 and 10 Gyr -we find a strong correlation between stellar mass and average age, whereas the spread of ages (defined by the RMS of the distribution) is roughly ∼ 1 Gyr and independent of stellar mass. The best-fit parameters suggest it is formation epoch and not formation timescale, that best correlates with mass in early-type galaxies. This result -along with the recently observed lack of evolution of the number density of massive galaxies -motivates the need for a channel of (massive) galaxy formation bypassing any phase in the blue cloud, as suggested by the simulations of Dekel et al. (2009).

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“…The ETGs identified spectroscopically so far up to z ≈ 2.5 are characterized by very red colors (R − K > 5 − 6), passively evolving old stellar populations with ages of 1-4 Gyr, e-folding timescales τ ∼0.1-0.3 Gyr (where SFR(t) ∝ exp(−t/τ)), very low dust extinction, stellar masses M ≥ 10 11 M ⊙ and strong clustering with r 0 ≈ 8-10 Mpc [38,99,19,54,75,28,91,69,63,65,72,21,26,44,63,41]. Preliminary estimates indicate that the number density of massive ETG photometric (pBzK) candidates at 1.4 < z < 2.5 is ≈20% of that at z = 0 [63].…”

Section: The Influence Of the Environmentmentioning

confidence: 99%

The formation and evolution of early-type galaxies: solid results and open questions

Cimatti

Giobbi²,

Tornambé³

et al. 2009

AIP Conference Proceedings

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The Disappearance of Telecommunications

Cited by 9 publications

References 0 publications

Old age and supersolar metallicity in a massivez∼ 1.4 early-type galaxy from VLT/X-Shooter spectroscopy

Old age and supersolar metallicity in a massivez∼ 1.4 early-type galaxy from VLT/X-Shooter spectroscopy

Early-Type Galaxies in the Pears Survey: Probing the Stellar Populations at Moderate Redshift

The formation and evolution of early-type galaxies: solid results and open questions

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