Fritze-von Alvensleben, Uta

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","11"],["dc.bibliographiccitation.volume","392"],["dc.contributor.author","Schulz, J."],["dc.contributor.author","Fritze-von Alvensleben, Uta"],["dc.contributor.author","Moller, C. S."],["dc.contributor.author","Fricke, K. J."],["dc.date.accessioned","2018-11-07T10:03:52Z"],["dc.date.available","2018-11-07T10:03:52Z"],["dc.date.issued","2002"],["dc.description.abstract","A new set of evolutionary synthesis spectra are presented for Simple Stellar Populations (SSPs) covering ranges in metallicity from 0.02 less than or equal to Z/Z(.) less than or equal to 2.5 and ages from 4 x 10(6) yr less than or equal to t less than or equal to 16 Gyr. They are based on the most recent isochrones from the Padova group that extend earlier models by the inclusion of the thermal pulsing AGB phase for stars in the mass range 2 M-. less than or equal to m less than or equal to 7 M-. in accordance with the fuel consumption theorem. We show that with respect to earlier models, inclusion of the TP-AGB phase leads to significant changes in the (V-I) and(V-K) colors of SSPs in the age range from 10(8) to greater than or similar to 10(9) yr. Using model atmosphere spectra from Lejeune et al. (1997, 1998), we calculate the spectral evolution of single burst populations of various metallicities covering the wavelength range from 90 Angstrom through 160 mum. Isochrone spectra are convolved with filter response functions to describe the time evolution of luminosities and colors in Johnson, Thuan & Gunn, Koo, HST, Washington and Stromgren filters. The models and their results are not only intended for use in the interpretation of star clusters but also for combination with any kind of dynamical galaxy formation and/or evolution model that contains a star formation criterion. Moreover, the evolution of these single burst single metallicity stellar populations is readily folded with any kind of star formation - and eventually chemical enrichment - history to describe the evolutionary spectral synthesis of composite stellar populations like galaxies of any type with continuous or discontinuous star formation. For these latter purposes we also present the time evolution of ejection rates for gas and metals for two different Initial Mass Functions (IMFs) as well as cosmological and evolutionary corrections for all the filters as a function of redshift for 0 less than or equal to z less than or equal to 5 and two different cosmologies. Extensive data files are provided in the electronic version, at CDS, and at our above www-address."],["dc.identifier.doi","10.1051/0004-6361:20020657"],["dc.identifier.isi","000177868700006"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9730"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/38572"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","E D P Sciences"],["dc.relation.issn","0004-6361"],["dc.relation.orgunit","Fakultät für Physik"],["dc.title","Spectral and photometric evolution of simple stellar populations at various metallicities"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","89"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","100"],["dc.bibliographiccitation.volume","398"],["dc.contributor.author","Schulz, J."],["dc.contributor.author","Fritze von Alvensleben, U."],["dc.contributor.author","Fricke, K. J."],["dc.date.accessioned","2018-11-07T10:42:00Z"],["dc.date.available","2018-11-07T10:42:00Z"],["dc.date.issued","2003"],["dc.description.abstract","HST has opened the possibility to decompose the surface brightness profiles of galaxies up to significant redshifts and look-back times into r(1/4)-bulge and exponential disk components. This should allow to study the redshift evolution of bulge and disk luminosity contributions and discriminate between the different formation scenarios for these galaxy components currently discussed, i.e. decide if star formation in bulges and disks started at the same time or was delayed in either of the two components. An indispensable prerequisite for the comparison of bulge-to-disk ratios of galaxies at different redshifts is to properly account for cosmological band shift and evolutionary effects. We present evolutionary synthesis models for both components and add their spectra in various proportions to obtain the full range of local galaxies' B-band bulge-to-total light ratios. Bulge star formation is assumed to occur on a short timescale of 10(9) yr, disk star formation proceeds at a constant rate. We study the evolution of the relative light contributions of both components backward in time and, for a given cosmological model, as a function of redshift. This allows us to see how far back into the past the locally well-established correlation between galaxy morphologies and spectral properties can hold. To cope with the present uncertainty about the formation epochs of bulge and disk components we present models for three scenarios: bulges and disks of equal age, old bulges and delayed disk star formation, and old disks with subsequent bulge star formation. We quantitatively show the wavelength dependence of bulge-to-total (=B/T) light ratios for local galaxies. The different star formation timescales for bulge and disk components lead to BIT ratios that significantly increase from U through I-bands (by factors 4-6 for weak bulge systems similar toSc) with the rate of increase slightly depending on the relative ages of the two components. The redshift evolution of B/T-ratios in various bands U, B, V, 1, H is calculated accounting both for cosmological and evolutionary corrections assuming a standard cosmology (H-0 = 65, Omega(0) = 0.1, Lambda(0) = 0). In particular, for the two scenarios with old bulges and old or younger disks, the redshift evolution of B/T-ratios is dramatic in every band and both for galaxies ending up at z similar to 0 with low and high B-band B/T light ratios. Our results clearly show that it does not make any sense to compare B/T ratios measured in one and the same band for galaxies at different redshifts without fully accounting for evolutionary and cosmological effects. These, unfortunately, significantly depend on the relative ages of the two components and, hence, on the galaxy formation scenario adopted. We also show that simultaneous decomposition of galaxy profiles in several bands can give direct information about these relative ages and constrain formation scenarios for the different galaxy components. Of the wavelength bands we explore (U, B, V, I, H), the I- and H-bands show the smoothest redshift evolution and, hence, are best suited for a first order comparison of galaxies over the redshift range from z = 0 to z greater than or similar to 1. Our robust result that - irrespective of the respective ages of the bulge and disk stellar components - I-band B/T-ratios apparently increase with increasing redshift for all galaxy types with present B/T > 0.1 implies that the scarcity of bulge-strong systems at z greater than or equal to 0.8 reported by Marleau & Simard (1998) and Aguerri & Trujillo (2002) for HDF and Hawaiian Deep Field galaxies is further enhanced."],["dc.identifier.doi","10.1051/0004-6361:20021631"],["dc.identifier.isi","000180395700011"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9789"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/46681"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","E D P Sciences"],["dc.relation.issn","0004-6361"],["dc.relation.orgunit","Fakultät für Physik"],["dc.title","Wavelength and redshift dependence of bulge/total light ratios in galaxies"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]