Spitzer View of Lyman Break Galaxies

Using a combination of deep MID-IR observations obtained by IRAC, MIPS and IRS on board Spitzer we investigate the MID-IR properties of Lyman Break Galaxies (LBGs) at z~3, establish a better understanding of their nature and attempt a complete characterisation of the population. With deep mid-infrared and optical observations of ~1000 LBGs covered by IRAC/MIPS and from the ground respectively, we extend the spectral energy distributions (SEDs) of the LBGs to mid-infrared. Spitzer data reveal for the first time that the mid-infrared properties of the population are inhomogeneous ranging from those with marginal IRAC detections to those with bright rest-frame near-infrared colors and those detected at 24mu MIPS band revealing the newly discovered population of the Infrared Luminous Lyman Break Galaxies (ILLBGs). To investigate this diversity, we examine the photometric properties of the population and we use stellar population synthesis models to probe the stellar content of these galaxies. We find that a fraction of LBGs have very red colors and large estimated stellar masses M* > 5x10^10Mo. We discuss the link between these LBGs and submm-luminous galaxies and we report the detection of rest frame 6.2 and 7.7mu emission features arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01.Comment: 4 pages, 2 figures, To appear in the proceedings of IAU Symposioum 245 : Formation and evolution of Galaxies Bulges (CUP

Ultra-Luminous Infrared Mergers: Elliptical Galaxies in Formation?

We report high quality near-infrared spectroscopy of 12 ultra-luminous infrared galaxy mergers (ULIRGs). Our new VLT and Keck data provide ~0.5" resolution, stellar and gas kinematics of these galaxies most of which are compact systems in the last merger stages. We confirm that ULIRG mergers are 'ellipticals-in-formation'. Random motions dominate their stellar dynamics, but significant rotation is common. Gas and stellar dynamics are decoupled in most systems. ULIRGs fall on or near the fundamental plane of hot stellar systems, and especially on its less evolution sensitive, r(eff)-sigma projection. The ULIRG velocity dispersion distribution, their location in the fundamental plane and their distribution of v(rot)*sin(i)/sigma closely resemble those of intermediate mass (~L*), elliptical galaxies with moderate rotation. As a group ULIRGs do not resemble giant ellipticals with large cores and little rotation. Our results are in good agreement with other recent studies indicating that disky ellipticals with compact cores or cusps can form through dissipative mergers of gas rich, disk galaxies while giant ellipticals with large cores have a different formation history.Comment: submitted to Ap

The influence of the brand name to brand’s success

Many questions related to the contribution and the role of the name of the Brand as a company asset, have not been explicitly answered through empirical research. This specific study attempts to provide some answers to these questions. Through the hypotheses tested, we came to the conclusion that the name is perceived by the executives as the most important defining element of the Brand (among others specified) and that the contribution of the Brand name to particular criteria of Brand success is significant according to all those aspects. Along these lines managerial insights into these findings could lead to a new role for the name in the context of the Strategic view of Brand building oriented to Brand Success.peer-reviewe

The nature and evolution of Ultraluminous Infrared Galaxies: A mid-infrared spectroscopic survey

We report the first results of a low resolution mid-infrared spectroscopic survey of an unbiased, far-infrared selected sample of 60 ultraluminous infrared galaxies, using ISOPHOT-S on board ISO. We use the ratio of the 7.7um `PAH' emission feature to the local continuum as a discriminator between starburst and AGN activity. About 80% of all the ULIRGs are found to be predominantly powered by star formation but the fraction of AGN powered objects increases with luminosity. Observed ratios of the PAH features in ULIRGs differ slightly from those in lower luminosity starbursts. This can be plausibly explained by the higher extinction and/or different physical conditions in the interstellar medium of ULIRGs. The PAH feature-to-continuum ratio is anticorrelated with the ratio of feature-free 5.9um continuum to the IRAS 60um continuum, confirming suggestions that strong mid-IR continuum is a prime AGN signature. The location of starburst-dominated ULIRGs in such a diagram is consistent with previous ISO-SWS spectroscopy which implies significant extinction even in the mid-infrared. We have searched for indications that ULIRGs which are advanced mergers might be more AGN-like, as postulated by the classical evolutionary scenario. No such trend has been found amongst those objects for which near infrared images are available to assess their likely merger status.Comment: aastex, 4 eps figures. Revised version, accepted by ApJ (Letters

The Scatter in the Relationship between Redshift and the Radio-to-Submm Spectral Index

We derive the scatter in the relationship between redshift and radio-to-submm spectral index, alpha^{350}_{1.4}, using the observed spectral energy distributions of 17 low redshift star forming galaxies. A mean galaxy model is derived, along with the rms scatter in alpha^{350}_{1.4}. The scatter is roughly constant with redshift. Constant rms scatter, combined with the flattening of the mean alpha^{350}_{1.4} -- z relationship with increasing redshift, leads to increasing uncertainty for redshift estimates at high redshifts. Normalizing by the dust temperature in the manner proposed by Blain decreases the scatter in alpha^{350}_{1.4} for most of the sample, but does not remove outliers, and free-free absorption at rest frequencies above 1.4 GHz is not likely to be a dominant cause for scatter in the alpha^{350}_{1.4} -- z relationship. We re-derive the cumulative redshift distribution of the 14 field galaxies in a recent submm and radio source sample of Smail et al.. The most likely median redshift for the distribution is 2.7, with a conservative lower limit of z = 2, as was also found by Smail et al. based on the original alpha^{350}_{1.4} -- z models. The normalization and shape of the redshift distribution for the faint submm sources are consistent with those expected for forming elliptical galaxies.Comment: Added Erratum, standard AAS LATEX forma

On the Origin of Lymanα\alpha Blobs at High Redshift: Submillimetric Evidence for a Hyperwind Galaxy at z=3.1

The most remarkable class of high-redshift objects observed so far is extended Ly$\alpha$ emission-line blobs found in an over-density region at redshift 3.1. They may be either a dust-enshrouded, extreme starburst galaxy with a large-scale galactic outflow (superwind) or cooling radiation from dark matter halos. Recently one of these Ly$\alpha$ blobs has been detected at submillimeter wavelengths (450 and 850 $\mu$m). Here we show that its rest-frame spectral energy distribution between optical and far-infrared is quite similar to that of Arp 220, which is a typical ultraluminous starburst/superwind galaxy in the local universe. This suggests strongly that the superwind model proposed by Taniguchi & Shioya is applicable to this Ly$\alpha$ blob. Since the blob is more luminous in the infrared by a factor of 30 than Arp 220, it comprises a new population of hyperwind galaxies at high redshift.Comment: 4 pages, 1 figure. ApJ (Letters), in pres

PRODUCT CHOICE ATTITUDE FORMATION: IT IS A MATTER OF A COLLECTIVE OR PERSONAL IDENTITY?

So far, specific social factors have been recognised as having a strong impact on the formation of consumer attitudes towards foreign products. At the same time, it has been argued that there is a need to explore other parameters that may affect the product choice attitude formation. In this context, this article explores cultural aspects that are associated with both, the collective and the personal identity of individuals by investigating whether and to what extent these aspects influence overall foreign product openness. The results allow us to argue that cultural aspects related to the collective identity have a significant impact on attitudes towards foreign products, while other aspects, related to the personal identity of individuals, seem to affect this attitude formation to a lesser extent

PRODUCT CHOICE ATTITUDE FORMATION: IT IS A MATTER OF A COLLECTIVE OR PERSONAL IDENTITY?

So far, specific social factors have been recognised as having a strong impact on the formation of consumer attitudes towards foreign products. At the same time, it has been argued that there is a need to explore other parameters that may affect the product choice attitude formation. In this context, this article explores cultural aspects that are associated with both, the collective and the personal identity of individuals by investigating whether and to what extent these aspects influence overall foreign product openness. The results allow us to argue that cultural aspects related to the collective identity have a significant impact on attitudes towards foreign products, while other aspects, related to the personal identity of individuals, seem to affect this attitude formation to a lesser extent

FORS spectroscopy of galaxies in the Hubble Deep Field South

We present low resolution multi-object spectroscopy of an I-band magnitude limited (I_{AB} ~ 23--23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscopic targets in the HST-WFPC2 HDFS were supplemented with galaxies detected in the Infrared Space Observatory's survey of the HDFS and the ESO Imaging Deep Survey to comprise a sample of 100 galaxies for spectroscopic observations. Based on detections of several emission lines, such as [OII]3727, H_beta and [OIII]5007, or other spectroscopic features, we have measured accurate redshifts for 50 objects in the central HDFS and flanking fields. The redshift range of the current sample of galaxies is 0.6--1.2, with a median redshift of 1.13 (at I ~ 23.5 not corrected for completeness). The sample is dominated by starburst galaxies with only a small fraction of ellipticals (~10%). For the emission line objects, the extinction corrected [OII]3727 line strengths yield estimates of star formation rates in the range 0.5--30 M_solar/yr. We have used the present data to derive the [OII]3727 luminosity function up to redshift of 1.2. When combined with [OII]3727 luminosity densities for the local and high redshift Universe, our results confirm the steep rise in the star formation rate (SFR) to z ~ 1.3.Comment: Tables 2 and 3 provided as separate files. Accepted for publication by Astronomy and Astrophysic