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Sample records for galaxy mass-metallicity relation

  1. ORIGIN OF THE GALAXY MASS-METALLICITY-STAR FORMATION RELATION

    SciTech Connect

    Harwit, Martin; Brisbin, Drew

    2015-02-20

    We describe an equilibrium model that links the metallicity of low-redshift galaxies to stellar evolution models. It enables the testing of different stellar initial mass functions and metal yields against observed galaxy metallicities. We show that the metallicities of more than 80,000 Sloan Digital Sky Survey galaxies in the low-redshift range 0.07 ≤ z ≤ 0.3 considerably constrain stellar evolution models that simultaneously relate galaxy stellar mass, metallicity, and star formation rates to the infall rate of low-metallicity extragalactic gas and outflow of enriched matter. A feature of our model is that it encompasses both the active star forming phases of a galaxy and epochs during which the same galaxy may lie fallow. We show that the galaxy mass-metallicity-star formation relation can be traced to infall of extragalactic gas mixing with native gas from host galaxies to form stars of observed metallicities, the most massive of which eject oxygen into extragalactic space. Most consequential among our findings is that, on average, extragalactic infall accounts for one half of the gas required for star formation, a ratio that is remarkably constant across galaxies with stellar masses ranging at least from M* = 2 × 10{sup 9} to 6 × 10{sup 10} M {sub ☉}. This leads us to propose that star formation is initiated when extragalactic infall roughly doubles the mass of marginally stable interstellar clouds. The processes described may also account quantitatively for the metallicity of extragalactic space, though to check this the fraction of extragalactic baryons will need to be more firmly established.

  2. Mass-metallicity relation for local star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Wu, Yu-Zhong; Zhang, Shuang-Nan; Zhao, Yong-Heng; Zhang, Wei

    2016-04-01

    We investigate the evolution of the mass-metallicity (M-Z) relation with a large sample of 53 444 star-forming galaxies (SFGs) at 0.04 < z < 0.12, selected from the catalogue of Max-Planck-Institute for Astrophysics-John Hopkins University (MPA-JHU) emission-line measurements for the Sloan Digital Sky Survey Data Release 7. Regarding the sample of SFGs, we correct the observational bias and raise the aperture covering fractions to check the reliability of the metallicity evolution. (i) We show that the redshift evolution of the log (Hα) and log([O III]) luminosities is displayed in our sample. (ii) We find the metallicity evolution of ˜0.15 dex at log (M*/M⊙) ˜ 9.3 in SFGs at 0.04 < z < 0.12. (iii) After applying the luminosity thresholds of log (LHα) > 41.0 and log (L_[O III])>39.7, we find that the metallicity evolution is shown well, and that the evolution of the star formation rate (SFR) is still shown well under the latter luminosity threshold, but the evolution is not observed under the former. (iv) The evolution of the M-Z relation seems to disappear at about log (M*/M⊙) > 10.0 after applying the luminosity threshold of log (LHα) > 41.0 or log (L_[O III])>39.7. (v) We find α = 0.09 and α = 0.07 in the equation, μ = log M* - αlog (SFR), for log (LHα) > 41.0 and log (L_[O III])>39.7 samples, respectively, and these imply that the evolution of the M-Z relation might have a weaker dependence on the SFR in our sample.

  3. Mass-metallicity relations and metallicity gradients of galaxies in chemodynamical simulations with AGN feedback

    NASA Astrophysics Data System (ADS)

    Kobayashi, Chiaki

    2015-08-01

    I show metallicities of high-redshift galaxies and their time evolution in our cosmological, hydrodynamical simulations with the feedback from active galactic nuclei (AGN). We have applied a new model for the formation of black holes motivated by the first star formation, in contrast to the merging scenario of previous works. The model parameters are determined from observational constraints, namely, the cosmic star formation rate history, black hole mass-galaxy mass relation, and the size-mass relation of galaxies. We then obtain better agreement with the observed down-sizing phenomena, namely, the colour-magnitude relation, specific star formation rates, and the \\alpha enhancement of early type galaxies. In massive galaxies, AGN-driven outflows transport metals into the circumgalactic medium and the intergalactic medium, which is important for a large-scale chemical enrichment in the Universe. Smaller galaxies can get external enrichment from nearby AGN depending on their environment. Nonetheless, these metallicity changes are negligible, and the mass-metallicity relations, which are mainly generated by supernova feedback at the first star burst, are preserved. The mass-metallicity relations evolve showing a steeper slope at higher redshifts. Metallicity radial gradients dramatically evolve depending on the their merging histories, and at the present we find a weak correlation between the gradients and galaxy mass. These predictions will be tested with on-going spectral and IFU surveys.

  4. THE MASS-METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES

    SciTech Connect

    Andrews, Brett H.; Martini, Paul

    2013-03-10

    The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of {approx}200,000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [O III] {lambda}4363 and [O II] {lambda}{lambda}7320, 7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M{sub *}/M{sub Sun }) = 7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H {proportional_to} M{sub *} {sup 1/2}) until it turns over at log(M{sub *}/M{sub Sun }) = 8.9 and asymptotes to 12 + log(O/H) = 8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.

  5. The Mass-Metallicity Relation with the Direct Method on Stacked Spectra of SDSS Galaxies

    NASA Astrophysics Data System (ADS)

    Andrews, Brett H.; Martini, Paul

    2013-03-01

    The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of ~200,000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [O III] λ4363 and [O II] λλ7320, 7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M sstarf/M ⊙) = 7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H vprop M sstarf 1/2) until it turns over at log(M sstarf/M ⊙) = 8.9 and asymptotes to 12 + log(O/H) = 8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.

  6. On the Origin of the Mass-Metallicity Relation for GRB Host Galaxies

    SciTech Connect

    Kocevski, Daniel; West, Andrew A.; /Boston U., Dept. Astron.

    2011-06-02

    We investigate the nature of the mass-metallicity (M-Z) relation for long gamma-ray burst (LGRB) host galaxies. Recent studies suggest that the M-Z relation for local LGRB host galaxies may be systematically offset towards lower metallicities relative to the M-Z relation defined by the general star forming galaxy (SDSS) population. The nature of this offset is consistent with suggestions that low metallicity environments may be required to produce high mass progenitors, although the detection of several GRBs in high-mass, high-metallicity galaxies challenges the notion of a strict metallicity cut-off for host galaxies that are capable of producing GRBs. We show that the nature of this reported offset may be explained by a recently proposed anti-correlation between the star formation rate (SFR) and the metallicity of star forming galaxies. If low metallicity galaxies produce more stars than their equally massive, high-metallicity counterparts, then transient events that closely trace the SFR in a galaxy would be more likely to be found in these low metallicity, low mass galaxies. Therefore, the offset between the GRB and SDSS defined M-Z relations may be the result of the different methods used to select their respective galaxy populations, with GRBs being biased towards low metallicity, high SFR, galaxies. We predict that such an offset should not be expected of transient events that do not closely follow the star formation history of their host galaxies, such as short duration GRBs and SN Ia, but should be evident in core collapse SNe found through upcoming untargeted surveys.

  7. The origin and evolution of the galaxy mass-metallicity relation

    NASA Astrophysics Data System (ADS)

    Ma, Xiangcheng; Hopkins, Philip F.; Faucher-Giguère, Claude-André; Zolman, Nick; Muratov, Alexander L.; Kereš, Dušan; Quataert, Eliot

    2016-02-01

    We use high-resolution cosmological zoom-in simulations from the Feedback in Realistic Environment (FIRE) project to study the galaxy mass-metallicity relations (MZR) from z = 0-6. These simulations include explicit models of the multiphase ISM, star formation, and stellar feedback. The simulations cover halo masses Mhalo = 109-1013 M⊙ and stellar masses M* = 104-1011 M⊙ at z = 0 and have been shown to produce many observed galaxy properties from z = 0-6. For the first time, our simulations agree reasonably well with the observed mass-metallicity relations at z = 0-3 for a broad range of galaxy masses. We predict the evolution of the MZR from z = 0-6, as log (Z_gas/Z_{{⊙}}) = {12 + log (O/H) - 9.0} = 0.35 [log (M_{*}/M_{{⊙}})-10] + 0.93 exp (-0.43z) - 1.05 and log (Z*/Z⊙) = [Fe/H] + 0.2 = 0.40[log (M*/M⊙) - 10] + 0.67exp ( - 0.50z) - 1.04, for gas-phase and stellar metallicity, respectively. Our simulations suggest that the evolution of MZR is associated with the evolution of stellar/gas mass fractions at different redshifts, indicating the existence of a universal metallicity relation between stellar mass, gas mass, and metallicities. In our simulations, galaxies above M* = 106 M⊙ are able to retain a large fraction of their metals inside the halo, because metal-rich winds fail to escape completely and are recycled into the galaxy. This resolves a longstanding discrepancy between `subgrid' wind models (and semi-analytic models) and observations, where common subgrid models cannot simultaneously reproduce the MZR and the stellar mass functions.

  8. FURTHER DEFINITION OF THE MASS-METALLICITY RELATION IN GLOBULAR CLUSTER SYSTEMS AROUND BRIGHTEST CLUSTER GALAXIES

    SciTech Connect

    Cockcroft, Robert; Harris, William E.; Wehner, Elizabeth M. H.; Whitmore, Bradley C.; Rothberg, Barry E-mail: harris@physics.mcmaster.ca E-mail: whitmore@stsci.edu

    2009-09-15

    We combine the globular cluster (GC) data for 15 brightest cluster galaxies and use this material to trace the mass-metallicity relations (MMRs) in their globular cluster systems (GCSs). This work extends previous studies which correlate the properties of the MMR with those of the host galaxy. Our combined data sets show a mean trend for the metal-poor subpopulation that corresponds to a scaling of heavy-element abundance with cluster mass Z {approx} M {sup 0.30{+-}}{sup 0.05}. No trend is seen for the metal-rich subpopulation which has a scaling relation that is consistent with zero. We also find that the scaling exponent is independent of the GCS specific frequency and host galaxy luminosity, except perhaps for dwarf galaxies. We present new photometry in (g',i') obtained with Gemini/GMOS for the GC populations around the southern giant ellipticals NGC 5193 and IC 4329. Both galaxies have rich cluster populations which show up as normal, bimodal sequences in the color-magnitude diagram. We test the observed MMRs and argue that they are statistically real, and not an artifact caused by the method we used. We also argue against asymmetric contamination causing the observed MMR as our mean results are no different from other contamination-free studies. Finally, we compare our method to the standard bimodal fitting method (KMM or RMIX) and find our results are consistent. Interpretation of these results is consistent with recent models for GC formation in which the MMR is determined by GC self-enrichment during their brief formation period.

  9. What stellar populations can tell us about the evolution of the mass-metallicity relation in SDSS galaxies

    NASA Astrophysics Data System (ADS)

    Vale Asari, N.; Stasińska, G.; Cid Fernandes, R.; Gomes, J. M.; Schlickmann, M.; Mateus, A.; Schoenell, W.

    2010-04-01

    During the last three decades, many papers have reported the existence of a luminosity metallicity or mass metallicity (M-Z) relation for all kinds of galaxies: The more massive galaxies are also the ones with more metal-rich interstellar medium. We have obtained the mass-metallicity relation at different lookback times for the same set of galaxies from the Sloan Digital Sky Survey (SDSS), using the stellar metallicities estimated with our spectral synthesis code starlight. Using stellar metallicities has several advantages: We are free of the biases that affect the calibration of nebular metallicities; we can include in our study objects for which the nebular metallicity cannot be measured, such as AGN hosts and passive galaxies; we can probe metallicities at different epochs of a galaxy evolution. We have found that the M-Z relation steepens and spans a wider range in both mass and metallicity at higher redshifts for SDSS galaxies. We also have modeled the time evolution of stellar metallicity with a closed-box chemical evolution model, for galaxies of different types and masses. Our results suggest that the M-Z relation for galaxies with present-day stellar masses down to 1010 M⊙ is mainly driven by the star formation history and not by inflows or outflows.

  10. Stellar mass - Metallicity Relation for AKARI-FMOS Infrared Luminous Galaxies at z~0.9

    NASA Astrophysics Data System (ADS)

    Oi, Nagisa; Matsuhara, Hideo; Goto, Tomo; Pearson, Chris; Buat, Véronique; Malkan, Matthew A.

    2015-08-01

    Heavy elements are synthesized in stars and returned into the interstellar medium reflecting the result of the past star formation activity in a galaxy. Thus, the gas phase metallicity is a key parameter in understanding the processes of the formation and the evolution of a galaxy. Many investigations of stellar mass (M*) and gas phase metallicity (Z) relation (MZ relation), which is more massive galaxies tend to be more metal-rich, and a fundamental relation (FMR), whereby galaxies define a tight surface in the three-dimensional space of M*, Z, and Star Formation Rate (SFR) have done up to z~3.3. However, this relation only holds to ultraviolet, optical, or near-infrared selected star forming galaxies. Since most of star formation activities in galaxies at high-z universe are hidden by dust, to fully understand the MZ relation and its evolution, it is critical to study dusty galaxies.Here, we investigate the MZ relation and FMR for infrared bright galaxies at z~0.9 discovered by AKARI NEP-Deep survey.We estimated the M* and Z from SED fitting using the AKARI NEP-Deep data with its follow-up multi-wavelength photometric data (from X-ray to FIR) and from Halpha-[NII] emission line ratio taken by Subaru/FMOS, respectively. We found that (1) the infrared bright galaxies at z~0.9 is already chemically evolved to the level of star-forming galaxies in the local universe, and (2) the metallicity of our sample is systematically larger than that of the FMR. The results suggest a possibility that metal was actively created in dusty galaxies up to z~1, then outflow blows out dust and gas, suddenly stopping the chemical evolution and star formation activity, and the galaxies end up being what they are today.

  11. Recycled stellar ejecta as fuel for star formation and implications for the origin of the galaxy mass-metallicity relation

    NASA Astrophysics Data System (ADS)

    Segers, Marijke C.; Crain, Robert A.; Schaye, Joop; Bower, Richard G.; Furlong, Michelle; Schaller, Matthieu; Theuns, Tom

    2016-02-01

    We use cosmological, hydrodynamical simulations from the Evolution and Assembly of GaLaxies and their Environments and OverWhelmingly Large Simulations projects to assess the significance of recycled stellar ejecta as fuel for star formation. The fractional contributions of stellar mass-loss to the cosmic star formation rate (SFR) and stellar mass densities increase with time, reaching 35 and 19 per cent, respectively, at z = 0. The importance of recycling increases steeply with galaxy stellar mass for M* < 1010.5 M⊙, and decreases mildly at higher mass. This trend arises from the mass dependence of feedback associated with star formation and AGN, which preferentially suppresses star formation fuelled by recycling. Recycling is more important for satellites than centrals and its contribution decreases with galactocentric radius. The relative contribution of asymptotic giant branch (AGB) stars increases with time and towards galaxy centres. This is a consequence of the more gradual release of AGB ejecta compared to that of massive stars, and the preferential removal of the latter by star formation-driven outflows and by lock up in stellar remnants. Recycling-fuelled star formation exhibits a tight, positive correlation with galaxy metallicity, with a secondary dependence on the relative abundance of alpha elements (which are predominantly synthesized in massive stars), that is insensitive to the subgrid models for feedback. Hence, our conclusions are directly relevant for the origin of the mass-metallicity relation and metallicity gradients. Applying the relation between recycling and metallicity to the observed mass-metallicity relation yields our best estimate of the mass-dependent contribution of recycling. For centrals with a mass similar to that of the Milky Way, we infer the contributions of recycled stellar ejecta to the SFR and stellar mass to be 35 and 20 per cent, respectively.

  12. The Gas Phase Mass Metallicity Relation for Dwarf Galaxies: Dependence on Star Formation Rate and H I Gas Mass

    NASA Astrophysics Data System (ADS)

    Jimmy; Tran, Kim-Vy; Saintonge, Amélie; Accurso, Gioacchino; Brough, Sarah; Oliva-Altamirano, Paola

    2015-10-01

    Using a sample of dwarf galaxies observed using the VIMOS IFU on the Very Large Telescope, we investigate the mass-metallicity relation (MZR) as a function of star formation rate (FMRSFR) as well as HI-gas mass (FMRHI). We combine our IFU data with a subsample of galaxies from the ALFALFA HI survey crossmatched to the Sloan Digital Sky Survey (SDSS) to study the FMRSFR and FMRHI across the stellar mass range 106.6-108.8 M⊙, with metallicities as low as 12 + log(O/H) = 7.67. We find the 1σ mean scatter in the MZR to be 0.05 dex. The 1σ mean scatter in the FMRSFR (0.02 dex) is significantly lower than that of the MZR. The FMRSFR is not consistent between the IFU observed galaxies and the ALFALFA/SDSS galaxies for SFRs lower than 10-2.4 M⊙ yr-1, however, this could be the result of limitations of our measurements in that regime. The lowest mean scatter (0.01 dex) is found in the FMRHI. We also find that the FMRHI is consistent between the IFU observed dwarf galaxies and the ALFALFA/SDSS crossmatched sample. We introduce the fundamental metallicity luminosity counterpart to the FMR, again characterized in terms of SFR (FMLSFR) and HI-gas mass (FMLHI). We find that the FMLHI relation is consistent between the IFU observed dwarf galaxy sample and the larger ALFALFA/SDSS sample. However, the 1σ scatter for the FMLHI relation is not improved over the FMRHI scenario. This leads us to conclude that the FMRHI is the best candidate for a physically motivated fundamental metallicity relation. Based on VLT service mode observations (Programs 081.B-0649 and 083.B-0662) gathered at the European Southern Observatory, Chile.

  13. THE METALLICITY BIMODALITY OF GLOBULAR CLUSTER SYSTEMS: A TEST OF GALAXY ASSEMBLY AND OF THE EVOLUTION OF THE GALAXY MASS-METALLICITY RELATION

    SciTech Connect

    Tonini, Chiara

    2013-01-01

    We build a theoretical model to study the origin of the globular cluster metallicity bimodality in the hierarchical galaxy assembly scenario. The model is based on empirical relations such as the galaxy mass-metallicity relation [O/H]-M {sub star} as a function of redshift, and on the observed galaxy stellar mass function up to redshift z {approx} 4. We make use of the theoretical merger rates as a function of mass and redshift from the Millennium simulation to build galaxy merger trees. We derive a new galaxy [Fe/H]-M {sub star} relation as a function of redshift, and by assuming that globular clusters share the metallicity of their original parent galaxy at the time of their formation, we populate the merger tree with globular clusters. We perform a series of Monte Carlo simulations of the galaxy hierarchical assembly, and study the properties of the final globular cluster population as a function of galaxy mass, assembly and star formation history, and under different assumptions for the evolution of the galaxy mass-metallicity relation. The main results and predictions of the model are the following. (1) The hierarchical clustering scenario naturally predicts a metallicity bimodality in the galaxy globular cluster population, where the metal-rich subpopulation is composed of globular clusters formed in the galaxy main progenitor around redshift z {approx} 2, and the metal-poor subpopulation is composed of clusters accreted from satellites, and formed at redshifts z {approx} 3-4. (2) The model reproduces the observed relations by Peng et al. for the metallicities of the metal-rich and metal-poor globular cluster subpopulations as a function of galaxy mass; the positions of the metal-poor and metal-rich peaks depend exclusively on the evolution of the galaxy mass-metallicity relation and the [O/Fe], both of which can be constrained by this method. In particular, we find that the galaxy [O/Fe] evolves linearly with redshift from a value of {approx}0.5 at redshift

  14. Planetary nebulae: the universal mass-metallicity relation for Local Group dwarf galaxies and the chemistry of NGC 205

    NASA Astrophysics Data System (ADS)

    Gonçalves, Denise R.; Magrini, Laura; Teodorescu, Ana M.; Carneiro, Carolina M.

    2014-10-01

    Here we study 16 planetary nebulae (PNe) in the dwarf irregular galaxy NGC 205 by using Gemini Multi-Object Spectrographs (GMOS@Gemini) spectra to derive their physical and chemical parameters. The chemical patterns and evolutionary tracks for 14 of our PNe suggest that there are no type I PNe among them. These PNe have an average oxygen abundance of 12+log(O/H) = 8.08 ± 0.28 and progenitor masses of 2-2.5 M⊙ and thus were born ˜1.0-1.7 Gyr ago. Our results are in good agreement with previous PN studies of NGC 205. The present 12+log(O/H) is combined with our previous work and results in the literature to study the PN metallicity trends of Local Group (LG) dwarf galaxies, in an effort to establish the PN luminosity-metallicity and mass-metallicity relations (LZR and MZR) for LG dwarf irregulars (dIrrs) and dwarf spheroidals (dSphs). Previous attempts to obtain such relations failed to provide correct conclusions because they were based on limited samples. As far as we are able to compare stellar with nebular metallicities, our MZR is in very good agreement with the slope of the MZR recently obtained for LG dwarf galaxies using spectroscopic stellar metallicities by Kirby and coauthors. In fact, we found that both dIrr and dSph galaxies follow the same MZR, at variance with the differences claimed in the past. Moreover, our MZR is also consistent with the global MZR of star-forming galaxies, which span a wider stellar mass range (˜106-1011 M⊙).

  15. The galaxy population of Abell 1367: the stellar mass-metallicity relation

    NASA Astrophysics Data System (ADS)

    Mouhcine, M.; Kriwattanawong, W.; James, P. A.

    2011-04-01

    Using wide baseline broad-band photometry, we analyse the stellar population properties of a sample of 72 galaxies, spanning a wide range of stellar masses and morphological types, in the nearby spiral-rich and dynamically young galaxy cluster Abell 1367. The sample galaxies are distributed from the cluster centre out to approximately half the cluster Abell radius. The optical/near-infrared colours are compared with simple stellar population synthesis models from which the luminosity-weighted stellar population ages and metallicities are determined. The locus of the colours of elliptical galaxies traces a sequence of varying metallicity at a narrow range of luminosity-weighted stellar ages. Lenticular galaxies in the red sequence, however, exhibit a substantial spread of luminosity-weighted stellar metallicities and ages. For red-sequence lenticular galaxies and blue cloud galaxies, low-mass galaxies tend to be on average dominated by stellar populations of younger luminosity-weighted ages. Sample galaxies exhibit a strong correlation between integrated stellar mass and luminosity-weighted stellar metallicity. Galaxies with signs of morphological disturbance and ongoing star formation activity, tend to be underabundant with respect to passive galaxies in the red sequence of comparable stellar masses. We argue that this could be due to tidally driven gas flows towards the star-forming regions, carrying less enriched gas and diluting the pre-existing gas to produce younger stellar populations with lower metallicities than would be obtained prior to the interaction. Finally, we find no statistically significant evidence for changes in the luminosity-weighted ages and metallicities for either red-sequence or blue-cloud galaxies, at fixed stellar mass, with location within the cluster. We dedicate this work to the memory of our friend and colleague C. Moss who died suddenly recently.

  16. The Subaru FMOS Galaxy Redshift Survey (FastSound). III. The mass-metallicity relation and the fundamental metallicity relation at z ˜ 1.4*

    NASA Astrophysics Data System (ADS)

    Yabe, Kiyoto; Ohta, Kouji; Akiyama, Masayuki; Bunker, Andrew; Dalton, Gavin; Ellis, Richard; Glazebrook, Karl; Goto, Tomotsugu; Imanishi, Masatoshi; Iwamuro, Fumihide; Okada, Hiroyuki; Shimizu, Ikkoh; Takato, Naruhisa; Tamura, Naoyuki; Tonegawa, Motonari; Totani, Tomonori

    2015-12-01

    We present the results from a large near-infrared spectroscopic survey made with Subaru/FMOS (FastSound) consisting of ˜ 4000 galaxies at z ˜ 1.4 with significant Hα detection. We measure the gas-phase metallicity from the [N II]λ6583/Hα emission line ratio of the composite spectra in various stellar mass and star-formation rate bins. The resulting mass-metallicity relation generally agrees with previous studies obtained in a similar redshift range to that of our sample. No clear dependence of the mass-metallicity relation on star-formation rate is found. Our result at z ˜ 1.4 is roughly in agreement with the fundamental metallicity relation at z ˜ 0.1 with a fiber aperture corrected star-formation rate. We detect significant [S II]λλ6716,6731 emission lines from the composite spectra. The electron density estimated from the [S II]λλ6716,6731 line ratio ranges from 10-500 cm-3, which generally agrees with that of local galaxies. On the other hand, the distribution of our sample on [N II]λ6583/Hα vs. [S II]λλ6716,6731/Hα is different to that found locally. We estimate the nitrogen-to-oxygen abundance ratio (N/O) from the N2S2 index, and find that the N/O in galaxies at z ˜ 1.4 is significantly higher than the local values at a fixed metallicity and stellar mass. The metallicity at z ˜ 1.4 recalculated with this N/O enhancement taken into account decreases by 0.1-0.2 dex. The resulting metallicity is lower than the local fundamental metallicity relation.

  17. CONSTRAINTS ON THE LOW-MASS END OF THE MASS-METALLICITY RELATION AT z = 1-2 FROM LENSED GALAXIES

    SciTech Connect

    Wuyts, Eva; Gladders, Michael D.; Rigby, Jane R.; Sharon, Keren

    2012-08-10

    We present multi-wavelength imaging and near-IR spectroscopy for 10 gravitationally lensed galaxies at 0.9 < z < 2.5 selected from a new, large sample of strong lens systems in the Sloan Digital Sky Survey Data Release 7. We derive stellar masses from the rest-frame UV to near-IR spectral energy distributions, star formation rates (SFRs) from the dust-corrected H{alpha} flux, and metallicities from the [N II]/H{alpha} flux ratio. We combine the lensed galaxies with a sample of 60 star-forming galaxies from the literature in the same redshift range for which measurements of [N II]/H{alpha} have been published. Due to the lensing magnification, the lensed galaxies probe intrinsic stellar masses that are on average a factor of 11 lower than have been studied so far at these redshifts. They have specific SFRs that are an order of magnitude higher than seen for main-sequence star-forming galaxies at z {approx} 2. We measure an evolution of 0.16 {+-} 0.06 dex in the mass-metallicity relation between z {approx} 1.4 and z {approx} 2.2. In contrast to previous claims, the redshift evolution is smaller at low stellar masses. We do not see a correlation between metallicity and SFR at fixed stellar mass. The combined sample is in general agreement with the local fundamental relation between metallicity, stellar mass, and SFR from Mannucci et al. Using the Kennicutt-Schmidt law to infer gas fractions, we investigate the importance of gas inflows and outflows on the shape of the mass-metallicity relation using simple analytical models. This suggests that the Maiolino et al. calibration of the [N II]/H{alpha} flux ratio is biased high.

  18. The Gas Phase Mass Metallicity Relation for Dwarf Galaxies: Dependence on Star Formation Rate and H I Gas Mass

    NASA Astrophysics Data System (ADS)

    Jimmy; Tran, Kim-Vy; Saintonge, Amélie; Accurso, Gioacchino; Brough, Sarah; Oliva-Altamirano, Paola

    2015-10-01

    Using a sample of dwarf galaxies observed using the VIMOS IFU on the Very Large Telescope, we investigate the mass–metallicity relation (MZR) as a function of star formation rate (FMRSFR) as well as HI-gas mass (FMRHI). We combine our IFU data with a subsample of galaxies from the ALFALFA HI survey crossmatched to the Sloan Digital Sky Survey (SDSS) to study the FMRSFR and FMRHI across the stellar mass range 106.6–108.8 M⊙, with metallicities as low as 12 + log(O/H) = 7.67. We find the 1σ mean scatter in the MZR to be 0.05 dex. The 1σ mean scatter in the FMRSFR (0.02 dex) is significantly lower than that of the MZR. The FMRSFR is not consistent between the IFU observed galaxies and the ALFALFA/SDSS galaxies for SFRs lower than 10‑2.4 M⊙ yr‑1, however, this could be the result of limitations of our measurements in that regime. The lowest mean scatter (0.01 dex) is found in the FMRHI. We also find that the FMRHI is consistent between the IFU observed dwarf galaxies and the ALFALFA/SDSS crossmatched sample. We introduce the fundamental metallicity luminosity counterpart to the FMR, again characterized in terms of SFR (FMLSFR) and HI-gas mass (FMLHI). We find that the FMLHI relation is consistent between the IFU observed dwarf galaxy sample and the larger ALFALFA/SDSS sample. However, the 1σ scatter for the FMLHI relation is not improved over the FMRHI scenario. This leads us to conclude that the FMRHI is the best candidate for a physically motivated fundamental metallicity relation. Based on VLT service mode observations (Programs 081.B-0649 and 083.B-0662) gathered at the European Southern Observatory, Chile.

  19. The mass-metallicity and fundamental metallicity relations at z > 2 using very large telescope and Subaru near-infrared spectroscopy of zCOSMOS galaxies

    SciTech Connect

    Maier, C.; Ziegler, B. L.; Lilly, S. J.; Peng, Y.; Contini, T.; Pérez Montero, E.; Balestra, I.

    2014-09-01

    In the local universe, there is good evidence that, at a given stellar mass M, the gas-phase metallicity Z is anti-correlated with the star formation rate (SFR) of the galaxies. It has also been claimed that the resulting Z(M, SFR) relation is invariant with redshift—the so-called 'fundamental metallicity relation' (FMR). Given a number of difficulties in determining metallicities, especially at higher redshifts, the form of the Z(M, SFR) relation and whether it is really independent of redshift is still very controversial. To explore this issue at z > 2, we used VLT-SINFONI and Subaru-MOIRCS near-infrared spectroscopy of 20 zCOSMOS-deep galaxies at 2.1 < z < 2.5 to measure the strengths of up to five emission lines: [O II] λ3727, Hβ, [O III] λ5007, Hα, and [N II] λ6584. This near-infrared spectroscopy enables us to derive O/H metallicities, and also SFRs from extinction corrected Hα measurements. We find that the mass-metallicity relation (MZR) of these star-forming galaxies at z ≈ 2.3 is lower than the local Sloan Digital Sky Survey (SDSS) MZR by a factor of three to five, a larger change than found by Erb et al. using [N II]/Hα-based metallicities from stacked spectra. We discuss how the different selections of the samples and metallicity calibrations used may be responsible for this discrepancy. The galaxies show direct evidence that the SFR is still a second parameter in the MZR at these redshifts. However, determining whether the Z(M, SFR) relation is invariant with epoch depends on the choice of extrapolation used from local samples, because z > 2 galaxies of a given mass have much higher SFRs than the local SDSS galaxies. We find that the zCOSMOS galaxies are consistent with a non-evolving FMR if we use the physically motivated formulation of the Z(M, SFR) relation from Lilly et al., but not if we use the empirical formulation of Mannucci et al.

  20. The FMOS-COSMOS survey of star-forming galaxies at z ∼ 1.6. II. The mass-metallicity relation and the dependence on star formation rate and dust extinction

    SciTech Connect

    Zahid, H. J.; Sanders, D. B.; Chu, J.; Hasinger, G.; Kashino, D.; Silverman, J. D.; Kewley, L. J.; Daddi, E.; Renzini, A.; Rodighiero, G.; Nagao, T.; Arimoto, N.; Kartaltepe, J.; Lilly, S. J.; Carollo, C. M.; Maier, C.; Geller, M. J.; Capak, P.; Ilbert, O.; Kajisawa, M.; Collaboration: COSMOS Team; and others

    2014-09-01

    We investigate the relationships between stellar mass, gas-phase oxygen abundance (metallicity), star formation rate (SFR), and dust content of star-forming galaxies at z ∼ 1.6 using Subaru/FMOS spectroscopy in the COSMOS field. The mass-metallicity (MZ) relation at z ∼ 1.6 is steeper than the relation observed in the local universe. The steeper MZ relation at z ∼ 1.6 is mainly due to evolution in the stellar mass where the MZ relation begins to turnover and flatten. This turnover mass is 1.2 dex larger at z ∼ 1.6. The most massive galaxies at z ∼ 1.6 (∼10{sup 11} M {sub ☉}) are enriched to the level observed in massive galaxies in the local universe. The MZ relation we measure at z ∼ 1.6 supports the suggestion of an empirical upper metallicity limit that does not significantly evolve with redshift. We find an anti-correlation between metallicity and SFR for galaxies at a fixed stellar mass at z ∼ 1.6, which is similar to trends observed in the local universe. We do not find a relation between stellar mass, metallicity, and SFR that is independent of redshift; rather, our data suggest that there is redshift evolution in this relation. We examine the relation between stellar mass, metallicity, and dust extinction, and find that at a fixed stellar mass, dustier galaxies tend to be more metal rich. From examination of the stellar masses, metallicities, SFRs, and dust extinctions, we conclude that stellar mass is most closely related to dust extinction.

  1. The universal relation of galactic chemical evolution: the origin of the mass-metallicity relation

    SciTech Connect

    Zahid, H. Jabran; Dima, Gabriel I.; Kudritzki, Rolf-Peter; Kewley, Lisa J.; Geller, Margaret J.; Hwang, Ho Seong; Silverman, John D.; Kashino, Daichi

    2014-08-20

    We examine the mass-metallicity relation for z ≲ 1.6. The mass-metallicity relation follows a steep slope with a turnover, or 'knee', at stellar masses around 10{sup 10} M {sub ☉}. At stellar masses higher than the characteristic turnover mass, the mass-metallicity relation flattens as metallicities begin to saturate. We show that the redshift evolution of the mass-metallicity relation depends only on the evolution of the characteristic turnover mass. The relationship between metallicity and the stellar mass normalized to the characteristic turnover mass is independent of redshift. We find that the redshift-independent slope of the mass-metallicity relation is set by the slope of the relationship between gas mass and stellar mass. The turnover in the mass-metallicity relation occurs when the gas-phase oxygen abundance is high enough that the amount of oxygen locked up in low-mass stars is an appreciable fraction of the amount of oxygen produced by massive stars. The characteristic turnover mass is the stellar mass, where the stellar-to-gas mass ratio is unity. Numerical modeling suggests that the relationship between metallicity and the stellar-to-gas mass ratio is a redshift-independent, universal relationship followed by all galaxies as they evolve. The mass-metallicity relation originates from this more fundamental universal relationship between metallicity and the stellar-to-gas mass ratio. We test the validity of this universal metallicity relation in local galaxies where stellar mass, metallicity, and gas mass measurements are available. The data are consistent with a universal metallicity relation. We derive an equation for estimating the hydrogen gas mass from measurements of stellar mass and metallicity valid for z ≲ 1.6 and predict the cosmological evolution of galactic gas masses.

  2. Exploring Systematic Effects in the Mass-Metallicity-SFR Relation

    NASA Astrophysics Data System (ADS)

    Telford, O. G.; Dalcanton, J.; Skillman, E.; Conroy, C.

    2016-06-01

    There is evidence that the well-established mass-metallicity relation in galaxies is correlated with a third parameter: star formation rate (SFR). The strength of the correlation between metallicity and SFR may be used along with chemical evolution models to disentangle the relative importance of different physical processes (e.g., infall of pristine gas, metal-enriched outflows), but the observed strength of this correlation varies widely among studies using both single-fiber and IFU spectroscopy. We analyze possible sources of systematic error that could affect the observed strength of this correlation, including choice of metallicity calibration. We present the first analysis of the relation between stellar mass, gas phase metallicity and SFR using a new set of theoretically calibrated abundance diagnostics from Dopita et al. (2013) for ~150,000 star-forming galaxies in the Sloan Digital Sky Survey. Using any of these new strong emission line abundance diagnostics yields a relatively weak correlation between metallicity and SFR at fixed stellar mass, in contrast to the stronger correlation found by some previous studies using other metallicity diagnostics. We also consider other possible sources of bias that can affect the metallicity correlation with SFR, including uncertainty in stellar mass determination, aperture effects, and dust. Finally, we present preliminary results from current work investigating the effect of the choice of binning technique on derivations of direct method metallicities for stacked galaxy spectra and the subsequent impact on the correlation between metallicity and SFR. The large uncertainty in the true strength of the relation between mass, metallicity, and SFR must be carefully accounted for in theoretical studies of chemical evolution.

  3. Mass-metallicity relation from z = 5 to the present: evidence for a transition in the mode of galaxy growth at z = 2.6 due to the end of sustained primordial gas infall

    NASA Astrophysics Data System (ADS)

    Møller, P.; Fynbo, J. P. U.; Ledoux, C.; Nilsson, K. K.

    2013-04-01

    We analyse the redshift evolution of the mass-metallicity relation in a sample of 110 Damped Lyman α absorbers (DLAs) spanning the redshift range z = 0.11-5.06 and find that the zero-point of the correlation changes significantly with redshift. The evolution is such that the zero-point is constant at the early phases of galaxy growth (i.e. no evolution) but then features a sharp break at z = 2.6 ± 0.2 with a rapid incline towards lower redshifts such that damped absorbers of identical masses are more metal rich at later times than earlier. The slope of this mass-metallicity correlation evolution is 0.35 ± 0.07 dex per unit redshift. We compare this result to similar studies of the redshift evolution of emission selected galaxy samples and find a remarkable agreement with the slope of the evolution of galaxies of stellar mass log(M*/M⊙) ≈ 8.5. This allows us to form an observational tie between damped absorbers and galaxies seen in emission. We use results from simulations to infer the virial mass of the dark matter halo of a typical DLA galaxy and find a ratio (Mvir/M*) ≈ 30. We compare our results to those of several other studies that have reported strong transition-like events at redshifts around z = 2.5-2.6 and argue that all those observations can be understood as the consequence of a transition from a situation where galaxies were fed more unprocessed infalling gas than they could easily consume to one where they suddenly become infall starved and turn to mainly processing, or re-processing, of previously acquired gas.

  4. Simulating the mass-metallicity relation from z ˜ 1

    NASA Astrophysics Data System (ADS)

    Mouhcine, M.; Gibson, B. K.; Renda, A.; Kawata, D.

    2008-08-01

    Context: The chemical properties of galaxies and their evolution as a function of cosmic epoch are powerful constraints on their evolutionary histories. Aims: This work provides a grid of numerical models for galaxy evolution over an extended cosmic epoch. The aims are to assess how well current models reproduce observed properties of galaxies, in particular the stellar mass versus gas phase metallicity relation, and to quantify the effect of the merging histories of galaxies on their final properties. Methods: We use 112 N-body/hydrodynamical simulations in the standard cold dark matter universe, to follow the formation of galaxy-sized halos and investigate the chemical enrichment of both the stellar component and the interstellar medium of galaxies, with stellar masses higher than ~109 M⊙. Results: The resulting chemical properties of the simulated galaxies are broadly consistent with the observations. The predicted relationship between the mean metallicity and the galaxy stellar mass for both the stellar and the gaseous components at z = 0 agree with the relationships observed locally. The predicted scatter about these relationships, which is traced to the differing merging histories amongst the simulated galaxies with similar final masses, is similar to what is observed. In the hierarchical formation scenario, we find that the more massive galaxies are typically more evolved than their low mass counterparts over the second half of the age of the Universe. The predicted correlations between the total mass and the stellar mass of galaxies in our simulated sample from the present epoch up to z ˜ 1 agree with observed ones. We find that the integrated stellar populations in the simulations are dominated by stars as old as 4-10 Gyr. In contrast with massive galaxies, for which the luminosity-weighted ages of the integrated stellar populations in the simulated sample agree with those derived from the modelling of observed spectral energy distributions, simulated

  5. Reassessing the Relation Between Stellar Mass, Metallicity, and Star Formation Rate in the Local Universe

    NASA Astrophysics Data System (ADS)

    Telford, Olivia Grace; Dalcanton, Julianne; Skillman, Evan D.; Conroy, Charlie

    2015-01-01

    There is considerable evidence that the well-established mass-metallicity relation in galaxies depends on a third parameter: star formation rate (SFR). The observed strength of this dependence varies substantially depending on the choice of metallicity calibration, but has significant implications for theories of galaxy evolution, as it constrains the interplay between infall of pristine gas, metal production due to star formation, and ejection of enriched gas from galaxies. We present a new analysis of the relation between stellar mass, gas phase metallicity and SFR for ~140,000 star-forming galaxies in the Sloan Digital Sky Survey. Using a new set of theoretically calibrated abundance diagnostics from Dopita et al. (2013), we find a weaker dependence of metallicity on SFR at fixed stellar mass than was found by previous studies using different calibration techniques for gas phase metallicity. We analyze possible biases in the derivation of mass, metallicity, and SFR that could cause the observed strength of the metallicity dependence on SFR to differ from reality, as the calculation of each of these quantities is subject to systematic errors. Chemical evolution models must carefully consider these sources of potential bias when accounting for metallicity dependence on SFR.

  6. INSIGHTS ON THE STELLAR MASS-METALLICITY RELATION FROM THE CALIFA SURVEY

    SciTech Connect

    González Delgado, R. M.; García-Benito, R.; Pérez, E.; Cortijo-Ferrero, C.; López Fernández, R.; Sánchez, S. F.; Alves, J.; Bland-Hawthorn, J.; Galbany, L.; Gallazzi, A.; Husemann, B.; Bekeraite, S.; Jungwiert, B.; López-Sánchez, A. R.; De Lorenzo-Cáceres, A.; Marino, R. A. [CEI Campus Moncloa, UCM-UPM, Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Avda. Complutense s Collaboration: CALIFA collaboration920; and others

    2014-08-10

    We use spatially and temporally resolved maps of stellar population properties of 300 galaxies from the CALIFA integral field survey to investigate how the stellar metallicity (Z {sub *}) relates to the total stellar mass (M {sub *}) and the local mass surface density (μ{sub *}) in both spheroidal- and disk-dominated galaxies. The galaxies are shown to follow a clear stellar mass-metallicity relation (MZR) over the whole 10{sup 9}-10{sup 12} M {sub ☉} range. This relation is steeper than the one derived from nebular abundances, which is similar to the flatter stellar MZR derived when we consider only young stars. We also find a strong relation between the local values of μ{sub *} and Z {sub *} (the μZR), betraying the influence of local factors in determining Z {sub *}. This shows that both local (μ{sub *}-driven) and global (M {sub *}-driven) processes are important in determining metallicity in galaxies. We find that the overall balance between local and global effects varies with the location within a galaxy. In disks, μ{sub *} regulates Z {sub *}, producing a strong μZR whose amplitude is modulated by M {sub *}. In spheroids it is M {sub *} that dominates the physics of star formation and chemical enrichment, with μ{sub *} playing a minor, secondary role. These findings agree with our previous analysis of the star formation histories of CALIFA galaxies, which showed that mean stellar ages are mainly governed by surface density in galaxy disks and by total mass in spheroids.

  7. LOW MASSES AND HIGH REDSHIFTS: THE EVOLUTION OF THE MASS-METALLICITY RELATION

    SciTech Connect

    Henry, Alaina; Straughn, Amber; Scarlata, Claudia; Bedregal, Alejandro G.; Domínguez, Alberto; Siana, Brian; Masters, Daniel; Malkan, Matthew; Ross, Nathaniel; Martin, Crystal L.; Atek, Hakim; Colbert, James W.; Rafelski, Marc; Teplitz, Harry; Bunker, Andrew J.; Dressler, Alan; Hathi, Nimish; McCarthy, Patrick

    2013-10-20

    We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10{sup 8} ∼< M/M {sub ☉} ∼< 10{sup 10}, obtained by stacking spectra of 83 emission-line galaxies with secure redshifts between 1.3 ∼< z ∼< 2.3. For these redshifts, infrared grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R {sub 23} metallicity diagnostic: ([O II] λλ3726, 3729 + [O III] λλ4959, 5007)/Hβ. Using spectra stacked in four mass quartiles, we find a MZ relation that declines significantly with decreasing mass, extending from 12+log(O/H) = 8.8 at M = 10{sup 9.8} M {sub ☉}, to 12+log(O/H) = 8.2 at M = 10{sup 8.2} M {sub ☉}. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M ∼> 10{sup 9.5} M {sub ☉} and z ∼ 2.3. Within the statistical uncertainties, our MZ relation agrees with the z ∼ 2.3 result, particularly since our somewhat higher metallicities (by around 0.1 dex) are qualitatively consistent with the lower mean redshift (z = 1.76) of our sample. For the masses probed by our data, the MZ relation shows a steep slope which is suggestive of feedback from energy-driven winds, and a cosmological downsizing evolution where high mass galaxies reach the local MZ relation at earlier times. In addition, we show that our sample falls on an extrapolation of the star-forming main sequence (the SFR-M {sub *} relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high star formation rates (SFRs). Finally, we report no evidence for evolution of the mass-metallicity-SFR plane; our stack-averaged measurements show excellent agreement with the local relation.

  8. Low Masses and High Redshifts: The Evolution of the Mass-Metallicity Relation

    NASA Technical Reports Server (NTRS)

    Henry, Alaina; Scarlata, Claudia; Dominguez, Alberto; Malkan, Matthew; Martin, Crystal L.; Siana, Brian; Atek, Hakim; Bedregal, Alejandro G.; Colbert, James W.; Rafelski, Marc; Ross, Nathaniel; Teplitz, Harry; Bunker, Andrew J.; Dressler, Alan; Hathi, Nimish; Masters, Daniel; McCarthy, Patrick; Straughn, Amber

    2013-01-01

    We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10(exp 8) < M/Stellar Mass < or approx. 10(exp 10), obtained by stacking spectra of 83 emission-line galaxies with secure redshifts between 1.3 < or approx. z < or approx. 2.3. For these redshifts, infrared grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R23 metallicity diagnostic: ([O II] (lambda)(lambda)3726, 3729 + [OIII] (lambda)(lambda)4959, 5007)/H(beta). Using spectra stacked in four mass quartiles, we find a MZ relation that declines significantly with decreasing mass, extending from 12+log(O/H) = 8.8 at M = 10(exp 9.8) Stellar Mass to 12+log(O/H)= 8.2 at M = 10(exp 8.2) Stellar Mass. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M > or approx. 10(exp 9.5) Stellar Mass and z approx. 2.3. Within the statistical uncertainties, our MZ relation agrees with the z approx. 2.3 result, particularly since our somewhat higher metallicities (by around 0.1 dex) are qualitatively consistent with the lower mean redshift (z = 1.76) of our sample. For the masses probed by our data, the MZ relation shows a steep slope which is suggestive of feedback from energy-driven winds, and a cosmological downsizing evolution where high mass galaxies reach the local MZ relation at earlier times. In addition, we show that our sample falls on an extrapolation of the star-forming main sequence (the SFR-M* relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high star formation rates (SFRs). Finally, we report no evidence for evolution of the mass-metallicity-SFR plane; our stack-averaged measurements show excellent agreement with the local relation.

  9. RE-EXAMINING HIGH ABUNDANCE SLOAN DIGITAL SKY SURVEY MASS-METALLICITY OUTLIERS: HIGH N/O, EVOLVED WOLF-RAYET GALAXIES?

    SciTech Connect

    Berg, Danielle A.; Skillman, Evan D.; Marble, Andrew R. E-mail: skillman@astro.umn.edu

    2011-09-01

    We present new MMT spectroscopic observations of four dwarf galaxies representative of a larger sample observed by the Sloan Digital Sky Survey and identified by Peeples et al. as low-mass, high oxygen abundance outliers from the mass-metallicity relation. Peeples showed that these four objects (with metallicity estimates of 8.5 {<=} 12 + log(O/H) {<=} 8.8) have oxygen abundance offsets of 0.4-0.6 dex from the M{sub B} luminosity-metallicity relation. Our new observations extend the wavelength coverage to include the [O II] {lambda}{lambda}3726, 3729 doublet, which adds leverage in oxygen abundance estimates and allows measurements of N/O ratios. All four spectra are low excitation, with relatively high N/O ratios (N/O {approx}> 0.10), each of which tend to bias estimates based on strong emission lines toward high oxygen abundances. These spectra all fall in a regime where the 'standard' strong-line methods for metallicity determinations are not well calibrated either empirically or by photoionization modeling. By comparing our spectra directly to photoionization models, we estimate oxygen abundances in the range of 7.9 {<=} 12 + log (O/H) {<=} 8.4, consistent with the scatter of the mass-metallicity relation. We discuss the physical nature of these galaxies that leads to their unusual spectra (and previous classification as outliers), finding their low excitation, elevated N/O, and strong Balmer absorption are consistent with the properties expected from galaxies evolving past the 'Wolf-Rayet galaxy' phase. We compare our results to the 'main' sample of Peeples and conclude that they are outliers primarily due to enrichment of nitrogen relative to oxygen and not due to unusually high oxygen abundances for their masses or luminosities.

  10. Globular Cluster Systems in Giant Ellipticals: The Mass/Metallicity Relation

    NASA Astrophysics Data System (ADS)

    Harris, William E.

    2009-07-01

    Data from the Hubble Space Telescope taken with the Advanced Camera for Surveys/WFC camera have been used to investigate the globular cluster (GC) populations around six giant elliptical galaxies that are ~40 Mpc distant. From these six fields, imaged in B and I, a total of more than 15,000 candidate GCs have been measured, of which 8000 or more are high-probability GCs. The data reach a limiting magnitude near MI sime -8, about 0.4 mag fainter than the GC luminosity function turnover point, and thus thoroughly cover the bright half of the GC population. Most of the individual GCs on these images are marginally resolved nonstellar objects, so King-model profiles convolved with the stellar point-spread functions are used to measure their individual total magnitudes, colors, and linear effective radii. The classic bimodal form of the GC color-magnitude distribution shows up unambiguously in all the galaxies, allowing an accurate definition of the mean colors along each of the two sequences as a function of magnitude (the mass/metallicity relation or MMR). The blue, metal-poor cluster sequence shows a clearly defined but nonlinear MMR: in this particular photometric data set the mean GC color changes smoothly from a near-vertical sequence at low luminosity (MI gsim -9.5) to an increasingly redward slope at higher luminosity. By contrast, the red, metal-rich sequence shows little trace of an MMR and is nearly vertical at all luminosities. The form and slope of the MMR along either sequence do not depend strongly on either cluster size rh or galactocentric distance R gc. All the observed features of the present data agree with the interpretation that the MMR is created primarily by GC self-enrichment, along the lines of the quantitative model of Bailin & Harris. During the protocluster formation stage, the more massive GCs are better able to hold back the enriched products of the earliest supernovae and to seed the lower-mass stars still in formation. The "threshold

  11. Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

    SciTech Connect

    Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc'h, Émeric; Pannella, Maurilio; Schreiber, Corentin; Trump, Jonathan R.; Dickinson, Mark

    2014-06-10

    Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

  12. Time Evolution of Galaxy Scaling Relations in Cosmological Simulations

    NASA Astrophysics Data System (ADS)

    Taylor, Philip; Kobayashi, Chiaki

    2016-08-01

    We predict the evolution of galaxy scaling relationships from cosmological, hydrodynamical simulations, that reproduce the scaling relations of present-day galaxies. Although we do not assume co-evolution between galaxies and black holes a priori, we are able to reproduce the black hole mass-velocity dispersion relation. This relation does not evolve, and black holes actually grow along the relation from significantly less massive seeds than have previously been used. AGN feedback does not very much affect the chemical evolution of our galaxies. In our predictions, the stellar mass-metallicity relation does not change its shape, but the metallicity significantly increases from z ˜ 2 to z ˜ 1, while the gas-phase mass-metallicity relation does change shape, having a steeper slope at higher redshifts (z ≲ 3). Furthermore, AGN feedback is required to reproduce observations of the most massive galaxies at z ≲ 1, specifically their positions on the star formation main sequence and galaxy mass-size relation.

  13. ON THE THREE-DIMENSIONAL STRUCTURE OF THE MASS, METALLICITY, AND STAR FORMATION RATE SPACE FOR STAR-FORMING GALAXIES

    SciTech Connect

    Lara-Lopez, Maritza A.; Lopez-Sanchez, Angel R.; Hopkins, Andrew M.

    2013-02-20

    We demonstrate that the space formed by the star formation rate (SFR), gas-phase metallicity (Z), and stellar mass (M {sub *}) can be reduced to a plane, as first proposed by Lara-Lopez et al. We study three different approaches to find the best representation of this 3D space, using a principal component analysis (PCA), a regression fit, and binning of the data. The PCA shows that this 3D space can be adequately represented in only two dimensions, i.e., a plane. We find that the plane that minimizes the {chi}{sup 2} for all variables, and hence provides the best representation of the data, corresponds to a regression fit to the stellar mass as a function of SFR and Z, M {sub *}= f(Z, SFR). We find that the distribution resulting from the median values in bins for our data gives the highest {chi}{sup 2}. We also show that the empirical calibrations to the oxygen abundance used to derive the Fundamental Metallicity Relation have important limitations, which contribute to the apparent inconsistencies. The main problem is that these empirical calibrations do not consider the ionization degree of the gas. Furthermore, the use of the N2 index to estimate oxygen abundances cannot be applied for 12 + log(O/H) {approx}> 8.8 because of the saturation of the [N II] {lambda}6584 line in the high-metallicity regime. Finally, we provide an update of the Fundamental Plane derived by Lara-Lopez et al.

  14. Mirages in galaxy scaling relations

    NASA Astrophysics Data System (ADS)

    Mosenkov, A. V.; Sotnikova, N. Ya.; Reshetnikov, V. P.

    2014-06-01

    We analysed several basic correlations between structural parameters of galaxies. The data were taken from various samples in different passbands which are available in the literature. We discuss disc scaling relations as well as some debatable issues concerning the so-called Photometric Plane for bulges and elliptical galaxies in different forms and various versions of the famous Kormendy relation. We show that some of the correlations under discussion are artificial (self-correlations), while others truly reveal some new essential details of the structural properties of galaxies. Our main results are as follows: At present, we cannot conclude that faint stellar discs are, on average, more thin than discs in high surface brightness galaxies. The `central surface brightness-thickness' correlation appears only as a consequence of the transparent exponential disc model to describe real galaxy discs. The Photometric Plane appears to have no independent physical sense. Various forms of this plane are merely sophisticated versions of the Kormendy relation or of the self-relation involving the central surface brightness of a bulge/elliptical galaxy and the Sérsic index n. The Kormendy relation is a physical correlation presumably reflecting the difference in the origin of bright and faint ellipticals and bulges. We present arguments that involve creating artificial samples to prove our main idea.

  15. THE OBSERVED RELATION BETWEEN STELLAR MASS, DUST EXTINCTION, AND STAR FORMATION RATE IN LOCAL GALAXIES

    SciTech Connect

    Zahid, H. J.; Kewley, L. J.; Kudritzki, R. P.; Yates, R. M.

    2013-02-15

    In this study, we investigate the relation between stellar mass, dust extinction, and star formation rate (SFR) using {approx}150,000 star-forming galaxies from SDSS DR7. We show that the relation between dust extinction and SFR changes with stellar mass. For galaxies at the same stellar mass, dust extinction is anti-correlated with the SFR at stellar masses <10{sup 10} M {sub Sun }. There is a sharp transition in the relation at a stellar mass of 10{sup 10} M {sub Sun }. At larger stellar masses, dust extinction is positively correlated with the SFR for galaxies at the same stellar mass. The observed relation between stellar mass, dust extinction, and SFR presented in this study helps to confirm similar trends observed in the relation between stellar mass, metallicity, and SFR. The relation reported in this study provides important new constraints on the physical processes governing the chemical evolution of galaxies. The correlation between SFR and dust extinction for galaxies with stellar masses >10{sup 10} M {sub Sun} is shown to extend to the population of quiescent galaxies suggesting that the physical processes responsible for the observed relation between stellar mass, dust extinction, and SFR may be related to the processes leading to the shutdown of star formation in galaxies.

  16. Galaxies, Axisymmetric Systems and Relativity

    NASA Astrophysics Data System (ADS)

    MacCallum, M. A. H.

    2011-06-01

    List of contributors; Preface; Prof. W. B. Bonnor: a biological sketch; Part I. Galaxies and Cosmology: 1. The origin of large scale cosmic structure B. J. T. Jones and P. L. Palmer; 2. The problem of origin of the primordial pertubations and the modern cosmology V. N. Lukash and I. D. Novikov; 3. The automorphism group and field equations for Bianchi universes W. L. Rogue and G. F. R. Ellis; 4. New perspectives on galaxy formation J. Silk; Part II. Axisymmetric Systems: 5. On exact radiative solutions representing finite sources J. Bicak; 6. Proof of a generalized Geroch conjecture I. Hauser and F. J. Ernst; 7. Limits of the double Kerr solution C. Hoenselaers; 8. Non-inheritance of static symmetry by Maxwell fields M. A. H. MacCallum and N. Van den Bergh; 9. Stationary axisymmetric electrovacuum fields in general relativity G. Neugebauer and D. Kramer; 10. An almost conformal approach to axial symmetry Z. Perjes; 11. Conformally stationary axisymmetric space-times J. Winicour; Part III. Relativity: 12. A family of conformally flat space-times having the same curvature tensor in a given co-ordinate frame C. D. Collinson; 13. On the Bell-Szekeres solution for colliding electromagnetic waves J. B. Griffiths; 14. A remark on the Hauser metric A. Held; 15. Numerical relativity by power series R. Penrose; 16. Projective relativity and the equation of motion E. Schmutzer; 17. On generalized equations of goedesic deviation B. F. Schutz; 18. Lobatchevski plane gravitational waves S. T. C. Siklos; 19. Perfect fluid and vacuum solutions of Einstein's field equations with flat 3-dimensional slices H. Stephani and Th. Wolf; 20. Self-similar solutions of Einstein's equations J. Wainwright.

  17. On the Kennicutt-Schmidt Relation of Low-Metallicity High-Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Gnedin, Nickolay Y.; Kravtsov, Andrey V.

    2010-05-01

    We present results of self-consistent, high-resolution cosmological simulations of galaxy formation at z ~ 3. The simulations employ a recently developed recipe for star formation based on the local abundance of molecular hydrogen, which is tracked self-consistently during the course of simulation. The phenomenological H2 formation model accounts for the effects of dissociating UV radiation of stars in each galaxy, as well as self-shielding and shielding of H2 by dust, and therefore allows us to explore effects of lower metallicities and higher UV fluxes prevalent in high-redshift galaxies on their star formation. We compare stellar masses, metallicities, and star formation rates of the simulated galaxies to available observations of the Lyman break galaxies (LBGs) and find a reasonable agreement. We find that the Kennicutt-Schmidt (KS) relation exhibited by our simulated galaxies at z ≈ 3 is substantially steeper and has a lower amplitude than the z = 0 relation at ΣH <~ 100 M odot pc-2. The predicted relation, however, is consistent with existing observational constraints for the z ≈ 3 damped Lyα and LBGs. Our tests show that the main reason for the difference from the local KS relation is lower metallicity of the interstellar medium in high-redshift galaxies. We discuss several implications of the metallicity-dependence of the KS relation for galaxy evolution and interpretation of observations. In particular, we show that the observed size of high-redshift exponential disks depends sensitively on their KS relation. Our results also suggest that significantly reduced star formation efficiency at low gas surface densities can lead to strong suppression of star formation in low-mass high-redshift galaxies and long gas consumption time scales over most of the disks in large galaxies. The longer gas consumption time scales could make disks more resilient to major and minor mergers and could help explain the prevalence of the thin stellar disks in the local

  18. Scaling Relations for Galaxies Prior to Reionization

    NASA Astrophysics Data System (ADS)

    Chen, Pengfei; Wise, John H.; Norman, Michael L.; Xu, Hao; O'Shea, Brian W.

    2014-11-01

    The first galaxies in the universe are the building blocks of all observed galaxies. We present scaling relations for galaxies forming at redshifts z >= 15 when reionization is just beginning. We utilize the "Rarepeak" cosmological radiation hydrodynamics simulation that captures the complete star formation history in over 3300 galaxies, starting with massive Population III stars that form in dark matter halos as small as ~106 M ⊙. We make various correlations between the bulk halo quantities, such as virial, gas, and stellar masses and metallicities and their respective accretion rates, quantifying a variety of properties of the first galaxies up to halo masses of 109 M ⊙. Galaxy formation is not solely relegated to atomic cooling halos with virial temperatures greater than 104 K, where we find a dichotomy in galaxy properties between halos above and below this critical mass scale. Halos below the atomic cooling limit have a stellar mass-halo mass relationship log M sstarf ~= 3.5 + 1.3log (M vir/107 M ⊙). We find a non-monotonic relationship between metallicity and halo mass for the smallest galaxies. Their initial star formation events enrich the interstellar medium and subsequent star formation to a median of 10-2 Z ⊙ and 10-1.5 Z ⊙, respectively, in halos of total mass 107 M ⊙, which is then diluted by metal-poor inflows well beyond Population III pre-enrichment levels of 10-3.5 Z ⊙. The scaling relations presented here can be employed in models of reionization, galaxy formation, and chemical evolution in order to consider these galaxies forming prior to reionization.

  19. Scaling relations for galaxies prior to reionization

    SciTech Connect

    Chen, Pengfei; Norman, Michael L.; Xu, Hao; Wise, John H.; O'Shea, Brian W. E-mail: mlnorman@ucsd.edu E-mail: jwise@gatech.edu

    2014-11-10

    The first galaxies in the universe are the building blocks of all observed galaxies. We present scaling relations for galaxies forming at redshifts z ≥ 15 when reionization is just beginning. We utilize the 'Rarepeak' cosmological radiation hydrodynamics simulation that captures the complete star formation history in over 3300 galaxies, starting with massive Population III stars that form in dark matter halos as small as ∼10{sup 6} M {sub ☉}. We make various correlations between the bulk halo quantities, such as virial, gas, and stellar masses and metallicities and their respective accretion rates, quantifying a variety of properties of the first galaxies up to halo masses of 10{sup 9} M {sub ☉}. Galaxy formation is not solely relegated to atomic cooling halos with virial temperatures greater than 10{sup 4} K, where we find a dichotomy in galaxy properties between halos above and below this critical mass scale. Halos below the atomic cooling limit have a stellar mass-halo mass relationship log M {sub *} ≅ 3.5 + 1.3log (M {sub vir}/10{sup 7} M {sub ☉}). We find a non-monotonic relationship between metallicity and halo mass for the smallest galaxies. Their initial star formation events enrich the interstellar medium and subsequent star formation to a median of 10{sup –2} Z {sub ☉} and 10{sup –1.5} Z {sub ☉}, respectively, in halos of total mass 10{sup 7} M {sub ☉}, which is then diluted by metal-poor inflows well beyond Population III pre-enrichment levels of 10{sup –3.5} Z {sub ☉}. The scaling relations presented here can be employed in models of reionization, galaxy formation, and chemical evolution in order to consider these galaxies forming prior to reionization.

  20. A Critical Look at the Mass-Metallicity-Star Formation Rate Relation in the Local Universe. I. An Improved Analysis Framework and Confounding Systematics

    NASA Astrophysics Data System (ADS)

    Salim, Samir; Lee, Janice C.; Ly, Chun; Brinchmann, Jarle; Davé, Romeel; Dickinson, Mark; Salzer, John J.; Charlot, Stéphane

    2014-12-01

    It has been proposed that the (stellar) mass-(gas) metallicity relation of galaxies exhibits a secondary dependence on star formation rate (SFR), and that the resulting M *-Z-SFR relation may be redshift-invariant, i.e., "fundamental." However, conflicting results on the character of the SFR dependence, and whether it exists, have been reported. To gain insight into the origins of the conflicting results, we (1) devise a non-parametric, astrophysically motivated analysis framework based on the offset from the star-forming ("main") sequence at a given M * (relative specific SFR); (2) apply this methodology and perform a comprehensive re-analysis of the local M *-Z-SFR relation, based on SDSS, GALEX, and WISE data; and (3) study the impact of sample selection and of using different metallicity and SFR indicators. We show that metallicity is anti-correlated with specific SFR regardless of the indicators used. We do not find that the relation is spurious due to correlations arising from biased metallicity measurements or fiber aperture effects. We emphasize that the dependence is weak/absent for massive galaxies (log M * > 10.5), and that the overall scatter in the M *-Z-SFR relation does not greatly decrease from the M *-Z relation. We find that the dependence is stronger for the highest SSFR galaxies above the star-forming sequence. This two-mode behavior can be described with a broken linear fit in 12+log(O/H) versus log (SFR/M *), at a given M *. Previous parameterizations used for comparative analysis with higher redshift samples that do not account for the more detailed behavior of the local M *-Z-SFR relation may incorrectly lead to the conclusion that those samples follow a different relationship.

  1. A CRITICAL LOOK AT THE MASS-METALLICITY-STAR FORMATION RATE RELATION IN THE LOCAL UNIVERSE. I. AN IMPROVED ANALYSIS FRAMEWORK AND CONFOUNDING SYSTEMATICS

    SciTech Connect

    Salim, Samir; Salzer, John J.; Lee, Janice C.; Ly, Chun; Brinchmann, Jarle; Davé, Romeel; Dickinson, Mark; Charlot, Stéphane

    2014-12-20

    It has been proposed that the (stellar) mass-(gas) metallicity relation of galaxies exhibits a secondary dependence on star formation rate (SFR), and that the resulting M {sub *}-Z-SFR relation may be redshift-invariant, i.e., ''fundamental''. However, conflicting results on the character of the SFR dependence, and whether it exists, have been reported. To gain insight into the origins of the conflicting results, we (1) devise a non-parametric, astrophysically motivated analysis framework based on the offset from the star-forming ({sup m}ain{sup )} sequence at a given M {sub *} (relative specific SFR); (2) apply this methodology and perform a comprehensive re-analysis of the local M {sub *}-Z-SFR relation, based on SDSS, GALEX, and WISE data; and (3) study the impact of sample selection and of using different metallicity and SFR indicators. We show that metallicity is anti-correlated with specific SFR regardless of the indicators used. We do not find that the relation is spurious due to correlations arising from biased metallicity measurements or fiber aperture effects. We emphasize that the dependence is weak/absent for massive galaxies (log M {sub *} > 10.5), and that the overall scatter in the M {sub *}-Z-SFR relation does not greatly decrease from the M {sub *}-Z relation. We find that the dependence is stronger for the highest SSFR galaxies above the star-forming sequence. This two-mode behavior can be described with a broken linear fit in 12+log(O/H) versus log (SFR/M {sub *}), at a given M {sub *}. Previous parameterizations used for comparative analysis with higher redshift samples that do not account for the more detailed behavior of the local M {sub *}-Z-SFR relation may incorrectly lead to the conclusion that those samples follow a different relationship.

  2. The Star Formation Relation in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Schruba, Andreas

    2013-03-01

    I review observational studies of the large-scale star formation process in nearby galaxies. A wealth of new multi-wavelength data provide an unprecedented view on the interplay of the interstellar medium and (young) stellar populations on a few hundred parsec scale in 100+ galaxies of all types. These observations enable us to relate detailed studies of star formation in the Milky Way to the zoo of galaxies in the distant universe. Within the disks of spiral galaxies, recent star formation strongly scales with the local amount of molecular gas (as traced by CO) with a molecular gas depletion time of ˜2 Gyr. This is consistent with the picture that stars form in giant molecular clouds that have about universal properties. Galaxy centers and star-bursting galaxies deviate from this normal trend as they show enhanced star formation per unit gas mass suggesting systematic changes in the molecular gas properties and especially the dense gas fraction. In the outer disks of spirals and in dwarf galaxies, the decreasing availability of atomic gas inevitably limits the amount of star formation, though with large local variations. The critical step for the gas-stars cycle seems therefore to be the formation of a molecular gas phase, a process that shows complex dependencies on various environmental properties and is being investigated by intensive simulational work.

  3. THE MOSDEF SURVEY: MASS, METALLICITY, AND STAR-FORMATION RATE AT z ∼ 2.3

    SciTech Connect

    Sanders, Ryan L.; Shapley, Alice E.; Kriek, Mariska; Price, Sedona H.; Reddy, Naveen A.; Freeman, William R.; Siana, Brian; Mobasher, Bahram; Shivaei, Irene; De Groot, Laura; Coil, Alison L.

    2015-02-01

    We present results on the z ∼ 2.3 mass-metallicity relation (MZR) using early observations from the MOSFIRE Deep Evolution Field survey. We use an initial sample of 87 star-forming galaxies with spectroscopic coverage of Hβ, [O III] λ5007, Hα, and [N II] λ6584 rest-frame optical emission lines, and estimate the gas-phase oxygen abundance based on the N2 and O3N2 strong-line indicators. We find a positive correlation between stellar mass and metallicity among individual z ∼ 2.3 galaxies using both the N2 and O3N2 indicators. We also measure the emission-line ratios and corresponding oxygen abundances for composite spectra in bins of stellar mass. Among composite spectra, we find a monotonic increase in metallicity with increasing stellar mass, offset ∼0.15-0.3 dex below the local MZR. When the sample is divided at the median star-formation rate (SFR), we do not observe significant SFR dependence of the z ∼ 2.3 MZR among either individual galaxies or composite spectra. We furthermore find that z ∼ 2.3 galaxies have metallicities ∼0.1 dex lower at a given stellar mass and SFR than is observed locally. This offset suggests that high-redshift galaxies do not fall on the local ''fundamental metallicity relation'' among stellar mass, metallicity, and SFR, and may provide evidence of a phase of galaxy growth in which the gas reservoir is built up due to inflow rates that are higher than star-formation and outflow rates. However, robust conclusions regarding the gas-phase oxygen abundances of high-redshift galaxies await a systematic reappraisal of the application of locally calibrated metallicity indicators at high redshift.

  4. The universal stellar mass-stellar metallicity relation for dwarf galaxies

    SciTech Connect

    Kirby, Evan N.; Bullock, James S.; Cohen, Judith G.; Guhathakurta, Puragra; Gallazzi, Anna

    2013-12-20

    We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z{sub ∗}∝M{sub ∗}{sup 0.30±0.02}. The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M {sub *} = 10{sup 12} M {sub ☉}. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping.

  5. The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Kirby, Evan N.; Cohen, Judith G.; Guhathakurta, Puragra; Cheng, Lucy; Bullock, James S.; Gallazzi, Anna

    2013-12-01

    We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z_* \\propto M_*^{0.30+/- 0.02}. The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M * = 1012 M ⊙. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  6. ON THE KENNICUTT-SCHMIDT RELATION OF LOW-METALLICITY HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Gnedin, Nickolay Y.; Kravtsov, Andrey V. E-mail: andrey@oddjob.uchicago.ed

    2010-05-01

    We present results of self-consistent, high-resolution cosmological simulations of galaxy formation at z {approx} 3. The simulations employ a recently developed recipe for star formation based on the local abundance of molecular hydrogen, which is tracked self-consistently during the course of simulation. The phenomenological H{sub 2} formation model accounts for the effects of dissociating UV radiation of stars in each galaxy, as well as self-shielding and shielding of H{sub 2} by dust, and therefore allows us to explore effects of lower metallicities and higher UV fluxes prevalent in high-redshift galaxies on their star formation. We compare stellar masses, metallicities, and star formation rates of the simulated galaxies to available observations of the Lyman break galaxies (LBGs) and find a reasonable agreement. We find that the Kennicutt-Schmidt (KS) relation exhibited by our simulated galaxies at z {approx} 3 is substantially steeper and has a lower amplitude than the z = 0 relation at {Sigma}{sub H} {approx_lt} 100 M{sub o-dot} pc{sup -2}. The predicted relation, however, is consistent with existing observational constraints for the z {approx} 3 damped Ly{alpha} and LBGs. Our tests show that the main reason for the difference from the local KS relation is lower metallicity of the interstellar medium in high-redshift galaxies. We discuss several implications of the metallicity-dependence of the KS relation for galaxy evolution and interpretation of observations. In particular, we show that the observed size of high-redshift exponential disks depends sensitively on their KS relation. Our results also suggest that significantly reduced star formation efficiency at low gas surface densities can lead to strong suppression of star formation in low-mass high-redshift galaxies and long gas consumption time scales over most of the disks in large galaxies. The longer gas consumption time scales could make disks more resilient to major and minor mergers and could help

  7. THE CHEMICAL EVOLUTION OF STAR-FORMING GALAXIES OVER THE LAST 11 BILLION YEARS

    SciTech Connect

    Zahid, H. Jabran; Kewley, Lisa J.; Geller, Margaret J.; Hwang, Ho Seong; Fabricant, Daniel G.; Kurtz, Michael J.

    2013-07-10

    We calculate the stellar mass-metallicity relation at five epochs ranging to z {approx} 2.3. We quantify evolution in the shape of the mass-metallicity relation as a function of redshift; the mass-metallicity relation flattens at late times. There is an empirical upper limit to the gas-phase oxygen abundance in star-forming galaxies that is independent of redshift. From examination of the mass-metallicity relation and its observed scatter, we show that the flattening at late times is a consequence of evolution in the stellar mass where galaxies enrich to this empirical upper metallicity limit; there is also evolution in the fraction of galaxies at a fixed stellar mass that enrich to this limit. The stellar mass where metallicities begin to saturate is {approx}0.7 dex smaller in the local universe than it is at z {approx} 0.8.

  8. A ring galaxy in Canes Venatici and related ring galaxies

    SciTech Connect

    Wakamatsu, Ken-ichi; Nishida, M.T. Kobe Women's University )

    1991-04-01

    A spectroscopic observation was made of a ring-shaped object in Canes Venatici. A bright knot at the edge of the ring has a recession velocity of 10,960 + or - 30 km/s and so is confirmed as an extragalactic object. It shows no sign of nuclear activity but appears to be an H II region of intermediate excitation class. The linear diameter of the ring is 14.2 + or - 0.8 kpc, a typical size for ring galaxies. Recession velocities of several other ring galaxies are also given. 24 refs.

  9. The MOSDEF Survey: Mass, Metallicity, and Star-formation Rate at z~2.3

    NASA Astrophysics Data System (ADS)

    Sanders, Ryan Lee

    2015-08-01

    We present results on the z~2.3 mass-metallicity relation (MZR) using early observations from the MOSFIRE Deep Evolution Field (MOSDEF) survey. We use a sample of star-forming galaxies with spectroscopic coverage of Hβ, [OIII]λ5007, Hα, and [NII]λ6584 rest-frame optical emission lines, and estimate the gas-phase oxygen abundance based on the N2 and O3N2 strong-line indicators. We find a positive correlation between stellar mass and metallicity among individual z ˜ 2.3 galaxies using both the N2 and O3N2 indicators. We also measure the emission-line ratios and corresponding oxygen abundances for composite spectra in bins of stellar mass. Among composite spectra, we find a monotonic increase in metallicity with increasing stellar mass, offset ~0.15 - 0.3 dex below the local MZR. When the sample is divided at the median star-formation rate (SFR), we do not observe significant SFR dependence of the z~2.3 MZR among either individual galaxies or composite spectra. By directly comparing bins of local and high-redshift galaxies with similar stellar mass and SFR, we furthermore find that z~2.3 galaxies have metallicities ~0.1 dex lower at a given stellar mass and SFR than is observed locally. This offset suggests that high-redshift galaxies do not fall on the local “fundamental metallicity relation” among stellar mass, metallicity, and SFR, and may provide evidence of a phase of galaxy growth in which the gas reservoir is built up due to inflow rates that are higher than star-formation and outflow rates. However, robust conclusions regarding the gas-phase oxygen abundances of high-redshift galaxies await a systematic reappraisal of the application of locally calibrated metallicity indicators at high redshift. Using the MOSDEF dataset and photoionization models, we can also constrain the physical conditions (density, ionization state, hardness of the ionizing spectrum, metallicity) of high-redshift star-forming regions, providing one method of producing calibrations

  10. The relation between velocity dispersion and central galaxy density in clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Bahcall, N. A.

    1981-01-01

    A correlation between cluster velocity dispersion and average central galaxy density is reported. The correlation covers the range from rich clusters to small groups of galaxies, or, in terms of velocity dispersion, from v sub r approximately 1500 to approximately 100 km/s. This result is useful for estimating unknown velocity dispersions in clusters with the aid of the relatively easily determined 0.5 Mpc central galaxy density parameter. When combined with the virial theorem, the above relation also suggests that the mass-to-light ratio of galaxy systems increases with the system's velocity dispersion.

  11. Do galaxy global relationships emerge from local ones? I. The SDSS IV MaNGA surface mass density - metallicity relation

    NASA Astrophysics Data System (ADS)

    Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zhu, Guangtun B.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Law, David; Wake, David.; Green, Jenny E.; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena; Pan, Kaike; Roman Lopes, Alexandre; Lane, Richard R.

    2016-08-01

    We present the stellar surface mass density vs. gas metallicity (Σ★ - Z) relation for more than 500,000 spatially-resolved star-forming resolution elements (spaxels) from a sample of 653 disk galaxies included in the SDSS IV MaNGA survey. We find a tight relation between these local properties, with higher metallicities as the surface density increases. This relation extends over three orders of magnitude in the surface mass density and a factor of four in metallicity. We show that this local relationship can simultaneously reproduce two well-known properties of disk galaxies: their global mass-metallicity relationship and their radial metallicity gradients. We also find that the Σ★ - Z relation is largely independent of the galaxy's total stellar mass and specific star-formation rate (sSFR), except at low stellar mass and high sSFR. These results suggest that in the present-day universe local properties play a key role in determining the gas-phase metallicity in typical disk galaxies.

  12. The relation of dust and atomic gas properties of galaxies

    NASA Technical Reports Server (NTRS)

    Spitzak, John G.; Schneider, Stephen E.

    1992-01-01

    The way in which the neutral atomic hydrogen and far-IR emission from galaxies relate to their environments is shown. It is found that isolated and interacting galaxies display a fairly narrow range of a temperature-adjusted 'H I/100-micron index', suggesting that atomic gas-to-dust ratios are relatively constant among most galaxies. Isolated normal galaxies are used to develop a fiducial standard for the H I/100-micron index, against which galaxies in other environments are compared. Galaxies undergoing tidal interactions prove to have the same value for the index once the proper temperature adjustment is applied according to their FIR color. Applied to clusters, the H I/100-micron index shows a clear discrimination between galaxies whose H I is 'stripped' or 'unstripped', implying that there is about 6 times less H I in stripped galaxies relative to the 100-micron-emitting dust. The stripped galaxies also appear to have a slightly lower mean dust temperature, which is surprising since the stripping process might be expected to remove preferentially cooler than average dust from the outer disk.

  13. The relation between infrared and radio emission in spiral galaxies

    NASA Technical Reports Server (NTRS)

    Helou, George

    1991-01-01

    A remarkable correlation between the far infrared and the radio continuum emission of star forming galaxies was one of the early results based on IRAS data, and has remained one of the most intriguing. Recent work has extended the correlation to early type galaxies, revealing a slightly different ratio in lenticulars. When radio and infrared maps of disk galaxies are compared, the radio disks appear systematically more diffuse. This has been interpreted as a manifestation of the diffusion of cosmic-ray electrons, and has allowed a fresh look at the behavior of magnetic fields and cosmic rays in spiral galaxies, and at their relation to the rest of the interstellar medium.

  14. The Tully-Fisher relations for Hickson compact group galaxies

    NASA Astrophysics Data System (ADS)

    Torres-Flores, S.; Mendes de Oliveira, C.; Plana, H.; Amram, P.; Epinat, B.

    2013-07-01

    We used K-band photometry, maximum rotational velocities derived from Fabry-Perot data and H I observed and predicted masses to study, for the first time, the K band, stellar and baryonic Tully-Fisher relations for galaxies in Hickson compact groups. We compared these relations with the ones defined for galaxies in less dense environments from the Gassendi HAlpha survey of Spirals and from a sample of gas-rich galaxies. We find that most of the Hickson compact group galaxies lie on the K-band Tully-Fisher relation defined by field galaxies with a few low-mass outliers, namely HCG 49b and HCG 96c, which appear to have had strong recent burst of star formation. The stellar Tully-Fisher relation for compact group galaxies presents a similar dispersion to that of the K-band relation, and it has no significant outliers when a proper computation of the stellar mass is done for the strongly star-forming galaxies. The scatter in these relations can be reduced if the gaseous component is taken into account, i.e. if a baryonic Tully-Fisher relation is considered. In order to explain the positions of the galaxies off the K-band Tully-Fisher relation, we favour a scenario in which their luminosities are brightened due to strong star formation or AGN activity. We argue that strong bursts of star formation can affect the B- and K-band luminosities of HCG 49b and HCG 96c and in the case of the latter also AGN activity may affect the K-band magnitude considerably, without affecting their total masses.

  15. The dustier early-type galaxies deviate from late-type galaxies' scaling relations

    NASA Astrophysics Data System (ADS)

    Lianou, S.; Xilouris, E.; Madden, S. C.; Barmby, P.

    2016-09-01

    Several dedicated surveys focusing on early-type galaxies (ETGs) reveal that significant fractions of them are detectable in all interstellar medium phases studied to date. We select ETGs from the Herschel Reference Survey that have both far-infrared Herschel and either H I or CO detection (or both). We derive their star formation rates (SFRs), stellar masses and dust masses via modelling their spectral energy distributions. We combine these with literature information on their atomic and molecular gas properties, in order to relate their star formation, total gas mass and dust mass on global scales. The ETGs deviate from the dust mass-SFR relation and the Schmidt-Kennicutt relation that SDSS star-forming galaxies define: compared to SDSS galaxies, ETGs have more dust at the same SFR, or less SFR at the same dust mass. When placing them in the M⋆-SFR plane, ETGs show a much lower specific SFR as compared to normal star-forming galaxies. ETGs show a large scatter compared to the Schmidt-Kennicutt relation found locally within our Galaxy, extending to lower SFRs and gas mass surface densities. Using an ETG's SFR and the Schmidt-Kennicutt law to predict its gas mass leads to an underestimate. ETGs have similar observed-gas-to-modelled-dust mass ratios to star-forming galaxies of the same stellar mass, as well as they exhibit a similar scatter.

  16. PRECISE TULLY-FISHER RELATIONS WITHOUT GALAXY INCLINATIONS

    SciTech Connect

    Obreschkow, D.; Meyer, M.

    2013-11-10

    Power-law relations between tracers of baryonic mass and rotational velocities of disk galaxies, so-called Tully-Fisher relations (TFRs), offer a wealth of applications in galaxy evolution and cosmology. However, measurements of rotational velocities require galaxy inclinations, which are difficult to measure, thus limiting the range of TFR studies. This work introduces a maximum likelihood estimation (MLE) method for recovering the TFR in galaxy samples with limited or no information on inclinations. The robustness and accuracy of this method is demonstrated using virtual and real galaxy samples. Intriguingly, the MLE reliably recovers the TFR of all test samples, even without using any inclination measurements—that is, assuming a random sin i-distribution for galaxy inclinations. Explicitly, this 'inclination-free MLE' recovers the three TFR parameters (zero-point, slope, scatter) with statistical errors only about 1.5 times larger than the best estimates based on perfectly known galaxy inclinations with zero uncertainty. Thus, given realistic uncertainties, the inclination-free MLE is highly competitive. If inclination measurements have mean errors larger than 10°, it is better not to use any inclinations than to consider the inclination measurements to be exact. The inclination-free MLE opens interesting perspectives for future H I surveys by the Square Kilometer Array and its pathfinders.

  17. Galaxy Zoo: spiral galaxy morphologies and their relation to the star-forming main sequence

    NASA Astrophysics Data System (ADS)

    Willett, Kyle; Schawinski, Kevin; Masters, Karen; Melvin, Tom; Skibba, Ramin A.; Nichol, Robert; Cheung, Edmond; Lintott, Chris; Simmons, Brooke D.; Kaviraj, Sugata; Keel, William C.; Fortson, Lucy; Galaxy Zoo volunteers

    2015-01-01

    We examine the relationship between stellar mass and star formation rate in disk galaxies at z<0.085, measuring different populations of spirals as classified by their kiloparsec-scale structure. The morphologies of disk galaxies are obtained from the Galaxy Zoo 2 project, which includes the number of spiral arms, the arm pitch angle, and the presence of strong galactic bars. We show that both the slope and dispersion of the star-forming main sequence (SFMS) is constant no matter what the morphology of the spiral disk. We also show that mergers (both major and minor), which represent the strongest conditions for increases in star formation at a constant mass, only boost the SFR above the main relation by 0.3 dex; this is a significant reduction over the increase seen in merging systems at higher redshifts (z > 1). Of the galaxies that do lie significantly above the SFMS in the local Universe, more than 50% are mergers, with a large contribution from the compact green pea galaxies. We interpret our results as evidence that the number and pitch angle of spiral arms, which are imperfect reflections of the galaxy's current gravitational potential, are either fully independent of the various quenching mechanisms for star formation or are completely overwhelmed by the combination of outflows and feedback.

  18. X-ray Scaling Relations of Early Type Galaxies

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Woo

    2015-08-01

    We will review recent results of the X-ray scaling relations of early type galaxies. With high quality Chandra X-ray data, the properties (Lx and T) of hot ISM are accurately measured from gas-poor to gas-rich galaxies. We found a strong correlation between Lx(gas) and M(total) among ETGs with independently measured M(total), indicating that the total mass is the primary factor in regulating the amount of hot gas. We found a tight correlation between Lx(gas) and T(gas) among normal (non-cD), genuine (passively evolving, sigma-supported) ellipticals. This relation holds in a large range of Lx (several 1038 - a few 1041 erg/s). While this relation can be understood among gas-rich galaxies (Lx > 1040 erg/s) as a consequence of virialized gaseous halos in the dark matter potentials, the same tight relation is unexpected among gas-poor galaxies where the hot gas is in a wind/outflow state. We also found an interesting difference between cDs and giant Es, the former having an order of magnitude higher Lx(gas) with a similar T(gas). We will discuss the implications of our results by comparing with other observations of galaxies/groups and recent simulations.

  19. Elliptical galaxies kinematics within general relativity with renormalization group effects

    SciTech Connect

    Rodrigues, Davi C.

    2012-09-01

    The renormalization group framework can be applied to Quantum Field Theory on curved space-time, but there is no proof whether the beta-function of the gravitational coupling indeed goes to zero in the far infrared or not. In a recent paper [1] we have shown that the amount of dark matter inside spiral galaxies may be negligible if a small running of the General Relativity coupling G is present (δG/G{sub 0}∼<10{sup −7} across a galaxy). Here we extend the proposed model to elliptical galaxies and present a detailed analysis on the modeling of NGC 4494 (an ordinary elliptical) and NGC 4374 (a giant elliptical). In order to compare our results to a well known alternative model to the standard dark matter picture, we also evaluate NGC 4374 with MOND. In this galaxy MOND leads to a significative discrepancy with the observed velocity dispersion curve and has a significative tendency towards tangential anisotropy. On the other hand, the approach based on the renormalization group and general relativity (RGGR) could be applied with good results to these elliptical galaxies and is compatible with lower mass-to-light ratios (of about the Kroupa IMF type)

  20. THE SAMI GALAXY SURVEY: TOWARD A UNIFIED DYNAMICAL SCALING RELATION FOR GALAXIES OF ALL TYPES

    SciTech Connect

    Cortese, L.; Glazebrook, K.; Mould, J.; Fogarty, L. M. R.; Bland-Hawthorn, J.; Croom, S. M.; Scott, N.; Allen, J. T.; Bloom, J.; Bryant, J. J.; Ho, I.-T.; Bekki, K.; Colless, M.; Sharp, R.; Couch, W.; Goodwin, M.; Tonini, C.; Cluver, M.; Davies, R. L.; Drinkwater, M. J.; and others

    2014-11-10

    We take advantage of the first data from the Sydney-AAO Multi-object Integral field Galaxy Survey to investigate the relation between the kinematics of gas and stars, and stellar mass in a comprehensive sample of nearby galaxies. We find that all 235 objects in our sample, regardless of their morphology, lie on a tight relation linking stellar mass (M {sub *}) to internal velocity quantified by the S {sub 0.5} parameter, which combines the contribution of both dispersion (σ) and rotational velocity (V {sub rot}) to the dynamical support of a galaxy (S{sub 0.5}=√(0.5 V{sub rot}{sup 2}+σ{sup 2})). Our results are independent of the baryonic component from which σ and V {sub rot} are estimated, as the S {sub 0.5} of stars and gas agree remarkably well. This represents a significant improvement compared to the canonical M {sub *} versus V {sub rot} and M {sub *} versus σ relations. Not only is no sample pruning necessary, but also stellar and gas kinematics can be used simultaneously, as the effect of asymmetric drift is taken into account once V {sub rot} and σ are combined. Our findings illustrate how the combination of dispersion and rotational velocities for both gas and stars can provide us with a single dynamical scaling relation valid for galaxies of all morphologies across at least the stellar mass range 8.5 relation appears to be more general and at least as tight as any other dynamical scaling relation, representing a unique tool for investigating the link between galaxy kinematics and baryonic content, and a less biased comparison with theoretical models.

  1. Photometric scaling relations of lenticular and spiral galaxies

    NASA Astrophysics Data System (ADS)

    Laurikainen, E.; Salo, H.; Buta, R.; Knapen, J. H.; Comerón, S.

    2010-06-01

    Photometric scaling relations are studied for S0 galaxies and compared with those obtained for spirals. New two-dimensional multi-component decompositions are presented for 122 early-type disc galaxies, using deep Ks-band images. Combining them with our previous decompositions, the final sample consists of 175 galaxies (Near-Infrared Survey of S0s, NIRS0S: 117 S0s + 22 S0/a and 36 Sa galaxies). As a comparison sample we use the Ohio State University Bright Spiral Galaxy Survey (OSUBSGS) of nearly 200 spirals, for which similar multi-component decompositions have previously been made by us. The improved statistics, deep images and the homogeneous decomposition method used allow us to re-evaluate the parameters of the bulges and discs. For spirals we largely confirm previous results, which are compared with those obtained for S0s. Our main results are as follows. (1) Important scaling relations are present, indicating that the formative processes of bulges and discs in S0s are coupled [e.g. M0K(disc) = 0.63 M0K(bulge) -9.3], as has been found previously for spirals [for OSUBSGS spirals M0K (disc) = 0.38 M0K(bulge) -15.5 the rms deviation from these relations is 0.5 mag for S0s and spirals]. (2) We obtain median reff/h0r ~ 0.20, 0.15 and 0.10 for S0, S0/a-Sa and Sab-Sc galaxies, respectively: these values are smaller than predicted by simulation models in which bulges are formed by galaxy mergers. (3) The properties of bulges of S0s are different from the elliptical galaxies, which are manifested in the versus reff relation, in the photometric plane (μ0, n, reff), and to some extent also in the Kormendy relation (< μ >eff versus reff). The bulges of S0s are similar to bulges of spirals with M0K(bulge) < -20 mag. Some S0s have small bulges, but their properties are not compatible with the idea that they could evolve to dwarfs by galaxy harassment. (4) The relative bulge flux (B/T) for S0s covers the full range found in the Hubble sequence, even with 13 per cent

  2. Galaxies

    SciTech Connect

    Not Available

    1981-01-01

    Normal galaxies, radio galaxies, and Seyfert galaxies are considered. The large magellanic cloud and the great galaxy in Andromedia are highlighted. Quasars and BL lacertae objects are also discussed and a review of the spectral observations of all of these galaxies and celestial objects is presented.

  3. On the [CII]-SFR Relation in High Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Vallini, L.; Gallerani, S.; Ferrara, A.; Pallottini, A.; Yue, B.

    2015-11-01

    After two Atacama Large Millimeter/submillimeter Array (ALMA) observing cycles, only a handful of [C ii] 158 μm emission line searches in z > 6 galaxies have reported a positive detection, questioning the applicability of the local [C ii]-star formation rate (SFR) relation to high-z systems. To investigate this issue we use the Vallini et al. (V13) model,based on high-resolution, radiative transfer cosmological simulations to predict the [C ii] emission from the interstellar medium of a z ≈ 7 (halo mass Mh = 1.17 × 1011 M⊙) galaxy. We improve the V13 model by including (a) a physically motivated metallicity (Z) distribution of the gas, (b) the contribution of photodissociation regions (PDRs), and (c) the effects of cosmic microwave background (CMB) on the [C ii] line luminosity. We study the relative contribution of diffuse neutral gas to the total [C ii] emission (Fdiff/Ftot) for different SFR and Z values. We find that the [C ii] emission arises predominantly from PDRs: regardless of the galaxy properties, Fdiff/Ftot ≤ 10%, since at these early epochs the CMB temperature approaches the spin temperature of the [C ii] transition in the cold neutral medium (TCMB ˜ {T}s{{CNM}} ˜ 20 K). Our model predicts a high-z [C ii]-SFR relation, consistent with observations of local dwarf galaxies (0.02 < Z/Z⊙ < 0.5). The [C ii] deficit suggested by actual data (LCii < 2.0 × 107 L⊙ in BDF3299 at z ≈ 7.1) if confirmed by deeper ALMA observations, can be ascribed to negative stellar feedback disrupting molecular clouds around star formation sites. The deviation from the local [C ii]-SFR would then imply a modified Kennicutt-Schmidt relation in z > 6 galaxies. Alternatively/in addition, the deficit might be explained by low gas metallicities (Z < 0.1 Z⊙).

  4. Scaling Relations of Galaxy Groups and PoorClusters

    NASA Astrophysics Data System (ADS)

    Sun, Ming

    Galaxy groups and poor clusters are ideal systems to study baryonic physics, which is important for both using clusters for precision cosmology and understanding galaxy formation and evolution. Over the last decade, our understanding of the ICM properties of galaxy groups and poor clusters has greatly improved. However, there are still many unresolved problems. We propose to study the X-ray scaling relations of galaxy groups and poor clusters with XMM data in the archive. The study of a large sample is important to address significant systematic uncertainties. The rich XMM archive on low-mass systems is of great value, as they are selected by the cluster, galaxy, and AGN panels with different effective selection functions. Our sample includes about 100 groups and poor clusters with sufficient XMM data. The state-of-the-art method to model the local X-ray background will be applied, which is key for deriving X-ray gas properties at low surface brightness. The important scaling relations including M-T, M-Y_X, f_gas-T, entropy-M, L-T, L-Y_X, L-M and abundance-M will be derived. The scatter of in these relations will also be examined, as well as their connection to other group properties. This project represents a significant improvement over previous work. The final results will greatly improve our understanding of baryon physics in clusters and groups, especially when combined with the active efforts in simulation and analytic theory which are currently ongoing.

  5. Fundamental Mass-Spin-Morphology Relation Of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Obreschkow, D.; Glazebrook, K.

    2014-03-01

    This work presents high-precision measurements of the specific baryon angular momentum j b contained in stars, atomic gas, and molecular gas, out to >~ 10 scale radii, in 16 nearby spiral galaxies of the THINGS sample. The accuracy of these measurements improves on existing studies by an order of magnitude, leading to the discovery of a strong correlation between the baryon mass M b, j b, and the bulge mass fraction β, fitted by \\beta =-(0.34+/- 0.03)\\,lg\\,(j_bM_b^{-1}/[10^{-7}\\, kpc\\,km\\,s^{-1}\\,{M}_{\\odot }^{-1}])-(0.04+/- 0.01) on the full sample range of 0 <= β <~ 0.3 and 109 M ⊙ < M b < 1011 M ⊙. The corresponding relation for the stellar quantities M * and j * is identical within the uncertainties. These M-j-β relations likely originate from the proportionality between jM -1 and the surface density of the disk that dictates its stability against (pseudo-)bulge formation. Using a cold dark matter model, we can approximately explain classical scaling relations, such as the fundamental plane of spiral galaxies, the Tully-Fisher relation, and the mass-size relation, in terms of the M-j(-β) relation. These results advocate the use of mass and angular momentum as the most fundamental quantities of spiral galaxies.

  6. The morphology-density relation for dwarf galaxies

    NASA Technical Reports Server (NTRS)

    Ferguson, H. C.; Sandage, A.

    1990-01-01

    The morphology-density relation is examined for dwarf galaxies with absolute magnitudes -18 less than or equal to M sub B sub T less than or equal to -12.5, based on a deep photographic survey of nearby groups and clusters of galaxies. Results are given. Compared to dwarf ellipticals, dwarf irregulars form a more extended population in nearby clusters, and may in fact be entirely absent from the cluster cores. The spatial distribution of dwarf ellipticals in clusters depends on luminosity and the presence or absence of nucleation. Nucleated dE's and non-nucleated dE's fainter than M sub B sub T approx. -13.5 are concentrated toward the centers of clusters like the giant E and S0 galaxies. In contrast, non-nucleated dE's brighter than M sub B sub T approx. -14.5 are distributed like the spirals and irregulars. The intrinsic shapes of the bright non-nucleated dE's are similar to those of the dwarf irregulars, suggesting a possible evolutionary connection between these two classes of galaxies.

  7. Age-density relation of Main galaxies at fixed parameters or for different galaxy families

    NASA Astrophysics Data System (ADS)

    Deng, Xin-Fa; Song, Jun; Chen, Yi-Qing; Jiang, Peng; Ding, Ying-Ping

    2015-09-01

    Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), we examine the environmental dependence of galaxy age at fixed parameters or for different galaxy families. Statistical results show that the environmental dependence of galaxy age is stronger for late type galaxies, but can be still observed for the early types: the age of galaxies in the densest regime is preferentially older than that in the lowest density regime with the same morphological type. We also find that the environmental dependence of galaxy age for red galaxies and Low Stellar Mass (LSM) galaxies is stronger, while the one for blue galaxies and High Stellar Mass ( HSM ) galaxies is very weak.

  8. Dissecting simulated disc galaxies - II. The age-velocity relation

    NASA Astrophysics Data System (ADS)

    Martig, Marie; Minchev, Ivan; Flynn, Chris

    2014-09-01

    We study the relation between stellar ages and vertical velocity dispersion (the age-velocity relation, or AVR) in a sample of seven simulated disc galaxies. In our simulations, the shape of the AVR for stars younger than 9 Gyr depends strongly on the merger history at low redshift, with even 1:10-1:15 mergers being able to create jumps in the AVR (although these jumps might not be detectable if the errors on stellar ages are of the order of 30 per cent). For galaxies with a quiescent history at low redshift, we find that the vertical velocity dispersion rises smoothly for ages up to 8-9 Gyr, following a power law with a slope of ˜0.5, similar to what is observed in the solar neighbourhood by the Geneva-Copenhagen Survey. For these galaxies, we show that the slope of the AVR is not imprinted at birth, but is the result of subsequent heating. By contrast, in all our simulations, the oldest stars form a significantly different population, with a high velocity dispersion. These stars are usually born kinematically hot in a turbulent phase of intense mergers at high redshift, and also include some stars accreted from satellites. This maximum in σz is strongly decreased when age errors are included, suggesting that observations can easily miss such a jump with the current accuracy of age measurements.

  9. Fundamental mass-spin-morphology relation of spiral galaxies

    SciTech Connect

    Obreschkow, D.; Glazebrook, K.

    2014-03-20

    This work presents high-precision measurements of the specific baryon angular momentum j {sub b} contained in stars, atomic gas, and molecular gas, out to ≳ 10 scale radii, in 16 nearby spiral galaxies of the THINGS sample. The accuracy of these measurements improves on existing studies by an order of magnitude, leading to the discovery of a strong correlation between the baryon mass M {sub b}, j {sub b}, and the bulge mass fraction β, fitted by β=−(0.34±0.03) lg (j{sub b}M{sub b}{sup −1}/[10{sup −7} kpc km s{sup −1} M{sub ⊙}{sup −1}])−(0.04±0.01) on the full sample range of 0 ≤ β ≲ 0.3 and 10{sup 9} M {sub ☉} < M {sub b} < 10{sup 11} M {sub ☉}. The corresponding relation for the stellar quantities M {sub *} and j {sub *} is identical within the uncertainties. These M-j-β relations likely originate from the proportionality between jM {sup –1} and the surface density of the disk that dictates its stability against (pseudo-)bulge formation. Using a cold dark matter model, we can approximately explain classical scaling relations, such as the fundamental plane of spiral galaxies, the Tully-Fisher relation, and the mass-size relation, in terms of the M-j(-β) relation. These results advocate the use of mass and angular momentum as the most fundamental quantities of spiral galaxies.

  10. Color-mass-to-light-ratio relations for disk galaxies

    SciTech Connect

    McGaugh, Stacy S.; Schombert, James M. E-mail: jschombe@uoregon.edu

    2014-11-01

    We combine Spitzer 3.6 μm observations of a sample of disk galaxies spanning over 10 mag in luminosity with optical luminosities and colors to test population synthesis prescriptions for computing stellar mass. Many commonly employed models fail to provide self-consistent results: the stellar mass estimated from the luminosity in one band can differ grossly from that of another band for the same galaxy. Independent models agree closely in the optical (V band), but diverge at longer wavelengths. This effect is particularly pronounced in recent models with substantial contributions from TP-AGB stars. We provide revised color-mass-to-light ratio relations that yield self-consistent stellar masses when applied to real galaxies. The B – V color is a good indicator of the mass-to-light ratio. Some additional information is provided by V – I, but neither it nor J – K{sub s} are particularly useful for constraining the mass-to-light ratio on their own. In the near-infrared, the mass-to-light ratio depends weakly on color, with typical values of 0.6 M {sub ☉}/L {sub ☉} in the K{sub s} band and 0.47 M {sub ☉}/L {sub ☉} at 3.6 μm.

  11. Merging galaxies produce outliers from the fundamental metallicity relation

    NASA Astrophysics Data System (ADS)

    Grønnow, Asger E.; Finlator, Kristian; Christensen, Lise

    2015-08-01

    From a large sample of ≈170 000 local SDSS (Sloan Digital Sky Survey) galaxies, we find that the fundamental metallicity relation (FMR) has an overabundance of outliers, compared to what would be expected from a Gaussian distribution of residuals, with significantly lower metallicities than predicted from their stellar mass and star formation rate (SFR). This low-metallicity population has lower stellar masses, bimodial specific SFRs with enhanced star formation within the aperture and smaller half-light radii than the general sample and is hence a physically distinct population. We show that they are consistent with being galaxies that are merging or have recently merged with a satellite galaxy. In this scenario, low-metallicity gas flows in from large radii, diluting the metallicity of star-forming regions and enhancing the specific SFR until the inflowing gas is processed and the metallicity has recovered. We introduce a simple model in which mergers with a mass ratio larger than a minimum dilute the central galaxy's metallicity by an amount that is proportional to the stellar mass ratio for a constant time, and show that it provides an excellent fit to the distribution of FMR residuals. We find the dilution time-scale to be τ =1.568_{-0.027}^{+0.029} Gyr, the average metallicity depression caused by a 1:1 merger to be α =0.2480_{-0.0020}^{+0.0017} dex and the minimum mass ratio merger that can be discerned from the intrinsic Gaussian scatter in the FMR to be ξ _min=0.2030_{-0.0095}^{+0.0127} (these are statistical errors only). From this we derive that the average metallicity depression caused by a merger with mass ratio between 1:5 and 1:1 is 0.114 dex.

  12. How absorption selected galaxies trace the general high-redshift galaxy population

    NASA Astrophysics Data System (ADS)

    Christensen, Lise

    2015-08-01

    Strong absorption lines seen in quasar spectra arise when the lines of sight to the quasars intersect intervening galaxies. The associated metal absorption lines from the strongest absorption lines, the damped Lyman alpha absorbers (DLAs), allow us to trace the metallicity of galaxies back to redshifts z>5. Typical metallicities range from 0.1-100% solar metallicities with a huge scatter at any given redshift. Understanding the nature of galaxies that host DLAs is one strategy to probe the early phase and origin of stars in the outskirts of present-day galaxy disks.The search for emission from the elusive high-redshift DLA galaxies has reached a mature state now that we have determined how to best identify the absorbing galaxies. From a growing number of emission-line detections from DLA galaxies at redshifts ranging between 0.1 and 3, we can analyse galaxies in both absorption and emission, and probe the gas-phase metallicities in the outskirts and halos of the galaxies.By combining information for galaxies seen in emission and absorption, I will show that there is a relation between DLA metallicities and the host galaxy luminosities similar to the well-known the mass-metallicity relation for luminosity selected galaxies. This implies that DLA galaxies are drawn from the general population of low- to intermediate mass galaxies. We can determine a metallicity gradient in the extended halo of the galaxies out to ~40 kpc, and this allows us to reproduce observed galaxy correlation functions derived from conventional samples of luminosity selected galaxies.

  13. Tidal dwarf galaxies and the luminosity-metallicity relation .

    NASA Astrophysics Data System (ADS)

    Sweet, S. M.; Drinkwater, M. J.; Meurer, G.; Bekki, K.; Dopita, M. A.; Kilborn, V.; Nicholls, D.

    We present a recalibration of the luminosity-metallicity relation for gas-rich, star-forming dwarfs to magnitudes as faint as M_R˜ -13. We use the \\citet{Dopita2013} metallicity calibrations to calibrate the relation for all of the data in this analysis. Metal-rich dwarfs classified as tidal dwarf galaxy (TDG) candidates in the literature are typically of metallicity 12 + log(O/H) = 8.70 ± 0.05, while SDSS dwarfs fainter than M_R = -16 have a mean metallicity of 12 + log(O/H) = 8.28 ± 0.10, regardless of their luminosity. Our hydrodynamical simuations predict that TDGs should have metallicities elevated above the normal luminosity-metallicity relation. Metallicity can therefore be a useful diagnostic for identifying TDG candidate populations in the absence of tidal tails. At magnitudes brighter than M_R˜ -16 our sample of 53 star-forming galaxies in 9 HI gas-rich groups is consistent with the normal relation defined by the SDSS sample. At fainter magnitudes there is an increase in dispersion in metallicity of our sample. In our sample we identify three (16% of dwarfs) strong TDG candidates (12 + log(O/H) > 8.6), and four (21%) very metal poor dwarfs (12 + log(O/H) < 8.0), which are likely gas-rich dwarfs with recently ignited star formation. Further details of this analysis are available in Sweet et al. (2013, ApJ submitted).

  14. The dynamical masses, densities, and star formation scaling relations of Lyα galaxies

    SciTech Connect

    Rhoads, James E.; Malhotra, Sangeeta; Richardson, Mark L. A.; McLinden, Emily M.; Finkelstein, Steven L.; Fynbo, Johan P. U.; Tilvi, Vithal S.

    2014-01-01

    We present the first dynamical mass measurements for Lyα galaxies at high redshift, based on velocity dispersion measurements from rest-frame optical emission lines and size measurements from Hubble Space Telescope imaging, for nine galaxies drawn from four surveys. We use these measurements to study Lyα galaxies in the context of galaxy scaling relations. The resulting dynamical masses range from 10{sup 9} to 10{sup 10} M {sub ☉}. We also fit stellar population models to our sample and use them to place the Lyα sample on a stellar mass versus line width relation. The Lyα galaxies generally follow the same scaling relation as star-forming galaxies at lower redshift, although, lower stellar mass fits are also acceptable in ∼1/3 of the Lyα galaxies. Using the dynamical masses as an upper limit on gas mass, we show that Lyα galaxies have unusually active star formation for their gas mass surface density. This behavior is consistent with what is observed in starburst galaxies, despite the typically smaller masses and sizes of the Lyα galaxy population. Finally, we examine the mass densities of these galaxies and show that their future evolution likely requires dissipational ('wet') merging. In short, we find that Lyα galaxies are low-mass cousins of larger starbursts.

  15. Faint Lyα Emitters, Star-forming Galaxies, and Damped Lyα Systems

    NASA Astrophysics Data System (ADS)

    Rauch, M.; Haehnelt, M.; Bunker, A.; Becker, G.; Marleau, F.; Graham, J.; Cristiani, S.; Jarvis, M.; Lacey, C.; Morris, S.; Peroux, C.; Roettgering, H.; Theuns, T.

    2008-10-01

    We have discovered a population of faint single line emitters, likely to be identified with faint z˜ 3 Lyα emitters and with the host galaxies of damped Lyman alpha systems. The objects appear to constitute the bulk of the star-forming galaxies detected so far from the ground, and are likely to provide the gaseous reservoir from which present-day Milky way type galaxies have formed. Unlike color-selected (yman break galaxies, these objects appear to have low star-formation rates, relatively strong Lyalpha emission, and low masses, metallicities, and dust content (s.a. arXiv:0711.1354).

  16. CLASH: The Concentration-Mass Relation of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Merten, J.; Meneghetti, M.; Postman, M.; Umetsu, K.; Zitrin, A.; Medezinski, E.; Nonino, M.; Koekemoer, A.; Melchior, P.; Gruen, D.; Moustakas, L. A.; Bartelmann, M.; Host, O.; Donahue, M.; Coe, D.; Molino, A.; Jouvel, S.; Monna, A.; Seitz, S.; Czakon, N.; Lemze, D.; Sayers, J.; Balestra, I.; Rosati, P.; Benítez, N.; Biviano, A.; Bouwens, R.; Bradley, L.; Broadhurst, T.; Carrasco, M.; Ford, H.; Grillo, C.; Infante, L.; Kelson, D.; Lahav, O.; Massey, R.; Moustakas, J.; Rasia, E.; Rhodes, J.; Vega, J.; Zheng, W.

    2015-06-01

    We present a new determination of the concentration-mass (c-M) relation for galaxy clusters based on our comprehensive lensing analysis of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble (CLASH). Our sample spans a redshift range between 0.19 and 0.89. We combine weak-lensing constraints from the Hubble Space Telescope (HST) and from ground-based wide-field data with strong lensing constraints from HST. The results are reconstructions of the surface-mass density for all CLASH clusters on multi-scale grids. Our derivation of Navarro-Frenk-White parameters yields virial masses between 0.53× {{10}15} {{M}⊙ }/h and 1.76× {{10}15} {{M}⊙ }/h and the halo concentrations are distributed around {{c}200c}˜ 3.7 with a 1σ significant negative slope with cluster mass. We find an excellent 4% agreement in the median ratio of our measured concentrations for each cluster and the respective expectation from numerical simulations after accounting for the CLASH selection function based on X-ray morphology. The simulations are analyzed in two dimensions to account for possible biases in the lensing reconstructions due to projection effects. The theoretical c-M relation from our X-ray selected set of simulated clusters and the c-M relation derived directly from the CLASH data agree at the 90% confidence level.

  17. The L-σ Relation of Local H II Galaxies

    NASA Astrophysics Data System (ADS)

    Bordalo, V.; Telles, E.

    2011-07-01

    For the first time we present a new data set of emission line widths for 118 star-forming regions in H II galaxies (HIIGs). This homogeneous set is used to investigate the L-σ relation in conjunction with optical spectrophotometric observations. We were able to classify their nebular emission line profiles due to our high-resolution spectra. Peculiarities in the line profiles such as sharp lines, wings, asymmetries, and in some cases more than one component in emission were verified. From a new independent homogeneous set of spectrophotometric data, we derived physical condition parameters and performed statistical principal component analysis. We have investigated the potential role of metallicity (O/H), Hβ equivalent width (W Hβ), and ionization ratio [O III]/[O II] to account for the observational scatter of the L-σ relation. Our results indicate that the L-σ relation for HIIGs is more sensitive to the evolution of the current starburst event (short-term evolution) and dated by W Hβ or even the [O III]/[O II] ratio. The long-term evolution measured by O/H also plays a potential role in determining the luminosity of the current burst for a given velocity dispersion and age as previously suggested. Additionally, galaxies showing Gaussian line profiles present tighter correlations indicating that they are the best targets for the application of the parametric relations as an extragalactic cosmological distance indicator. Best fits for a restricted homogeneous sample of 45 HIIGs provide us with a set of new extragalactic distance indicators with an rms scatter compatible with observational errors of δlog L Hα = 0.2 dex or 0.5 mag. Improvements may still come from future optimized observational programs to reduce the observational uncertainties on the predicted luminosities of HIIGs in order to achieve the precision required for the application of these relations as tests of cosmological models.

  18. The surface-brightness-effective-size relation for elliptical galaxies in the cores of clusters

    NASA Technical Reports Server (NTRS)

    Hoessel, J. G.; Oegerle, W. R.; Schneider, D. P.

    1987-01-01

    Surface photometry of 372 elliptical galaxies has been performed using CCD images of the centers of 97 nearby rich Abell clusters. The strong correlation between surface brightness and effective size, originally found by Kormendy (1977), is clear in the data. Brightest cluster galaxies show much less scatter about the mean relation defined by these data than do lower-luminosity cluster ellipticals, and the slope of the relation is shallower for the brightest galaxies; these two results are tentative, however, because of uncertain selection and environmental effects. When combined with published central velocity dispersions, the photometry yields a relation for brightest cluster galaxies that is in good agreement with the mean relation for elliptical galaxies found by Djorgovski and Davis (1987). Use of the surface-brightness/scale-length relation to measure the lookback luminosity evolution of the stellar content in galaxies is promising.

  19. The role of galaxy interaction in the SFR-M {sub *} relation: characterizing morphological properties of Herschel-selected galaxies at 0.2 < z < 1.5

    SciTech Connect

    Hung, Chao-Ling; Sanders, D. B.; Casey, C. M.; Lee, N.; Barnes, J. E.; Koss, M.; Larson, K. L.; Lockhart, K.; Man, A. W. S.; Mann, A. W.; Capak, P.; Kartaltepe, J. S.; Le Floc'h, E.; Riguccini, L.; Scoville, N.; Symeonidis, M.

    2013-12-01

    Galaxy interactions/mergers have been shown to dominate the population of IR-luminous galaxies (L {sub IR} ≳ 10{sup 11.6} L {sub ☉}) in the local universe (z ≲ 0.25). Recent studies based on the relation between galaxies' star formation rates and stellar mass (the SFR-M {sub *} relation or the {sup g}alaxy main sequence{sup )} have suggested that galaxy interaction/mergers may only become significant when galaxies fall well above the galaxy main sequence. Since the typical SFR at a given M {sub *} increases with redshift, the existence of the galaxy main sequence implies that massive, IR-luminous galaxies at high z may not necessarily be driven by galaxy interactions. We examine the role of galaxy interactions in the SFR-M {sub *} relation by carrying out a morphological analysis of 2084 Herschel-selected galaxies at 0.2 < z < 1.5 in the COSMOS field. Using a detailed visual classification scheme, we show that the fraction of 'disk galaxies' decreases and the fraction of 'irregular' galaxies increases systematically with increasing L {sub IR} out to z ≲ 1.5 and z ≲ 1.0, respectively. At L {sub IR} >10{sup 11.5} L {sub ☉}, ≳ 50% of the objects show evident features of strongly interacting/merger systems, where this percentage is similar to the studies of local IR-luminous galaxies. The fraction of interacting/merger systems also systematically increases with the deviation from the SFR-M {sub *} relation, supporting the view that galaxies falling above the main sequence are more dominated by mergers than the main-sequence galaxies. Meanwhile, we find that ≳ 18% of massive IR-luminous 'main-sequence galaxies' are classified as interacting systems, where this population may not evolve through the evolutionary track predicted by a simple gas exhaustion model.

  20. GAS REGULATION OF GALAXIES: THE EVOLUTION OF THE COSMIC SPECIFIC STAR FORMATION RATE, THE METALLICITY-MASS-STAR-FORMATION RATE RELATION, AND THE STELLAR CONTENT OF HALOS

    SciTech Connect

    Lilly, Simon J.; Carollo, C. Marcella; Pipino, Antonio; Peng Yingjie; Renzini, Alvio

    2013-08-01

    A very simple physical model of galaxies is one in which the formation of stars is instantaneously regulated by the mass of gas in a reservoir with mass loss scaling with the star-formation rate (SFR). This model links together three different aspects of the evolving galaxy population: (1) the cosmic time evolution of the specific star-formation rate (sSFR) relative to the growth of halos, (2) the gas-phase metallicities across the galaxy population and over cosmic time, and (3) the ratio of the stellar to dark matter mass of halos. The gas regulator is defined by the gas consumption timescale ({epsilon}{sup -1}) and the mass loading {lambda} of the wind outflow {lambda}{center_dot}SFR. The simplest regulator, in which {epsilon} and {lambda} are constant, sets the sSFR equal to exactly the specific accretion rate of the galaxy; more realistic situations lead to an sSFR that is perturbed from this precise relation. Because the gas consumption timescale is shorter than the timescale on which the system evolves, the metallicity Z is set primarily by the instantaneous operation of the regulator system rather than by the past history of the system. The metallicity of the gas reservoir depends on {epsilon}, {lambda}, and sSFR, and the regulator system therefore naturally produces a Z(m{sub star}, SFR) relation if {epsilon} and {lambda} depend on the stellar mass m{sub star}. Furthermore, this relation will be the same at all epochs unless the parameters {epsilon} and {lambda} themselves change with time. A so-called fundamental metallicity relation is naturally produced by these conditions. The overall mass-metallicity relation Z(m{sub star}) directly provides the fraction f{sub star}(m{sub star}) of incoming baryons that are being transformed into stars. The observed Z(m{sub star}) relation of Sloan Digital Sky Survey (SDSS) galaxies implies a strong dependence of stellar mass on halo mass that reconciles the different faint-end slopes of the stellar and halo mass

  1. Galaxy cluster scaling relations measured with APEX-SZ

    NASA Astrophysics Data System (ADS)

    Bender, A. N.; Kennedy, J.; Ade, P. A. R.; Basu, K.; Bertoldi, F.; Burkutean, S.; Clarke, J.; Dahlin, D.; Dobbs, M.; Ferrusca, D.; Flanigan, D.; Halverson, N. W.; Holzapfel, W. L.; Horellou, C.; Johnson, B. R.; Kermish, Z. D.; Klein, M.; Kneissl, R.; Lanting, T.; Lee, A. T.; Mehl, J.; Menten, K. M.; Muders, D.; Nagarajan, A.; Pacaud, F.; Reichardt, C. L.; Richards, P. L.; Schaaf, R.; Schwan, D.; Sommer, M. W.; Spieler, H.; Tucker, C.; Westbrook, B.

    2016-08-01

    We present thermal Sunyaev-Zel'dovich effect (SZE) measurements for 42 galaxy clusters observed at 150 GHz with the APEX-SZ experiment. For each cluster, we model the pressure profile and calculate the integrated Comptonization Y to estimate the total thermal energy of the intracluster medium (ICM). We compare the measured Y values to X-ray observables of the ICM from the literature (cluster gas mass Mgas, temperature TX, and YX = MgasTX) that relate to total cluster mass. We measure power-law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for three subsamples within the set of 42 clusters that have uniform X-ray analysis in the literature. We observe that differences between these X-ray analyses introduce significant variance into the measured scaling relations, particularly affecting the normalization. For all three subsamples, we find results consistent with a self-similar model of cluster evolution dominated by gravitational effects. Comparing to predictions from numerical simulations, these scaling relations prefer models that include cooling and feedback in the ICM. Lastly, we measure an intrinsic scatter of ˜28 per cent in the Y - YX scaling relation for all three subsamples.

  2. Weighing the Giants V: Galaxy Cluster Scaling Relations

    NASA Astrophysics Data System (ADS)

    Mantz, Adam B.; Allen, Steven W.; Morris, R. Glenn; von der Linden, Anja; Applegate, Douglas E.; Kelly, Patrick L.; Burke, David L.; Donovan, David; Ebeling, Harald

    2016-09-01

    We present constraints on the scaling relations of galaxy cluster X-ray luminosity, temperature and gas mass (and derived quantities) with mass and redshift, employing masses from robust weak gravitational lensing measurements. These are the first such results obtained from an analysis that simultaneously accounts for selection effects and the underlying mass function, and directly incorporates lensing data to constrain total masses. Our constraints on the scaling relations and their intrinsic scatters are in good agreement with previous studies, and reinforce a picture in which departures from self-similar scaling laws are primarily limited to cluster cores. However, the data are beginning to reveal new features that have implications for cluster astrophysics and provide new tests for hydrodynamical simulations. We find a positive correlation in the intrinsic scatters of luminosity and temperature at fixed mass, which is related to the dynamical state of the clusters. While the evolution of the nominal scaling relations over the redshift range 0.0 < z < 0.5 is consistent with self similarity, we find tentative evidence that the luminosity and temperature scatters respectively decrease and increase with redshift. Physically, this likely related to the development of cool cores and the rate of major mergers. We also examine the scaling relations of redMaPPer richness and Compton Y from Planck. While the richness-mass relation is in excellent agreement with recent work, the measured Y-mass relation departs strongly from that assumed in the Planck cluster cosmology analysis. The latter result is consistent with earlier comparisons of lensing and Planck scaling-relation-derived masses.

  3. Implicit Priors in Galaxy Cluster Mass and Scaling Relation Determinations

    NASA Technical Reports Server (NTRS)

    Mantz, A.; Allen, S. W.

    2011-01-01

    Deriving the total masses of galaxy clusters from observations of the intracluster medium (ICM) generally requires some prior information, in addition to the assumptions of hydrostatic equilibrium and spherical symmetry. Often, this information takes the form of particular parametrized functions used to describe the cluster gas density and temperature profiles. In this paper, we investigate the implicit priors on hydrostatic masses that result from this fully parametric approach, and the implications of such priors for scaling relations formed from those masses. We show that the application of such fully parametric models of the ICM naturally imposes a prior on the slopes of the derived scaling relations, favoring the self-similar model, and argue that this prior may be influential in practice. In contrast, this bias does not exist for techniques which adopt an explicit prior on the form of the mass profile but describe the ICM non-parametrically. Constraints on the slope of the cluster mass-temperature relation in the literature show a separation based the approach employed, with the results from fully parametric ICM modeling clustering nearer the self-similar value. Given that a primary goal of scaling relation analyses is to test the self-similar model, the application of methods subject to strong, implicit priors should be avoided. Alternative methods and best practices are discussed.

  4. The Relation between Galaxy Morphology and Environment in the Local Universe: An RC3-SDSS Picture

    NASA Astrophysics Data System (ADS)

    Wilman, David J.; Erwin, Peter

    2012-02-01

    We present results of an analysis of the local (z ~ 0) morphology-environment relation for 911 bright (MB < -19) galaxies, based on matching classical RC3 morphologies with the Sloan Digital Sky Survey based group catalog of Yang et al., which includes halo mass estimates. This allows us to study how the relative fractions of spirals, lenticulars, and ellipticals depend on halo mass over a range of 1011.7-1014.8 h -1 M ⊙, from isolated single-galaxy halos to massive groups and low-mass clusters. We pay particular attention to how morphology relates to central versus satellite status (where "central" galaxies are the most massive within their halo). The fraction of galaxies which are elliptical is a strong function of stellar mass; it is also a strong function of halo mass, but only for central galaxies. We interpret this as evidence for a scenario where elliptical galaxies are always formed, probably via mergers, as central galaxies within their halos, with satellite ellipticals being previously central galaxies accreted onto a larger halo. The overall fraction of galaxies which are S0 increases strongly with halo mass, from ~10% to ~70%. Here, too, we find striking differences between the central and satellite populations. 20% ± 2% of central galaxies with stellar masses M * > 1010.5 M ⊙ are S0 regardless of halo mass, but satellite S0 galaxies are only found in massive (>1013 h -1 M ⊙) halos, where they are 69% ± 4% of the M * > 1010.5 M ⊙ satellite population. This suggests two channels for forming S0 galaxies: one which operates for central galaxies and another which transforms lower-mass ( M * <~ 1011 M ⊙) accreted spirals into satellite S0 galaxies in massive halos. Analysis of finer morphological structure (bars and rings in disk galaxies) shows some trends with stellar mass, but none with halo mass; this is consistent with other recent studies which indicate that bars are not strongly influenced by galaxy environment. Radio sources in high

  5. THE L-{sigma} RELATION OF LOCAL H II GALAXIES

    SciTech Connect

    Bordalo, V.; Telles, E. E-mail: etelles@on.br

    2011-07-01

    For the first time we present a new data set of emission line widths for 118 star-forming regions in H II galaxies (HIIGs). This homogeneous set is used to investigate the L-{sigma} relation in conjunction with optical spectrophotometric observations. We were able to classify their nebular emission line profiles due to our high-resolution spectra. Peculiarities in the line profiles such as sharp lines, wings, asymmetries, and in some cases more than one component in emission were verified. From a new independent homogeneous set of spectrophotometric data, we derived physical condition parameters and performed statistical principal component analysis. We have investigated the potential role of metallicity (O/H), H{beta} equivalent width (W{sub H{beta}}), and ionization ratio [O III]/[O II] to account for the observational scatter of the L-{sigma} relation. Our results indicate that the L-{sigma} relation for HIIGs is more sensitive to the evolution of the current starburst event (short-term evolution) and dated by W{sub H}{beta} or even the [O III]/[O II] ratio. The long-term evolution measured by O/H also plays a potential role in determining the luminosity of the current burst for a given velocity dispersion and age as previously suggested. Additionally, galaxies showing Gaussian line profiles present tighter correlations indicating that they are the best targets for the application of the parametric relations as an extragalactic cosmological distance indicator. Best fits for a restricted homogeneous sample of 45 HIIGs provide us with a set of new extragalactic distance indicators with an rms scatter compatible with observational errors of {delta}log L{sub H}{alpha} = 0.2 dex or 0.5 mag. Improvements may still come from future optimized observational programs to reduce the observational uncertainties on the predicted luminosities of HIIGs in order to achieve the precision required for the application of these relations as tests of cosmological models.

  6. UNCOVERING DRIVERS OF DISK ASSEMBLY: BULGELESS GALAXIES AND THE STELLAR MASS TULLY-FISHER RELATION

    SciTech Connect

    Miller, Sarah H.; Sullivan, Mark; Ellis, Richard S.

    2013-01-01

    In order to determine what processes govern the assembly history of galaxies with rotating disks, we examine the stellar mass Tully-Fisher (TF) relation over a wide range in redshift partitioned according to whether or not galaxies contain a prominent bulge. Using our earlier Keck spectroscopic sample, for which bulge/total parameters are available from analyses of Hubble Space Telescope images, we find that bulgeless disk galaxies with z > 0.8 present a significant offset from the local (TF) relation whereas, at all redshifts probed, those with significant bulges fall along the local relation. Our results support the suggestion that bulge growth may somehow expedite the maturing of disk galaxies onto the (TF) relation. We discuss a variety of physical hypotheses that may explain this result in the context of kinematic observations of star-forming galaxies at redshifts z = 0 and z > 2.

  7. Source of the Stellar Age-Velocity Dispersion Relation in Simulated Galaxies

    NASA Astrophysics Data System (ADS)

    Wills, Drew; Christensen, Charlotte

    2016-01-01

    We investigated the source of the stellar age-velocity dispersion relation using six high-resolution simulated galaxies. Observations show that velocity dispersion increases with stellar age. This trend is thought to be due to a combination of the evolution of the velocity dispersion of the interstellar media (ISM), interactions within the disk, and galactic mergers. Our simulated galaxies show redshift zero age-velocity dispersion relations consistent with those of observed galaxies. In order to determine how the velocity dispersion of stars evolves after their formation, we calculated the velocity dispersion versus the age of the stars at both redshift zero and at their time of formation. We found that while the ISM velocity dispersion evolves, it cannot be the sole source of the relation. Additionally, dwarf galaxies display a greater relative change in their velocity dispersion than more massive galaxies. Furthermore, we show that major mergers markedly increase the velocity dispersion of stars.

  8. Supernovae and their host galaxies - IV. The distribution of supernovae relative to spiral arms

    NASA Astrophysics Data System (ADS)

    Aramyan, L. S.; Hakobyan, A. A.; Petrosian, A. R.; de Lapparent, V.; Bertin, E.; Mamon, G. A.; Kunth, D.; Nazaryan, T. A.; Adibekyan, V.; Turatto, M.

    2016-07-01

    Using a sample of 215 supernovae (SNe), we analyse their positions relative to the spiral arms of their host galaxies, distinguishing grand-design (GD) spirals from non-GD (NGD) galaxies. We find that: (1) in GD galaxies, an offset exists between the positions of Ia and core-collapse (CC) SNe relative to the peaks of arms, while in NGD galaxies the positions show no such shifts; (2) in GD galaxies, the positions of CC SNe relative to the peaks of arms are correlated with the radial distance from the galaxy nucleus. Inside (outside) the corotation radius, CC SNe are found closer to the inner (outer) edge. No such correlation is observed for SNe in NGD galaxies nor for SNe Ia in either galaxy class; (3) in GD galaxies, SNe Ibc occur closer to the leading edges of the arms than do SNe II, while in NGD galaxies they are more concentrated towards the peaks of arms. In both samples of hosts, the distributions of SNe Ia relative to the arms have broader wings. These observations suggest that shocks in spiral arms of GD galaxies trigger star formation in the leading edges of arms affecting the distributions of CC SNe (known to have short-lived progenitors). The closer locations of SNe Ibc versus SNe II relative to the leading edges of the arms supports the belief that SNe Ibc have more massive progenitors. SNe Ia having less massive and older progenitors, have more time to drift away from the leading edge of the spiral arms.

  9. The Color-Magnitude Relation of Cluster Galaxies: Observations and Model Predictions

    NASA Astrophysics Data System (ADS)

    Jiménez, N.; Smith Castelli, A. V.; Cora, S. A.; Bassino, L. P.

    We investigate the origin of the color-magnitude relation (CMR) observed in cluster galaxies by using a combination of cosmological N-body/SPH simulations of galaxy clusters, and a semi-analaytic model of galaxy formation (Lagos, Cora & Padilla 2008). Simulated results are compared with the photometric properties of early-type galaxies in the Antlia cluster (Smith Castelli et al. 2008). The good agreement obtained between observations and simulations allows us to use the information provided by the model for unveiling the physical processes that yield the tigh observed CMR.

  10. The Relative Kinematics of Galaxy Emission and Multiple Gas Phases in z~0.5 Extended Galaxy Halos

    NASA Astrophysics Data System (ADS)

    Churchill, Christopher

    2010-09-01

    Evidence abounds from quasar absorption line data that the extended gaseous halos of galaxies comprise multiple phases {densities, temperatures, ionization conditions}. Developing a comprehensive and deeper understanding of the origin and persistence of extended galaxy halos, and their role in galaxy evolution, requires that these multiple phases be observed and analyzed. However, such studies that incorporate the host galaxies are virtually non-existent. The new COS instrument opens a new window in which the forest of FUV lines arising in neutral, low, AND high ionization halo gas can be probed with high resolution and sensitivity for multiple chemical species. For intermediate redshift galaxies, these lines are free of Ly-alpha forest contamination. We propose to obtain G160M COS/FUV high resolution spectra of the two quasars Q0454-220 {J0456-2159} and Q1038+064 {4c 06.41} in order to measure the neutral hydrogen Ly-beta, gamma, and delta transitions and the OVI 1031,1038 doublet and CII 1036 and CIII 977 transitions {as well as a few others that fall on the spectral format} in three intervening z 0.45 intervening gaseous halos. We augment the proposed observations with a similar pending COS spectrum {scheduled May 2010, PID 11667, PI Churchill} of the quasar TON 153, which will provide the multiphase absorption kinematics for two additional gaseous halos at z 0.67. The proposed observations will bring our final sample size to five.For these five systems, we have quantified the host galaxy morphologies {WFCP-2/HST images}, measured the galaxy emission lines and rotation curves {ESI/Keck spectra}, and analyzed the MgII 2796,2803 and FeII multiplet absorption {HIRES/Keck spectra}. Our goal is to undertake a comprehensive analysis of the multiphase physical conditions in these five galaxy-absorber pairs. We aim to perform the first ever quantitative comparison of the relative relationships between neutral, low, and high ionization absorbing halo gas kinematics with

  11. SUPERDENSE GALAXIES AND THE MASS-SIZE RELATION AT LOW REDSHIFT

    SciTech Connect

    Poggianti, B. M.; Calvi, R.; Fasano, G.; Vulcani, B.; Bettoni, D.; Gullieuszik, M.; Omizzolo, A.; Bindoni, D.; D'Onofrio, M.; Moretti, A.; Valentinuzzi, T.; Fritz, J.; De Lucia, G.

    2013-01-10

    We search for massive and compact galaxies (superdense galaxies, hereafter SDGs) at z = 0.03-0.11 in the Padova-Millennium Galaxy and Group Catalogue, a spectroscopically complete sample representative of the general field population of the local universe. We find that compact galaxies with radii and mass densities comparable to high-z massive and passive galaxies represent 4.4% of all galaxies with stellar masses above 3 Multiplication-Sign 10{sup 10} M {sub Sun }, yielding a number density of 4.3 Multiplication-Sign 10{sup -4} h {sup 3} Mpc{sup -3}. Most of them are S0s (70%) or ellipticals (23%), are red, and have intermediate-to-old stellar populations, with a median luminosity-weighted age of 5.4 Gyr and a median mass-weighted age of 9.2 Gyr. Their velocity dispersions and dynamical masses are consistent with the small radii and high stellar mass estimates. Comparing with the WINGS sample of cluster galaxies at similar redshifts, the fraction of SDGs is three times smaller in the field than in clusters, and cluster SDGs are on average 4 Gyr older than field SDGs. We confirm the existence of a universal trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass. As a consequence, the median mass-size relation shifts toward smaller radii for galaxies with older stars, but the effect is much more pronounced in clusters than in the field. Our results show that, on top of the well-known dependence of stellar age on galaxy mass, the luminosity-weighted age of galaxies depends on galaxy compactness at fixed mass and, for a fixed mass and radius, on environment. This effect needs to be taken into account in order not to overestimate the evolution of galaxy sizes from high to low z. Our results and hierarchical simulations suggest that a significant fraction of the massive compact galaxies at high z have evolved into compact galaxies in galaxy clusters today. When stellar age and environmental effects are taken into account, the average amount of

  12. Scaling Relations in Dissipationless Spiral-Like Galaxy Mergers

    NASA Astrophysics Data System (ADS)

    Aceves, H.; Velázquez, H.; Cruz, F.

    2009-06-01

    We determine both representations of the Fundamental Plane [FP; R e vprop σ a 0langIrang-b e and R e vprop (σ2 0langIrang-1 e)λ] and the luminosity-effective phase-space density (L vprop f -γ e ) scaling relation for N-body remnants of binary mergers of spiral-like galaxies. The main set of merger simulations involves a mass ratio of the progenitors in the range of about 1:1 to 1:5, harboring or not a bulge-like component, and are constructed using a cosmological motivated model. Equal-mass mergers are also considered. Remnants lead to average values for the scaling indices of langarang ≈ 1.6, langbrang ≈ 0.6, langλrang ≈ 0.7, and langγrang ≈ 0.65. These values are consistent with those of K-band observations of ellipticals: langarang ≈ 1.5, langbrang ≈ 0.8, langλrang ≈ 0.7, and langγrang ≈ 0.60. The b index is, however, not well reproduced. This study does not allow us to establish a conclusive preference for models with or without a bulge as progenitors. Our results indicate that the L-f e and FP scalings might be determined to a large extent by dissipationless processes, a result that appears to be in contradiction to other dissipationless results.

  13. A universal ultraviolet-optical colour-colour-magnitude relation of galaxies

    NASA Astrophysics Data System (ADS)

    Chilingarian, Igor V.; Zolotukhin, Ivan Yu.

    2012-01-01

    The bimodal galaxy distribution in the optical colour-magnitude diagram (CMD) comprises a narrow 'red sequence' populated mostly by early-type galaxies and a broad 'blue cloud' dominated by star-forming systems. Although the optical CMD allows one to select red sequence objects, neither can it be used for galaxy classification without additional observational data such as spectra or high-resolution images, nor to identify blue galaxies at unknown redshifts. We show that adding the near ultraviolet (NUV) colour [Galaxy Evolution Explorer (GALEX) NUV λeff= 227 nm] to the optical (g - r versus Mr) CMD reveals a tight relation in the 3D colour-colour-magnitude space smoothly continuing from the 'blue cloud' to the 'red sequence'. We found that 98 per cent of 225 000 low-redshift (Z < 0.27) galaxies follow a smooth surface ? with a standard deviation of 0.03-0.07 mag making it the tightest known galaxy photometric relation, given the ˜0.9 mag range of k-corrected g - r colours. Similar relations exist in other NUV-optical colours. There is a strong correlation between morphological types and integrated ? colours of galaxies, while the connection with g - r is ambiguous. Rare galaxy classes such as E+A or tidally stripped systems become outliers that occupy distinct regions in the 3D parameter space. Using stellar population models for galaxies with different star formation histories, we show that (a) the (?) distribution at a given luminosity is formed by objects having constant and exponentially declining star formation rates with different characteristic time-scales with the red sequence part consistent also with simple stellar population; (b) colour evolution for exponentially declining models goes along the relation suggesting a weak evolution of its shape up to a redshift of 0.9; (c) galaxies with truncated star formation histories have very short transition phase offset from the relation thus explaining the rareness of E+A galaxies. This relation can be used as

  14. The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

    NASA Technical Reports Server (NTRS)

    Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

    2013-01-01

    We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.

  15. Galaxy luminosity function and Tully-Fisher relation: reconciled through rotation-curve studies

    SciTech Connect

    Cattaneo, Andrea; Salucci, Paolo; Papastergis, Emmanouil E-mail: salucci@sissa.it

    2014-03-10

    The relation between galaxy luminosity L and halo virial velocity v {sub vir} required to fit the galaxy luminosity function differs from the observed Tully-Fisher relation between L and disk speed v {sub rot}. Because of this, the problem of reproducing the galaxy luminosity function and the Tully-Fisher relation simultaneously has plagued semianalytic models since their inception. Here we study the relation between v {sub rot} and v {sub vir} by fitting observational average rotation curves of disk galaxies binned in luminosity. We show that the v {sub rot}-v {sub vir} relation that we obtain in this way can fully account for this seeming inconsistency. Therefore, the reconciliation of the luminosity function with the Tully-Fisher relation rests on the complex dependence of v {sub rot} on v {sub vir}, which arises because the ratio of stellar mass to dark matter mass is a strong function of halo mass.

  16. Supernovae and their host galaxies - II. The relative frequencies of supernovae types in spirals

    NASA Astrophysics Data System (ADS)

    Hakobyan, A. A.; Nazaryan, T. A.; Adibekyan, V. Zh.; Petrosian, A. R.; Aramyan, L. S.; Kunth, D.; Mamon, G. A.; de Lapparent, V.; Bertin, E.; Gomes, J. M.; Turatto, M.

    2014-11-01

    We present an analysis of the relative frequencies of different supernova (SN) types in spirals with various morphologies and in barred or unbarred galaxies. We use a well-defined and homogeneous sample of spiral host galaxies of 692 SNe from the Sloan Digital Sky Survey in different stages of galaxy-galaxy interaction and activity classes of nucleus. We propose that the underlying mechanisms shaping the number ratios of SNe types can be interpreted within the framework of interaction-induced star formation, in addition to the known relations between morphologies and stellar populations. We find a strong trend in behaviour of the NIa/NCC ratio depending on host morphology, such that early spirals include more Type Ia SNe. The NIbc/NII ratio is higher in a broad bin of early-type hosts. The NIa/NCC ratio is nearly constant when changing from normal, perturbed to interacting galaxies, then declines in merging galaxies, whereas it jumps to the highest value in post-merging/remnant galaxies. In contrast, the NIbc/NII ratio jumps to the highest value in merging galaxies and slightly declines in post-merging/remnant subsample. The interpretation is that the star formation rates and morphologies of galaxies, which are strongly affected in the final stages of interaction, have an impact on the number ratios of SNe types. The NIa/NCC (NIbc/NII) ratio increases (decreases) from star-forming to active galactic nuclei (AGN) classes of galaxies. These variations are consistent with the scenario of an interaction-triggered starburst evolving into AGN during the later stages of interaction, accompanied with the change of star formation and transformation of the galaxy morphology into an earlier type.

  17. Extragalactic SETI: The Tully-Fisher Relation as a Probe of Dysonian Astroengineering in Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Zackrisson, Erik; Calissendorff, Per; Asadi, Saghar; Nyholm, Anders

    2015-09-01

    If advanced extraterrestrial civilizations choose to construct vast numbers of Dyson spheres to harvest radiation energy, this could affect the characteristics of their host galaxies. Potential signatures of such astroengineering projects include reduced optical luminosity, boosted infrared luminosity, and morphological anomalies. Here, we apply a technique pioneered by Annis to search for Kardashev type III civilizations in disk galaxies, based on the predicted offset of these galaxies from the optical Tully-Fisher (TF) relation. By analyzing a sample of 1359 disk galaxies, we are able to set a conservative upper limit of ≲ 3% on the fraction of local disks subject to Dysonian astroengineering on galaxy-wide scales. However, the available data suggests that a small subset of disk galaxies actually may be underluminous with respect to the TF relation in the way expected for Kardashev type III objects. Based on the optical morphologies and infrared-to-optical luminosity ratios of such galaxies in our sample, we conclude that none of them stand out as strong Kardashev type III candidates and that their inferred properties likely have mundane explanations. This allows us to set a tentative upper limit at ≲ 0.3% on the fraction of Karashev type III disk galaxies in the local universe.

  18. The colour-magnitude relation as a constraint on the formation of rich cluster galaxies

    NASA Astrophysics Data System (ADS)

    Bower, Richard G.; Kodama, Tadayuki; Terlevich, Ale

    1998-10-01

    The colours and magnitudes of early-type galaxies in galaxy clusters are strongly correlated. The existence of such a correlation has been used to infer that early-type galaxies must be old passively evolving systems. Given the dominance of early-type galaxies in the cores of rich clusters, this view sits uncomfortably with the increasing fraction of blue galaxies found in clusters at intermediate redshifts, and with the late formation of galaxies favoured by cold dark matter type cosmologies. In this paper, we make a detailed investigation of these issues and examine the role that the colour-magnitude relation can play in constraining the formation history of galaxies currently found in the cores of rich clusters. We start by considering the colour evolution of galaxies after star formation ceases. We show that the scatter of the colour-magnitude relation places a strong constraint on the spread in age that is allowed for the bulk of the stellar population. In the extreme case that the stars are formed in a single event, the spread in age cannot be more than 4 Gyr. Although the bulk of stars must be formed in a short period, continuing formation of stars in a fraction of the galaxies is not so strongly constrained. We examine a model in which star formation occurs over an extended period of time in most galaxies with star formation being truncated randomly. This model is consistent with the formation of stars in a few systems until look-back times of ~5Gyr. An extension of this type of star formation history allows us to reconcile the small present-day scatter of the colour-magnitude relation with the observed blue galaxy fractions of intermediate redshift galaxy clusters. In addition to setting a limit on the variations in luminosity-weighted age between the stellar populations of cluster galaxies, the colour-magnitude relation can also be used to constrain the degree of merging between pre-existing stellar systems. This test relies on the slope of the colour

  19. EARLY-TYPE GALAXIES WITH TIDAL DEBRIS AND THEIR SCALING RELATIONS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

    SciTech Connect

    Kim, Taehyun; Sheth, Kartik; Munoz-Mateos, Juan-Carlos; Lee, Myung Gyoon; Gadotti, Dimitri A.; Knapen, Johan H.; Schinnerer, Eva; Ho, Luis C.; Madore, Barry F.; Laurikainen, Eija; Salo, Heikki; Athanassoula, E.; Bosma, Albert; Comeron, Sebastien; Regan, Michael W.; Menendez-Delmestre, Karin; De Paz, Armando Gil; and others

    2012-07-01

    Tidal debris around galaxies can yield important clues on their evolution. We have identified tidal debris in 11 early-type galaxies (T {<=} 0) from a sample of 65 early types drawn from the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G). The tidal debris includes features such as shells, ripples, and tidal tails. A variety of techniques, including two-dimensional decomposition of galactic structures, were used to quantify the residual tidal features. The tidal debris contributes {approx}3%-10% to the total 3.6 {mu}m luminosity of the host galaxy. Structural parameters of the galaxies were estimated using two-dimensional profile fitting. We investigate the locations of galaxies with tidal debris in the fundamental plane and Kormendy relation. We find that galaxies with tidal debris lie within the scatter of early-type galaxies without tidal features. Assuming that the tidal debris is indicative of recent gravitational interaction or merger, this suggests that these galaxies have either undergone minor merging events so that the overall structural properties of the galaxies are not significantly altered, or they have undergone a major merging events but already have experienced sufficient relaxation and phase mixing so that their structural properties become similar to those of the non-interacting early-type galaxies.

  20. Exploring the X-ray Size-Temperature Relation for Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Reese, E.; Mohr, J.

    2002-05-01

    Clusters of galaxies appear to be regular objects, illustrated by scaling relations of global properties of galaxy clusters. Nearby galaxy clusters and simulations of galaxy clusters show a tight correlation between the X-ray isophotal size of a galaxy cluster and its X-ray temperature. With a simple model for clusters and standard models for the redshift evolution of clusters we expect that the X-ray isophotal size-temperature (ST) relation does not evolve with redshift. Our initial study of archival ROSAT data for a sample of intermediate redshift galaxy clusters supported the lack of evolution. In addition, we used our sample to measure distances to intermediate redshift, enabling weak constraints on the geometry of the universe. Here we extend our sample size and redshift range, further testing the standard evolution model of galaxy clusters. In addition, we extend our analysis method in this study and also explore possible evolution in the intracluster medium mass-temperature (MT) relation as well as the ST relation. EDR acknowledges support from Chandra Fellowship grant PF1-20020, awarded through the Chandra Science Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under under contract NAS8-39073. JJM acknowledged support from NASA LTSA award NAG5-11415.

  1. THE NATURE OF THE SECOND PARAMETER IN THE IRX-{beta} RELATION FOR LOCAL GALAXIES

    SciTech Connect

    Grasha, Kathryn; Calzetti, Daniela; Andrews, Jennifer E.; Lee, Janice C.; Dale, Daniel A.

    2013-08-20

    We present an analysis of 98 galaxies of low-dust content, selected from the Spitzer Local Volume Legacy survey, aimed at examining the relation between the ultraviolet (UV) color and dust attenuation in normal star-forming galaxies. The IRX-{beta} diagram relates the total dust attenuation in a galaxy, traced by the far-IR (FIR) to UV ratio, to the observed UV color, indicated by {beta}. Previous research has indicated that while starburst galaxies exhibit a relatively tight IRX-{beta} relation, normal star-forming galaxies do not, and have a much larger spread in the total-IR to far-UV (FUV) luminosity for a fixed UV color. We examine the role that the age of the stellar population plays as the ''second parameter'' responsible for the observed deviation and spread of star-forming galaxies from the starburst relation. We model the FUV to FIR spectral energy distribution of each galaxy according to two broad bins of star formation history (SFH): constant and instantaneous burst. We find clear trends between stellar population mean age estimators (extinction-corrected FUV/NIR, U - B, and EW(H{alpha})) and the UV color {beta}; the trends are mostly driven by the galaxies best-described by instantaneous burst populations. We also find a significant correlation between {beta} and the mean age directly determined from the best-fit instantaneous models. As already indicated by other authors, the UV attenuation in star-forming galaxies may not be recovered with the UV color alone and is highly influenced by the stellar population's mean age and SFH. Overall, the scatter in the IRX-{beta} diagram is better correlated with {beta} than with the perpendicular distance, d{sub p}.

  2. Feedback in the local Universe: Relation between star formation and AGN activity in early type galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher; Baum, Stefi; Jones, Christine; Forman, William; Whitmore, Samantha; Ahmed, Rabeea; Pierce, Katherine; Leary, Sara

    2015-08-01

    Aim: We address the relation between star formation and AGN activity in a large sample of nearby early type (E and S0) galaxies. The redshift range of the galaxies is 0.0002galaxy evolution and formation. Evidence of AGN feedback is found in massive galaxies in galaxy clusters. However, how common AGN feedback is in the local universe and in small scale systems is still not evident.Methods: To answer this question, we carried out a multiple wavelength study of a sample of 231 early type galaxies which were selected to have an apparent K-band magnitude brighter than 13.5 and whose positions correlate with Chandra ACIS-I and ACIS-S sources. The galaxies in the sample are unbiased regarding their star formation and radio source properties. Using the archival observations at radio, IR and UV from VLA, WISE and GALEX respectively, we obtained the radio power, estimate FUV star formation rate (SFR) and other galaxy properties to study AGN activity and ongoing star formation.Results: The relationship between radio power and stellar mass shows that there is an upper envelope of radio power that is a steep function of stellar luminosity. This suggests that less massive galaxies have low radio power while massive galaxies are capable of hosting powerful radio sources. The Radio-MIR relation shows that galaxies with P>=1022 WHz-1 are potential candidates for being AGN. About ~ 7% of the sample show evidence of ongoing star formation with SFR ranging from 10-3 to 1 M⊙yr-1. These are also less massive and radio faint suggesting the absence of active accretion. There is nearly equal fraction of star forming galaxies in radio faint (P<1022 WHz-1) and radio bright galaxies (P>=1022 WHz-1) . Only ~ 5% of the galaxies in our sample have P>=1022 WHz-1 and most of them do not show evidence of bright accretion disks. We see a weak correlation and a dispersion of

  3. A Local Baseline of the Black Hole Mass Scaling Relations for Active Galaxies. III.The MBH– Relation

    NASA Astrophysics Data System (ADS)

    Bennert, Vardha N.; Treu, Tommaso; Auger, Matthew W.; Cosens, Maren; Park, Daeseong; Rosen, Rebecca; Harris, Chelsea E.; Malkan, Matthew A.; Woo, Jong-Hak

    2015-08-01

    We create a baseline of the black hole (BH) mass ({M}{BH})—stellar-velocity dispersion (σ) relation for active galaxies, using a sample of 66 local (0.02\\lt z\\lt 0.09) Seyfert-1 galaxies, selected from the Sloan Digital Sky Survey (SDSS). Analysis of SDSS images yields AGN luminosities free of host-galaxy contamination, and morphological classification. 51/66 galaxies have spiral morphology. Out of these, 28 bulges have Sérsic index n\\lt 2 and are considered candidate pseudo-bulges, with eight being definite pseudo-bulges based on multiple classification criteria met. Only 4/66 galaxies show signs of interaction/merging. High signal-to-noise ratio Keck spectra provide the width of the broad Hβ emission line free of Fe ii emission and stellar absorption. AGN luminosity and Hβ line widths are used to estimate {M}{BH}. The Keck-based spatially resolved kinematics is used to determine stellar-velocity dispersion within the spheroid effective radius ({σ }{spat,{reff}}). We find that σ can vary on average by up to 40% across definitions commonly used in the literature, emphasizing the importance of using self-consistent definitions in comparisons and evolutionary studies. The {M}{BH}–σ relation for our Seyfert-1 galaxy sample has the same intercept and scatter as that of reverberation-mapped AGNs as well as that of quiescent galaxies, consistent with the hypothesis that our single epoch {M}{BH} estimator and sample selection function do not introduce significant biases. Barred galaxies, merging galaxies, and those hosting pseudo-bulges do not represent outliers in the {M}{BH}–σ relation. This is in contrast with previous work, although no firm conclusion can be drawn on this matter due to the small sample size and limited resolution of the SDSS images.

  4. USING COLORS TO IMPROVE PHOTOMETRIC METALLICITY ESTIMATES FOR GALAXIES

    SciTech Connect

    Sanders, N. E.; Soderberg, A. M.; Levesque, E. M.

    2013-10-01

    There is a well known correlation between the mass and metallicity of star-forming galaxies. Because mass is correlated with luminosity, this relation is often exploited, when spectroscopy is not available, to estimate galaxy metallicities based on single band photometry. However, we show that galaxy color is typically more effective than luminosity as a predictor of metallicity. This is a consequence of the correlation between color and the galaxy mass-to-light ratio and the recently discovered correlation between star formation rate (SFR) and residuals from the mass-metallicity relation. Using Sloan Digital Sky Survey spectroscopy of ∼180, 000 nearby galaxies, we derive 'LZC relations', empirical relations between metallicity (in seven common strong line diagnostics), luminosity, and color (in 10 filter pairs and four methods of photometry). We show that these relations allow photometric metallicity estimates, based on luminosity and a single optical color, that are ∼50% more precise than those made based on luminosity alone; galaxy metallicity can be estimated to within ∼0.05-0.1 dex of the spectroscopically derived value depending on the diagnostic used. Including color information in photometric metallicity estimates also reduces systematic biases for populations skewed toward high or low SFR environments, as we illustrate using the host galaxy of the supernova SN 2010ay. This new tool will lend more statistical power to studies of galaxy populations, such as supernova and gamma-ray burst host environments, in ongoing and future wide-field imaging surveys.

  5. Examining early-type galaxy scaling relations using simple dynamical models

    NASA Astrophysics Data System (ADS)

    Zhang, Huanian; Zaritsky, Dennis

    2016-01-01

    We use dynamical models that include bulk rotation, velocity dispersion anisotropy and both stars and dark matter to explore the conditions that give rise to the early-type galaxy scaling relations referred to as the Fundamental Plane (FP) and Manifold (FM). The modelled scaling relations generally match the observed relations and are remarkably robust to all changes allowed within these models. The empirical relationships can fail beyond the parameter ranges where they were calibrated and we discuss the nature of those failures. Because the location of individual models relative to the FP and FM is sensitive to the adopted physical scaling of the models, unconstrained rescaling produces a much larger scatter about the scaling relations than that observed. We conclude that only certain combinations of scaling values, which define the physical radial and kinematic scale of the model, produce low scatter versions of the FP and FM. These combinations further result in reproducing a condition observed previously for galaxies, rcρ0 = constant, where rc is the scaling radius and ρ0 is the central density. As such, we conclude that this empirical finding and global galaxy scaling relations are not independent and that finding the physical cause of one should lead to the solution to the other. Although our models are strictly for pressure supported galaxies, these results may well hold generally because the central density constraint was first identified in dwarf spheroidals but later extended to rotating giant galaxies and the FM applies to galaxies of any morphological type and luminosity class.

  6. The Relation between Stellar and Dynamical Surface Densities in the Central Regions of Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Lelli, Federico; McGaugh, Stacy S.; Schombert, James M.; Pawlowski, Marcel S.

    2016-08-01

    We use the Spitzer Photometry and Accurate Rotation Curves database to study the relation between the central surface density of stars {{{Σ }}}\\star (0) and dynamical mass {{{Σ }}}{{dyn}}(0) in 135 disk galaxies (S0 to dIrr). We find that {{{Σ }}}{{dyn}}(0) correlates tightly with {{{Σ }}}\\star (0) over 4 dex. This central density relation can be described by a double power law. High surface brightness galaxies are consistent with a 1:1 relation, suggesting that they are self-gravitating and baryon dominated in the inner parts. Low surface brightness (LSB) galaxies systematically deviate from the 1:1 line, indicating that the dark matter contribution progressively increases but remains tightly coupled to the stellar one. The observed scatter is small (∼0.2 dex) and largely driven by observational uncertainties. The residuals show no correlations with other galaxy properties like stellar mass, size, or gas fraction.

  7. The Relation between Stellar and Dynamical Surface Densities in the Central Regions of Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Lelli, Federico; McGaugh, Stacy S.; Schombert, James M.; Pawlowski, Marcel S.

    2016-08-01

    We use the Spitzer Photometry and Accurate Rotation Curves database to study the relation between the central surface density of stars {{{Σ }}}\\star (0) and dynamical mass {{{Σ }}}{{dyn}}(0) in 135 disk galaxies (S0 to dIrr). We find that {{{Σ }}}{{dyn}}(0) correlates tightly with {{{Σ }}}\\star (0) over 4 dex. This central density relation can be described by a double power law. High surface brightness galaxies are consistent with a 1:1 relation, suggesting that they are self-gravitating and baryon dominated in the inner parts. Low surface brightness (LSB) galaxies systematically deviate from the 1:1 line, indicating that the dark matter contribution progressively increases but remains tightly coupled to the stellar one. The observed scatter is small (˜0.2 dex) and largely driven by observational uncertainties. The residuals show no correlations with other galaxy properties like stellar mass, size, or gas fraction.

  8. New lessons from the H I size-mass relation of galaxies

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Koribalski, Bärbel S.; Serra, Paolo; van der Hulst, Thijs; Roychowdhury, Sambit; Kamphuis, Peter; Chengalur, Jayaram N.

    2016-08-01

    We revisit the H I size-mass (D_{H I}-MH I) relation of galaxies with a sample of more than 500 nearby galaxies covering over five orders of magnitude in H I mass and more than 10 B-band magnitudes. The relation is remarkably tight with a scatter σ ˜ 0.06 dex, or 14 per cent. The scatter does not change as a function of galaxy luminosity, H I richness or morphological type. The relation is linked to the fact that dwarf and spiral galaxies have a homogeneous radial profile of H I surface density in the outer regions when the radius is normalized by DH I. The early-type disc galaxies typically have shallower H I radial profiles, indicating a different gas accretion history. We argue that the process of atomic-to-molecular gas conversion or star formation cannot explain the tightness of the DH I-MH I relation. This simple relation puts strong constraints on simulation models for galaxy formation.

  9. Revisiting the Scaling Relations of Black Hole Masses and Host Galaxy Properties

    NASA Astrophysics Data System (ADS)

    McConnell, Nicholas J.; Ma, Chung-Pei

    2013-02-01

    New kinematic data and modeling efforts in the past few years have substantially expanded and revised dynamical measurements of black hole masses (M •) at the centers of nearby galaxies. Here we compile an updated sample of 72 black holes and their host galaxies, and present revised scaling relations between M • and stellar velocity dispersion (σ), V-band luminosity (L), and bulge stellar mass (M bulge), for different galaxy subsamples. Our best-fitting power-law relations for the full galaxy sample are log10(M •) = 8.32 + 5.64log10(σ/200 km s-1), log10(M •) = 9.23 + 1.11log10(L/1011 L ⊙), and log10(M •) = 8.46 + 1.05log10(M bulge/1011 M ⊙). A log-quadratic fit to the M •-σ relation with an additional term of β2 [log10(σ/200 km s-1)]2 gives β2 = 1.68 ± 1.82 and does not decrease the intrinsic scatter in M •. Including 92 additional upper limits on M • does not change the slope of the M •-σ relation. When the early- and late-type galaxies are fit separately, we obtain similar slopes of 5.20 and 5.06 for the M •-σ relation but significantly different intercepts—M • in early-type galaxies are about two times higher than in late types at a given sigma. Within early-type galaxies, our fits to M •(σ) give M • that is about two times higher in galaxies with central core profiles than those with central power-law profiles. Our M •-L and M •-M bulge relations for early-type galaxies are similar to those from earlier compilations, and core and power-law galaxies yield similar L- and M bulge-based predictions for M •. When the conventional quadrature method is used to determine the intrinsic scatter in M •, our data set shows weak evidence for increased scatter at M bulge < 1011 M ⊙ or LV < 1010.3 L ⊙, while the scatter stays constant for 1011 < M bulge < 1012.3 M ⊙ and 1010.3 < LV < 1011.5 L ⊙. A Bayesian analysis indicates that a larger sample of M • measurements would be needed to detect any statistically

  10. VizieR Online Data Catalog: Tully-Fisher relation for SDSS galaxies (Reyes+, 2011)

    NASA Astrophysics Data System (ADS)

    Reyes, R.; Mandelbaum, R.; Gunn, J. E.; Pizagno, J.; Lackner, C. N.

    2012-05-01

    In this paper, we derive scaling relations between photometric observable quantities and disc galaxy rotation velocity Vrot or Tully-Fisher relations (TFRs). Our methodology is dictated by our purpose of obtaining purely photometric, minimal-scatter estimators of Vrot applicable to large galaxy samples from imaging surveys. To achieve this goal, we have constructed a sample of 189 disc galaxies at redshifts z<0.1 with long-slit Hα spectroscopy from Pizagno et al. (2007, Cat. J/AJ/134/945) and new observations. By construction, this sample is a fair subsample of a large, well-defined parent disc sample of ~170000 galaxies selected from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7). (4 data files).

  11. The Hercules Cluster Environment Impact on the Chemical History of Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Petropoulou, V.; VíLchez, J. M.; Iglesias-Páramo, J.; Papaderos, P.

    In this work we study the effects of the Hercules cluster environment on the chemical history of star-forming (SF) galaxies. For this purpose we have derived the gas metallicities, the mean stellar metallicities and ages, the masses and the luminosities of our sample of galaxies. We have found that our Hercules SF galaxies are either chemically evolved spirals with nearly flat oxygen gradients, or less metal-rich dwarf galaxies which appear to be the "newcomers" in the cluster. Most Hercules SF galaxies follow well defined mass-metallicity and luminosity-metallicity sequences; nevertheless significant outliers to these relations have been identified, illustrating how environmental effects can provide a physical source of dispersion in these fundamental relations.

  12. Galaxy And Mass Assembly (GAMA): The connection between metals, specific SFR and H I gas in galaxies: the Z-SSFR relation

    NASA Astrophysics Data System (ADS)

    Lara-López, M. A.; Hopkins, A. M.

    2014-10-01

    We study the interplay between gas phase metallicity (Z), specific star formation rate (SSFR) and neutral hydrogen gas (HI) for galaxies of different stellar masses. Our study uses spectroscopic data from Galaxy and Mass Assembly (GAMA) and Sloan Digital Sky Survey (SDSS) star-forming galaxies, as well as HI detection from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) and Galex Arecibo SDSS Survey (GASS) public catalogues. We present a model based on the Z-SSFR relation that shows that at a given stellar mass, depending on the amount of gas, galaxies will follow opposite behaviours. Low-mass galaxies with a large amount of gas will show high SSFR and low metallicities, while low-mass galaxies with small amounts of gas will show lower SSFR and high metallicities. In contrast, massive galaxies with a large amount of gas will show moderate SSFR and high metallicities, while massive galaxies with small amounts of gas will show low SSFR and low metallicities. Using ALFALFA and GASS counterparts, we find that the amount of gas is related to those drastic differences in Z and SSFR for galaxies of a similar stellar mass. The results of this study were publish recently in a ``letter to the editor" (Lara-Lopez, M. A. et al. 2013, MNRAS, 433, L35).

  13. Galaxy And Mass Assembly (GAMA): the connection between metals, specific SFR and H I gas in galaxies: the Z-SSFR relation

    NASA Astrophysics Data System (ADS)

    Lara-López, M. A.; Hopkins, A. M.; López-Sánchez, A. R.; Brough, S.; Colless, M.; Bland-Hawthorn, J.; Driver, S.; Foster, C.; Liske, J.; Loveday, J.; Robotham, A. S. G.; Sharp, R. G.; Steele, O.; Taylor, E. N.

    2013-06-01

    We study the interplay between gas phase metallicity (Z), specific star formation rate (SSFR) and neutral hydrogen gas (H I) for galaxies of different stellar masses. Our study uses spectroscopic data from Galaxy and Mass Assembly and Sloan Digital Sky Survey (SDSS) star-forming galaxies, as well as H I detection from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) and Galex Arecibo SDSS Survey (GASS) public catalogues. We present a model based on the Z-SSFR relation that shows that at a given stellar mass, depending on the amount of gas, galaxies will follow opposite behaviours. Low-mass galaxies with a large amount of gas will show high SSFR and low metallicities, while low-mass galaxies with small amounts of gas will show lower SSFR and high metallicities. In contrast, massive galaxies with a large amount of gas will show moderate SSFR and high metallicities, while massive galaxies with small amounts of gas will show low SSFR and low metallicities. Using ALFALFA and GASS counterparts, we find that the amount of gas is related to those drastic differences in Z and SSFR for galaxies of a similar stellar mass.

  14. H I scaling relations of galaxies in the environment of H I-rich and control galaxies observed by the Bluedisk project

    NASA Astrophysics Data System (ADS)

    Wang, Enci; Wang, Jing; Kauffmann, Guinevere; Józsa, Gyula I. G.; Li, Cheng

    2015-05-01

    Our work is based on the `Bluedisk' project, a programme to map the neutral gas in a sample of 25 H I-rich spirals and a similar number of control galaxies with the Westerbork Synthesis Radio Telescope (WSRT). In this paper, we focus on the H I properties of the galaxies in the environment of our targeted galaxies. In total, we extract 65 galaxies from the WSRT cubes with stellar masses between 108 and 1011 M⊙. Most of these galaxies are located on the same H I mass-size relation and `H I-plane' as normal spiral galaxies. We find that companions around H I-rich galaxies tend to be H I-rich as well and to have larger R_{90,H I}/R_{50,H I}. This suggests a scenario of `H I conformity', similar to the colour conformity found by Weinmann et al.: galaxies tend to adopt the H I properties of their neighbours. We visually inspect the outliers from the H I mass-size relation and galaxies which are offset from the H I plane and find that they show morphological and kinematical signatures of recent interactions with their environment. We speculate that these outliers have been disturbed by tidal or ram-pressure stripping processes, or in a few cases, by accretion events.

  15. The Relation between Galaxy Structure and Spectral Type: Implications for the Buildup of the Quiescent Galaxy Population at 0.5 < z < 2.0

    NASA Astrophysics Data System (ADS)

    Yano, Michael; Kriek, Mariska; van der Wel, Arjen; Whitaker, Katherine E.

    2016-02-01

    We present the relation between galaxy structure and spectral type, using a K-selected galaxy sample at 0.5 < z < 2.0. Based on similarities between the UV-to-NIR spectral energy distributions (SEDs), we classify galaxies into 32 spectral types. The different types span a wide range in evolutionary phases, and thus—in combination with available CANDELS/F160W imaging—are ideal to study the structural evolution of galaxies. Effective radii (Re) and Sérsic parameters (n) have been measured for 572 individual galaxies, and for each type, we determine Re at fixed stellar mass by correcting for the mass-size relation. We use the rest-frame U - V versus V - J diagram to investigate evolutionary trends. When moving into the direction perpendicular to the star-forming sequence, in which we see the Hα equivalent width and the specific star formation rate (sSFR) decrease, we find a decrease in Re and an increase in n. On the quiescent sequence we find an opposite trend, with older redder galaxies being larger. When splitting the sample into redshift bins, we find that young post-starburst galaxies are most prevalent at z > 1.5 and significantly smaller than all other galaxy types at the same redshift. This result suggests that the suppression of star formation may be associated with significant structural evolution at z > 1.5. At z < 1, galaxy types with intermediate sSFRs (10-11.5-10-10.5 yr-1) do not have post-starburst SED shapes. These galaxies have similar sizes as older quiescent galaxies, implying that they can passively evolve onto the quiescent sequence, without increasing the average size of the quiescent galaxy population.

  16. Mapping the Galaxy Color-Redshift Relation: Optimal Photo-z Calibration Strategies for Cosmology Surveys

    NASA Astrophysics Data System (ADS)

    Masters, Daniel C.; Capak, Peter L.; Stern, Daniel; Rhodes, Jason; Mobasher, Bahram; Schmidt, Samuel; Steinhardt, Charles L.; Faisst, Andreas; Speagle, Josh S.

    2016-01-01

    A primary objective of the upcoming dark energy surveys LSST, Euclid, and WFIRST is to map the 3D distribution of matter over a significant fraction of the universe via the weak lensing cosmic shear field. Doing so will require accurate distance estimates to billions of faint galaxies, meaning that photo-z's will be essential for the ultimate scientific success of these missions. Because galaxy colors drive photo-z estimates, spectroscopic calibration samples must at least be representative in color. Here we present a technique, based on the self-organizing map (Kohonen 1990), to map the empirical distribution of galaxies in the high-dimensional color space of a given survey. We apply the technique to Euclid-like data for ~131k galaxies from the COSMOS survey, allowing us to determine where - in galaxy color space - spectroscopic coverage exists and where it is systematically missing. We show that the mapping technique lets us develop efficient spectroscopic sampling strategies to measure the color-redshift relation by focusing effort on poorly constrained regions of multicolor space. We discuss the nature of the galaxies in un-sampled regions of galaxy color space, and show that a fiducial survey with Keck (making use of LRIS, DEIMOS, and MOSFIRE) could meet the Euclid calibration requirements in ~40 nights of observing.

  17. The baryonic Tully-Fisher relation cares about the galaxy sample

    NASA Astrophysics Data System (ADS)

    Sorce, Jenny G.; Guo, Quan

    2016-05-01

    The baryonic Tully-Fisher relation (BTFR) is a clear manifestation of the underlying physics of galaxy formation. As such, it is used to constrain and test galaxy formation and evolution models. Of particular interest, apart from the slope of the relation, is its intrinsic scatter. In this article, we use the EAGLE simulation to study the dependence of the BTFR on the size of the simulated galaxy sample. The huge number of data points available in the simulation is indeed not available with current observations. Observational studies that computed the BTFR used various (small) size samples, with the only obligation to have galaxies spanning a large range of masses and rotation rates. Accordingly, to compare observational and theoretical results, we build a large number of various size data sets using the same criterion and derive the BTFR for all of them. Unmistakably, there is an effect resulting from the number of galaxies used to derive the relation. The smaller the number, the larger the standard deviation around the average slope and intrinsic scatter of a given size sample of galaxies. This observation allows us to alleviate the tensions between observational measurements and ΛCDM predictions. Namely, the size of the observational samples adds up to the complexity in comparing observed and simulated relations to discredit or confirm ΛCDM. Similarly, samples, even large, that do not reflect the galaxy distribution give biased results on average. Large size samples reproducing the underlying distribution of galaxies constitute a supplementary necessity to compare observations and simulations efficiently.

  18. The equilibrium view on dust and metals in galaxies: Galactic outflows drive low dust-to-metal ratios in dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Feldmann, Robert

    2015-05-01

    Most galaxy evolution simulations as well as a variety of observational methods assume a linear scaling between the (galaxy-averaged) dust-to-gas ratio D and metallicity Z of the interstellar medium (ISM). Indeed, nearby galaxies with solar or moderately subsolar metallicities clearly follow this trend albeit with significant scatter. However, a growing number of observations show that the linear scaling breaks down for metal-poor galaxies (Z ≲ 0.2 Z⊙), highlighting the need for a more sophisticated modelling of the dust-to-metal ratio of galaxies. Here, we study the co-evolution of dust and metal abundances in galaxies with the help of a dynamical, one-zone model that incorporates dust formation and destruction processes in addition to gas inflows, outflows, and metal enrichment. The dynamical model is consistent with various observational constraints, including the stellar mass-metallicity relation, the stellar mass-halo mass relation, and the observed Z-D relation for both metal-poor and metal-rich galaxies. The functional form of the Z-D relation follows from a basic equilibrium ansatz, similar to the ideas used previously to model the stellar mass-metallicity relation. Galactic outflows regulate the inflow rate of gas from the cosmic web for galaxies of a given star formation rate. The mass loading factor of outflows thus dictates the rate at which the dust and metal content of the ISM is diluted. The stellar mass dependence of the mass loading factor drives the evolution of metallicities, dust-to-gas ratios, and dust-to-metal ratios in galaxies.

  19. The Black Hole–Bulge Mass Relation in Megamaser Host Galaxies

    NASA Astrophysics Data System (ADS)

    Läsker, Ronald; Greene, Jenny E.; Seth, Anil; van de Ven, Glenn; Braatz, James A.; Henkel, Christian; Lo, K. Y.

    2016-07-01

    We present Hubble Space Telescope (HST) images for nine megamaser disk galaxies with the primary goal of studying photometric BH-galaxy scaling relations. The megamaser disks provide the highest-precision extragalactic BH mass measurements, while our high-resolution HST imaging affords us the opportunity to decompose the complex nuclei of their late-type hosts in detail. Based on the morphologies and shapes of the galaxy nuclei, we argue that most of these galaxies’ central regions contain secularly evolving components (pseudo-bulges), and in many cases we photometrically identify co-existing “classical” bulge components as well. Using these decompositions, we draw the following conclusions. (1) The megamaser BH masses span two orders of magnitude (106–{10}8 {M}ȯ ) while the stellar mass of their spiral host galaxies are all ∼ {10}11 {M}ȯ within a factor of three. (2) The BH masses at a given bulge mass or total stellar mass in the megamaser host spiral galaxies tend to be lower than expected when compared to an extrapolation of the BH-bulge relation based on early-type galaxies. (3) The observed large intrinsic scatter of BH masses in the megamaser host galaxies raises the question of whether scaling relations exist in spiral galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 12185.

  20. The Black Hole–Bulge Mass Relation in Megamaser Host Galaxies

    NASA Astrophysics Data System (ADS)

    Läsker, Ronald; Greene, Jenny E.; Seth, Anil; van de Ven, Glenn; Braatz, James A.; Henkel, Christian; Lo, K. Y.

    2016-07-01

    We present Hubble Space Telescope (HST) images for nine megamaser disk galaxies with the primary goal of studying photometric BH-galaxy scaling relations. The megamaser disks provide the highest-precision extragalactic BH mass measurements, while our high-resolution HST imaging affords us the opportunity to decompose the complex nuclei of their late-type hosts in detail. Based on the morphologies and shapes of the galaxy nuclei, we argue that most of these galaxies’ central regions contain secularly evolving components (pseudo-bulges), and in many cases we photometrically identify co-existing “classical” bulge components as well. Using these decompositions, we draw the following conclusions. (1) The megamaser BH masses span two orders of magnitude (106–{10}8 {M}ȯ ) while the stellar mass of their spiral host galaxies are all ˜ {10}11 {M}ȯ within a factor of three. (2) The BH masses at a given bulge mass or total stellar mass in the megamaser host spiral galaxies tend to be lower than expected when compared to an extrapolation of the BH-bulge relation based on early-type galaxies. (3) The observed large intrinsic scatter of BH masses in the megamaser host galaxies raises the question of whether scaling relations exist in spiral galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 12185.

  1. THE REDSHIFT EVOLUTION OF THE RELATION BETWEEN STELLAR MASS, STAR FORMATION RATE, AND GAS METALLICITY OF GALAXIES

    SciTech Connect

    Niino, Yuu

    2012-12-20

    We investigate the relation between stellar mass (M{sub *}), star formation rate (SFR), and metallicity (Z) of galaxies, the so-called fundamental metallicity relation, in the galaxy sample of the Sloan Digital Sky Survey Data Release 7. We separate the galaxies into narrow redshift bins and compare the relation at different redshifts and find statistically significant (>99%) evolution. We test various observational effects that might cause seeming Z evolution and find it difficult to explain the evolution of the relation only by the observational effects. In the current sample of low-redshift galaxies, galaxies with different M{sub *} and SFR are sampled from different redshifts, and there is degeneracy between M{sub *}/SFR and redshift. Hence, it is not straightforward to distinguish a relation between Z and SFR from a relation between Z and redshift. The separation of the intrinsic relation from the redshift evolution effect is a crucial issue in the understanding of the evolution of galaxies.

  2. The Tully-Fisher Relation and its Residuals for a Broadly Selected Sample of Galaxies

    NASA Astrophysics Data System (ADS)

    Pizagno, James; Prada, Francisco; Weinberg, David H.; Rix, Hans-Walter; Pogge, Richard W.; Grebel, Eva K.; Harbeck, Daniel; Blanton, Michael; Brinkmann, J.; Gunn, James E.

    2007-09-01

    We measure the relation between galaxy luminosity and disk circular velocity (the Tully-Fisher [TF] relation), in the g, r, i, and z bands, for a broadly selected sample of galaxies from the Sloan Digital Sky Survey, with the goal of providing well-defined observational constraints for theoretical models of galaxy formation. The input sample of 234 galaxies has a roughly flat distribution of absolute magnitudes in the range -18.5 > Mr > -22, and our only morphological selection is an isophotal axis ratio cut b/a < 0.6 to allow accurate inclination corrections. Long-slit spectroscopy from the Calar Alto and MDM observatories yields usable Hα rotation curves for 162 galaxies (69%), with a representative color and morphology distribution. We define circular velocities V80 by evaluating the rotation curve at the radius containing 80% of the i-band light. Observational errors, including estimated distance errors due to peculiar velocities, are small compared to the intrinsic scatter of the TF relation. The slope of the forward TF relation steepens from -5.5 ± 0.2 mag (log10 km s-1)-1 in the g band to -6.6 ± 0.2 mag (log10 km s-1)-1 in the z band. The intrinsic scatter is σ approx 0.4 mag in all bands, and residuals from either the forward or inverse relations have an approximately Gaussian distribution. We discuss how Malmquist-type biases may affect the observed slope, intercept, and scatter. The scatter is not dominated by rare outliers or by any particular class of galaxies, although it drops slightly, to σ approx 0.36 mag, if we restrict the sample to nearly bulgeless systems. Correlations of TF residuals with other galaxy properties are weak: bluer galaxies are significantly brighter than average in the g-band TF relation but only marginally brighter in the i band; more concentrated (earlier type) galaxies are slightly fainter than average, and the TF residual is virtually independent of half-light radius, contrary to the trend expected for gravitationally

  3. The velocity-distance relation for galaxies on a bubble

    NASA Technical Reports Server (NTRS)

    Bothun, Gregory D.; Geller, Margaret J.; Kurtz, Michael J.; Huchra, John P.; Schild, Rudolph E.

    1992-01-01

    The characteristic diameter of the most prominent void in the redshift survey of de Lapparent et al. (1986) is measured. Distances and peculiar velocities to individual galaxies are derived, and it is shown that the void is approximately a 'Hubble Bubble' in which the near and far edges are separating with the general expansion of the universe. At the 3 sigma level, infall toward the Coma cluster is detected for a portion of the bubble wall. Limits on the net outflow from the void and infall into Coma are used to estimate Omega.

  4. The Luminosity-Metallicity relation of distant luminous infrared galaxies

    NASA Astrophysics Data System (ADS)

    Liang, Y. C.; Hammer, F.; Flores, H.; Elbaz, D.; Marcillac, D.; Cesarsky, C. J.

    2004-09-01

    One hundred and five 15 \\mum-selected objects in three ISO (Infrared Space Observatory) deep survey fields (CFRS 3h, UDSR and UDSF) are studied on the basis of their high-quality optical spectra with resolution R>1000 from VLT/FORS2. ˜92 objects (88%) have secure redshifts, ranging from 0 to 1.16 with a median value of z_med=0.587. Considerable care is taken in estimating the extinction properties of individual galaxy, which can seriously affect diagnostic diagrams and estimates of star formation rates (SFRs) and of metal abundances. Two independent estimates of the extinction have been made, e.g. Balmer line ratio and energy balance between infrared (IR) and H\\beta luminosities. For most of the sources, we find a good agreement between the two extinction coefficients (within ±0.64 rms in AV, the extinction in V band), with median values of A_V(IR) = 2.36 and A_V(Balmer)= 1.82 for z>0.4 luminous IR galaxies (LIRGs). At z >0.4, our sample show many properties (IR luminosity, continuum color, ionization and extinction) strikingly in common with those of local (IRAS) LIRGs studied by Veilleux et al. (\\cite{Veilleux1995}). Thus, our sample can provide a good representation of LIRGs in the distant Universe. We confirm that most (>77%) ISO 15 μm-selected galaxies are dominated by star formation. Oxygen abundances in interstellar medium in the galaxies are estimated from the extinction-corrected ``strong'' emission line ratios (e.g. \\ion{[O}{ii]}/Hβ, \\ion{[O}{iii]}/Hβ and \\ion{[O}{iii]}/\\ion{[O}{ii]}). The derived 12+log(O/H) values range from 8.36 to 8.93 for the z>0.4 galaxies with a median value of 8.67. Distant LIRGs present a metal content less than half of that of the local bright disks (i.e. L*). Their properties can be reproduced with infall models although one has to limit the infall time to avoid overproduction of metals at late times. The models predict that total masses (gas + stars) of the distant LIRGs are from 1011 M⊙ to ≤1012 M⊙. A

  5. THE STELLAR-TO-HALO MASS RELATION FOR LOCAL GROUP GALAXIES

    SciTech Connect

    Brook, C. B.; Cintio, A. Di; Knebe, A.; Yepes, G.; Gottlöber, S.; Hoffman, Y.; Garrison-Kimmel, S.

    2014-03-20

    We contend that a single power-law halo mass distribution is appropriate for direct matching to the stellar masses of observed Local Group dwarf galaxies, allowing the determination of the slope of the stellar mass-halo mass relation for low-mass galaxies. Errors in halo masses are well defined as the Poisson noise of simulated Local Group realizations, which we determine using local volume simulations. For the stellar mass range 10{sup 7} M {sub ☉}galaxies, we find that the stellar mass-halo mass relation follows a power law with slope of 3.1, significantly steeper than most values in the literature. This steep relation between stellar and halo masses would indicate that Local Group dwarf galaxies are hosted by dark matter halos with a small range of mass. Our methodology is robust down to the stellar mass to which the census of observed Local Group galaxies is complete, but the significant uncertainty in the currently measured slope of the stellar-to-halo mass relation will decrease dramatically if the Local Group completeness limit was 10{sup 6.5} M {sub ☉} or below, highlighting the importance of pushing such limit to lower masses and larger volumes.

  6. X-Ray Scaling Relations of 'Core' and 'Coreless' E and S0 Galaxies

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Woo; Fabbiano, Giuseppina

    2015-10-01

    We have re-examined the two X-ray scaling relations of early-type galaxies (ETGs), LX,GAS-LK and LX,GAS-TGAS, using 61 ATLAS3D E and S0 galaxies observed with Chandra (including ROSAT results for a few X-ray bright galaxies with extended hot gas). With this sample, which doubles the number of ETGs available for study we confirm the strong, steep correlations reported by Boroson et al. Moreover, the larger sample allows us to investigate the effect of structural and dynamical properties of ETGs in these relations. Using the sub-sample of 11 “genuine” E galaxies with central surface brightness cores, slow stellar rotations and old stellar populations, we find that the scatter of the correlations is strongly reduced, yielding an extremely tight relation of the form LX,GAS ˜ {{T}{GAS}}4.5+/- 0.3. The rms deviation is only 0.13 dex. For the gas-rich galaxies in this sample (LX,GAS > 1040 erg s-1), this relation is consistent with recent simulations for velocity dispersion supported E galaxies. However, the tight LX,GAS-TGAS relation of genuine E galaxies extends down into the LX ˜ 1038 erg s-1 range, where simulations predict the gas to be in outflow/wind state, with resulting LX much lower than observed in our sample. The observed correlation may suggest the presence of small bound hot halos even in this low luminosity range. At the high luminosity end, the LX,GAS-TGAS correlation of core elliptical galaxies is similar to that found in samples of cD galaxies and groups, but shifted down toward relatively lower LX,GAS for a given TGAS. In particular cDs, central dominant galaxies sitting at the bottom of the potential well imposed by the group dark matter, have an order of magnitude higher LX,GAS than our sample core galaxies for the same LK and TGAS. We suggest that enhanced cooling in cDs, which have higher hot gas densities and lower entropies, could lower TGAS to the range observed in giant Es; this conclusion is supported by the presence of extended cold gas

  7. Mapping the Galaxy Color–Redshift Relation: Optimal Photometric Redshift Calibration Strategies for Cosmology Surveys

    NASA Astrophysics Data System (ADS)

    Masters, Daniel; Capak, Peter; Stern, Daniel; Ilbert, Olivier; Salvato, Mara; Schmidt, Samuel; Longo, Giuseppe; Rhodes, Jason; Paltani, Stephane; Mobasher, Bahram; Hoekstra, Henk; Hildebrandt, Hendrik; Coupon, Jean; Steinhardt, Charles; Speagle, Josh; Faisst, Andreas; Kalinich, Adam; Brodwin, Mark; Brescia, Massimo; Cavuoti, Stefano

    2015-11-01

    Calibrating the photometric redshifts of ≳109 galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST.

  8. THE RELATION BETWEEN MID-PLANE PRESSURE AND MOLECULAR HYDROGEN IN GALAXIES: ENVIRONMENTAL DEPENDENCE

    SciTech Connect

    Feldmann, Robert; Hernandez, Jose; Gnedin, Nickolay Y.

    2012-12-20

    Molecular hydrogen (H{sub 2}) is the primary component of the reservoirs of cold, dense gas that fuel star formation in our Galaxy. While the H{sub 2} abundance is ultimately regulated by physical processes operating on small scales in the interstellar medium (ISM), observations have revealed a tight correlation between the ratio of molecular to atomic hydrogen in nearby spiral galaxies and the pressure in the mid-plane of their disks. This empirical relation has been used to predict H{sub 2} abundances in galaxies with potentially very different ISM conditions, such as metal-deficient galaxies at high redshifts. Here, we test the validity of this approach by studying the dependence of the pressure-H{sub 2} relation on environmental parameters of the ISM. To this end, we follow the formation and destruction of H{sub 2} explicitly in a suite of hydrodynamical simulations of galaxies with different ISM parameters. We find that a pressure-H{sub 2} relation arises naturally in our simulations for a variety of dust-to-gas ratios or strengths of the interstellar radiation field in the ISM. Fixing the dust-to-gas ratio and the UV radiation field to values measured in the solar neighborhood results in fair agreement with the relation observed in nearby galaxies with roughly solar metallicity. However, the parameters (slope and normalization) of the pressure-H{sub 2} relation vary in a systematical way with ISM properties. A particularly strong trend is the decrease of the normalization of the relation with a lowering of the dust-to-gas ratio of the ISM. We show how this trend and other properties of the pressure-H{sub 2} relation arise from the atomic-to-molecular phase transition in the ISM caused by a combination of H{sub 2} formation, destruction, and shielding mechanisms.

  9. Dynamical Mass Determinations and Scaling Relations of Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Cappellari, Michele

    2015-04-01

    I review our understanding of classic dynamical scaling relations, relating luminosity, size and kinematics of early-type galaxies. Using unbiased determinations of galaxy mass profiles from stellar dynamical models, a simple picture has emerged in which scaling relations are driven by virial equilibrium, accompanied by a trend in the stellar mass-to-light ratio (M/L). This picture confirms the earliest insights. The trend is mainly due to the combined variation of age, metallicity and the stellar initial mass function (IMF). The systematic variations best correlate with the galaxy velocity dispersion, which traces the bulge mass fraction. This indicates a link between bulge growth and quenching of star formation. Dark matter is unimportant within the half-light radius, where the total mass profile is close to isothermal (ρ ~ r -2).

  10. REVISITING SCALING RELATIONS FOR GIANT RADIO HALOS IN GALAXY CLUSTERS

    SciTech Connect

    Cassano, R.; Brunetti, G.; Venturi, T.; Kale, R.; Pratt, G. W.; Markevitch, M.

    2013-11-10

    Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R{sub 500} as P{sub 1.4}∼L{sup 2.1±0.2}{sub 500}. Our bigger and more homogenous sample confirms that the X-ray luminous (L{sub 500} > 5 × 10{sup 44} erg s{sup –1}) clusters branch into two populations—radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P{sub 1.4} scales with the cluster integrated SZ signal within R{sub 500}, measured by Planck, as P{sub 1.4}∼Y{sup 2.05±0.28}{sub 500}, in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that 'SZ-luminous' Y{sub 500} > 6 × 10{sup –5} Mpc{sup 2} clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle

  11. Revisiting Scaling Relations for Giant Radio Halos in Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Cassano, R.; Ettori, S.; Brunetti, G.; Giacintucci, S.; Pratt, G. W.; Venturi, T.; Kale, R.; Dolag, K.; Markevitch, Maxim L.

    2013-01-01

    Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R(sub 500) as P(sub 1.4) approx. L(2.1+/-0.2) - 500). Our bigger and more homogenous sample confirms that the X-ray luminous (L(sub 500) > 5 × 10(exp 44) erg/s)) clusters branch into two populations-radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P(sub 1.4) scales with the cluster integrated SZ signal within R(sub 500), measured by Planck, as P(sub 1.4) approx. Y(2.05+/-0.28) - 500), in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that "SZ-luminous" Y(sub 500) > 6×10(exp -5) Mpc(exp 2) clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle acceleration.

  12. The Near-Infrared Ca II Triplet-σ Relation for Bulges of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Falcón-Barroso, Jesús; Peletier, Reynier F.; Vazdekis, Alexandre; Balcells, Marc

    2003-05-01

    We present measurements of the near-infrared Ca II triplet (CaT, CaT*), Paschen (PaT), and magnesium (Mg I) indices for a well-studied sample of 19 bulges of early to intermediate spiral galaxies. We find that both the CaT* and CaT indices decrease with central velocity dispersion σ with small scatter. This dependence is similar to that recently found by Cenarro for elliptical galaxies, implying a uniform CaT*-σ relation that applies to galaxies from ellipticals to intermediate-type spirals. The decrease of CaT and CaT* with σ contrasts with the well-known increase of another α-element index, Mg2, with σ. We discuss the role of Ca underabundance ([Ca/Fe]<0) and initial mass function variations in the onset of the observed relations.

  13. DEVIATIONS FROM THE SCHMIDT-KENNICUTT RELATIONS DURING EARLY GALAXY EVOLUTION

    SciTech Connect

    Papadopoulos, Padelis P.; Pelupessy, Federico I.

    2010-07-10

    We utilize detailed time-varying models of the coupled evolution of stars and the H I, H{sub 2}, and CO-bright H{sub 2} gas phases in galaxy-sized numerical simulations to explore the evolution of gas-rich and/or metal-poor systems, which are expected to be numerous in the early universe. The inclusion of the CO-bright H{sub 2} gas phase and the realistic rendering of star formation as an H{sub 2}-regulated process (and the new feedback processes that this entails) allow the most realistic tracking of strongly evolving galaxies and much better comparison with observations. We find that while galaxies eventually settle into states conforming to the Schmidt-Kennicutt (S-K) relations, significant and systematic deviations of their star formation rates (SFRs) from the latter occur, and are especially pronounced and prolonged for metal-poor systems. The largest such deviations occur for gas-rich galaxies during not only the early evolutionary stages but also during brief periods at later stages. Given that gas-rich and/or metal-poor states of present-epoch galaxies are expected in the early universe while a much larger number of mergers frequently reset non-isolated systems to gas-rich states, even brief periods of sustained deviations of their SFRs from those expected from the S-K relations may come to characterize significant periods of their stellar mass built-up. This indicates potentially serious limitations of S-K-type relations as reliable sub-grid elements of star formation physics in simulations of structure formation in the early universe. We anticipate that galaxies with marked deviations from the S-K relations will be found at high redshifts as unbiased inventories of total gas mass become possible with ALMA and the EVLA.

  14. Disk galaxy scaling relations at intermediate redshifts. I. The Tully-Fisher and velocity-size relations

    NASA Astrophysics Data System (ADS)

    Böhm, Asmus; Ziegler, Bodo L.

    2016-07-01

    Aims: Galaxy scaling relations such as the Tully-Fisher relation (between the maximum rotation velocity Vmax and luminosity) and the velocity-size relation (between Vmax and the disk scale length) are powerful tools to quantify the evolution of disk galaxies with cosmic time. Methods: We took spatially resolved slit spectra of 261 field disk galaxies at redshifts up to z ≈ 1 using the FORS instruments of the ESO Very Large Telescope. The targets were selected from the FORS Deep Field and William Herschel Deep Field. Our spectroscopy was complemented with HST/ACS imaging in the F814W filter. We analyzed the ionized gas kinematics by extracting rotation curves from the two-dimensional spectra. Taking into account all geometrical, observational, and instrumental effects, these rotation curves were used to derive the intrinsic Vmax. Results: Neglecting galaxies with disturbed kinematics or insufficient spatial rotation curve extent, Vmax was reliably determined for 124 galaxies covering redshifts 0.05 < z < 0.97. This is one of the largest kinematic samples of distant disk galaxies to date. We compared this data set to the local B-band Tully-Fisher relation and the local velocity-size relation. The scatter in both scaling relations is a factor of ~2 larger at z ≈ 0.5 than at z ≈ 0. The deviations of individual distant galaxies from the local Tully-Fisher relation are systematic in the sense that the galaxies are increasingly overluminous toward higher redshifts, corresponding to an overluminosity ΔMB = -(1.2 ± 0.5) mag at z = 1. This luminosity evolution at given Vmax is probably driven by younger stellar populations of distant galaxies with respect to their local counterparts, potentially combined with modest changes in dark matter mass fractions. The analysis of the velocity-size relation reveals that disk galaxies of a given Vmax have grown in size by a factor of ~1.5 over the past ~8 Gyr, most likely through accretion of cold gas and/or small satellites

  15. THE STRIKINGLY SIMILAR RELATION BETWEEN SATELLITE AND CENTRAL GALAXIES AND THEIR DARK MATTER HALOS SINCE z = 2

    SciTech Connect

    Watson, Douglas F.; Conroy, Charlie

    2013-08-01

    Satellite galaxies in rich clusters are subject to numerous physical processes that can significantly influence their evolution. However, the typical L* satellite galaxy resides in much lower mass galaxy groups, where the processes capable of altering their evolution are generally weaker and have had less time to operate. To investigate the extent to which satellite and central galaxy evolution differs, we separately model the stellar mass-halo mass (M{sub *}-M{sub h} ) relation for these two populations over the redshift interval 0 < z < 1. This relation for central galaxies is constrained by the galaxy stellar mass function while the relation for satellite galaxies is constrained against recent measurements of the galaxy two-point correlation function (2PCF). Our approach does not rely on the abundance matching technique but instead adopts a flexible functional form for the relation between satellite galaxy stellar mass and subhalo mass, where subhalo mass is considered as the maximum mass that a subhalo has ever reached in its merger history, M{sub peak}. At z {approx} 0 the satellites, on average, have {approx}10% larger stellar masses at fixed M{sub peak} compared to central galaxies of the same halo mass (although the two relations are consistent at 2{sigma}-3{sigma} for M{sub peak} {approx}> 10{sup 13} M{sub Sun }). This is required in order to reproduce the observed stellar mass-dependent 2PCF and satellite fractions. At low masses our model slightly under-predicts the correlation function at {approx}1 Mpc scales. At z {approx} 1 the satellite and central galaxy M{sub *}-M{sub h} relations are consistent within the errors, and the model provides an excellent fit to the clustering data. At present, the errors on the clustering data at z {approx} 2 are too large to constrain the satellite model. A simple model in which satellite and central galaxies share the same M{sub *}-M{sub h} relation is able to reproduce the extant z {approx} 2 clustering data. We

  16. Galaxy Zoo: the dependence of the star formation-stellar mass relation on spiral disc morphology

    NASA Astrophysics Data System (ADS)

    Willett, Kyle W.; Schawinski, Kevin; Simmons, Brooke D.; Masters, Karen L.; Skibba, Ramin A.; Kaviraj, Sugata; Melvin, Thomas; Wong, O. Ivy; Nichol, Robert C.; Cheung, Edmond; Lintott, Chris J.; Fortson, Lucy

    2015-05-01

    We measure the stellar mass-star formation rate (SFR) relation in star-forming disc galaxies at z ≤ 0.085, using Galaxy Zoo morphologies to examine different populations of spirals as classified by their kiloparsec-scale structure. We examine the number of spiral arms, their relative pitch angle, and the presence of a galactic bar in the disc, and show that both the slope and dispersion of the M⋆-SFR relation is constant when varying all the above parameters. We also show that mergers (both major and minor), which represent the strongest conditions for increases in star formation at a constant mass, only boost the SFR above the main relation by ˜0.3 dex; this is significantly smaller than the increase seen in merging systems at z > 1. Of the galaxies lying significantly above the M⋆-SFR relation in the local Universe, more than 50 per cent are mergers. We interpret this as evidence that the spiral arms, which are imperfect reflections of the galaxy's current gravitational potential, are either fully independent of the various quenching mechanisms or are completely overwhelmed by the combination of outflows and feedback. The arrangement of the star formation can be changed, but the system as a whole regulates itself even in the presence of strong dynamical forcing.

  17. The X-ray luminosity temperature relation of a complete sample of low mass galaxy clusters

    NASA Astrophysics Data System (ADS)

    Zou, S.; Maughan, B. J.; Giles, P. A.; Vikhlinin, A.; Pacaud, F.; Burenin, R.; Hornstrup, A.

    2016-08-01

    We present Chandra observations of 23 galaxy groups and low-mass galaxy clusters at 0.03 < z < 0.15 with a median temperature of ˜2 KeV. The sample is a statistically complete flux-limited subset of the 400 deg2 survey. We investigated the scaling relation between X-ray luminosity (L) and temperature (T), taking selection biases fully into account. The logarithmic slope of the bolometric L - T relation was found to be 3.29 ± 0.33, consistent with values typically found for samples of more massive clusters. In combination with other recent studies of the L - T relation we show that there is no evidence for the slope, normalisation, or scatter of the L - T relation of galaxy groups being different than that of massive clusters. The exception to this is that in the special case of the most relaxed systems, the slope of the core-excised L - T relation appears to steepen from the self-similar value found for massive clusters to a steeper slope for the lower mass sample studied here. Thanks to our rigorous treatment of selection biases, these measurements provide a robust reference against which to compare predictions of models of the impact of feedback on the X-ray properties of galaxy groups.

  18. The MUSIC of Galaxy Clusters - III. Properties, evolution and Y-M scaling relation of protoclusters of galaxies

    NASA Astrophysics Data System (ADS)

    Sembolini, Federico; De Petris, Marco; Yepes, Gustavo; Foschi, Emma; Lamagna, Luca; Gottlöber, Stefan

    2014-06-01

    In this work, we study the properties of protoclusters of galaxies by employing the MultiDark SImulations of galaxy Clusters (MUSIC) set of hydrodynamical simulations, featuring a sample of 282 resimulated clusters with available merger trees up to z = 4. We study the characteristics and redshift evolution of the mass and the spatial distribution for all the protoclusters, which we define as the most massive progenitors of the clusters identified at z = 0. We extend the study of the baryon content to redshifts larger than 1 also in terms of gas and stars budgets: no remarkable variations with redshift are discovered. Furthermore, motivated by the proven potential of Sunyaev-Zel'dovich surveys to blindly search for faint distant objects, we compute the scaling relation between total object mass and integrated Compton y-parameter. We find that the slope of this scaling law is steeper than what expected for a self-similarity assumption among these objects, and it increases with redshift mainly when radiative processes are included. We use three different criteria to account for the dynamical state of the protoclusters, and find no significant dependence of the scaling parameters on the level of relaxation. We exclude the dynamical state as the cause of the observed deviations from self-similarity in protoclusters.

  19. Dynamical Family Properties and Dark Halo Scaling Relations of Giant Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Gerhard, Ortwin; Kronawitter, Andi; Saglia, R. P.; Bender, Ralf

    2001-04-01

    Based on a uniform dynamical analysis of the line-profile shapes of 21 mostly luminous, slowly rotating, and nearly round elliptical galaxies, we have investigated the dynamical family relations and dark halo properties of ellipticals. Our results include: (i) The circular velocity curves (CVCs) of elliptical galaxies are flat to within ~=10% for R>~0.2Re. (ii) Most ellipticals are moderately radially anisotropic; their dynamical structure is surprisingly uniform. (iii) Elliptical galaxies follow a Tully-Fisher (TF) relation with marginally shallower slope than spiral galaxies, and vmaxc~=300 km s-1 for an L*B galaxy. At given circular velocity, they are ~1 mag fainter in B and ~0.6 mag in R and appear to have slightly lower baryonic mass than spirals, even for the maximum M/LB allowed by the kinematics. (iv) The luminosity dependence of M/LB indicated by the tilt of the fundamental plane (FP) is confirmed. The tilt of the FP is not caused by dynamical or photometric nonhomology, although the latter might influence the slope of M/L versus L. It can also not be due only to an increasing dark matter fraction with L for the range of IMF currently discussed. It is, however, consistent with stellar population models based on published metallicities and ages. The main driver is therefore probably metallicity, and a secondary population effect is needed to explain the K-band tilt. (v) These results make it likely that elliptical galaxies have nearly maximal M/LB (minimal halos). (vi) Despite the uniformly flat CVCs, there is a spread in the luminous to dark matter ratio and in cumulative M/LB(r). Some galaxies have no indication for dark matter within 2Re, whereas for others we obtain local M/LB-values of 20-30 at 2Re. (vii) In models with maximum stellar mass, the dark matter contributes ~10%-40% of the mass within Re. Equal interior mass of dark and luminous matter is predicted at ~2-4Re. (viii) Even in these maximum stellar mass models, the halo core densities and

  20. The mass discrepancy acceleration relation in early-type galaxies: extended mass profiles and the phantom menace to MOND

    NASA Astrophysics Data System (ADS)

    Janz, Joachim; Cappellari, Michele; Romanowsky, Aaron J.; Ciotti, Luca; Alabi, Adebusola; Forbes, Duncan A.

    2016-09-01

    The dark matter (DM) haloes around spiral galaxies appear to conspire with their baryonic content: empirically, significant amounts of DM are inferred only below a universal characteristic acceleration scale. Moreover, the discrepancy between the baryonic and dynamical mass, which is usually interpreted as the presence of DM, follows a very tight mass discrepancy acceleration (MDA) relation. Its universality, and its tightness in spiral galaxies, poses a challenge for the DM interpretation and was used to argue in favour of MOdified Newtonian Dynamics (MOND). Here, we test whether or not this applies to early-type galaxies. We use the dynamical models of fast-rotator early-type galaxies by Cappellari et al. based on ATLAS3D and SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) data, which was the first homogenous study of this kind, reaching ˜4 Re, where DM begins to dominate the total mass budget. We find the early-type galaxies to follow an MDA relation similar to spiral galaxies, but systematically offset. Also, while the slopes of the mass density profiles inferred from galaxy dynamics show consistency with those expected from their stellar content assuming MOND, some profiles of individual galaxies show discrepancies.

  1. Constraints on Feedback in the Local Universe: The Relation Between Star Formation and AGN Activity in Early Type Galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher P.; Baum, Stefi Alison

    2016-01-01

    We address the relation between star formation and AGN activity in a sample of 231 nearby (0.0002 < z < 0.0358) early type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR and radio. Our results indicate that early type galaxies in the current epoch are rarely powerful AGNs, with P < 1022 WHz-1 for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The SFR of these galaxies is less than 0.1 M⊙yr-1. They also tend to be radio faint (P < 1022 WHz-1). There is a nearly equal fraction of star forming galaxies in radio faint (P < 1022 WHz-1) and radio bright galaxies (P ≥ 1022 WHz-1) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies (BCGs) follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.

  2. Constraints on Feedback in the Local Universe: The Relation between Star Formation and AGN Activity in Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher P.; Baum, Stefi A.; Whitmore, Samantha; Ahmed, Rabeea; Pierce, Katherine; Leary, Sara

    2016-02-01

    We address the relation between star formation and active galactic nucleus (AGN) activity in a sample of 231 nearby (0.0002 < z < 0.0358) early-type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR, and radio. Our results indicate that early-type galaxies in the current epoch are rarely powerful AGNs, with P\\lt {10}22 {{WHz}}-1 for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The star formation rate (SFR) of these galaxies is less than 0.1 M⊙ yr-1. They also tend to be radio faint (P\\lt {10}22 {{WHz}}-1). There is a nearly equal fraction of star-forming galaxies in radio faint (P\\lt {10}22 {{WHz}}-1) and radio bright galaxies (P≥slant {10}22 {{WHz}}-1) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.

  3. Cross identification of 238 galaxies and use of a colour magnitude relation in the coma cluster

    NASA Astrophysics Data System (ADS)

    Mazure, A.; Proust, D.; Mathez, G.; Mellier, Y.

    1988-12-01

    A catalogue of 238 galaxies is obtained by the cross identification of data from Kent and Gunn (1982), Godwin and Peach (1977) and Godwin, Metcalfe and Peach (1983). It contains the radial velocities, bvr magnitudes, colour indices, isophotal radii and other characteristics of individual galaxies. This leads to the definition of various samples of radial velocities complete to various limiting magnitudes depending on radius. The use of the colour magnitude relation is discussed to define a class of 1340 objects ({sequence} objects) likely to belong to the cluster from their photometry only.

  4. The Tully-Fisher Relation and the dynamical evolution of galaxies

    NASA Astrophysics Data System (ADS)

    De Rossi, M. E.; Tissera, P. B.; Pedrosa, S. E.

    We studied the dynamical and kinematical properties of galaxies since z 3 by performing numerical simulations in a CDM universe. Our results sug- gest that the maximum gas-phase rotation velocity of the disc component is a good proxy for the circular velocity at that radius regardless of the galaxy morphology. We also found that velocity scales which combine dispersion and rotation velocity in their definition lead to a tighter Tully-Fisher Rela- tion. In particular, the lowest scatter in the correlation between mass and velocity is obtained if the kinematical indicator is evaluated at the radius corresponding to the maximum of the rotation curve. In these simulations, the evolution of the scatter of the Tully-Fisher Relation seems to be strongly modulating by galaxy interactions and mergers which can drive gas inflows and outflows regulating the star formation process and feedback mecha- nisms inside these systems.

  5. THE NON-CAUSAL ORIGIN OF THE BLACK-HOLE-GALAXY SCALING RELATIONS

    SciTech Connect

    Jahnke, Knud; Maccio, Andrea V. E-mail: maccio@mpia.de

    2011-06-20

    We show that the M{sub BH}-M{sub bulge} scaling relations observed from the local to the high-z universe can be largely or even entirely explained by a non-causal origin, i.e., they do not imply the need for any physically coupled growth of black hole (BH) and bulge mass, for example, through feedback by active galactic nuclei (AGNs). Provided some physics for the absolute normalization, the creation of the scaling relations can be fully explained by the hierarchical assembly of BH and stellar mass through galaxy merging, from an initially uncorrelated distribution of BH and stellar masses in the early universe. We show this with a suite of dark matter halo merger trees for which we make assumptions about (uncorrelated) BH and stellar mass values at early cosmic times. We then follow the halos in the presence of global star formation and BH accretion recipes that (1) work without any coupling of the two properties per individual galaxy and (2) correctly reproduce the observed star formation and BH accretion rate density in the universe. With disk-to-bulge conversion in mergers included, our simulations even create the observed slope of {approx}1.1 for the M{sub BH}-M{sub bulge} relation at z = 0. This also implies that AGN feedback is not a required (though still a possible) ingredient in galaxy evolution. In light of this, other mechanisms that can be invoked to truncate star formation in massive galaxies are equally justified.

  6. Modeling abundances in star forming galaxies

    NASA Astrophysics Data System (ADS)

    Kobayashi, Chiaki

    2015-08-01

    Heavy elements are produced from various types of supernovae (and AGB stars). I first show that elemental abundances of extremely metal-poor stars are consistent not with pair-instability supernovae but with faint supernovae. Then I introduce subclasses of Type Ia supernovae such as SN 2002cx-like objects and sub-Chandrasekhar mass explosions. These "minor" supernovae are important in the early Universe or metal-poor systems such as dwarf spheroidal galaxies. With "major" chemical enrichment sources, I show cosmic chemical enrichment in our cosmological, hydrodynamical simulations. The feedback from active galactic nuclei (AGN) is also included with a new model for the formation of black holes motivated by the first star formation. AGN-driven outflows transport metals into the circumgalactic medium and the intergalactic medium. Nonetheless, the metallicity changes of galaxies are negligible, and the mass-metallicity relations, which are mainly generated by supernova feedback at the first star burst, are preserved. Within galaxies, metallicity radial gradients are produced, which can be affected by AGN feedback but are more sensitive to the merging histories. We find a weak correlation between the gradients and galaxy mass, which is consistent with available observations. These simulations also provide predictions of supernova/hypernova/GRB rates and the properties of their host galaxies.

  7. A spectroscopic sample of massive, quiescent z ∼ 2 galaxies: implications for the evolution of the mass-size relation

    SciTech Connect

    Krogager, J.-K.; Zirm, A. W.; Toft, S.; Man, A.; Brammer, G.

    2014-12-10

    We present deep, near-infrared Hubble Space Telescope/Wide Field Camera 3 grism spectroscopy and imaging for a sample of 14 galaxies at z ≈ 2 selected from a mass-complete photometric catalog in the COSMOS field. By combining the grism observations with photometry in 30 bands, we derive accurate constraints on their redshifts, stellar masses, ages, dust extinction, and formation redshifts. We show that the slope and scatter of the z ∼ 2 mass-size relation of quiescent galaxies is consistent with the local relation, and confirm previous findings that the sizes for a given mass are smaller by a factor of two to three. Finally, we show that the observed evolution of the mass-size relation of quiescent galaxies between z = 2 and 0 can be explained by the quenching of increasingly larger star forming galaxies at a rate dictated by the increase in the number density of quiescent galaxies with decreasing redshift. However, we find that the scatter in the mass-size relation should increase in the quenching-driven scenario in contrast to what is seen in the data. This suggests that merging is not needed to explain the evolution of the median mass-size relation of massive galaxies, but may still be required to tighten its scatter, and explain the size growth of individual z = 2 galaxies quiescent galaxies.

  8. THE STELLAR-TO-HALO MASS RELATION OF LOCAL GALAXIES SEGREGATES BY COLOR

    SciTech Connect

    Rodríguez-Puebla, Aldo; Yang, Xiaohu; Foucaud, Sebastien; Jing, Y. P.; Avila-Reese, Vladimir; Drory, Niv

    2015-02-01

    By means of a statistical approach that combines different semi-empirical methods of galaxy-halo connection, we derive the stellar-to-halo mass relations (SHMR) of local blue and red central galaxies. We also constrain the fraction of halos hosting blue/red central galaxies and the occupation statistics of blue and red satellites as a function of halo mass, M {sub h}. For the observational input we use the blue and red central/satellite galaxy stellar mass functions and two-point correlation functions in the stellar mass range of 9 < log(M {sub *}/M {sub ☉}) <12. We find that: (1) the SHMR of central galaxies is segregated by color, with blue centrals having a SHMR above that of red centrals; at log(M {sub h}/M {sub ☉}) ∼12, the M {sub *}-to-M {sub h} ratio of the blue centrals is ≈0.05, which is ∼1.7 times larger than the value of red centrals. (2) The constrained scatters around the SHMRs of red and blue centrals are ≈0.14 and ≈0.11 dex, respectively. The scatter of the average SHMR of all central galaxies changes from ∼0.20 dex to ∼0.14 dex in the 11.3 < log(M {sub h}/M {sub ☉}) <15 range. (3) The fraction of halos hosting blue centrals at M{sub h}=10{sup 11} M {sub ☉} is 87%, but at 2 × 10{sup 12} M {sub ☉} decays to ∼20%, approaching a few percent at higher masses. The characteristic mass at which this fraction is the same for blue and red galaxies is M{sub h}≈7×10{sup 11} M {sub ☉}. Our results suggest that the SHMR of central galaxies at large masses is shaped by mass quenching. At low masses processes that delay star formation without invoking too strong supernova-driven outflows could explain the high M {sub *}-to-M {sub h} ratios of blue centrals as compared to those of the scarce red centrals.

  9. The galaxy cluster concentration-mass scaling relation

    NASA Astrophysics Data System (ADS)

    Groener, A. M.; Goldberg, D. M.; Sereno, M.

    2016-01-01

    Scaling relations of clusters have made them particularly important cosmological probes of structure formation. In this work, we present a comprehensive study of the relation between two profile observables, concentration (cvir) and mass (Mvir). We have collected the largest known sample of measurements from the literature which make use of one or more of the following reconstruction techniques: weak gravitational lensing (WL), strong gravitational lensing (SL), weak+strong lensing (WL+SL), the caustic method (CM), line-of-sight velocity dispersion (LOSVD), and X-ray. We find that the concentration-mass (c-M) relation is highly variable depending upon the reconstruction technique used. We also find concentrations derived from dark matter-only simulations (at approximately Mvir ˜ 1014 M⊙) to be inconsistent with the WL and WL+SL relations at the 1σ level, even after the projection of triaxial haloes is taken into account. However, to fully determine consistency between simulations and observations, a volume-limited sample of clusters is required, as selection effects become increasingly more important in answering this. Interestingly, we also find evidence for a steeper WL+SL relation as compared to WL alone, a result which could perhaps be caused by the varying shape of cluster isodensities, though most likely reflects differences in selection effects caused by these two techniques. Lastly, we compare concentration and mass measurements of individual clusters made using more than one technique, highlighting the magnitude of the potential bias which could exist in such observational samples.

  10. GAMA/H-ATLAS: THE DUST OPACITY-STELLAR MASS SURFACE DENSITY RELATION FOR SPIRAL GALAXIES

    SciTech Connect

    Grootes, M. W.; Tuffs, R. J.; Andrae, E.; Popescu, C. C.; Pastrav, B.; Gunawardhana, M.; Taylor, E. N.; Kelvin, L. S.; Driver, S. P.; Liske, J.; Seibert, M.; Graham, Alister W.; Baes, M.; Baldry, I. K.; Bourne, N.; Brough, S.; Cooray, A.; Dariush, A.; De Zotti, G.; Dunne, L.; and others

    2013-03-20

    We report the discovery of a well-defined correlation between B-band face-on central optical depth due to dust, {tau}{sup f}{sub B}, and the stellar mass surface density, {mu}{sub *}, of nearby (z {<=} 0.13) spiral galaxies. This relation was derived from a sample of spiral galaxies taken from the Galaxy and Mass Assembly (GAMA) survey, which were detected in the FIR/submillimeter (submm) in the Herschel-ATLAS science demonstration phase field. Using a quantitative analysis of the NUV attenuation-inclination relation for complete samples of GAMA spirals categorized according to stellar mass surface density, we demonstrate that this correlation can be used to statistically correct for dust attenuation purely on the basis of optical photometry and Sersic-profile morphological fits. Considered together with previously established empirical relationships of stellar mass to metallicity and gas mass, the near linearity and high constant of proportionality of the {tau}{sub B}{sup f} - {mu}{sub *} relation disfavors a stellar origin for the bulk of refractory grains in spiral galaxies, instead being consistent with the existence of a ubiquitous and very rapid mechanism for the growth of dust in the interstellar medium. We use the {tau}{sub B}{sup f} - {mu}{sub *} relation in conjunction with the radiation transfer model for spiral galaxies of Popescu and Tuffs to derive intrinsic scaling relations between specific star formation rate (SFR), stellar mass, and stellar surface density, in which attenuation of the UV light used for the measurement of SFR is corrected on an object-to-object basis. A marked reduction in scatter in these relations is achieved which we demonstrate is due to correction of both the inclination-dependent and face-on components of attenuation. Our results are consistent with a general picture of spiral galaxies in which most of the submm emission originates from grains residing in translucent structures, exposed to UV in the diffuse interstellar

  11. The Kennicutt-Schmidt Relation in Extremely Metal-Poor Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Filho, M. E.; Sánchez Almeida, J.; Amorín, R.; Muñoz-Tuñón, C.; Elmegreen, B. G.; Elmegreen, D. M.

    2016-04-01

    The Kennicutt-Schmidt (KS) relation between the gas mass and star formation rate (SFR) describes the star formation regulation in disk galaxies. It is a function of gas metallicity, but the low-metallicity regime of the KS diagram is poorly sampled. We have analyzed data for a representative set of extremely metal-poor galaxies (XMPs), as well as auxiliary data, and compared these to empirical and theoretical predictions. The majority of the XMPs possess high specific SFRs, similar to high-redshift star-forming galaxies. On the KS plot, the XMP H i data occupy the same region as dwarfs and extend the relation for low surface brightness galaxies. Considering the H i gas alone, a considerable fraction of the XMPs already fall off the KS law. Significant quantities of “dark” H2 mass (i.e., not traced by CO) would imply that XMPs possess low star formation efficiencies (SFEgas). Low SFEgas in XMPs may be the result of the metal-poor nature of the H i gas. Alternatively, the H i reservoir may be largely inert, the star formation being dominated by cosmological accretion. Time lags between gas accretion and star formation may also reduce the apparent SFEgas, as may galaxy winds, which can expel most of the gas into the intergalactic medium. Hence, on global scales, XMPs could be H i-dominated, high-specific-SFR (≳10-10 yr-1), low-SFEgas (≲10-9 yr-1) systems, in which the total H i mass is likely not a good predictor of the total H2 mass, nor of the SFR.

  12. Galaxy and mass assembly (GAMA): Mid-infrared properties and empirical relations from WISE

    SciTech Connect

    Cluver, M. E.; Jarrett, T. H.; Hopkins, A. M.; Gunawardhana, M. L. P.; Bauer, A. E.; Lara-López, M. A.; Driver, S. P.; Robotham, A. S. G.; Liske, J.; Taylor, E. N.; Alpaslan, M.; Baldry, I.; Brown, M. J. I.; Peacock, J. A.; Popescu, C. C.; Tuffs, R. J.; Bland-Hawthorn, J.; Colless, M.; Holwerda, B. W.; Leschinski, K.; and others

    2014-02-20

    The Galaxy And Mass Assembly (GAMA) survey furnishes a deep redshift catalog that, when combined with the Wide-field Infrared Survey Explorer (WISE), allows us to explore for the first time the mid-infrared properties of >110, 000 galaxies over 120 deg{sup 2} to z ≅ 0.5. In this paper we detail the procedure for producing the matched GAMA-WISE catalog for the G12 and G15 fields, in particular characterizing and measuring resolved sources; the complete catalogs for all three GAMA equatorial fields will be made available through the GAMA public releases. The wealth of multiwavelength photometry and optical spectroscopy allows us to explore empirical relations between optically determined stellar mass (derived from synthetic stellar population models) and 3.4 μm and 4.6 μm WISE measurements. Similarly dust-corrected Hα-derived star formation rates can be compared to 12 μm and 22 μm luminosities to quantify correlations that can be applied to large samples to z < 0.5. To illustrate the applications of these relations, we use the 12 μm star formation prescription to investigate the behavior of specific star formation within the GAMA-WISE sample and underscore the ability of WISE to detect star-forming systems at z ∼ 0.5. Within galaxy groups (determined by a sophisticated friends-of-friends scheme), results suggest that galaxies with a neighbor within 100 h {sup –1} kpc have, on average, lower specific star formation rates than typical GAMA galaxies with the same stellar mass.

  13. Covariance in the thermal SZ-weak lensing mass scaling relation of galaxy clusters

    NASA Astrophysics Data System (ADS)

    Shirasaki, Masato; Nagai, Daisuke; Lau, Erwin T.

    2016-08-01

    The thermal Sunyaev-Zel'dovich (tSZ) effect signal is widely recognized as a robust mass proxy of galaxy clusters with small intrinsic scatter. However, recent observational calibration of the tSZ scaling relation using weak lensing (WL) mass exhibits considerably larger scatter than the intrinsic scatter predicted from numerical simulations. This raises a question as to whether we can realize the full statistical power of ongoing and upcoming tSZ-WL observations of galaxy clusters. In this work, we investigate the origin of observed scatter in the tSZ-WL scaling relation, using mock maps of galaxy clusters extracted from cosmological hydrodynamic simulations. We show that the inferred intrinsic scatter from mock tSZ-WL analyses is considerably larger than the intrinsic scatter measured in simulations, and comparable to the scatter in the observed tSZ-WL relation. We show that this enhanced scatter originates from the combination of the projection of correlated structures along the line of sight and the uncertainty in the cluster radius associated with WL mass estimates, causing the amplitude of the scatter to depend on the covariance between tSZ and WL signals. We present a statistical model to recover the unbiased cluster scaling relation and cosmological parameter by taking into account the covariance in the tSZ-WL mass relation from multiwavelength cluster surveys.

  14. Covariance in the thermal SZ-weak lensing mass scaling relation of galaxy clusters

    NASA Astrophysics Data System (ADS)

    Shirasaki, Masato; Nagai, Daisuke; Lau, Erwin T.

    2016-08-01

    The thermal Sunyaev-Zel'dovich (tSZ) effect signal is widely recognized as a robust mass proxy of galaxy clusters with small intrinsic scatter. However, recent observational calibration of the tSZ scaling relation using weak lensing (WL) mass exhibits considerably larger scatter than the intrinsic scatter predicted from numerical simulations. This raises a question as to whether we can realize the full statistical power of ongoing and upcoming tSZ-WL observations of galaxy clusters. In this work, we investigate the origin of observed scatter in the tSZ-WL scaling relation, using mock maps of galaxy clusters extracted from cosmological hydrodynamic simulations. We show that the inferred intrinsic scatter from mock tSZ-WL analyses is considerably larger than the intrinsic scatter measured in simulations, and comparable to the scatter in the observed tSZ-WL relation. We show that this enhanced scatter originates from the combination of the projection of correlated structures along the line of sight and the uncertainty in the cluster radius associated with WL mass estimates, causing the amplitude of the scatter to depend on the covariance between tSZ and WL signals. We present a statistical model to recover the unbiased cluster scaling relation and cosmological parameter by taking into account the covariance in the tSZ-WL mass relation from multi-wavelength cluster surveys.

  15. THE RELATION BETWEEN MORPHOLOGY AND DYNAMICS OF POOR GROUPS OF GALAXIES

    SciTech Connect

    Tovmassian, Hrant M.; Plionis, M. E-mail: mplionis@astro.noa.gr

    2009-05-10

    We investigate the relation between the projected morphology and the velocity dispersion of groups of galaxies using two recently compiled group catalogs, one based on the Two Micron All Sky Survey redshift survey (Crook et al.) and the other on the Sloan Digital Sky Survey Data Release 5 galaxy catalog (Tago et al.). We analyze a suitable subsample of groups from each catalog selected such that it minimizes possible systematic effects. We find that the velocity dispersion of groups is strongly correlated with the group-projected shape and size, with elongated and larger groups having a lower velocity dispersion. Such a correlation could be attributed to the dynamical evolution of groups, with groups in the initial stages of formation, before virialization is complete, having small velocity dispersion, a large size, and an elongated shape that reflects the anisotropic accretion of galaxies along filamentary structures. However, we show that the same sort of correlations could also be reproduced in prolatelike groups, irrespective of their dynamical state, if the net galaxy motion is preferentially along the group elongation, since then the groups oriented close to the line of sight will appear more spherical, will have a small projected size and high-velocity dispersion, while groups oriented close to the sky plane will appear larger in projection, more elongated, and will have smaller velocity dispersion. Although both factors must play a role in shaping the observed correlations, we attempt to disentangle them by performing tests that relate only to the dynamical evolution of groups (i.e., calculating the fraction of early-type galaxies in groups and the projected group compactness). Indeed we find a strong positive (negative) correlation between the group velocity dispersion (group-projected major axis) with the fraction of early-type galaxy members. We conclude that (1) the observed dependences of the group velocity dispersion on the group-projected size and

  16. The far-infrared emitting region in local galaxies and QSOs: Size and scaling relations

    NASA Astrophysics Data System (ADS)

    Lutz, D.; Berta, S.; Contursi, A.; Förster Schreiber, N. M.; Genzel, R.; Graciá-Carpio, J.; Herrera-Camus, R.; Netzer, H.; Sturm, E.; Tacconi, L. J.; Tadaki, K.; Veilleux, S.

    2016-06-01

    We use Herschel 70 to 160 μm images to study the size of the far-infrared emitting region in about 400 local galaxies and quasar (QSO) hosts. The sample includes normal "main-sequence" star-forming galaxies, as well as infrared luminous galaxies and Palomar-Green QSOs, with different levels and structures of star formation. Assuming Gaussian spatial distribution of the far-infrared (FIR) emission, the excellent stability of the Herschel point spread function (PSF) enables us to measure sizes well below the PSF width, by subtracting widths in quadrature. We derive scalings of FIR size and surface brightness of local galaxies with FIR luminosity, with distance from the star-forming main-sequence, and with FIR color. Luminosities LFIR~ 1011 L⊙ can be reached with a variety of structures spanning 2 dex in size. Ultraluminous LFIR≳ 1012 L⊙ galaxies far above the main-sequence inevitably have small Re,70~ 0.5 kpc FIR emitting regions with large surface brightness, and can be close to optically thick in the FIR on average over these regions. Compared to these local relations, first ALMA sizes for the dust emission regions in high redshift galaxies, measured at somewhat longer rest wavelengths, suggest larger sizes at the same IR luminosity. We report a remarkably tight relation with 0.15 dex scatter between FIR surface brightness and the ratio of [Cii] 158 μm emission and FIR emission - the so-called [Cii]-deficit is more tightly linked to surface brightness than to FIR luminosity or FIR color. Among 33 z ≤ 0.1 PG QSOs with typical LFIR/LBol,AGN ≈ 0.1, 19 have a measured 70 μm half light radius, with median Re,70 = 1.1 kpc. This is consistent with the FIR size for galaxies with similar LFIR but lacking a QSO, in accordance with a scenario where the rest FIR emission of these types of QSOs is, in most cases, due to host star formation.

  17. SARCS strong-lensing galaxy groups. II. Mass-concentration relation and strong-lensing bias

    NASA Astrophysics Data System (ADS)

    Foëx, G.; Motta, V.; Jullo, E.; Limousin, M.; Verdugo, T.

    2014-12-01

    Aims: Various studies have shown a lensing bias in the mass-concentration relation of cluster-scale structures that is the result of an alignment of the major axis and the line of sight. In this paper, we aim to study this lensing bias through the mass-concentration relation of galaxy groups, thus extending observational constraints to dark matter haloes of mass ~1013-1014 M⊙. Methods: Our work is based on the stacked weak-lensing analysis of a sample of 80 strong-lensing galaxy groups. By combining several lenses, we significantly increase the signal-to-noise ratio of the lensing signal, thus providing constraints on the mass profile that cannot be obtained for individual objects. The resulting shear profiles were fitted with various mass models, among them the Navarro-Frank-White (NFW) profile, which provides an estimate of the total mass and of the concentration of the composite galaxy groups. Results: The main results of our analysis are the following: (i) the lensing signal does not allow us to firmly distinguish between a simple singular isothermal sphere mass distribution and the expected NFW mass profile; (ii) we obtain an average concentration c200 = 8.6-1.3+2.1 that is much higher than the value expected from numerical simulations for the corresponding average mass M200 = 0.73-0.10+0.11 × 1014 M⊙; (iii) the combination of our results with those at larger mass scales gives a mass-concentration relation c(M) of more than two decades in mass, whose slope disagrees with predictions from numerical simulations using unbiased populations of dark matter haloes; (iv) our combined c(M) relation matches results from simulations that only used haloes with a large strong-lensing cross-section, that is, elongated with a major axis close to the line of sight; (v) for the simplest case of prolate haloes, we estimate a lower limit on the minor-to-major axis ratio a/c = 0.5 for the average SARCS galaxy group with a toy model. Conclusions: Our analysis based on galaxy

  18. What can the spatial distribution of galaxy clusters tell about their scaling relations?

    NASA Astrophysics Data System (ADS)

    Balaguera-Antolínez, Andrés

    2014-03-01

    Context. The clustering of galaxy clusters is sensitive not only to the parameters characterizing a given cosmological model, but also to the links between cluster intrinsic properties (e.g., the X-ray luminosity, X-ray temperature) and the total cluster mass. These links, referred to as the cluster scaling relations, represent the tip of the iceberg of the so-called cross-roads between cosmology and astrophysics on the cluster scale. Aims: In this paper we aim to quantify the capability of the inhomogeneous distribution of galaxy clusters, represented by the two-point statistics in Fourier space, to retrieve information on the underlying scaling relations. To that end, we make a case study using the mass-X-ray luminosity scaling relation for galaxy clusters and study its impact on the clustering pattern of these objects. Methods: To characterize the clustering of galaxy clusters, we define the luminosity-weighted power spectrum and introduce the luminosity power spectrum as direct assessment of the clustering of the property of interest, in our case, the cluster X-ray luminosity. Using a suite of halo catalogs extracted from N-body simulations and realistic estimates of the mass-X-ray luminosity relation, we measured these statistics with their corresponding covariance matrices. By carrying out a Fisher matrix analysis, we quantified the content of information (by means of a figure of merit) encoded in the amplitude, shape, and full shape of our probes for two-point statistics. Results: The full shape of the luminosity power spectrum, when analyzed up to scales of k ~ 0.2 h Mpc-1, yields a figure of merit that is two orders of magnitude above the figure obtained from the unweighted power spectrum, and only one order of magnitude below the value encoded in X-ray luminosity function estimated from the same sample. This is a significant improvement over the analysis developed with the standard (i.e., unweighted) clustering probes. Conclusions: The measurements of the

  19. Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies With Relatively Old Stellar Populations at z Approx. 2

    NASA Technical Reports Server (NTRS)

    Tease, Katherine Whitaker; vanDokkum, Pieter G.; Brammer, Gabriel; Momcheva, Ivelina; Skelton, Rosalind; Franx, Marijin; Kriek, Mariska; Labbe, Ivo; Fumagalli, Mattia; Lundgren, Britt F.; Nelson, Erica J.; Patel, Shannon G.; Rix, Hans-Walter

    2013-01-01

    Quiescent galaxies at z approx. 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically quiescent galaxies at 1.4 < z < 2.2 from the 3D-HST grism survey. In addition to H (4861 ),we unambiguously identify metal absorption lines in the stacked spectrum, including the G band (4304 ),Mgi (5175 ), and Na i (5894 ). This finding demonstrates that galaxies with relatively old stellar populations already existed when the universe was approx. 3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3+0.10.3 Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80 of galaxies are dominated by metal lines and have a relatively old mean age of 1.6+0.50.4 Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9+0.20.1 Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [O iii] and H emission. Interestingly, this emission is more centrally concentrated than the continuum with LOiii = 1.7+/- 0.3 x 10(exp 40) erg/s, indicating residual central star formation or nuclear activity.

  20. Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at Z approx. 2

    NASA Technical Reports Server (NTRS)

    Tease, Katherine Whitaker; VanDokkum, Pieter G.; Brammer, Gabriel; Momcheva, Ivelina G.; Skelton, Rosalind; Franx, Marijn; Kriek, Mariska; Labbe, Ivo; Fumagalli, Mattia; Lundgren, Britt F.; Nelson, Erica J.; Patel, Shannon G.; Rix, Hans-Walter

    2013-01-01

    Quiescent galaxies at zeta approximately 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically quiescent galaxies at 1.4 less than z less than 2.2 from the 3D-HST grism survey. In addition to H(Beta) (lambda 4861 Angstroms), we unambiguously identify metal absorption lines in the stacked spectrum, including the G band (lambda 4304 Angstroms), Mg I (lambda 5175 Angstroms), and Na i (lambda 5894 Angstroms). This finding demonstrates that galaxies with relatively old stellar populations already existed when the universe was approximately 3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3(+0.1/-0.3) Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80% of galaxies are dominated by metal lines and have a relatively old mean age of 1.6(+0.5/-0.4) Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9(+0.2/-0.1) Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [O III] and Hß emission. Interestingly, this emission is more centrally concentrated than the continuum with L(sub OIII) = 1.7 +/- 0.3 × 10(exp 40 erg s-1, indicating residual central star formation or nuclear activity.

  1. QUIESCENT GALAXIES IN THE 3D-HST SURVEY: SPECTROSCOPIC CONFIRMATION OF A LARGE NUMBER OF GALAXIES WITH RELATIVELY OLD STELLAR POPULATIONS AT z {approx} 2

    SciTech Connect

    Whitaker, Katherine E.; Van Dokkum, Pieter G.; Momcheva, Ivelina G.; Skelton, Rosalind; Nelson, Erica J.; Brammer, Gabriel; Franx, Marijn; Labbe, Ivo; Fumagalli, Mattia; Patel, Shannon G.; Kriek, Mariska; Lundgren, Britt F.; Rix, Hans-Walter

    2013-06-20

    Quiescent galaxies at z {approx} 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically quiescent galaxies at 1.4 < z < 2.2 from the 3D-HST grism survey. In addition to H{beta} ({lambda}4861 A), we unambiguously identify metal absorption lines in the stacked spectrum, including the G band ({lambda}4304 A), Mg I ({lambda}5175 A), and Na I ({lambda}5894 A). This finding demonstrates that galaxies with relatively old stellar populations already existed when the universe was {approx}3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3{sup +0.1}{sub -0.3} Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80% of galaxies are dominated by metal lines and have a relatively old mean age of 1.6{sup +0.5}{sub -0.4} Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9{sup +0.2}{sub -0.1} Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [O III] and H{beta} emission. Interestingly, this emission is more centrally concentrated than the continuum with L{sub OIII}=1.7{+-}0.3 Multiplication-Sign 10{sup 40} erg s{sup -1}, indicating residual central star formation or nuclear activity.

  2. Two new tests to the distance duality relation with galaxy clusters

    NASA Astrophysics Data System (ADS)

    Santos-da-Costa, Simony; Busti, Vinicius C.; Holanda, Rodrigo F. L.

    2015-10-01

    The cosmic distance duality relation is a milestone of cosmology involving the luminosity and angular diameter distances. Any departure of the relation points to new physics or systematic errors in the observations, therefore tests of the relation are extremely important to build a consistent cosmological framework. Here, two new tests are proposed based on galaxy clusters observations (angular diameter distance and gas mass fraction) and H(z) measurements. By applying Gaussian Processes, a non-parametric method, we are able to derive constraints on departures of the relation where no evidence of deviation is found in both methods, reinforcing the cosmological and astrophysical hypotheses adopted so far.

  3. The Metallicity Evolution of Blue Compact Dwarf Galaxies from the Intermediate Redshift to the Local Universe

    NASA Astrophysics Data System (ADS)

    Lian, Jianhui; Hu, Ning; Fang, Guanwen; Ye, Chengyun; Kong, Xu

    2016-03-01

    We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and Dn(4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass-metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower Dn(4000) index values. The insignificant deviation in the mass-metallicity and mass-SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.

  4. The formation of galaxy bulges: Spectrophotometric constraints

    NASA Astrophysics Data System (ADS)

    Prugniel, Ph.; Maubon, G.; Simien, F.

    2001-01-01

    We have measured Mg2, Fe 5270 and Fe 5335 spectrophotometric indices (LICK system) in the bulge of 89 galaxies, mostly spirals from the Héraudeau (\\cite{her96}) sample. The indices are reduced to a null velocity dispersion and normalized to an aperture of 0.2 h-1 kpc. The mean errors are 0.009 mag on Mg2, and 0.3 Å on the iron indices. These measurements almost double the amount of similar data already available on spiral galaxies. Our data confirm the existence of the relation between Mg2, and sigma0, the central stellar velocity dispersion; we find an even tighter relation between Mg2, and Vmrot, the maximum rotational velocity of the galaxy, deduced from HI observations. For the most massive bulges, these correlations may be interpreted as a mass-metallicity relation. However, the presence of young stellar populations, traced by the detection of [OIII] lambda 5007 Å, emission, provides clear evidence that age effects do play a role. Since the contribution of the young population is anti-correlated to the mass of the galaxy, it continues the Mg2, vs. sigma0 , relation toward the low-sigma0, region and globally increases its slope. We also present evidence for a new positive correlation between Fe indices and sigma0, and for a significant correlation between the line-strength indices and the total or disk luminosity. We propose to model the whole sequence of bulges within the folowing framework: bulges are composed of a primary population formed prior to the disk, during the initial collapse, and of a secondary population formed during its evolution. The whole family of bulges can be classified into three classes: (A) the bulges dominated by young populations are generally small, have ionized gas, low velocity dispersion and low line strengths; (B) the bulges dominated by the primary population lie along the mass-metallicity sequence defined for elliptical galaxies; and (C) the bulges where the secondary population is significant are less Mg-over-abundant than

  5. THE SIZE-STAR FORMATION RELATION OF MASSIVE GALAXIES AT 1.5 < z < 2.5

    SciTech Connect

    Toft, S.; Franx, M.; Van Dokkum, P.; Foerster Schreiber, N. M.; Labbe, I.; Wuyts, S.; Marchesini, D. E-mail: franx@strw.leidenuniv.n E-mail: forster@mpe.mpg.d E-mail: swuyts@cfa.harvard.ed

    2009-11-01

    We study the relation between size and star formation activity in a complete sample of 225 massive (M{sub *} > 5 x 10{sup 10} M {sub sun}) galaxies at 1.5 < z < 2.5, selected from the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis model fits to the observed rest-frame UV-NIR spectral energy distributions, and independent MIPS 24 mum observations, 65% of the galaxies are actively forming stars, while 35% are quiescent. Using sizes derived from two-dimensional surface brightness profile fits to high-resolution (FWHM{sub PSF} approx 0.''45) ground-based ISAAC data, we confirm and improve the significance of the relation between star formation activity and compactness found in previous studies, using a large, complete mass-limited sample. At z approx 2, massive quiescent galaxies are significantly smaller than massive star-forming galaxies, and a median factor of 0.34 +- 0.02 smaller than galaxies of similar mass in the local universe. Thirteen percent of the quiescent galaxies are unresolved in the ISAAC data, corresponding to sizes <1 kpc, more than five times smaller than galaxies of similar mass locally. The quiescent galaxies span a Kormendy relation which, compared to the relation for local early types, is shifted to smaller sizes and brighter surface brightnesses and is incompatible with passive evolution. The progenitors of the quiescent galaxies were likely dominated by highly concentrated, intense nuclear starbursts at z approx 3-4, in contrast to star-forming galaxies at z approx 2 which are extended and dominated by distributed star formation.

  6. Confirmation of general relativity on large scales from weak lensing and galaxy velocities.

    PubMed

    Reyes, Reinabelle; Mandelbaum, Rachel; Seljak, Uros; Baldauf, Tobias; Gunn, James E; Lombriser, Lucas; Smith, Robert E

    2010-03-11

    Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, E(G), that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to 'galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of E(G) different from the general relativistic prediction because, in these theories, the 'gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that E(G) = 0.39 +/- 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of E(G) approximately 0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f(R) theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models. PMID:20220843

  7. Extrinsic Sources of Scatter in the Richness-mass Relation of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Rozo, Eduardo; Rykoff, Eli; Koester, Benjamin; Nord, Brian; Wu, Hao-Yi; Evrard, August; Wechsler, Risa

    2011-10-01

    Maximizing the utility of upcoming photometric cluster surveys requires a thorough understanding of the richness-mass relation of galaxy clusters. We use Monte Carlo simulations to study the impact of various sources of observational scatter on this relation. Cluster ellipticity, photometric errors, photometric redshift errors, and cluster-to-cluster variations in the properties of red-sequence galaxies contribute negligible noise. Miscentering, however, can be important, and likely contributes to the scatter in the richness-mass relation of galaxy maxBCG clusters at the low-mass end, where centering is more difficult. We also investigate the impact of projection effects under several empirically motivated assumptions about cluster environments. Using Sloan Digital Sky Survey data and the maxBCG cluster catalog, we demonstrate that variations in cluster environments can rarely (≈1%-5% of the time) result in significant richness boosts. Due to the steepness of the mass/richness function, the corresponding fraction of optically selected clusters that suffer from these projection effects is ≈5%-15%. We expect these numbers to be generic in magnitude, but a precise determination requires detailed, survey-specific modeling.

  8. Extrinsic Sources of Scatter in the Richness-Mass Relation of Galaxy Clusters

    SciTech Connect

    Rozo, Eduardo; Rykoff, Eli; Koester, Benjamin; Nord, Brian; Wu, Hao-Yi; Evrard, August; Wechsler, Risa; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2012-03-27

    Maximizing the utility of upcoming photometric cluster surveys requires a thorough understanding of the richness-mass relation of galaxy clusters. We use Monte Carlo simulations to study the impact of various sources of observational scatter on this relation. Cluster ellipticity, photometric errors, photometric redshift errors, and cluster-to-cluster variations in the properties of red-sequence galaxies contribute negligible noise. Miscentering, however, can be important, and likely contributes to the scatter in the richness - mass relation of galaxy maxBCG clusters at the low mass end, where centering is more difficult. We also investigate the impact of projection effects under several empirically motivated assumptions about cluster environments. Using SDSS data and the maxBCG cluster catalog, we demonstrate that variations in cluster environments can rarely ({approx} 1%-5% of the time) result in significant richness boosts. Due to the steepness of the mass/richness function, the corresponding fraction of optically selected clusters that suffer from these projection effects is {approx} 5%-15%. We expect these numbers to be generic in magnitude, but a precise determination requires detailed, survey-specific modeling.

  9. COSMIC EVOLUTION OF BLACK HOLES AND SPHEROIDS. V. THE RELATION BETWEEN BLACK HOLE MASS AND HOST GALAXY LUMINOSITY FOR A SAMPLE OF 79 ACTIVE GALAXIES

    SciTech Connect

    Park, Daeseong; Woo, Jong-Hak; Bennert, Vardha N.; Treu, Tommaso; Auger, Matthew W.; Malkan, Matthew A. E-mail: woo@astro.snu.ac.kr E-mail: vbennert@calpoly.edu E-mail: malkan@astro.ucla.edu

    2015-02-01

    We investigate the cosmic evolution of the black hole (BH) mass-bulge luminosity relation using a sample of 52 active galaxies at z ∼ 0.36 and z ∼ 0.57 in the BH mass range of 10{sup 7.4}-10{sup 9.1} M {sub ☉}. By consistently applying multicomponent spectral and structural decomposition to high-quality Keck spectra and high-resolution Hubble Space Telescope images, BH masses (M {sub BH}) are estimated using the Hβ broad emission line combined with the 5100 Å nuclear luminosity, and bulge luminosities (L {sub bul}) are derived from surface photometry. Comparing the resulting M {sub BH} – L {sub bul} relation to local active galaxies and taking into account selection effects, we find evolution of the form M {sub BH}/L {sub bul}∝(1 + z){sup γ} with γ = 1.8 ± 0.7, consistent with BH growth preceding that of the host galaxies. Including an additional sample of 27 active galaxies with 0.5 < z < 1.9 taken from the literature and measured in a consistent way, we obtain γ = 0.9 ± 0.7 for the M {sub BH} – L {sub bul} relation and γ = 0.4 ± 0.5 for the M {sub BH}-total host galaxy luminosity (L {sub host}) relation. The results strengthen the findings from our previous studies and provide additional evidence for host galaxy bulge growth being dominated by disk-to-bulge transformation via minor mergers and/or disk instabilities.

  10. ON THE OXYGEN AND NITROGEN CHEMICAL ABUNDANCES AND THE EVOLUTION OF THE 'GREEN PEA' GALAXIES

    SciTech Connect

    Amorin, Ricardo O.; Perez-Montero, Enrique; Vilchez, J. M. E-mail: epm@iaa.e

    2010-06-01

    We have investigated the oxygen and nitrogen chemical abundances in extremely compact star-forming galaxies (SFGs) with redshifts between {approx}0.11 and 0.35, popularly referred to as 'green peas'. Direct and strong-line methods sensitive to the N/O ratio applied to their Sloan Digital Sky Survey (SDSS) spectra reveal that these systems are genuine metal-poor galaxies, with mean oxygen abundances {approx}20% solar. At a given metallicity these galaxies display systematically large N/O ratios compared to normal galaxies, which can explain the strong difference between our metallicities measurements and previous ones. While their N/O ratios follow the relation with stellar mass of local SFGs in the SDSS, we find that the mass-metallicity relation of the 'green peas' is offset {approx_gt}0.3 dex to lower metallicities. We argue that recent interaction-induced inflow of gas, possibly coupled with a selective metal-rich gas loss, driven by supernova winds, may explain our findings and the known galaxy properties, namely high specific star formation rates, extreme compactness, and disturbed optical morphologies. The 'green pea' galaxy properties seem to be uncommon in the nearby universe, suggesting a short and extreme stage of their evolution. Therefore, these galaxies may allow us to study in great detail many processes, such as starburst activity and chemical enrichment, under physical conditions approaching those in galaxies at higher redshifts.

  11. ABOUT THE LINEARITY OF THE COLOR-MAGNITUDE RELATION OF EARLY-TYPE GALAXIES IN THE VIRGO CLUSTER

    SciTech Connect

    Smith Castelli, Analia V.; Faifer, Favio R.

    2013-07-20

    We revisit the color-magnitude relation of Virgo Cluster early-type galaxies in order to explore its alleged nonlinearity. To this aim, we reanalyze the relation already published from data obtained within the ACS Virgo Cluster Survey of the Hubble Space Telescope and perform our own photometry and analysis of the images of 100 early-type galaxies observed as part of this survey. In addition, we compare our results with those reported in the literature from data of the Sloan Digital Sky Survey. We have found that when the brightest galaxies and untypical systems are excluded from the sample, a linear relation arises in agreement with what is observed in other groups and clusters. The central regions of the brightest galaxies also follow this relation. In addition, we notice that Virgo contains at least four compact elliptical galaxies besides the well-known object VCC 1297 (NGC 4486B). Their locations in the ({mu}{sub eff})-luminosity diagram define a trend different from that followed by normal early-type dwarf galaxies, setting an upper limit in effective surface brightness and a lower limit in the effective radius for their luminosities. Based on the distribution of different galaxy sub-samples in the color-magnitude and ({mu}{sub eff})-luminosity diagrams, we draw some conclusions on their formation and the history of their evolution.

  12. Weak lensing calibrated M-T scaling relation of galaxy groups in the cosmos field

    SciTech Connect

    Kettula, K.; Finoguenov, A.; Massey, R.; Rhodes, J.; Hoekstra, H.; Taylor, J. E.; Spinelli, P. F.; Tanaka, M.; Ilbert, O.; Capak, P.; McCracken, H. J.; Koekemoer, A.

    2013-11-20

    The scaling between X-ray observables and mass for galaxy clusters and groups is instrumental for cluster-based cosmology and an important probe for the thermodynamics of the intracluster gas. We calibrate a scaling relation between the weak lensing mass and X-ray spectroscopic temperature for 10 galaxy groups in the COSMOS field, combined with 55 higher-mass clusters from the literature. The COSMOS data includes Hubble Space Telescope imaging and redshift measurements of 46 source galaxies per arcminute{sup 2}, enabling us to perform unique weak lensing measurements of low-mass systems. Our sample extends the mass range of the lensing calibrated M-T relation an order of magnitude lower than any previous study, resulting in a power-law slope of 1.48{sub −0.09}{sup +0.13}. The slope is consistent with the self-similar model, predictions from simulations, and observations of clusters. However, X-ray observations relying on mass measurements derived under the assumption of hydrostatic equilibrium have indicated that masses at group scales are lower than expected. Both simulations and observations suggest that hydrostatic mass measurements can be biased low. Our external weak lensing masses provide the first observational support for hydrostatic mass bias at group level, showing an increasing bias with decreasing temperature and reaching a level of 30%-50% at 1 keV.

  13. The luminosity function of cluster galaxies: relations among M_1_, M^*^ and the morphological type.

    NASA Astrophysics Data System (ADS)

    Trevese, D.; Cirimele, G.; Appodia, B.

    1996-11-01

    A study of the luminosity function of 36 Abell clusters of galaxies has been carried out using photographic plates obtained with the Palomar 1.2 m Schmidt telescope. The relation between the magnitude M_1_ of the brightest cluster member and the Schechter function parameter M^*^ has been analyzed. A positive correlation between M^*^ and M_1_ is found. However clusters appear segregated in the M_1_-M^*^ plane according to their Rood & Sastry class in such a way that on average M_1_ becomes brighter while M^*^ becomes fainter going from late to early Rood & Sastry and also Bautz & Morgan classes. Also a partial correlation analysis involving the magnitude M_10_ of the 10th brightest galaxy, shows a negative intrinsic correlation between M_1_ and M^*^. These results agree with the cannibalism model for the formation of brightest cluster members, and provide new constraints for theories of cluster formation and evolution.

  14. Searching for systematics in SNIa and galaxy cluster data using the cosmic duality relation

    SciTech Connect

    Shafieloo, Arman; Majumdar, Subhabrata; Sahni, Varun; Starobinsky, Alexei A. E-mail: subha@tifr.res.in E-mail: alstar@landau.ac.ru

    2013-04-01

    We compare two different probes of the expansion history of the universe, namely, luminosity distances from type Ia supernovae and angular diameter distances from galaxy clusters, using the Bayesian interpretation of Crossing statistic [1,2] in conjunction with the assumption of cosmic duality relation. Our analysis is conducted independently of any a-priori assumptions about the nature of dark energy. The model independent method which we invoke searches for inconsistencies between SNIa and galaxy cluster data sets. If detected such an inconsistency would imply the presence of systematics in either of the two data sets. Simulating observations based on expected WFIRST supernovae data and X-ray eROSITA + SZ Planck cluster data, we show that our method allows one to detect systematics with high precision and without advancing any hypothesis about the nature of dark energy.

  15. Metallicity properties of the simulated host galaxies of long gamma-ray bursts and the fundamental metallicity relation

    NASA Astrophysics Data System (ADS)

    Campisi, M. A.; Tapparello, C.; Salvaterra, R.; Mannucci, F.; Colpi, M.

    2011-10-01

    By combining high-resolution N-body simulations with semi-analytical models of galaxy formation, we study the implications of the collapsar model for long-duration gamma-ray bursts (LGRBs) on the metallicity properties of the host galaxies. The cosmological model that we use reproduces the fundamental metallicity relation - the metallicity decreases with increasing star formation rate for galaxies of a given stellar mass. This was recently discovered for the Sloan Digital Sky Survey galaxies. We select host galaxies that house pockets of gas particles, that are young and that have different thresholds for their metallicities; these can be sites of LRGB events, according to the collapsar model. The simulated samples are compared with 18 observed LGRB hosts with the aim of discovering whether the metallicity is a primary parameter. We find that a threshold of metallicity for the LGRB progenitors, within the model galaxies, is not necessary to reproduce the observed distribution of host metallicities. The low metallicities of most LGRB hosts are consistent with the expectation that GRBs trace star formation. The star formation rate appears to be the primary parameter tracing the occurrence of a burst event. Finally, we show that only a few LGRBs are observed in massive, highly extinct galaxies, despite the fact that these galaxies are expected to produce many such events. We identify these missing events with the fraction of dark LGRBs.

  16. How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos

    NASA Astrophysics Data System (ADS)

    Tumlinson, Jason

    2009-07-01

    We propose to address two of the biggest open questions in galaxy formation - how galaxies acquire their gas and how they return it to the IGM - with a concentrated COS survey of diffuse multiphase gas in the halos of SDSS galaxies at z = 0.15 - 0.35. Our chief science goal is to establish a basic set of observational facts about the physical state, metallicity, and kinematics of halo gas, including the sky covering fraction of hot and cold material, the metallicity of infall and outflow, and correlations with galaxy stellar mass, type, and color - all as a function of impact parameter from 10 - 150 kpc. Theory suggests that the bimodality of galaxy colors, the shape of the luminosity function, and the mass-metallicity relation are all influenced at a fundamental level by accretion and feedback, yet these gas processes are poorly understood and cannot be predicted robustly from first principles. We lack even a basic observational assessment of the multiphase gaseous content of galaxy halos on 100 kpc scales, and we do not know how these processes vary with galaxy properties. This ignorance is presently one of the key impediments to understanding galaxy formation in general. We propose to use the high-resolution gratings G130M and G160M on the Cosmic Origins Spectrograph to obtain sensitive column density measurements of a comprehensive suite of multiphase ions in the spectra of 43 z < 1 QSOs lying behind 43 galaxies selected from the Sloan Digital Sky Survey. In aggregate, these sightlines will constitute a statistically sound map of the physical state and metallicity of gaseous halos, and subsets of the data with cuts on galaxy mass, color, and SFR will seek out predicted variations of gas properties with galaxy properties. Our interpretation of these data will be aided by state-of-the-art hydrodynamic simulations of accretion and feedback, in turn providing information to refine and test such models. We will also use Keck, MMT, and Magellan {as needed} to obtain

  17. The Magnesium-Velocity Dispersion Relation and the Genesis of Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Worthey, Guy; Collobert, Maela

    2003-03-01

    Available data on the magnesium-velocity dispersion (Mg-σ) relation for ~2000 early-type galaxies is analyzed. As noted previously, the Mg residuals from a fitted line are roughly Gaussian near the median but have an asymmetric blue tail, probably from subpopulations of relatively young stars. We define statistics for scatter and asymmetry of scatter in the Mg dimension and find impressive uniformity among data sets. We construct models of galaxy formation built to be as unbiased as possible toward the question of the importance of mergers in the formation of early-type galaxies. The observational constraints (Mg-σ width, asymmetry, and mean Mg strength, plus mean age and width of abundance distribution) are severe enough to eliminate almost all models. Eliminated are models with merger rates proportional to (1+z)n with n>0, models that assume early formation followed by recent drizzling of new stars, merger-only models in which the number of mergers exceeds ~80, merger-only models with less than ~20 mergers, and models with a cold dark matter power spectrum (at least within our approximations). The most successful models were those with merger probability constant or mildly declining with time, with the number of mergers needed to form the galaxy around 50 and gas fractions of ~0.2-0.35. These models are characterized by mean light-weighted ages of 8-9 Gyr (consistent with spectroscopic studies), an abundance distribution that does not exceed local constraints, and a look-back time behavior nearly indistinguishable from passive evolution of old stellar populations. Our simulations suggest that the evolution of median Mg index strength is not a good discriminator between mergers and passive evolution and that better discriminators such as Mg-σ scatter and asymmetry require N>1000 sample sizes with accuracies similar to today's local measurements.

  18. Dynamical Properties of z ~ 2 Star-forming Galaxies and a Universal Star Formation Relation

    NASA Astrophysics Data System (ADS)

    Bouché, N.; Cresci, G.; Davies, R.; Eisenhauer, F.; Förster Schreiber, N. M.; Genzel, R.; Gillessen, S.; Lehnert, M.; Lutz, D.; Nesvadba, N.; Shapiro, K. L.; Sternberg, A.; Tacconi, L. J.; Verma, A.; Cimatti, A.; Daddi, E.; Renzini, A.; Erb, D. K.; Shapley, A.; Steidel, C. C.

    2007-12-01

    We present the first comparison of the dynamical properties of different samples of z~1.4-3.4 star-forming galaxies from spatially resolved imaging spectroscopy from SINFONI/VLT integral field spectroscopy and IRAM CO millimeter interferometry. Our samples include 16 rest-frame UV-selected, 16 rest-frame optically selected, and 13 submillimeter galaxies (SMGs). We find that rest-frame UV and optically bright (K<20) z~2 star forming galaxies are dynamically similar, and follow the same velocity-size relation as disk galaxies at z~0. In the theoretical framework of rotating disks forming from dissipative collapse in dark matter halos, the two samples require a spin parameter <λ> ranging from 0.06 to 0.2. In contrast, bright SMGs (S850μm>=5 mJy) have larger velocity widths and are much more compact. Hence, SMGs have lower angular momenta and higher matter densities than either the UV or optically selected populations. This indicates that dissipative major mergers may dominate the SMGs population, resulting in early spheroids, and that a significant fraction of the UV/optically bright galaxies have evolved less violently, either in a series of minor mergers, or in rapid dissipative collapse from the halo, given that either process may leads to the formation of early disks. These early disks may later evolve into spheroids via disk instabilities or mergers. Because of their small sizes and large densities, SMGs lie at the high surface density end of a universal (out to z=2.5) ``Schmidt-Kennicutt'' relation between gas surface density and star formation rate surface density. The best-fit relation suggests that the star formation rate per unit area scales as the surface gas density to a power of ~1.7, and that the star formation efficiency increases by a factor of 4 between non-starbursts and strong starbursts. Based on observations at the Very Large Telescope (VLT) of the European Southern Observatory (ESO), Paranal, Chile, under programs GTO 073.B-9018, 074.A-9011

  19. SNLS: Relating the properties of type Ia supernovae to the stellar populations of their host galaxies

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Pritchet, C. J.; Le Borgne, D.; Hodsman, A.; Howell, D. A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, J.; Filliol, M.; Perlmutter, S.; Tao, C.; SNLS Collaboration

    2005-12-01

    We examine the rates and properties of type Ia supernovae (SNe Ia) in relation to the physical parameters defining their host galaxy stellar populations. Using a sample of 114 spectroscopically confirmed SNe Ia discovered via the Supernova Legacy Survey (SNLS) distributed over 0.2galaxies - more vigorously star-forming galaxies have a higher SN Ia rate. Further, we identify a dependence of the SN rate on both the stellar mass and the current total SFRs of the host systems, suggesting SNe Ia can be generated from both very young and old stellar populations. We further demonstrate a dependence of SN light-curve shapes on the mean age of the stellar population from which the progenitor is drawn -- older systems preferentially host faster/dimmer SNe Ia, as observed in the local Universe. Though with current sample sizes, existing analysis techniques adequately account for these trends when using SNe Ia to constrain cosmological parameters, identifying and understanding the relationship between SNe Ia and their environments will lead to a future improved cosmological candle.

  20. Understanding the Relations between QSOs and Their Host Galaxies from Combined HST Imaging and VLT Spectroscopy

    NASA Astrophysics Data System (ADS)

    Letawe, Y.; Magain, P.; Letawe, G.; Courbin, F.; Hutsemékers, D.

    2008-06-01

    The host galaxies of six nearby QSOs are studied on the basis of high-resolution HST optical images and spatially resolved VLT slit spectra. The gas ionization and velocity are mapped as a function of the distance to the central QSO. In the majority of the cases, the QSO significantly contributes to the gas ionization in its whole host galaxy, and sometimes even outside. Reflection or scattering of the QSO Hα line from remote regions of the galaxy is detected in several instances. The line shifts show that, in all cases, the matter responsible for the light reflection moves away from the QSO, likely accelerated by its radiation pressure. The two faintest QSOs reside in spirals, with some signs of a past gravitational perturbation. One of the intermediate-luminosity QSOs resides in a massive elliptical containing gas ionized (and probably pushed away) by the QSO radiation. The other medium-power object is found in a spiral galaxy displaying complex velocity structure, with the central QSO moving with respect to the bulge, probably as a result of a galactic collision. The two most powerful objects are involved in violent gravitational interactions, and one of them has no detected host. These results suggest that (1) large-scale phenomena, such as galactic collisions, are closely related to the triggering and the feeding of the QSO and (2) once ignited, the QSO has significant influence on its large-scale neighborhood (often the whole host and sometimes further away). Based on observations made with the Nasa/ESA Hubble Space Telescope (Cycle 13 proposal 10238), and with ANTU/UT1 at ESO-Paranal observatory in Chile [programs 65.P-0361(A) and 66.B-0139(A)].

  1. Molecular gas as the driver of fundamental galactic relations

    NASA Astrophysics Data System (ADS)

    Bothwell, M. S.; Maiolino, R.; Peng, Y.; Cicone, C.; Griffith, H.; Wagg, J.

    2016-01-01

    There has been much recent work dedicated to exploring secondary correlations in the mass-metallicity relation, with significant dependence on both the SFR (SFR) and H I content being demonstrated. Previously, a paucity of molecular gas data (combined with sample selection bias) hampered the investigation of any such relation with molecular gas content. In this work, we assemble a sample of 221 galaxies from a variety of surveys in the redshift range 0 < z < 2, to explore the connection between molecular gas content and metallicity. We explore the effect of gas mass on the mass-metallicity relation, finding that the offset from the relation is negatively correlated against both molecular and total gas mass. We then employ a principle component analysis technique to explore secondary dependences in the mass-metallicity relation, finding that the secondary dependence with gas mass is significantly stronger than with SFR, and as such the underlying `fundamental metallicity relation' is between stellar mass, metallicity, and gas mass. In particular, the metallicity dependence on SFR is simply a byproduct of the dependence on the molecular gas content, via the Schmidt-Kennicutt relation. Finally, we note that our principle component analysis finds essentially no connection between gas-phase metallicity and the efficiency of star formation.

  2. The mass-concentration relation for galaxy clusters at z˜0.5

    NASA Astrophysics Data System (ADS)

    Cibirka, Nathália; Figueiró Spinelli, Patrícia; Serra Cypriano, Eduardo; Brimioulle, Fabrice; Finoguenov, Alexis; Van Waerbeke, Ludovic

    2015-08-01

    Galaxy clusters have a special position in the hierarchical scenario, as they are the largest structures (dark matter halos) to reach equilibrium. Therefore, these objects can be used as tracers to probe cosmological structure formation. The radial density profile of these halos, spanning over 5 decades in mass, can be described by the same law, with only two parameters. A profile often used to that end is the so-called NFW. In this model, one of the two parameters is related to the concentration of the halo and the other is the cluster mass. Our study has the aim to measuring the mass-concentration (M-c) relation of galaxy clusters at z˜0.5 using the weak gravitational lensing technique. By determining the M-c relation it is possible to test if the observed data from galaxy clusters are in tension with the cosmological standard model. The shear and photometric redshift catalogs are derived from a sub-sample of 27 CODEX (Constrain Dark Energy with X-ray Clusters) clusters observed with the CFHT telescope in the ugriz bands. For this sub-sample, we have performed an NFW-profile fit to the observed stacked tangential shear of all 27 clusters. We further compare our results with predictions from numerical simulations and other observational results. The full CODEX sample consists of 294 clusters at intermediate redshift (0.25 < z < 0.55), and its goal is to measure the cluster mass through x-ray and Sunyaev-Zeldovich data in order to determine the mass function variation, constraining parameters related to dark energy and cosmological models.

  3. EXPLORING THE LOW-MASS END OF THE M{sub BH}-{sigma}{sub *} RELATION WITH ACTIVE GALAXIES

    SciTech Connect

    Xiao Ting; Barth, Aaron J.; Greene, Jenny E.; Ludwig, Randi R.; Ho, Luis C.; Bentz, Misty C.; Jiang Yanfei E-mail: barth@uci.edu E-mail: lho@obs.carnegiescience.edu E-mail: yanfei@astro.princeton.edu

    2011-09-20

    We present new measurements of stellar velocity dispersions, using spectra obtained with the Keck Echellette Spectrograph and Imager (ESI) and the Magellan Echellette (MagE), for 76 Seyfert 1 galaxies from the recent catalog of Greene and Ho. These objects were selected from the Sloan Digital Sky Survey (SDSS) to have estimated black hole (BH) masses below 2 x 10{sup 6} M{sub sun}. Combining our results with previous ESI observations of similar objects, we obtain an expanded sample of 93 galaxies and examine the relation between BH mass and velocity dispersion (the M{sub BH}-{sigma}{sub *} relation) for active galaxies with low BH masses. The low-mass active galaxies tend to follow the extrapolation of the M{sub BH}-{sigma}{sub *} relation of inactive galaxies. Including results for active galaxies of higher BH mass from the literature, we find a zero point {alpha} = 7.68 {+-} 0.08 and slope of {beta} = 3.32 {+-} 0.22 for the M{sub BH}-{sigma}{sub *} relation (in the form log M{sub BH} = {alpha} + {beta}log ({sigma}{sub *}/200 km s{sup -1})), with intrinsic scatter of 0.46 {+-} 0.03 dex. This result is consistent, within the uncertainties, with the slope of the M{sub BH}-{sigma}{sub *} relation for reverberation-mapped active galaxies with BH masses from 10{sup 6} to 10{sup 9} M{sub sun}. For the subset of our sample having morphological information from Hubble Space Telescope images, we examine the slope of the M{sub BH}-{sigma}{sub *} relation separately for subsamples of barred and unbarred host galaxies, and find no significant evidence for a difference in slope. We do find a mild offset between low-inclination and high-inclination disk galaxies, such that more highly inclined galaxies tend to have larger {sigma}{sub *} at a given value of BH mass, presumably due to the contribution of disk rotation within the spectroscopic aperture. We also find that the velocity dispersion of the ionized gas, measured from narrow emission lines including [N II] {lambda}6583

  4. ALFALFA Hα Reveals How Galaxies Use their HI Fuel

    NASA Astrophysics Data System (ADS)

    Jaskot, Anne; Oey, Sally; Salzer, John; Van Sistine, Angela; Bell, Eric; Haynes, Martha

    2015-08-01

    Atomic hydrogen traces the raw material from which molecular clouds and stars form. With the ALFALFA Hα survey, a statistically complete subset of the ALFALFA survey, we examine the processes that affect galaxies’ abilities to access and consume their HI gas. On galaxy-wide scales, HI gas fractions correlate only weakly with instantaneous specific star formation rates (sSFRs) but tightly with galaxy color. We show that a connection between dust and HI content, arising from the fundamental mass-metallicity-HI relation, leads to this tight color correlation. We find that disk galaxies follow a relation between stellar surface density and HI depletion time, consistent with a scenario in which higher mid-plane pressure leads to more efficient molecular cloud formation from HI. In contrast, spheroids show no such trend. Starbursts, identified by Hα equivalent width, do not show enhanced HI gas fractions relative to similar mass non-starburst galaxies. The starbursts’ shorter HI depletion times indicate more efficient consumption of HI, and galaxy interactions drive this enhanced star formation efficiency in several starbursts. Interestingly, the most disturbed starbursts show greater enhancements in HI gas fraction, which may indicate an excess of HI at early merger stages. At low galaxy stellar masses, the triggering mechanism for starbursts is less clear; the high scatter in efficiency and sSFR among low-mass galaxies may result from periodic bursts. We find no evidence for depleted HI reservoirs in starbursts, which suggests that galaxies may maintain sufficient HI to fuel multiple starburst episodes.

  5. Scaling relations for galaxies of all types with CALIFA and MaNGA surveys.

    NASA Astrophysics Data System (ADS)

    Aquino-Ortíz, E.; Sánchez-Sánchez, S. F.; Valenzuela, O.; Cano-Díaz, M.; Hernández-Toledo, H.

    2016-06-01

    We used gas and stellar kinematics for the final Data Release of 667 spatially resolved galaxies publicly available from Calar Alto Legacy Integral Field Area survey (CALIFA) with the aim of study dynamical scaling relations as Tully & Fisher for rotation velocity, Faber & Jackson for velocity dispersion and also a combination of them through the S_{K} parameter defined as S_{K}^2 = KV_{rot}^2 + σ^2. We found a offset between gas and stellar kinematics in Tully & Fisher and Faber & Jackson relations, however when we used the S_{K} parameter all galaxies regardless of the morphological type lie in this M_{*} vs S_{k} scaling relation with a significant improvement compared with the M_{*} vs V_{rot} and M_{*} vs σ relations, in agreement with previous studies with SAMI survey, however the slope ant zero-point are different with them. We also explored different values of the K parameter, as well as different proxys to estimate V_{rot} in order to understand and characterize the physical source of scatter, slope and zero-point.

  6. Evolution of the stellar-to-dark matter relation: Separating star-forming and passive galaxies from z = 1 to 0

    SciTech Connect

    Tinker, Jeremy L.; Leauthaud, Alexie; Bundy, Kevin; George, Matthew R.; Behroozi, Peter; Wechsler, Risa H.; Massey, Richard; Rhodes, Jason

    2013-12-01

    We use measurements of the stellar mass function, galaxy clustering, and galaxy-galaxy lensing within the COSMOS survey to constrain the stellar-to-halo mass relation (SHMR) of star forming and quiescent galaxies over the redshift range z = [0.2, 1.0]. For massive galaxies, M {sub *} ≳ 10{sup 10.6} M {sub ☉}, our results indicate that star-forming galaxies grow proportionately as fast as their dark matter halos while quiescent galaxies are outpaced by dark matter growth. At lower masses, there is minimal difference in the SHMRs, implying that the majority low-mass quiescent galaxies have only recently been quenched of their star formation. Our analysis also affords a breakdown of all COSMOS galaxies into the relative numbers of central and satellite galaxies for both populations. At z = 1, satellite galaxies dominate the red sequence below the knee in the stellar mass function. But the number of quiescent satellites exhibits minimal redshift evolution; all evolution in the red sequence is due to low-mass central galaxies being quenched of their star formation. At M {sub *} ∼ 10{sup 10} M {sub ☉}, the fraction of central galaxies on the red sequence increases by a factor of 10 over our redshift baseline, while the fraction of quenched satellite galaxies at that mass is constant with redshift. We define a 'migration rate' to the red sequence as the time derivative of the passive galaxy abundances. We find that the migration rate of central galaxies to the red sequence increases by nearly an order of magnitude from z = 1 to z = 0. These results imply that the efficiency of quenching star formation for centrals is increasing with cosmic time, while the mechanisms that quench the star formation of satellite galaxies in groups and clusters is losing efficiency.

  7. Stellar feedback in galaxies and the origin of galaxy-scale winds

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Quataert, Eliot; Murray, Norman

    2012-04-01

    Feedback from massive stars is believed to play a critical role in driving galactic super-winds that enrich the intergalactic medium and shape the galaxy mass function, mass-metallicity relation and other global galaxy properties. In previous papers, we have introduced new numerical methods for implementing stellar feedback on sub-giant molecular cloud (sub-GMC) through galactic scales in numerical simulations of galaxies; the key physical processes include radiation pressure in the ultraviolet through infrared, supernovae (Type I and Type II), stellar winds ('fast' O star through 'slow' asymptotic giant branch winds), and H II photoionization. Here, we show that these feedback mechanisms drive galactic winds with outflow rates as high as ˜10-20 times the galaxy star formation rate. The mass-loading efficiency (wind mass-loss rate divided by the star formation rate) scales roughly as ? (where Vc is the galaxy circular velocity), consistent with simple momentum-conservation expectations. We use our suite of simulations to study the relative contribution of each feedback mechanism to the generation of galactic winds in a range of galaxy models, from Small Magellanic Cloud like dwarfs and Milky Way (MW) analogues to z˜ 2 clumpy discs. In massive, gas-rich systems (local starbursts and high-z galaxies), radiation pressure dominates the wind generation. By contrast, for MW-like spirals and dwarf galaxies the gas densities are much lower and sources of shock-heated gas such as supernovae and stellar winds dominate the production of large-scale outflows. In all of our models, however, the winds have a complex multiphase structure that depends on the interaction between multiple feedback mechanisms operating on different spatial scales and time-scales: any single feedback mechanism fails to reproduce the winds observed. We use our simulations to provide fitting functions to the wind mass loading and velocities as a function of galaxy properties, for use in cosmological

  8. Gravitational redshift of galaxies in clusters as predicted by general relativity.

    PubMed

    Wojtak, Radosław; Hansen, Steen H; Hjorth, Jens

    2011-09-29

    The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the Lambda Cold Dark Matter (ΛCDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independently of the assumptions of the ΛCDM model. Here we report an observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based on archival data. Our measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (the f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter. PMID:21956329

  9. Normalization and scatter of the mass-temperature relation for supermassive galaxy clusters

    NASA Astrophysics Data System (ADS)

    Mandelbaum, Rachel; Nakajima, Reiko; Bernstein, Gary; Donahue, Megan; Keeton, Charles R.; Hughes, John P.; Bahcall, Neta; Schrabback, Tim; Padmanabhan, Nikhil; Miyazaki, Satoshi; Kravtsov, Andrey V.; Cavagnolo, Kenneth

    2009-02-01

    We propose a high-accuracy survey of the 20 most massive clusters in the northern hemisphere at 0.15galaxy, and dark-matter properties (from weak gravitational lensing, WL). All quantities will be determined with high S/N and low systematic errors. The major scientific goals are to (a) determine the normalization and scatter in the mass-temperature relation for massive clusters, which is essential for the use of clusters to constrain cosmological parameters, and (b) use the relations between WL mass, X-ray temperature, and other structural variables to validate numerical models of cluster evolution. There has to date been no cluster lensing survey with sufficiently large sample size and sufficiently low random and systematic errors to infer the intrinsic component of the M-T scatter. We expect to determine the scatter in the M-T relation to +/- 5%. All targets have existing Chandra, XMM, and ASCA X-ray data, HST strong-lensing imaging, and all but two have existing good-seeing image from Subaru or scheduled observation time at MMT. Our project will complete the WL imaging and, with this proposal, obtain multiband Mosaic observations for photometric redshifts. Uniform photo-z's are essential to properly calibrate the WL data and isolate the (unlensed) cluster member galaxies.

  10. Sunyaev-Zeldovich Effect Scaling Relations in Simulated Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Motl, P. M.; Burns, J. O.

    2004-05-01

    We investigate the form and evolution of scaling relations between cluster observables derived from the thermal Sunyaev-Zeldovich effect (SZE) and mass in simulated clusters of galaxies. We use a sophisticated, hybrid Eulerian adaptive mesh refinement / n-body code to simulate both the dark matter and baryonic fluid in the clusters; utilizing the piecewise parabolic scheme for the hydrodynamics. With up to seven levels of dynamic refinement in high density regions, we attain spatial resolution up to ˜ ; 16 kpc in the clusters and we assume a concordance Λ CDM cosmological model. We use four catalogs of clusters of galaxies where each catalog is assembled from simulations assuming different input physics including adiabatic physics only, radiative cooling only, star formation and finally star formation with feedback from supernovae. Each sample contains approximately 100 clusters at the present epoch in the mass range from 1 × 1014 ; M⊙ to 2 × 1015 ; M⊙ and approximately 10 clusters more massive than 1 × 1014 ; M⊙ at a redshift of 2. As the thermal SZE depends on the projection of the gas pressure through the cluster and the cluster medium is in approximate hydrostatic equilibrium with the dark matter potential, we expect that the integrated SZE is relatively insensitive to the detailed heating and cooling processes in the cores of clusters. We confirm this expectation by demonstrating that the derived scaling relations are nearly identical between the four cluster samples considered.

  11. EARLY-TYPE GALAXIES AT z {approx} 1.3. IV. SCALING RELATIONS IN DIFFERENT ENVIRONMENTS

    SciTech Connect

    Raichoor, A.; Mei, S.; Huertas-Company, M.; Stanford, S. A.; Rettura, A.; Jee, M. J.; Holden, B. P.; Illingworth, G.; Rosati, P.; Shankar, F.; Tanaka, M.; Ford, H.; Postman, M.; White, R. L.; Blakeslee, J. P.; Demarco, R.

    2012-02-01

    We present the Kormendy and mass-size relations (MSR) for early-type galaxies (ETGs) as a function of environment at z {approx} 1.3. Our sample includes 76 visually classified ETGs with masses 10{sup 10} < M/M{sub Sun} < 10{sup 11.5}, selected in the Lynx supercluster and in the Great Observatories Origins Deep Survey/Chandra Deep Field South field; 31 ETGs in clusters, 18 in groups, and 27 in the field, all with multi-wavelength photometry and Hubble Space Telescope/Advanced Camera for Surveys observations. The Kormendy relation, in place at z {approx} 1.3, does not depend on the environment. The MSR reveals that ETGs overall appear to be more compact in denser environments: cluster ETGs have sizes on average around 30%-50% smaller than those of the local universe and a distribution with a smaller scatter, whereas field ETGs show an MSR with a similar distribution to the local one. Our results imply that (1) the MSR in the field did not evolve overall from z {approx} 1.3 to present; this is interesting and in contrast to the trend found at higher masses from previous works; (2) in denser environments, either ETGs have increased in size by 30%-50% on average and spread their distributions, or more ETGs have been formed within the dense environment from non-ETG progenitors, or larger galaxies have been accreted to a pristine compact population to reproduce the MSR observed in the local universe. Our results are driven by galaxies with masses M {approx}< 2 Multiplication-Sign 10{sup 11} M{sub Sun} and those with masses M {approx} 10{sup 11} M{sub Sun} follow the same trends as that of the entire sample. Following the Valentinuzzi et al. definition of superdense ETGs, {approx}35%-45% of our cluster sample is made up of superdense ETGs.

  12. THE SUPERMASSIVE BLACK HOLE MASS-SPHEROID STELLAR MASS RELATION FOR SERSIC AND CORE-SERSIC GALAXIES

    SciTech Connect

    Scott, Nicholas; Graham, Alister W; Schombert, James

    2013-05-01

    We have examined the relationship between supermassive black hole mass (M{sub BH}) and the stellar mass of the host spheroid (M{sub sph,*}) for a sample of 75 nearby galaxies. To derive the spheroid stellar masses we used improved Two Micron All Sky Survey K{sub s}-band photometry from the ARCHANGEL photometry pipeline. Dividing our sample into core-Sersic and Sersic galaxies, we find that they are described by very different M{sub BH}-M{sub sph,*} relations. For core-Sersic galaxies-which are typically massive and luminous, with M{sub BH} {approx}> 2 Multiplication-Sign 10{sup 8} M{sub Sun }-we find M{sub BH}{proportional_to} M{sub sph,*}{sup 0.97{+-}0.14}, consistent with other literature relations. However, for the Sersic galaxies-with typically lower masses, M{sub sph,*} {approx}< 3 Multiplication-Sign 10{sup 10} M{sub Sun }-we find M{sub BH}{proportional_to}M{sub sph,*}{sup 2.22{+-}0.58}, a dramatically steeper slope that differs by more than 2 standard deviations. This relation confirms that, for Sersic galaxies, M{sub BH} is not a constant fraction of M{sub sph,*}. Sersic galaxies can grow via the accretion of gas which fuels both star formation and the central black hole, as well as through merging. Their black hole grows significantly more rapidly than their host spheroid, prior to growth by dry merging events that produce core-Sersic galaxies, where the black hole and spheroid grow in lockstep. We have additionally compared our Sersic M{sub BH}-M{sub sph,*} relation with the corresponding relation for nuclear star clusters, confirming that the two classes of central massive object follow significantly different scaling relations.

  13. MOND implications for spectral line profiles of shell galaxies: shell formation history and mass-velocity scaling relations

    NASA Astrophysics Data System (ADS)

    Bílek, M.; Jungwiert, B.; Ebrová, I.; Bartošková, K.

    2015-03-01

    Context. Many ellipticals are surrounded by round stellar shells probably stemming from minor mergers. A new method for constraining gravitational potential in elliptical galaxies has recently been suggested. It uses the spectral line profiles of these shells to measure the circular velocity at the edge of the shell and the expansion velocity of the shell itself. MOND is an alternative to the dark matter framework aiming to solve the missing mass problem. Aims: We study how the circular and expansion velocities behave in MOND for large shells. Methods: The asymptotic behavior for infinitely large shells is derived analytically. The applicability of the asymptotic results for finitely sized shells is studied numerically on a grid of galaxies modeled with Sérsic spheres. Results: Circular velocity settles asymptotically at a value determined by the baryonic mass of the galaxy forming the baryonic Tully-Fisher relation known for disk galaxies. Shell expansion velocity also becomes asymptotically constant. The expansion velocities of large shells form a multibranched analogy to the baryonic Tully-Fisher relation, together with the galactic baryonic masses. For many - but not all - shell galaxies, the asymptotic values of these two types of velocities are reached under the effective radius. If MOND is assumed to work in ellipticals, then the shell spectra allow many details of the history to be revealed about the formation of the shell system, including its age. The results pertaining to circular velocities apply to all elliptical galaxies, not only those with shells.

  14. New candidates for extremely metal-poor emission-line galaxies in the SDSS/BOSS DR10

    NASA Astrophysics Data System (ADS)

    Guseva, N. G.; Izotov, Y. I.; Fricke, K. J.; Henkel, C.

    2015-07-01

    We present a spectroscopic study of eight extremely low-metallicity candidate emission-line galaxies with oxygen abundances possibly below 12 + log O/H = 7.35. These galaxies were selected from data release 10 of the Sloan Digital Sky Survey/Baryon Oscillation Spectroscopic Survey (SDSS/BOSS DR10). We will call these extremely metal-deficient (XMD) galaxies. The electron temperature-sensitive emission line [O iii] λ4363 is detected in three galaxies and marginally detected in two galaxies, allowing for abundance determination by a "direct" method. Because of large uncertainties in the [O iii]λ4363 Å line fluxes, we also calculated oxygen abundance in these galaxies together with the remaining three galaxies using a strong-line semi-empirical method. This method gives oxygen abundances higher than 7.35 for three galaxies with detected [O iii]λ4363 Å line and lower than 7.35 for the remaining five objects of the sample. The newly-discovered galaxies represent excellent targets for follow-up spectroscopic observations with the largest telescopes to improve the oxygen abundance determination and to increase the number of these very rare low-metallicity objects. The extreme location of the most massive and luminous XMD galaxies and XMD candidates in the stellar mass-metallicity diagram implies that these galaxies may be genuine young objects. With stellar masses of up to ~107-108M⊙, the galaxies are not chemically enriched and strongly deviate to lower metallicity as compared to the relation obtained for a large sample of low-redshift, star-forming galaxies. Tables 2-4 are available in electronic form at http://www.aanda.org

  15. The Impact of the Integrated Galaxy IMF on Supernovae Rate

    NASA Astrophysics Data System (ADS)

    Molina, F.; Weidner, C.; Zoccali, M.

    2009-05-01

    Recent research regarding the star formation in star clusters on galaxy wide scales indicates that, in the hypothesis that all stars are born within clusters, the supposedly universal initial stellar mass function (IMF) within young star clusters, does not necessarily yield the same IMF for whole galaxies. As star clusters also follow an embedded cluster mass function (ECMF), the whole integrated galaxy initial stellar mass function (IGIMF) has to be steeper than the individual IMFs of star clusters -- depending on the steepness of the ECMF (Kroupa & Weidner 2003, ApJ, 598, 1076; Weidner & Kroupa 2005, ApJ, 625, 754). This result has found to be able to explain the mass-metallicity relation of galaxies (Köppen et al. 2007, MNRAS, 375, 673). Investigating the effects of the IGIMF further, this project concentrates on the expected temporal evolution of the supernova rate in comparison with a rate for a single-slope Salpeter-like IMF, for a wide range of galaxies with different masses and star-formation histories. Type II and type Ia supernovae are included at a later stage, as well as the influence of massive starbursts.

  16. Galaxy satellites; building blocks and the hierarchical clustering paradigm

    NASA Astrophysics Data System (ADS)

    Padilla, N. D.; Lagos, C.; Cora, S. A.

    We study the properties of building blocks (BBs, i.e. accreted satellites) and surviving satellites of present-day galaxies using a semi-analytic model of galaxy formation in the context of a concordance Cold Dark Mat- ter (CDM) cosmology. We consider large numbers of dark-matter (DM) halo merger trees spanning a wide range of masses ( 1 × 1010 to 2.14 × 1015 M ). Our simulated galaxies show higher metallicities for BBs with respect to surviving satellites, an effect produced by the same processes re- sponsible for the build-up of the mass-metallicity relation. We prove that these metallicity differences arise from the higher peak in the density fluctu- ation field occupied by BBs and central galaxies which have collapsed into a single object earlier than surviving satellites. BBs start to form stars ear- lier, during the peak of the merger activity in the universe, and build up half of their final stellar mass (measured at the moment of disruption) up to four times faster than surviving satellites. Surviving satellites keep increasing their stellar masses rather quiescently from their formation until z 1. The difference between the metallicities of satellites, BBs and central galaxies depends on the host DM halo mass, in a way that can be used as a further test for the concordance cosmology.

  17. THE X-FACTOR IN GALAXIES. II. THE MOLECULAR-HYDROGEN-STAR-FORMATION RELATION

    SciTech Connect

    Feldmann, Robert; Gnedin, Nickolay Y.; Kravtsov, Andrey V. E-mail: feldmann@fnal.gov

    2012-10-20

    There is ample observational evidence that the star formation rate (SFR) surface density, {Sigma}{sub SFR}, is closely correlated with the surface density of molecular hydrogen, {Sigma}{sub H{sub 2}}. This empirical relation holds both for galaxy-wide averages and for individual {approx}>kpc sized patches of the interstellar medium, but appears to degrade substantially at a sub-kpc scale. Identifying the physical mechanisms that determine the scale-dependent properties of the observed {Sigma}{sub H{sub 2}}-{Sigma}{sub SFR} relation using a set of cosmological, galaxy formation simulations with a peak resolution of {approx}100 pc. These simulations include a chemical network for molecular hydrogen, a model for the CO emission, and a simple, stochastic prescription for star formation that operates on {approx}100 pc scales. Specifically, star formation is modeled as a Poisson process in which the average SFR is directly proportional to the present mass of H{sub 2}. The predictions of our numerical model are in good agreement with the observed Kennicutt-Schmidt and {Sigma}{sub H{sub 2}}-{Sigma}{sub SFR} relations. We show that observations based on CO emission are ill suited to reliably measure the slope of the latter relation at low ({approx}< 20 M {sub Sun} pc{sup -2}) H{sub 2} surface densities on sub-kpc scales. Our models also predict that the inferred {Sigma}{sub H{sub 2}}-{Sigma}{sub SFR} relation steepens at high H{sub 2} surface densities as a result of the surface density dependence of the CO/H{sub 2} conversion factor. Finally, we show that on sub-kpc scales most of the scatter of the relation is a consequence of discreteness effects of the star formation process. In contrast, variations of the CO/H{sub 2} conversion factor are responsible for most of the scatter measured on super-kpc scales.

  18. TESTING THE DISTANCE-DUALITY RELATION WITH GALAXY CLUSTERS AND TYPE Ia SUPERNOVAE

    SciTech Connect

    Holanda, R. F. L.; Lima, J. A. S.; Ribeiro, M. B.

    2010-10-20

    In this Letter, we propose a new and model-independent cosmological test for the distance-duality (DD) relation, {eta} = D{sub L} (z)(1 + z){sup -2}/D{sub A} (z) = 1, where D{sub L} and D{sub A} are, respectively, the luminosity and angular diameter distances. For D{sub L} we consider two sub-samples of Type Ia supernovae (SNe Ia) taken from Constitution data whereas D{sub A} distances are provided by two samples of galaxy clusters compiled by De Filippis et al. and Bonamente et al. by combining Sunyaev-Zeldovich effect and X-ray surface brightness. The SNe Ia redshifts of each sub-sample were carefully chosen to coincide with the ones of the associated galaxy cluster sample ({Delta}z < 0.005), thereby allowing a direct test of the DD relation. Since for very low redshifts, D{sub A} (z) ape D{sub L} (z), we have tested the DD relation by assuming that {eta} is a function of the redshift parameterized by two different expressions: {eta}(z) = 1 + {eta}{sub 0} z and {eta}(z) = 1 + {eta}{sub 0} z/(1 + z), where {eta}{sub 0} is a constant parameter quantifying a possible departure from the strict validity of the reciprocity relation ({eta}{sub 0} = 0). In the best scenario (linear parameterization), we obtain {eta}{sub 0} = -0.28{sup +0.44} {sub -0.44} (2{sigma}, statistical + systematic errors) for the De Filippis et al. sample (elliptical geometry), a result only marginally compatible with the DD relation. However, for the Bonamente et al. sample (spherical geometry) the constraint is {eta}{sub 0} = -0.42{sup +0.34} {sub -0.34} (3{sigma}, statistical + systematic errors), which is clearly incompatible with the duality-distance relation.

  19. MEASUREMENT OF GALAXY CLUSTER INTEGRATED COMPTONIZATION AND MASS SCALING RELATIONS WITH THE SOUTH POLE TELESCOPE

    SciTech Connect

    Saliwanchik, B. R.; Montroy, T. E.; Aird, K. A.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Bocquet, S.; Desai, S.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, W. R.; and others

    2015-02-01

    We describe a method for measuring the integrated Comptonization (Y {sub SZ}) of clusters of galaxies from measurements of the Sunyaev-Zel'dovich (SZ) effect in multiple frequency bands and use this method to characterize a sample of galaxy clusters detected in the South Pole Telescope (SPT) data. We use a Markov Chain Monte Carlo method to fit a β-model source profile and integrate Y {sub SZ} within an angular aperture on the sky. In simulated observations of an SPT-like survey that include cosmic microwave background anisotropy, point sources, and atmospheric and instrumental noise at typical SPT-SZ survey levels, we show that we can accurately recover β-model parameters for inputted clusters. We measure Y {sub SZ} for simulated semi-analytic clusters and find that Y {sub SZ} is most accurately determined in an angular aperture comparable to the SPT beam size. We demonstrate the utility of this method to measure Y {sub SZ} and to constrain mass scaling relations using X-ray mass estimates for a sample of 18 galaxy clusters from the SPT-SZ survey. Measuring Y {sub SZ} within a 0.'75 radius aperture, we find an intrinsic log-normal scatter of 21% ± 11% in Y {sub SZ} at a fixed mass. Measuring Y {sub SZ} within a 0.3 Mpc projected radius (equivalent to 0.'75 at the survey median redshift z = 0.6), we find a scatter of 26% ± 9%. Prior to this study, the SPT observable found to have the lowest scatter with mass was cluster detection significance. We demonstrate, from both simulations and SPT observed clusters that Y {sub SZ} measured within an aperture comparable to the SPT beam size is equivalent, in terms of scatter with cluster mass, to SPT cluster detection significance.

  20. Measurement of Galaxy Cluster Integrated Comptonization and Mass Scaling Relations with the South Pole Telescope

    NASA Astrophysics Data System (ADS)

    Saliwanchik, B. R.; Montroy, T. E.; Aird, K. A.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Hlavacek-Larrondo, J.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Jones, C.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Murray, S. S.; Nurgaliev, D.; Padin, S.; Patej, A.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2015-02-01

    We describe a method for measuring the integrated Comptonization (Y SZ) of clusters of galaxies from measurements of the Sunyaev-Zel'dovich (SZ) effect in multiple frequency bands and use this method to characterize a sample of galaxy clusters detected in the South Pole Telescope (SPT) data. We use a Markov Chain Monte Carlo method to fit a β-model source profile and integrate Y SZ within an angular aperture on the sky. In simulated observations of an SPT-like survey that include cosmic microwave background anisotropy, point sources, and atmospheric and instrumental noise at typical SPT-SZ survey levels, we show that we can accurately recover β-model parameters for inputted clusters. We measure Y SZ for simulated semi-analytic clusters and find that Y SZ is most accurately determined in an angular aperture comparable to the SPT beam size. We demonstrate the utility of this method to measure Y SZ and to constrain mass scaling relations using X-ray mass estimates for a sample of 18 galaxy clusters from the SPT-SZ survey. Measuring Y SZ within a 0.'75 radius aperture, we find an intrinsic log-normal scatter of 21% ± 11% in Y SZ at a fixed mass. Measuring Y SZ within a 0.3 Mpc projected radius (equivalent to 0.'75 at the survey median redshift z = 0.6), we find a scatter of 26% ± 9%. Prior to this study, the SPT observable found to have the lowest scatter with mass was cluster detection significance. We demonstrate, from both simulations and SPT observed clusters that Y SZ measured within an aperture comparable to the SPT beam size is equivalent, in terms of scatter with cluster mass, to SPT cluster detection significance.

  1. The Relation Between Accretion Rate And Jet Power in X-Ray Luminous Elliptical Galaxies

    SciTech Connect

    Allen, Steven W.; Dunn, R.J.H.; Fabian, A.C.; Taylor, G.B.; Reynolds, C.S.; /Maryland U.

    2006-03-10

    Using Chandra X-ray observations of nine nearby, X-ray luminous elliptical galaxies with good optical velocity dispersion measurements, we show that a tight correlation exists between the Bondi accretion rates calculated from the observed gas temperature and density profiles and estimated black hole masses, and the power emerging from these systems in relativistic jets. The jet powers, which are inferred from the energies and timescales required to inflate cavities observed in the surrounding X-ray emitting gas, can be related to the accretion rates using a power law model of the form log (P{sub Bondi}/10{sup 43} erg s{sup -1}) = A + B log (P{sub jet}/10{sup 43} erg s{sup -1}), with A = 0.62 {+-} 0.15 and B = 0.77 {+-} 0.18. Our results show that a significant fraction of the energy associated with the rest mass of material entering the Bondi accretion radius (2.4{sub -0.7}{sup +1.0} per cent, for P{sub jet} = 10{sup 43} erg s{sup -1}) eventually emerges in the relativistic jets. Our results have significant implications for studies of accretion, jet formation and galaxy formation. The observed tight correlation suggests that the Bondi formulae provide a reasonable description of the accretion process in these systems, despite the likely presence of magnetic pressure and angular momentum in the accreting gas. The similarity of the P{sub Bondi} and P{sub jet} values argues that a significant fraction of the matter entering the accretion radius flows down to regions close to the black holes, where the jets are presumably formed. The tight correlation between P{sub Bondi} and P{sub jet} also suggests that the accretion flows are approximately stable over timescales of a few million years. Our results show that the black hole ''engines'' at the hearts of large elliptical galaxies and groups feed back sufficient energy to stem cooling and star formation, leading naturally to the observed exponential cut off at the bright end of the galaxy luminosity function.

  2. THE GALAXY-HALO/SUBHALO CONNECTION: MASS RELATIONS AND IMPLICATIONS FOR SOME SATELLITE OCCUPATIONAL DISTRIBUTIONS

    SciTech Connect

    Rodriguez-Puebla, A.; Avila-Reese, V.; Drory, N.

    2013-04-10

    We infer the local stellar-to-halo/subhalo mass relations (MRs) for central and satellite galaxies separately. Our statistical method is an extension of the abundance matching, halo occupation distribution, and conditional stellar mass function formalisms. We constrain the model using several combinations of observational data, consisting of the total galaxy stellar mass function (GSMF), its decomposition into centrals and satellites, and the projected two-point correlation functions (2PCFs) measured in different stellar mass (M{sub *}) bins. In addition, we use the {Lambda}CDM halo and subhalo mass functions. The differences among the resulting MRs are within the model-fit uncertainties (which are very small, smaller than the intrinsic scatter between galaxy and halo mass), no matter what combination of data are used. This shows that matching abundances or occupational numbers is equivalent, and that the GSMFs and 2PCFs are tightly connected. We also constrain the values of the intrinsic scatter around the central-halo (CH) and satellite-subhalo (SS) MRs assuming them to be constant: {sigma}{sub c} = 0.168 {+-} 0.051 dex and {sigma}{sub s} = 0.172 {+-} 0.057 dex, respectively. The CH and SS MRs are actually different, in particular when we take the subhalo mass at the present-day epoch instead of at their accretion time. When using the MRs for studying the satellite population (e.g., in the Milky Way, MW), the SS MR should be chosen instead of the average one. Our model allows one to calculate several population statistics. We find that the central galaxy M{sub *} is not on average within the mass distribution of the most massive satellite, even for cluster-sized halos, i.e., centrals are not a mere realization of the high end of the satellite mass function; however for >3 Multiplication-Sign 10{sup 13} M{sub Sun} halos, {approx}15% of centrals could be. We also find that the probabilities of MW-sized halos of having N Magellanic Cloud (MC) sized satellites agree

  3. Galaxy And Mass Assembly (GAMA): mass-size relations of z < 0.1 galaxies subdivided by Sérsic index, colour and morphology

    NASA Astrophysics Data System (ADS)

    Lange, Rebecca; Driver, Simon P.; Robotham, Aaron S. G.; Kelvin, Lee S.; Graham, Alister W.; Alpaslan, Mehmet; Andrews, Stephen K.; Baldry, Ivan K.; Bamford, Steven; Bland-Hawthorn, Joss; Brough, Sarah; Cluver, Michelle E.; Conselice, Christopher J.; Davies, Luke J. M.; Haeussler, Boris; Konstantopoulos, Iraklis S.; Loveday, Jon; Moffett, Amanda J.; Norberg, Peder; Phillipps, Steven; Taylor, Edward N.; López-Sánchez, Ángel R.; Wilkins, Stephen M.

    2015-03-01

    We use data from the Galaxy And Mass Assembly (GAMA) survey in the redshift range 0.01 < z < 0.1 (8399 galaxies in g to Ks bands) to derive the stellar mass-half-light radius relations for various divisions of `early'- and `late'-type samples. We find that the choice of division between early and late (i.e. colour, shape, morphology) is not particularly critical; however, the adopted mass limits and sample selections (i.e. the careful rejection of outliers and use of robust fitting methods) are important. In particular, we note that for samples extending to low stellar mass limits (<10^{10} M_{⊙}) the Sérsic index bimodality, evident for high-mass systems, becomes less distinct and no-longer acts as a reliable separator of early- and late-type systems. The final set of stellar mass-half-light radius relations are reported for a variety of galaxy population subsets in 10 bands (ugrizZY JHKs) and are intended to provide a comprehensive low-z benchmark for the many ongoing high-z studies. Exploring the variation of the stellar mass-half-light radius relations with wavelength, we confirm earlier findings that galaxies appear more compact at longer wavelengths albeit at a smaller level than previously noted: at 10^{10} M_{⊙}} both spiral systems and ellipticals show a decrease in size of 13 per cent from g to Ks (which is near linear in log wavelength). Finally, we note that the sizes used in this work are derived from 2D Sérsic light profile fitting (using GALFIT3), i.e. elliptical semimajor half-light radii, improving on earlier low-z benchmarks based on circular apertures.

  4. LONG GRBs ARE METALLICITY-BIASED TRACERS OF STAR FORMATION: EVIDENCE FROM HOST GALAXIES AND REDSHIFT DISTRIBUTION

    SciTech Connect

    Wang, F. Y.; Dai, Z. G. E-mail: dzg@nju.edu.cn

    2014-07-01

    We investigate the mass distribution of long gamma-ray burst (GRB) host galaxies and the redshift distribution of long GRBs by considering that long GRBs occur in low-metallicity environments. We calculate the upper limit on the stellar mass of a galaxy which can produce long GRBs by utilizing the mass-metallicity (M-Z) relation of galaxies. After comparing with the observed GRB host galaxies masses, we find that the observed GRB host galaxy masses can fit the predicted masses well if GRBs occur in low-metallicity 12 + log (O/H){sub KK04} < 8.7. GRB host galaxies have low metallicity, low mass, and high star formation rate compared with galaxies of seventh data release of the Sloan Digital Sky Survey. We also study the cumulative redshift distribution of the latest Swift long GRBs by adding dark GRBs and 10 new GRBs redshifts from the TOUGH survey. The observed discrepancy between the GRB rate and the star formation history can be reconciled by considering that GRBs tend to occur in low-metallicity galaxies with 12 + log (O/H){sub KK04} < 8.7. We conclude that the metallicity cutoff that can produce long GRBs is about 12 + log (O/H){sub KK04} < 8.7 from the host mass distribution and redshift distribution.

  5. UNBIASED CORRECTION RELATIONS FOR GALAXY CLUSTER PROPERTIES DERIVED FROM CHANDRA AND XMM-NEWTON

    SciTech Connect

    Zhao, Hai-Hui; Li, Cheng-Kui; Chen, Yong; Jia, Shu-Mei; Song, Li-Ming

    2015-01-20

    We use a sample of 62 clusters of galaxies to investigate the discrepancies between the gas temperature and total mass within r {sub 500} from XMM-Newton and Chandra data. Comparisons of the properties show that (1) both the de-projected and projected temperatures determined by Chandra are higher than those of XMM-Newton and there is a good linear relationship for the de-projected temperatures: T {sub Chandra} = 1.25 × T {sub XMM}–0.13. (2) The Chandra mass is much higher than the XMM-Newton mass with a bias of 0.15 and our mass relation is log{sub 10} M {sub Chandra} = 1.02 × log{sub 10} M {sub XMM}+0.15. To explore the reasons for the discrepancy in mass, we recalculate the Chandra mass (expressed as M{sub Ch}{sup mo/d}) by modifying its temperature with the de-projected temperature relation. The results show that M{sub Ch}{sup mo/d} is closer to the XMM-Newton mass with the bias reducing to 0.02. Moreover, M{sub Ch}{sup mo/d} are corrected with the r {sub 500} measured by XMM-Newton and the intrinsic scatter is significantly improved with the value reducing from 0.20 to 0.12. These mean that the temperature bias may be the main factor causing the mass bias. Finally, we find that M{sub Ch}{sup mo/d} is consistent with the corresponding XMM-Newton mass derived directly from our mass relation at a given Chandra mass. Thus, the de-projected temperature and mass relations can provide unbiased corrections for galaxy cluster properties derived from Chandra and XMM-Newton.

  6. A CENSUS OF OXYGEN IN STAR-FORMING GALAXIES: AN EMPIRICAL MODEL LINKING METALLICITIES, STAR FORMATION RATES, AND OUTFLOWS

    SciTech Connect

    Zahid, H. J.; Dima, G. I.; Kewley, L. J.; Erb, D. K.; Dave, R.

    2012-09-20

    In this contribution, we present the first census of oxygen in star-forming galaxies in the local universe. We examine three samples of galaxies with metallicities and star formation rates (SFRs) at z = 0.07, 0.8, and 2.26, including the Sloan Digital Sky Survey (SDSS) and DEEP2 survey. We infer the total mass of oxygen produced and mass of oxygen found in the gas-phase from our local SDSS sample. The star formation history is determined by requiring that galaxies evolve along the relation between stellar mass and SFR observed in our three samples. We show that the observed relation between stellar mass and SFR for our three samples is consistent with other samples in the literature. The mass-metallicity relation is well established for our three samples, and from this we empirically determine the chemical evolution of star-forming galaxies. Thus, we are able to simultaneously constrain the SFRs and metallicities of galaxies over cosmic time, allowing us to estimate the mass of oxygen locked up in stars. Combining this work with independent measurements reported in the literature, we conclude that the loss of oxygen from the interstellar medium of local star-forming galaxies is likely to be a ubiquitous process with the oxygen mass loss scaling (almost) linearly with stellar mass. We estimate the total baryonic mass loss and argue that only a small fraction of the baryons inferred from cosmological observations accrete onto galaxies.

  7. Energy, entropy and mass scaling relations for elliptical galaxies. Towards a physical understanding of their photometric properties

    NASA Astrophysics Data System (ADS)

    Márquez, I.; Lima Neto, G. B.; Capelato, H.; Durret, F.; Lanzoni, B.; Gerbal, D.

    2001-12-01

    In the present paper, we show that elliptical galaxies (Es) obey a scaling relation between potential energy and mass. Since they are relaxed systems in a post violent-relaxation stage, they are quasi-equilibrium gravitational systems and therefore they also have a quasi-constant specific entropy. Assuming that light traces mass, these two laws imply that in the space defined by the three Sérsic law parameters (intensity Sigma0 , scale a and shape nu ), elliptical galaxies are distributed on two intersecting 2-manifolds: the Entropic Surface and the Energy-Mass Surface. Using a sample of 132 galaxies belonging to three nearby clusters, we have verified that ellipticals indeed follow these laws. This also implies that they are distributed along the intersection line (the Energy-Entropy line), thus they constitute a one-parameter family. These two physical laws (separately or combined), allow to find the theoretical origin of several observed photometrical relations, such as the correlation between absolute magnitude and effective surface brightness, and the fact that ellipticals are located on a surface in the [log Reff, -2.5 log Sigma0, log nu ] space. The fact that elliptical galaxies are a one-parameter family has important implications for cosmology and galaxy formation and evolution models. Moreover, the Energy-Entropy line could be used as a distance indicator.

  8. Weak Lensing Calibrated M-T Scaling Relation of Galaxy Groups in the COSMOS Fieldsstarf

    NASA Astrophysics Data System (ADS)

    Kettula, K.; Finoguenov, A.; Massey, R.; Rhodes, J.; Hoekstra, H.; Taylor, J. E.; Spinelli, P. F.; Tanaka, M.; Ilbert, O.; Capak, P.; McCracken, H. J.; Koekemoer, A.

    2013-11-01

    The scaling between X-ray observables and mass for galaxy clusters and groups is instrumental for cluster-based cosmology and an important probe for the thermodynamics of the intracluster gas. We calibrate a scaling relation between the weak lensing mass and X-ray spectroscopic temperature for 10 galaxy groups in the COSMOS field, combined with 55 higher-mass clusters from the literature. The COSMOS data includes Hubble Space Telescope imaging and redshift measurements of 46 source galaxies per arcminute2, enabling us to perform unique weak lensing measurements of low-mass systems. Our sample extends the mass range of the lensing calibrated M-T relation an order of magnitude lower than any previous study, resulting in a power-law slope of 1.48^{+0.13}_{-0.09}. The slope is consistent with the self-similar model, predictions from simulations, and observations of clusters. However, X-ray observations relying on mass measurements derived under the assumption of hydrostatic equilibrium have indicated that masses at group scales are lower than expected. Both simulations and observations suggest that hydrostatic mass measurements can be biased low. Our external weak lensing masses provide the first observational support for hydrostatic mass bias at group level, showing an increasing bias with decreasing temperature and reaching a level of 30%-50% at 1 keV. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc., under NASA contract NAS 5-26555. Also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and the National Optical Astronomy Observatory, which

  9. MOIRCS DEEP SURVEY. V. A UNIVERSAL RELATION FOR STELLAR MASS AND SURFACE BRIGHTNESS OF GALAXIES

    SciTech Connect

    Ichikawa, Takashi; Kajisawa, Masaru; Yamada, Toru; Akiyama, Masayuki; Yoshikawa, Tomohiro; Onodera, Masato

    2010-02-01

    We present a universal linear correlation between the stellar mass and surface brightness (SB) of galaxies at 0.3 < z < 3, using a deep K-band-selected catalog in the GOODS-North region. The correlation has a nearly constant slope, independent of redshift and color of galaxies in the rest-z frame. Considering unresolved compact galaxies, the tight correlation gives a lower boundary of SB for a given stellar mass; lower SB galaxies are prohibited over the boundary. The universal slope suggests that the stellar mass in galaxies was built up over their cosmic histories in a similar manner irrelevant to galaxy mass, as opposed to the scenario that massive galaxies mainly accumulated their stellar mass by major merging. In contrast, SB shows a strong dependence on redshift for a given stellar mass. It evolves as approx(1 + z){sup -2.0a}pprox{sup -0.8}, in addition to dimming as (1 + z){sup 4} by the cosmological expansion effect. The brightening depends on galaxy color and stellar mass. The blue population (rest-frame U - V < 0), which is dominated by young and star-forming galaxies, evolves as approx(1 + z){sup -0.8+}-{sup 0.3} in the rest-V band. On the other hand, the red population (U - V>0) and the massive galaxies (M{sub *}>10{sup 10} M{sub sun}) show stronger brightening, (1 + z){sup -1.5+}-{sup 0.1}. By comparison with galaxy evolution models, the phenomena are well understood by the pure luminosity evolution of galaxies out to z approx 3.

  10. Measuring the distance-redshift relation with the baryon acoustic oscillations of galaxy clusters

    NASA Astrophysics Data System (ADS)

    Veropalumbo, A.; Marulli, F.; Moscardini, L.; Moresco, M.; Cimatti, A.

    2016-05-01

    We analyse the largest spectroscopic samples of galaxy clusters to date, and provide observational constraints on the distance-redshift relation from baryon acoustic oscillations. The cluster samples considered in this work have been extracted from the Sloan Digital Sky Survey at three median redshifts, z = 0.2, 0.3 and 0.5. The number of objects is 12 910, 42 215 and 11 816, respectively. We detect the peak of baryon acoustic oscillations for all the three samples. The derived distance constraints are rs/DV(z = 0.2) = 0.18 ± 0.01, rs/DV(z = 0.3) = 0.124 ± 0.004 and rs/DV(z = 0.5) = 0.080 ± 0.002. Combining these measurements with the sound horizon scale measured from the cosmic microwave background, we obtain robust constraints on cosmological parameters. Our results are in agreement with the standard Λ cold dark matter (ΛCDM) model. Specifically, we constrain the Hubble constant in a ΛCDM model, H_0 = 64_{-8}^{+17} km s^{-1} Mpc^{-1} , the density of curvature energy, in the oΛCDM context, Ω _K = -0.01_{-0.33}^{+0.34}, and finally the parameter of the dark energy equation of state in the wCDM case, w = -1.06_{-0.52}^{+0.49}. This is the first time the distance-redshift relation has been constrained using only the peak of baryon acoustic oscillations of galaxy clusters.

  11. The relation between the gas, dust and total mass in edge-on spiral galaxies

    NASA Astrophysics Data System (ADS)

    Allaert, Flor

    2015-02-01

    Each component of a galaxy plays its own unique role in regulating the galaxy's evolution. In order to understand how galaxies form and evolve, it is therefore crucial to study the distribution and properties of each of the various components, and the links between them, both radially and vertically. The latter is only possible in edge-on systems. We present the HEROES project, which aims to investigate the 3D structure of the interstellar gas, dust, stars and dark matter in a sample of 7 massive early-type spiral galaxies based on a multi-wavelength data set including optical, NIR, FIR and radio data.

  12. The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for MaxBCG Galaxy Clusters

    SciTech Connect

    Becker, M.R.; McKay, T.A.; Koester, B.; Wechsler, R.H.; Rozo, E.; Evrard, A.; Johnston, D.; Sheldon, E.; Annis, J.; Lau, E.; Nichol, R.; Miller, C.; /Michigan U.

    2007-06-05

    The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG--galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202 {+-} 10 km s{sup -1} for small groups to more than 854 {+-} 102 km s{sup -1} for large clusters. We show the scatter to be at most 40.5{+-}3.5%, declining to 14.9{+-}9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass--observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.

  13. Refining the M {sub BH}-V {sub c} scaling relation with H I rotation curves of water megamaser galaxies

    SciTech Connect

    Sun, Ai-Lei; Greene, Jenny E.; Impellizzeri, C. M. Violette; Braatz, James A.; Kuo, Cheng-Yu; Tuttle, Sarah

    2013-11-20

    Black-hole-galaxy scaling relations provide information about the coevolution of supermassive black holes and their host galaxies. We compare the black-hole mass-circular-velocity (M {sub BH}-V {sub c}) relation with the black-hole-mass-bulge-stellar-velocity-dispersion (M {sub BH}-σ{sub *}) relation to see whether the scaling relations can passively emerge from a large number of mergers or require a physical mechanism, such as feedback from an active nucleus. We present Very Large Array H I observations of five galaxies, including three water megamaser galaxies, to measure the circular velocity. Using 22 galaxies with dynamical M {sub BH} measurements and V {sub c} measurements extending to large radius, our best-fit M {sub BH}-V {sub c} relation, log M{sub BH}=α+βlog (V{sub c}/200 km s{sup −1}), yields α=7.43{sub −0.13}{sup +0.13}, β=3.68{sub −1.20}{sup +1.23}, and an intrinsic scatter ϵ{sub int}=0.51{sub −0.09}{sup +0.11}. The intrinsic scatter may well be higher than 0.51, as we take great care to ascribe conservatively large observational errors. We find comparable scatter in the M {sub BH}-σ{sub *} relations, ϵ{sub int}=0.48{sub −0.08}{sup +0.10}, while pure merging scenarios would likely result in a tighter scaling with the dark halo (as traced by V {sub c}) properties rather than the baryonic (σ{sub *}) properties. Instead, feedback from the active nucleus may act on bulge scales to tighten the M {sub BH}-σ{sub *} relation with respect to the M {sub BH}-V {sub c} relation, as observed.

  14. The radio continuum-star formation rate relation in WSRT sings galaxies

    SciTech Connect

    Heesen, Volker; Brinks, Elias; Leroy, Adam K.; Heald, George; Braun, Robert; Bigiel, Frank; Beck, Rainer E-mail: v.heesen@soton.ac.uk E-mail: heald@astron.nl E-mail: bigiel@uni-heidelberg.de

    2014-05-01

    We present a study of the spatially resolved radio continuum-star formation rate (RC-SFR) relation using state-of-the-art star formation tracers in a sample of 17 THINGS galaxies. We use SFR surface density (Σ{sub SFR}) maps created by a linear combination of GALEX far-UV (FUV) and Spitzer 24 μm maps. We use RC maps at λλ22 and 18 cm from the WSRT SINGS survey and Hα emission maps to correct for thermal RC emission. We compare azimuthally averaged radial profiles of the RC and FUV/mid-IR (MIR) based Σ{sub SFR} maps and study pixel-by-pixel correlations at fixed linear scales of 1.2 and 0.7 kpc. The ratio of the integrated SFRs from the RC emission to that of the FUV/MIR-based SF tracers is R{sub int}=0.78±0.38, consistent with the relation by Condon. We find a tight correlation between the radial profiles of the radio and FUV/MIR-based Σ{sub SFR} for the entire extent of the disk. The ratio R of the azimuthally averaged radio to FUV/MIR-based Σ{sub SFR} agrees with the integrated ratio and has only quasi-random fluctuations with galactocentric radius that are relatively small (25%). Pixel-by-pixel plots show a tight correlation in log-log diagrams of radio to FUV/MIR-based Σ{sub SFR}, with a typical standard deviation of a factor of two. Averaged over our sample we find (Σ{sub SFR}){sub RC}∝(Σ{sub SFR}){sub hyb}{sup 0.63±0.25}, implying that data points with high Σ{sub SFR} are relatively radio dim, whereas the reverse is true for low Σ{sub SFR}. We interpret this as a result of spectral aging of cosmic-ray electrons (CREs), which are diffusing away from the star formation sites where they are injected into the interstellar medium. This is supported by our finding that the radio spectral index is a second parameter in pixel-by-pixel plots: those data points dominated by young CREs are relatively radio dim, while those dominated by old CREs are slightly more RC bright than what would be expected from a linear extrapolation. We studied the ratio R of

  15. The relation between mass and concentration in X-ray galaxy clusters at high redshift

    NASA Astrophysics Data System (ADS)

    Amodeo, S.; Ettori, S.; Capasso, R.; Sereno, M.

    2016-05-01

    Context. Galaxy clusters are the most recent, gravitationally bound products of the hierarchical mass accretion over cosmological scales. How the mass is concentrated is predicted to correlate with the total mass in the halo of the cluster, wherein systems at higher mass are less concentrated at given redshift and, for any given mass, systems with lower concentration are found at higher redshifts. Aims: Through a spatial and spectral X-ray analysis, we reconstruct the total mass profile of 47 galaxy clusters observed with Chandra in the redshift range 0.4 relation between the mass and dark matter concentration and the evolution of this relation with redshift. This sample is the largest investigated so far at z> 0.4, and is well suited to providing the first constraint on the concentration-mass relation at z> 0.7 from X-ray analysis. Methods: Under the assumption that the distribution of the X-ray emitting gas is spherically symmetric and in the hydrostatic equilibrium with the underlined gravitational potential, we combine the deprojected gas density and spectral temperature profiles through the hydrostatic equilibrium equation to recover the parameters that describe a Navarro-Frenk-White total mass distribution. The comparison with results from weak-lensing analysis reveals a very good agreement both for masses and concentrations. The uncertainties are however too large to make any robust conclusion about the hydrostatic bias of these systems. Results: The distribution of concentrations is well approximated by a log-normal function in all the mass and redshift ranges investigated. The relation is well described by the form c ∝ MB(1 + z)C with B = -0.50 ± 0.20, C = 0.12 ± 0.61 (at 68.3% confidence). This relation is slightly steeper than that predicted by numerical simulations (B ~ -0.1) and does not show any evident redshift evolution. We obtain the first constraints on the properties of

  16. Mass-Concentration Relation of Clusters of Galaxies from CFHTLenS

    NASA Astrophysics Data System (ADS)

    Du, Wei; Fan, Zuhui; Shan, Huanyuan; Zhao, Gong-Bo; Covone, Giovanni; Fu, Liping; Kneib, Jean-Paul

    2015-12-01

    Based on weak lensing data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), in this paper we study the mass-concentration (M-c) relation for ˜200 redMaPPer clusters in the fields. We extract the M-c relation by measuring the density profiles of individual clusters instead of using stacked weak lensing signals. By performing Monte Carlo simulations, we demonstrate that although the signal-to-noise ratio for each individual cluster is low, the unbiased M-c relation can still be reliably derived from a large sample of clusters by carefully taking into account the impacts of shape noise, cluster center offset, dilution effect from member or foreground galaxies, and the projection effect. Our results show that within error bars the derived M-c relation for redMaPPer clusters is in agreement with simulation predictions. There is a weak deviation in that the halo concentrations calibrated by Monte Carlo simulations are somewhat higher than that predicted from Planck cosmology.

  17. Fossil group origins - VI. Global X-ray scaling relations of fossil galaxy clusters

    NASA Astrophysics Data System (ADS)

    Kundert, A.; Gastaldello, F.; D'Onghia, E.; Girardi, M.; Aguerri, J. A. L.; Barrena, R.; Corsini, E. M.; De Grandi, S.; Jiménez-Bailón, E.; Lozada-Muñoz, M.; Méndez-Abreu, J.; Sánchez-Janssen, R.; Wilcots, E.; Zarattini, S.

    2015-11-01

    We present the first pointed X-ray observations of 10 candidate fossil galaxy groups and clusters. With these Suzaku observations, we determine global temperatures and bolometric X-ray luminosities of the intracluster medium (ICM) out to r500 for six systems in our sample. The remaining four systems show signs of significant contamination from non-ICM sources. For the six objects with successfully determined r500 properties, we measure global temperatures in the range 2.8 ≤ TX ≤ 5.3 keV, bolometric X-ray luminosities of 0.8 × 1044 ≤ LX, bol ≤ 7.7 × 1044 erg s-1, and estimate masses, as derived from TX, of M500 ≳ 1014 M⊙. Fossil cluster scaling relations are constructed for a sample that combines our Suzaku observed fossils with fossils in the literature. Using measurements of global X-ray luminosity, temperature, optical luminosity, and velocity dispersion, scaling relations for the fossil sample are then compared with a control sample of non-fossil systems. We find the fits of our fossil cluster scaling relations are consistent with the relations for normal groups and clusters, indicating fossil clusters have global ICM X-ray properties similar to those of comparable mass non-fossil systems.

  18. A Theoretical Study of the Luminosity-Temperature Relation for Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Del Popolo, A.; Hiotelis, N.; Peñarrubia, J.

    2005-07-01

    A luminosity-temperature relation is derived for clusters of galaxies. The two models used take into account the angular momentum acquisition by the protostructures during their expansion and collapse. The first model is a modification of the self-similar model, while the second is a modification of the punctuated equilibria model of Cavaliere et al. In both models the mass-temperature relation (M-T) used is based on previous calculations of Del Popolo. We show that the above models lead, in X-rays, to a luminosity-temperature relation that scales as L~T5 at the scale of groups, flattening to L~T3 for rich clusters and converging to L~T2 at higher temperatures. However, a fundamental result of our paper is that the nonsimilarity in the L-T relation can be explained by a simple model that takes into account the amount of angular momentum of a protostructure. This result is in disagreement with the widely accepted idea that the nonsimilarity is due to nongravitating processes, such as heating and/or cooling.

  19. Inferences on the Relations Between Central Black Hole Mass and Total Galaxy Stellar Mass in the High-redshift Universe

    NASA Astrophysics Data System (ADS)

    Volonteri, Marta; Reines, Amy E.

    2016-03-01

    At the highest redshifts, z\\gt 6, several tens of luminous quasars have been detected. The search for fainter active galactic nucleus (AGN), in deep X-ray surveys, has proven less successful, with few candidates to date. An extrapolation of the relationship between black hole (BH) and bulge mass would predict that the sample of z\\gt 6 galaxies host relatively massive BHs (\\gt {10}6 {M}⊙ ), if one assumes that total stellar mass is a good proxy for bulge mass. At least a few of these BHs should be luminous enough to be detectable in the 4Ms CDFS. The relation between BH and stellar mass defined by local moderate-luminosity AGNs in low-mass galaxies, however, has a normalization that is lower by approximately an order of magnitude compared to the BH-bulge mass relation. We explore how this scaling changes the interpretation of AGNs in the high-z universe. Despite large uncertainties, driven by those in the stellar mass function, and in the extrapolation of local relations, one can explain the current non-detection of moderate-luminosity AGNs in Lyman Break Galaxies if galaxies below {10}11 {M}⊙ are characterized by the low-normalization scaling, and, even more so, if their Eddington ratio is also typical of moderate-luminosity AGNs rather than luminous quasars. AGNs being missed by X-ray searches due to obscuration or instrinsic X-ray weakness also remain a possibility.

  20. A relation between the dark mass of elliptical galaxies and their shape

    NASA Astrophysics Data System (ADS)

    Deur, A.

    2014-02-01

    We have studied a large number of elliptical galaxies and found a correlation between their dark matter content and the ellipticity of their visible shape. The galaxies were strictly selected so that only typical medium-size elliptical galaxies were considered. Galaxies with unusual characteristics were rejected to minimize point-to-point data scatter and avoid systematic biases. Data from six different techniques of extracting the galactic dark matter content were used to avoid methodological biases. A thorough investigation of the interrelation between attributes of elliptical galaxies was carried out to assess whether the correlation originates from an observational bias, but no such origin could be identified. At face value, the correlation found implies that at equal luminosities, rounder medium-size elliptical galaxies appear to contain less dark matter than flatter elliptical galaxies, e.g. the rounder galaxies are on average four times less massive than the flatter ones. This is puzzling in the context of the conventional model of cosmological structure formation.

  1. COLOR-MAGNITUDE RELATIONS OF EARLY-TYPE DWARF GALAXIES IN THE VIRGO CLUSTER: AN ULTRAVIOLET PERSPECTIVE

    SciTech Connect

    Kim, Suk; Rey, Soo-Chang; Lisker, Thorsten; Sohn, Sangmo Tony E-mail: screy@cnu.ac.k

    2010-09-20

    We present ultraviolet (UV) color-magnitude relations (CMRs) of early-type dwarf galaxies in the Virgo cluster, based on Galaxy Evolution Explorer (GALEX) UV and Sloan Digital Sky Survey (SDSS) optical imaging data. We find that dwarf lenticular galaxies (dS0s), including peculiar dwarf elliptical galaxies (dEs) with disk substructures and blue centers, show a surprisingly distinct and tight locus separated from that of ordinary dEs, which is not clearly seen in previous CMRs. The dS0s in UV CMRs follow a steeper sequence than dEs and show bluer UV-optical color at a given magnitude. We also find that the UV CMRs of dEs in the outer cluster region are slightly steeper than that of their counterparts in the inner region, due to the existence of faint, blue dEs in the outer region. We explore the observed CMRs with population models of a luminosity-dependent delayed exponential star formation history. We confirm that the feature of delayed star formation of early-type dwarf galaxies in the Virgo cluster is strongly correlated with their morphology and environment. The observed CMR of dS0s is well matched by models with relatively long delayed star formation. Our results suggest that dS0s are most likely transitional objects at the stage of subsequent transformation of late-type progenitors to ordinary red dEs in the cluster environment. In any case, UV photometry provides a powerful tool to disentangle the diverse subpopulations of early-type dwarf galaxies and uncover their evolutionary histories.

  2. The MUSIC of galaxy clusters - II. X-ray global properties and scaling relations

    NASA Astrophysics Data System (ADS)

    Biffi, V.; Sembolini, F.; De Petris, M.; Valdarnini, R.; Yepes, G.; Gottlöber, S.

    2014-03-01

    We present the X-ray properties and scaling relations of a large sample of clusters extracted from the Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC) data set. We focus on a sub-sample of 179 clusters at redshift z ˜ 0.11, with 3.2 × 1014 h-1 M⊙ < Mvir < 2 × 1015 h-1 M⊙, complete in mass. We employed the X-ray photon simulator PHOX to obtain synthetic Chandra observations and derive observable-like global properties of the intracluster medium (ICM), as X-ray temperature (TX) and luminosity (LX). TX is found to slightly underestimate the true mass-weighted temperature, although tracing fairly well the cluster total mass. We also study the effects of TX on scaling relations with cluster intrinsic properties: total (M500 and gas Mg,500 mass; integrated Compton parameter (YSZ) of the Sunyaev-Zel'dovich (SZ) thermal effect; YX = Mg,500 TX. We confirm that YX is a very good mass proxy, with a scatter on M500-YX and YSZ-YX lower than 5 per cent. The study of scaling relations among X-ray, intrinsic and SZ properties indicates that simulated MUSIC clusters reasonably resemble the self-similar prediction, especially for correlations involving TX. The observational approach also allows for a more direct comparison with real clusters, from which we find deviations mainly due to the physical description of the ICM, affecting TX and, particularly, LX.

  3. Robust automatic photometry of local galaxies from SDSS. Dissecting the color magnitude relation with color profiles

    NASA Astrophysics Data System (ADS)

    Consolandi, Guido; Gavazzi, Giuseppe; Fumagalli, Michele; Dotti, Massimo; Fossati, Matteo

    2016-06-01

    We present an automatic procedure to perform reliable photometry of galaxies on SDSS images. We selected a sample of 5853 galaxies in the Coma and Virgo superclusters. For each galaxy, we derive Petrosian g and i magnitudes, surface brightness and color profiles. Unlike the SDSS pipeline, our procedure is not affected by the well known shredding problem and efficiently extracts Petrosian magnitudes for all galaxies. Hence we derived magnitudes even from the population of galaxies missed by the SDSS which represents ~25% of all local supercluster galaxies and ~95% of galaxies with g < 11 mag. After correcting the g and i magnitudes for Galactic and internal extinction, the blue and red sequences in the color magnitude diagram are well separated, with similar slopes. In addition, we study (i) the color-magnitude diagrams in different galaxy regions, the inner (r ≤ 1 kpc), intermediate (0.2RPet ≤ r ≤ 0.3RPet) and outer, disk-dominated (r ≥ 0.35RPet)) zone; and (ii), we compute template color profiles, discussing the dependences of the templates on the galaxy masses and on their morphological type. The two analyses consistently lead to a picture where elliptical galaxies show no color gradients, irrespective of their masses. Spirals, instead, display a steeper gradient in their color profiles with increasing mass, which is consistent with the growing relevance of a bulge and/or a bar component above 1010 M⊙. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A38

  4. Which Galaxies Are the Most Habitable?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-09-01

    Habitable zones are a hot topic in exoplanet studies: where, around a given star, could a planet exist that supports life? But if you scale this up, you get a much less common question: which type of galaxy is most likely to host complex life in the universe? A team of researchers from the UK believes it has the answer.Criteria for HabitabilityLed by Pratika Dayal of the University of Durham, the authors of this study set out to estimate the habitability of a large population of galaxies. The first step in this process is to determine what elements contribute to a galaxys habitability. The authors note three primary factors:Total number of starsMore stars means more planets!Metallicity of the starsPlanets are more likely to form in stellar vicinities with higher metallicities, since planet formation requires elements heavier than iron.Likelihood of Type II supernovae nearbyPlanets that are located out of range of supernovae have a higher probability of being habitable, since a major dose of cosmic radiation is likely to cause mass extinctions or delay evolution of complex life. Galaxies supernova rates can be estimated from their star formation rates (the two are connected via the initial mass function).Hospitable Cosmic GiantsLower panel: the number of Earth-like habitable planets (given by the color bar, which shows the log ratio relative to the Milky Way) increases in galaxies with larger stellar mass and lower star formation rates. Upper panel: the larger stellar-mass galaxies tend to be elliptical (blue line) rather than spiral (red line). Click for larger view. [Dayal et al. 2015]Interestingly, these three conditions have previously been shown to be linked via something termed the fundamental metallicity relation, which relates the total stellar masses, metallicities, and star formation rates of galaxies. By using this relation, the authors were able to create predictions for the number of habitable planets in more than 100,000 galaxies in the local universe

  5. TESTING THE UNIVERSALITY OF THE FUNDAMENTAL METALLICITY RELATION AT HIGH REDSHIFT USING LOW-MASS GRAVITATIONALLY LENSED GALAXIES

    SciTech Connect

    Belli, Sirio; Ellis, Richard S.; Jones, Tucker; Richard, Johan

    2013-08-01

    We present rest-frame optical spectra for a sample of nine low-mass star-forming galaxies in the redshift range 1.5 < z < 3 which are gravitationally lensed by foreground clusters. We used Triplespec, an echelle spectrograph at the Palomar 200 inch telescope that is very effective for this purpose as it samples the entire near-infrared spectrum simultaneously. By measuring the flux of nebular emission lines, we derive gas-phase metallicities and star formation rates, and by fitting the optical to infrared spectral energy distributions we obtain stellar masses. Taking advantage of the high magnification due to strong lensing, we are able to probe the physical properties of galaxies with stellar masses in the range 7.8 < log M/M{sub Sun} < 9.4 whose star formation rates are similar to those of typical star-forming galaxies in the local universe. We compare our results with the locally determined relation between stellar mass, gas metallicity, and star formation rate. Our data are in excellent agreement with this relation, with an average offset ({Delta}log (O/H)) = 0.01 {+-} 0.08, suggesting a universal relationship. Remarkably, the scatter around the fundamental metallicity relation is only 0.24 dex, smaller than that observed locally at the same stellar masses, which may provide an important additional constraint for galaxy evolution models.

  6. KPC-Scale Properties of Emission-line Galaxies

    NASA Astrophysics Data System (ADS)

    Hemmati, Shoubaneh; Mobasher, Bahram; Candels

    2015-01-01

    We perform a detailed -combined spectroscopic and photometric- study of resolved properties of galaxies at kpc scale and investigate how small-scale and global properties of galaxies are related. The sample consists of 119 galaxies to z~1.3 with the unique feature of having very high-resolution spectroscopic data from long exposure observations with the KECK/DEIMOS. Using HST/ACS and WFC3 data taken as part of the CANDELS project, we produce resolved rest-frame (U-V) color, stellar mass and star formation surface densities, stellar age and extinction maps and profiles along the galaxies rotation axes. We model the optical nebular emission lines using the high-resolution DEIMOS spectra and construct the optical line ratio profiles diagnostic of metallicity (R23) and nebular extinction (Ha/Hb). We find that the nebular dust extinction profile, inferred from Balmer decrement, is in agreement with the average extinction derived from the resolved SED modeling. Using the R23 metallicity profiles we examine, for the first time, the mass metallicity relation across galaxies and explore how this relation changes as a function of spatial position. We identify red and blue 'regions' of statistical significance within individual galaxies, using their rest-frame color maps. As expected, for any given galaxy, the red regions are found to have higher stellar mass surface densities and older ages compared to the blue regions. Furthermore, we quantify the spatial distribution of red and blue regions with respect to both redshift and stellar mass, finding that the stronger concentration of red regions toward the centers of galaxies is not a significant function of either redshift or stellar mass. We find that the 'main sequence' of star forming galaxies exists among both red and blue regions inside galaxies, with the median of blue regions forming a tighter relation with a slope of 1.1±0.1 and a scatter of ˜ 0.2 dex compared to red regions with a slope of 1.3 ± 0.1 and a scatter

  7. THE LICK AGN MONITORING PROJECT: THE M {sub BH}-{sigma}{sub *} RELATION FOR REVERBERATION-MAPPED ACTIVE GALAXIES

    SciTech Connect

    Woo, Jong-Hak; Treu, Tommaso; Bennert, Vardha N.; Barth, Aaron J.; Walsh, Jonelle L.; Bentz, Misty C.; Wright, Shelley A.; Filippenko, Alexei V.; Li, Weidong; Martini, Paul; Canalizo, Gabriela; Gates, Elinor; Greene, Jenny; Malkan, Matthew A.; Stern, Daniel; Minezaki, Takeo

    2010-06-10

    To investigate the black hole mass versus stellar velocity dispersion (M {sub BH}-{sigma}{sub *}) relation of active galaxies, we measured the velocity dispersions of a sample of local Seyfert 1 galaxies, for which we have recently determined black hole masses using reverberation mapping. For most objects, stellar velocity dispersions were measured from high signal-to-noise ratio optical spectra centered on the Ca II triplet region ({approx}8500 A), obtained at the Keck, Palomar, and Lick Observatories. For two objects, in which the Ca II triplet region was contaminated by nuclear emission, the measurement was based on high-quality H-band spectra obtained with the OH-Suppressing Infrared Imaging Spectrograph at the Keck-II telescope. Combining our new measurements with data from the literature, we assemble a sample of 24 active galaxies with stellar velocity dispersions and reverberation-based black hole mass measurements in the range of black hole mass 10{sup 6} < M {sub BH}/M {sub sun} < 10{sup 9}. We use this sample to obtain reverberation-mapping constraints on the slope and intrinsic scatter of the M {sub BH}-{sigma}{sub *} relation of active galaxies. Assuming a constant virial coefficient f for the reverberation-mapping black hole masses, we find a slope {beta} = 3.55 {+-} 0.60 and the intrinsic scatter {sigma}{sub int} = 0.43 {+-} 0.08 dex in the relation log(M {sub BH}/M {sub sun}) = {alpha} + {beta} log({sigma}{sub *}/200 km s{sup -1}), which are consistent with those found for quiescent galaxies. We derive an updated value of the virial coefficient f by finding the value which places the reverberation masses in best agreement with the M {sub BH}-{sigma}{sub *} relation of quiescent galaxies; using the quiescent M {sub BH}-{sigma}{sub *} relation determined by Gueltekin et al., we find log f = 0.72{sup +0.09} {sub -0.10} with an intrinsic scatter of 0.44 {+-} 0.07 dex. No strong correlations between f and parameters connected to the physics of accretion

  8. The abundance properties of nearby late-type galaxies. II. The relation between abundance distributions and surface brightness profiles

    SciTech Connect

    Pilyugin, L. S.; Grebel, E. K.; Zinchenko, I. A.; Kniazev, A. Y. E-mail: grebel@ari.uni-heidelberg.de E-mail: akniazev@saao.ac.za

    2014-12-01

    The relations between oxygen abundance and disk surface brightness (OH–SB relation) in the infrared W1 band are examined for nearby late-type galaxies. The oxygen abundances were presented in Paper I. The photometric characteristics of the disks are inferred here using photometric maps from the literature through bulge-disk decomposition. We find evidence that the OH–SB relation is not unique but depends on the galactocentric distance r (taken as a fraction of the optical radius R{sub 25}) and on the properties of a galaxy: the disk scale length h and the morphological T-type. We suggest a general, four-dimensional OH–SB relation with the values r, h, and T as parameters. The parametric OH–SB relation reproduces the observed data better than a simple, one-parameter relation; the deviations resulting when using our parametric relation are smaller by a factor of ∼1.4 than that of the simple relation. The influence of the parameters on the OH–SB relation varies with galactocentric distance. The influence of the T-type on the OH–SB relation is negligible at the centers of galaxies and increases with galactocentric distance. In contrast, the influence of the disk scale length on the OH–SB relation is at a maximum at the centers of galaxies and decreases with galactocentric distance, disappearing at the optical edges of galaxies. Two-dimensional relations can be used to reproduce the observed data at the optical edges of the disks and at the centers of the disks. The disk scale length should be used as a second parameter in the OH–SB relation at the center of the disk while the morphological T-type should be used as a second parameter in the relation at optical edge of the disk. The relations between oxygen abundance and disk surface brightness in the optical B and infrared K bands at the center of the disk and at optical edge of the disk are also considered. The general properties of the abundance–surface brightness relations are similar for the

  9. Testing the gas mass density profile of galaxy clusters with distance duality relation

    NASA Astrophysics Data System (ADS)

    Cao, Shuo; Biesiada, Marek; Zheng, Xiaogang; Zhu, Zong-Hong

    2016-03-01

    In this paper, assuming the validity of distance duality relation, η = DL(z)(1 + z)-2/DA(z) = 1, where DA(z) and DL(z) are the angular and the luminosity distance, respectively, we explore two kinds of gas mass density profiles of clusters: the isothermal β model and the non-isothermal double-β model. In our analysis, performed on 38 massive galaxy clusters observed by Chandra (within the redshift range of 0.14 < z < 0.89), we use two types of cluster gas mass fraction data corresponding to different mass density profiles fitted to the X-ray data. Using two general parameterizations of η(z) (phenomenologically allowing for distance duality violation), we find that the non-isothermal double-β model agrees better with the distance duality relation, while the isothermal β model tends to be marginally incompatible with the Etherington theorem at 68.3 per cent confidence level (CL). However, current accuracy of the data does not allow to distinguish between the two models for the gas-density distribution at a significant level.

  10. Can Massive Gravity Explain the Mass Discrepancy-Acceleration Relation of Disk Galaxies?

    NASA Astrophysics Data System (ADS)

    Trippe, Sascha

    2013-06-01

    The empirical mass discrepancy-acceleration (MDA) relation of disk galaxies provides a key test for models of galactic dynamics. In terms of modified laws of gravity and/or inertia, the MDA relation quantifies the transition from Newtonian to modified dynamics at low centripetal accelerations a_c≲10^{-10} m s^{-2}. As yet, neither dynamical models based on dark matter nor proposed modifications of the laws of gravity/inertia have predicted the functional form of the MDA relation. In this work, I revisit the MDA data and compare them to four different theoretical scaling laws. Three of these scaling laws are entirely empirical; the fourth one - the ``simple μ'' function of Modified Newtonian Dynamics - derives from a toy model of gravity based on massive gravitons (the ``graviton picture''). All theoretical MDA relations comprise one free parameter of the dimension of an acceleration, Milgrom's constant am. I find that the ``simple μ'' function provides a good fit to the data free of notable systematic residuals and provides the best fit among the four scaling laws tested. The best-fit value of Milgrom's constant is am=(1.06±0.05)×10^{-10} m s^{-2}. Given the successful prediction of the functional form of the MDA relation, plus an overall agreement with the observed kinematics of stellar systems spanning eight orders of magnitude in size and 14 orders of magnitude in mass, I conclude that the ``graviton picture'' is sufficient (albeit probably not a necessary nor unique approach) to describe galactic dynamics on all scales well beyond the scale of the solar system. This suggests that, at least on galactic scales, gravity behaves as if it was mediated by massive particles.

  11. Metal enrichment in a semi-analytical model, fundamental scaling relations, and the case of Milky Way galaxies

    NASA Astrophysics Data System (ADS)

    Cousin, M.; Buat, V.; Boissier, S.; Bethermin, M.; Roehlly, Y.; Génois, M.

    2016-05-01

    Context. Gas flows play a fundamental role in galaxy formation and evolution, providing the fuel for the star formation process. These mechanisms leave an imprint in the amount of heavy elements that enrich the interstellar medium. Thus, the analysis of this metallicity signature provides additional constraint on the galaxy formation scenario. Aims: We aim to discriminate between four different galaxy formation models based on two accretion scenarios and two different star formation recipes. We address the impact of a bimodal accretion scenario and a strongly regulated star formation recipe on the metal enrichment process of galaxies. Methods: We present a new extension of the eGalICS model, which allows us to track the metal enrichment process in both stellar populations and in the gas phase. Based on stellar metallicity bins from 0 to 2.5 Z⊙, our new chemodynamical model is applicable for situations ranging from metal-free primordial accretion to very enriched interstellar gas contents. We use this new tool to predict the metallicity evolution of both the stellar populations and gas phase. We compare these predictions with recent observational measurements. We also address the evolution of the gas metallicity with the star formation rate (SFR). We then focus on a sub-sample of Milky Way-like galaxies. We compare both the cosmic stellar mass assembly and the metal enrichment process of such galaxies with observations and detailed chemical evolution models. Results: Our models, based on a strong star formation regulation, allow us to reproduce well the stellar mass to gas-phase metallicity relation observed in the local Universe. The shape of our average stellar mass to stellar metallicity relations is in good agreement with observations. However, we observe a systematic shift towards high masses. Our M⋆ - Zg -SFR relation is in good agreement with recent measurements: our best model predicts a clear dependence with the SFR. Both SFR and metal enrichment

  12. The XXL Survey. X. K-band luminosity - weak-lensing mass relation for groups and clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Ziparo, F.; Smith, G. P.; Mulroy, S. L.; Lieu, M.; Willis, J. P.; Hudelot, P.; McGee, S. L.; Fotopoulou, S.; Lidman, C.; Lavoie, S.; Pierre, M.; Adami, C.; Chiappetti, L.; Clerc, N.; Giles, P.; Maughan, B.; Pacaud, F.; Sadibekova, T.

    2016-06-01

    Galaxy clusters and groups are important cosmological probes and giant cosmic laboratories for studying galaxy evolution. Much effort has been devoted to understanding how and when baryonic matter cools at the centre of potential wells. However, a clear picture of the efficiency with which baryons are converted into stars is still missing. We present the K-band luminosity-halo mass relation, LK,500-M500,WL, for a subsample of 20 of the 100 brightest clusters in the XXL Survey observed with WIRCam at the Canada-France-Hawaii Telescope (CFHT). For the first time, we have measured this relation via weak-lensing analysis down to M500,WL = 3.5 × 1013 M⊙. This allows us to investigate whether the slope of the LK-M relation is different for groups and clusters, as seen in other works. The clusters in our sample span a wide range in mass, M500,WL = 0.35-12.10 × 1014 M⊙, at 0 < z < 0.6. The K-band luminosity scales as log 10(LK,500/ 1012 L⊙) ∝ βlog 10(M500,WL/ 1014 M⊙) with β = 0.85+0.35-0.27 and an intrinsic scatter of σlnLK|M = 0.37+0.19-0.17. Combining our sample with some clusters in the Local Cluster Substructure Survey (LoCuSS) present in the literature, we obtain a slope of 1.05+0.16-0.14 and an intrinsic scatter of 0.14+0.09-0.07. The flattening in the LK-M seen in previous works is not seen here and might be a result of a bias in the mass measurement due to assumptions on the dynamical state of the systems. We also study the richness-mass relation and find that group-sized halos have more galaxies per unit halo mass than massive clusters. However, the brightest cluster galaxy (BCG) in low-mass systems contributes a greater fraction to the total cluster light than BCGs do in massive clusters; the luminosity gap between the two brightest galaxies is more prominent for group-sized halos. This result is a natural outcome of the hierarchical growth of structures, where massive galaxies form and gain mass within low-mass groups and are ultimately accreted

  13. Metal enrichment in a semi-analytical model, fundamental scaling relations, and the case of Milky Way galaxies

    NASA Astrophysics Data System (ADS)

    Cousin, M.; Buat, V.; Boissier, S.; Bethermin, M.; Roehlly, Y.; Génois, M.

    2016-04-01

    Context. Gas flows play a fundamental role in galaxy formation and evolution, providing the fuel for the star formation process. These mechanisms leave an imprint in the amount of heavy elements that enrich the interstellar medium. Thus, the analysis of this metallicity signature provides additional constraint on the galaxy formation scenario. Aims: We aim to discriminate between four different galaxy formation models based on two accretion scenarios and two different star formation recipes. We address the impact of a bimodal accretion scenario and a strongly regulated star formation recipe on the metal enrichment process of galaxies. Methods: We present a new extension of the eGalICS model, which allows us to track the metal enrichment process in both stellar populations and in the gas phase. Based on stellar metallicity bins from 0 to 2.5 Z⊙, our new chemodynamical model is applicable for situations ranging from metal-free primordial accretion to very enriched interstellar gas contents. We use this new tool to predict the metallicity evolution of both the stellar populations and gas phase. We compare these predictions with recent observational measurements. We also address the evolution of the gas metallicity with the star formation rate (SFR). We then focus on a sub-sample of Milky Way-like galaxies. We compare both the cosmic stellar mass assembly and the metal enrichment process of such galaxies with observations and detailed chemical evolution models. Results: Our models, based on a strong star formation regulation, allow us to reproduce well the stellar mass to gas-phase metallicity relation observed in the local Universe. The shape of our average stellar mass to stellar metallicity relations is in good agreement with observations. However, we observe a systematic shift towards high masses. Our M⋆ - Zg -SFR relation is in good agreement with recent measurements: our best model predicts a clear dependence with the SFR. Both SFR and metal enrichment

  14. Determination of the Cosmic Radio Background from the Radio-Infrared Relation in Galaxies

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Barker, Michael K.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We use the radioactive flux correlation for star forming galaxies in the local universe to derive their contribution to the cosmic radio background (CRB). The CRB from these galaxies is therefore determined by the evolution of the comoving infrared luminosity density with redshift, which is constrained by galaxy number counts at various infrared wavelengths and by the cosmic infrared background. The research of ED was supported by NASA NRA 99-OSS-01 Astrophysics Theory Program. MB acknowledges the support of the "Research Opportunities for Undergraduates in the Laboratory for Astronomy and Solar Physics" for the summer student internship program at NASA/GSFC.

  15. The Relation between Star-Formation Rate and Stellar Mass of Galaxies at z ~ 1-4

    NASA Astrophysics Data System (ADS)

    Katsianis, A.; Tescari, E.; Wyithe, J. S. B.

    2016-07-01

    The relation between the star-formation Rate and stellar mass (M ⋆) of galaxies represents a fundamental constraint on galaxy formation, and has been studied extensively both in observations and cosmological hydrodynamic simulations. However, the observed amplitude of the star-formation rate-stellar mass relation has not been successfully reproduced in simulations, indicating either that the halo accretion history and baryonic physics are poorly understood/modelled or that observations contain biases. In this paper, we examine the evolution of the SFR - M ⋆ relation of z ~ 1-4 galaxies and display the inconsistency between observed relations that are obtained using different techniques. We employ cosmological hydrodynamic simulations from various groups which are tuned to reproduce a range of observables and compare these with a range of observed SFR - M ⋆ relations. We find that numerical results are consistent with observations that use Spectral Energy Distribution techniques to estimate star-formation rates, dust corrections, and stellar masses. On the contrary, simulations are not able to reproduce results that were obtained by combining only UV and IR luminosities (UV+IR). These imply star-formation rates at a fixed stellar mass that are larger almost by a factor of 5 than those of Spectral Energy Distribution measurements for z ~ 1.5-4. For z < 1.5, the results from simulations, Spectral Energy Distribution fitting techniques and IR+UV conversion agree well. We find that surveys that preferably select star-forming galaxies (e.g. by adopting Lyman-break or blue selection) typically predict a larger median/average star-formation rate at a fixed stellar mass especially for high mass objects, with respect to mass selected samples and hydrodynamic simulations. Furthermore, we find remarkable agreement between the numerical results from various authors who have employed different cosmological codes and run simulations with different resolutions. This is

  16. ENVIRONMENTAL EFFECTS ON THE METAL ENRICHMENT OF LOW-MASS GALAXIES IN NEARBY CLUSTERS

    SciTech Connect

    Petropoulou, V.; Vilchez, J.; Iglesias-Paramo, J.

    2012-04-20

    In this paper, we study the chemical history of low-mass star-forming (SF) galaxies in the local universe clusters Coma, A1367, A779, and A634. The aim of this work is to search for the imprint of the environment on the chemical evolution of these galaxies. Galaxy chemical evolution is linked to the star formation history, as well as to the gas interchange with the environment, and low-mass galaxies are well known to be vulnerable systems to environmental processes affecting both these parameters. For our study we have used spectra from the SDSS-III DR8. We have examined the spectroscopic properties of SF galaxies of stellar masses 10{sup 8}-10{sup 10} M{sub Sun }, located from the core to the cluster's outskirts. The gas-phase O/H and N/O chemical abundances have been derived using the latest empirical calibrations. We have examined the mass-metallicity relation of cluster galaxies, finding well-defined sequences. The slope of these sequences, for galaxies in low-mass clusters and galaxies at large cluster-centric distances, follows the predictions of recent hydrodynamic models. A flattening of this slope has been observed for galaxies located in the core of the two more massive clusters of the sample, principally in Coma, suggesting that the imprint of the cluster environment on the chemical evolution of SF galaxies should be sensitive to both the galaxy mass and the host cluster mass. The H I gas content of Coma and A1367 galaxies indicates that low-mass SF galaxies, located at the core of these clusters, have been severely affected by ram-pressure stripping (RPS). The observed mass-dependent enhancement of the metal content of low-mass galaxies in dense environments seems plausible, according to hydrodynamic simulations. This enhanced metal enrichment could be produced by the combination of effects such as wind reaccretion, due to pressure confinement by the intracluster medium (ICM), and the truncation of gas infall, as a result of the RPS. Thus, the

  17. An early phase of environmental effects on galaxy properties unveiled by near-infrared spectroscopy of protocluster galaxies at z > 2

    NASA Astrophysics Data System (ADS)

    Shimakawa, Rhythm; Kodama, Tadayuki; Tadaki, Ken-ichi; Hayashi, Masao; Koyama, Yusei; Tanaka, Ichi

    2015-03-01

    This work presents the results from our near-infrared spectroscopy of narrow-band-selected Hα emitters (HAEs) in two rich overdensities (PKS 1138-262 at z = 2.2 and USS 1558-003 at z = 2.5) with the Multi-Object Infrared Camera and Spectrograph on the Subaru telescope. These protoclusters are promising candidates for the most massive class of galaxy clusters seen today (Paper I). The confirmed HAEs in the protoclusters at z > 2 show high excitation levels as characterized by much higher [O III]/Hβ or [O III]/Hα line ratios than those of general galaxies at low-z. Such a high excitation level may not only be driven by high specific star formation rates and lower gaseous metallicities, but also be contributed by some other effects. We investigate the environmental dependence of gaseous metallicities by comparing the HAEs in the protoclustrers with those in the general field at similar redshifts. We find that the gaseous metallicities of protocluster galaxies are more chemically enriched than those of field galaxies at a given stellar mass in the range of M⋆ ≲ 1011 M⊙. This can be attributed to many processes, such as intrinsic (or nature) effects, external (or nurture) effects, and/or some systematic sampling effects. The intrinsic (nature) effect leads to the advanced stage of `downsizing' galaxy evolution in protoclusters. On the other hand, the external (nurture) effects include the recycling of chemically enriched gas due to the higher pressure of intergalactic medium and/or stripping of outer gas in the reservoir in protoclusters. We also find that the offset of the mass-metallicity relation in dense environment becomes larger at higher redshifts. This can be naturally understood by the fact that the inflow/outflow rates in star-forming galaxies are much higher at higher redshifts. Therefore, the environmental dependence of such `feeding' and `feedback' mechanisms in galaxy formation is probably playing major roles in producing the offset of the mass-metallicity

  18. An Empirical Relation between the Large-scale Magnetic Field and the Dynamical Mass in Galaxies

    NASA Astrophysics Data System (ADS)

    Tabatabaei, F. S.; Martinsson, T. P. K.; Knapen, J. H.; Beckman, J. E.; Koribalski, B.; Elmegreen, B. G.

    2016-02-01

    The origin and evolution of cosmic magnetic fields as well as the influence of the magnetic fields on the evolution of galaxies are unknown. Though not without challenges, the dynamo theory can explain the large-scale coherent magnetic fields that govern galaxies, but observational evidence for the theory is so far very scarce. Putting together the available data of non-interacting, non-cluster galaxies with known large-scale magnetic fields, we find a tight correlation between the integrated polarized flux density, SPI, and the rotation speed, vrot, of galaxies. This leads to an almost linear correlation between the large-scale magnetic field \\bar{B} and vrot, assuming that the number of cosmic-ray electrons is proportional to the star formation rate, and a super-linear correlation assuming equipartition between magnetic fields and cosmic rays. This correlation cannot be attributed to an active linear α-Ω dynamo, as no correlation holds with global shear or angular speed. It indicates instead a coupling between the large-scale magnetic field and the dynamical mass of the galaxies, \\bar{B}˜ \\{M}{{dyn}}0.25-0.4. Hence, faster rotating and/or more massive galaxies have stronger large-scale magnetic fields. The observed \\bar{B}-{v}{{rot}} correlation shows that the anisotropic turbulent magnetic field dominates \\bar{B} in fast rotating galaxies as the turbulent magnetic field, coupled with gas, is enhanced and ordered due to the strong gas compression and/or local shear in these systems. This study supports a stationary condition for the large-scale magnetic field as long as the dynamical mass of galaxies is constant.

  19. The Atacama Cosmology Telescope: Relation Between Galaxy Cluster Optical Richness and Sunyaev-Zel'dovich Effect

    NASA Technical Reports Server (NTRS)

    Sehgal, Neelima; Addison, Graeme; Battaglia, Nick; Battistelli, Elia S.; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Duenner, Rolando; Gralla, Megan; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Hughes, John P.; Kosowsky, Arthur; Lin, Yen-Ting; Louis, Thibaut; Marriage, Tobias A.; Marsden, Danica; Menateau, Felipe; Moodley, Kavilan; Wollack, Ed

    2012-01-01

    MaxBCG sample, a lower normalization of the mass-richness relation, radio or infrared galaxy contamination of the SZ flux, and a low intrinsic SZ signal. In the latter two cases, the effects would need to be preferentially more significant in the optically-selected MaxBCG sample than in the MCXC X-ray sample.

  20. Constraints on the Hubble Parameter from Galaxy Clusters and the Validity of the Cosmic Distance Duality Relation

    NASA Astrophysics Data System (ADS)

    Holanda, R. F. L.

    Constraints on the Hubble parameter, H0, via X-ray surface brightness and Sunyaev-Zel'dovich effect (SZE) observations of the galaxy clusters depend on the validity of the cosmic distance duality relation (DD relation), η = DL(z)(1+z)-2/DA(z) = 1, where DL and DA are the luminosity distance and angular diameter distance (ADD), respectively. In this work, we argue that if the DD relation does not hold, the X-ray plus SZE technique furnishes a H*0 = H0/η 2. We use 25 ADD of galaxy clusters to obtain simultaneous constraints on H0 and possible violation of the DD relation in a flat ΛCDM model. Such a violation is parametrized by two functions: η(z) = 1 + η0z and η(z) = 1 + η0z/(1+z), where η0 is a constant parameter quantifying possible departures from the strict validity. Finally, by marginalizing on the η0 in both parametrizations, we obtain constraints on H0 regardless of the validity of the DD relation. For the linear and nonlinear η(z) functions, we obtain H0 = 75{+ 7}-7 km/s/Mpc and H0 = 75{+ 10}-7 km/s/Mpc, respectively (without systematic errors). Our results support recent H0 measurements by using X-ray and SZE observations of galaxy clusters which have taken the distance duality as valid.

  1. Galaxies Collide to Create Hot, Huge Galaxy

    NASA Technical Reports Server (NTRS)

    2009-01-01

    This image of a pair of colliding galaxies called NGC 6240 shows them in a rare, short-lived phase of their evolution just before they merge into a single, larger galaxy. The prolonged, violent collision has drastically altered the appearance of both galaxies and created huge amounts of heat turning NGC 6240 into an 'infrared luminous' active galaxy.

    A rich variety of active galaxies, with different shapes, luminosities and radiation profiles exist. These galaxies may be related astronomers have suspected that they may represent an evolutionary sequence. By catching different galaxies in different stages of merging, a story emerges as one type of active galaxy changes into another. NGC 6240 provides an important 'missing link' in this process.

    This image was created from combined data from the infrared array camera of NASA's Spitzer Space Telescope at 3.6 and 8.0 microns (red) and visible light from NASA's Hubble Space Telescope (green and blue).

  2. The spatially resolved Kennicutt-Schmidt relation in the H I-dominated regions of spiral and dwarf irregular galaxies

    NASA Astrophysics Data System (ADS)

    Roychowdhury, Sambit; Huang, Mei-Ling; Kauffmann, Guinevere; Wang, Jing; Chengalur, Jayaram N.

    2015-06-01

    We study the Kennicutt-Schmidt relation between average star formation rate (SFR) and average cold gas surface density in the H I-dominated ISM of nearby spiral and dwarf irregular galaxies. We divide galaxies into grid cells varying from sub-kpc to tens of kpc in size. Grid-cell measurements of low SFRs using Hα emission can be biased and scatter may be introduced because of non-uniform sampling of the IMF or because of stochastically varying star formation. In order to alleviate these issues, we use far-ultraviolet emission to trace SFR, and we sum up the fluxes from different bins with the same gas surface density to calculate the average ΣSFR at a given value of Σgas. We study the resulting Kennicutt-Schmidt relation in 400 pc, 1 kpc and 10 kpc scale grids in nearby massive spirals and in 400 pc scale grids in nearby faint dwarf irregulars. We find a relation with a power-law slope of 1.5 in the H I-dominated regions for both kinds of galaxies. The relation is offset towards longer gas consumption time-scales compared to the molecular-hydrogen-dominated centres of spirals, but the offset is an order of magnitude less than that quoted by earlier studies. Our results lead to the surprising conclusion that conversion of gas to stars is independent of metallicity in the H I-dominated regions of star-forming galaxies. Our observed relations are better fit by a model of star formation based on thermal and hydrostatic equilibrium in the ISM, in which stellar heating and supernova feedback set the thermal and turbulent pressure.

  3. The observed growth of massive galaxy clusters - II. X-ray scaling relations

    NASA Astrophysics Data System (ADS)

    Mantz, A.; Allen, S. W.; Ebeling, H.; Rapetti, D.; Drlica-Wagner, A.

    2010-08-01

    This is the second in a series of papers in which we derive simultaneous constraints on cosmology and X-ray scaling relations using observations of massive, X-ray flux-selected galaxy clusters. The data set consists of 238 clusters with 0.1-2.4keV luminosities >2.5 × 1044h-270ergs-1, and incorporates follow-up observations of 94 of those clusters using the Chandra X-ray Observatory or ROSAT (11 were observed with both). The clusters are drawn from three samples based on the ROSAT All-Sky Survey: the ROSAT Brightest Cluster Sample (78/37 clusters detected/followed-up), the ROSAT-ESO Flux-Limited X-ray sample (126/25) and the bright sub-sample of the Massive Cluster Survey (34/32). Our analysis accounts self-consistently for all selection effects, covariances and systematic uncertainties. Here we describe the reduction of the follow-up X-ray observations, present results on the cluster scaling relations, and discuss their implications. Our constraints on the luminosity-mass and temperature-mass relations, measured within r500, lead to three important results. First, the data support the conclusion that excess heating of the intracluster medium (or a combination of heating and condensation of the coldest gas) has altered its thermodynamic state from that expected in a simple, gravitationally dominated system; however, this excess heat is primarily limited to the central regions of clusters (r < 0.15r500). Secondly, the intrinsic scatter in the centre-excised luminosity-mass relation is remarkably small, being bounded at the <10 per cent level in current data; for the hot, massive clusters under investigation, this scatter is smaller than in either the temperature-mass or YX-mass relations (10-15 per cent). Thirdly, the evolution with redshift of the scaling relations is consistent with the predictions of simple, self-similar models of gravitational collapse, indicating that the mechanism responsible for heating the central regions of clusters was in operation before

  4. ON THE DISCREPANCY BETWEEN THEORETICAL AND X-RAY CONCENTRATION-MASS RELATIONS FOR GALAXY CLUSTERS

    SciTech Connect

    Rasia, E.; Borgani, S.; Ettori, S.; Meneghetti, M.; Mazzotta, P.

    2013-10-10

    In the past 15 years, the concentration-mass relation has been investigated diffusely in theoretical studies. On the other hand, only recently has this relation been derived from X-ray observations. When that happened, the results caused a certain level of concern: the X-ray normalizations and slopes were found significantly dissimilar from those predicted by theory. We analyzed 52 galaxy clusters and groups, simulated with different descriptions of the physical processes that affect the baryonic component, with the purpose of determining whether these discrepancies are real or induced by biases in the computation of the concentration parameter or in the determination of the selection function of the cluster sample for which the analysis is carried out. In particular, we investigate how the simulated concentration-mass relation depends (1) on the radial range used to derive the concentration; (2) on the presence of baryons in the simulations, and on the effect of star formation and feedback from supernovae and active galactic nuclei (AGNs). Finally, we evaluate (3) how the results differ when adopting an X-ray approach for the analysis and (4) how the selection function based on X-ray luminosity can impact the results. All effects studied go in the direction of alleviating the discrepancy between observations and simulations, although with different significance: while the choice of the radial range to fit the profiles and the inclusion of the baryonic component play only a minor role, the X-ray approach to reconstruct the mass profiles and the selection of the cluster sample have a strong impact on the resulting concentration-mass relation. Extending the fit to the most central regions or reducing the fitting radius from the virial boundary to the typical X-ray external radius causes an increase of the normalization in radiative simulations by 5%-10%. In the second case, we measure a slope that is up to twice steeper than that derived by using the typical

  5. Cosmology and astrophysics from relaxed galaxy clusters - III. Thermodynamic profiles and scaling relations

    NASA Astrophysics Data System (ADS)

    Mantz, A. B.; Allen, S. W.; Morris, R. G.; Schmidt, R. W.

    2016-03-01

    This is the third in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot (i.e. massive) in Papers I and II of this series. Here we consider the thermodynamics of the intracluster medium, in particular the profiles of density, temperature and related quantities, as well as integrated measurements of gas mass, average temperature, total luminosity and centre-excluded luminosity. We fit power-law scaling relations of each of these quantities as a function of redshift and cluster mass, which can be measured precisely and with minimal bias for these relaxed clusters using hydrostatic arguments. For the thermodynamic profiles, we jointly model the density and temperature and their intrinsic scatter as a function of radius, thus also capturing the behaviour of the gas pressure and entropy. For the integrated quantities, we also jointly fit a multidimensional intrinsic covariance. Our results reinforce the view that simple hydrodynamical models provide a good description of relaxed clusters outside their centres, but that additional heating and cooling processes are important in the inner regions (radii r ≲ 0.5 r2500 ≈ 0.15 r500). The thermodynamic profiles remain regular, with small intrinsic scatter, down to the smallest radii where deprojection is straightforward (˜20 kpc); within this radius, even the most relaxed systems show clear departures from spherical symmetry. Our results suggest that heating and cooling are continuously regulated in a tight feedback loop, allowing the cluster atmosphere to remain stratified on these scales.

  6. Star formation in semi-analytic galaxy formation models with multiphase gas

    NASA Astrophysics Data System (ADS)

    Somerville, Rachel S.; Popping, Gergö; Trager, Scott C.

    2015-11-01

    We implement physically motivated recipes for partitioning cold gas into different phases (atomic, molecular, and ionized) in galaxies within semi-analytic models of galaxy formation based on cosmological merger trees. We then model the conversion of molecular gas into stars using empirical recipes motivated by recent observations. We explore the impact of these new recipes on the evolution of fundamental galaxy properties such as stellar mass, star formation rate (SFR), and gas and stellar phase metallicity. We present predictions for stellar mass functions, stellar mass versus SFR relations, and cold gas phase and stellar mass-metallicity relations for our fiducial models, from redshift z ˜ 6 to the present day. In addition we present predictions for the global SFR, mass assembly history, and cosmic enrichment history. We find that the predicted stellar properties of galaxies (stellar mass, SFR, metallicity) are remarkably insensitive to the details of the recipes used for partitioning gas into H I and H2. We see significant sensitivity to the recipes for H2 formation only in very low mass haloes (M_h ≲ 10^{10.5} M_{⊙}), which host galaxies with stellar masses m_* ≲ 10^8 M_{⊙}. The properties of low-mass galaxies are also quite insensitive to the details of the recipe used for converting H2 into stars, while the formation epoch of massive galaxies does depend on this significantly. We argue that this behaviour can be interpreted within the framework of a simple equilibrium model for galaxy evolution, in which the conversion of cold gas into stars is balanced on average by inflows and outflows.

  7. SPATIALLY RESOLVED SPECTROSCOPY AND CHEMICAL HISTORY OF STAR-FORMING GALAXIES IN THE HERCULES CLUSTER: THE EFFECTS OF THE ENVIRONMENT

    SciTech Connect

    Petropoulou, V.; Vilchez, J.; Iglesias-Paramo, J.; Cedres, B.; Papaderos, P.; Magrini, L.; Reverte, D.

    2011-06-10

    Spatially resolved spectroscopy has been obtained for a sample of 27 star-forming (SF) galaxies selected from our deep H{alpha} survey of the Hercules cluster. We have applied spectral synthesis models to all emission-line spectra of this sample using the population synthesis code STARLIGHT and have obtained fundamental parameters of stellar components such as mean metallicity and age. The emission-line spectra were corrected for underlying stellar absorption using these spectral synthesis models. Line fluxes were measured and O/H and N/O gas chemical abundances were obtained using the latest empirical calibrations. We have derived the masses and total luminosities of the galaxies using available Sloan Digital Sky Survey broadband photometry. The effects of cluster environment on the chemical evolution of galaxies and on their mass-metallicity (MZ) and luminosity-metallicity (LZ) relations were studied by combining the derived gas metallicities, the mean stellar metallicities and ages, the masses and luminosities of the galaxies, and their existing H I data. Our Hercules SF galaxies are divided into three main subgroups: (1) chemically evolved spirals with truncated ionized-gas disks and nearly flat oxygen gradients, demonstrating the effect of ram-pressure stripping; (2) chemically evolved dwarfs/irregulars populating the highest local densities, possible products of tidal interactions in preprocessing events; and (3) less metallic dwarf galaxies that appear to be 'newcomers' to the cluster and are experiencing pressure-triggered star formation. Most Hercules SF galaxies follow well-defined MZ and LZ sequences (for both O/H and N/O), though the dwarf/irregular galaxies located at the densest regions appear to be outliers to these global relations, suggesting a physical reason for the dispersion in these fundamental relations. The Hercules cluster appears to be currently assembling via the merger of smaller substructures, providing an ideal laboratory where the

  8. Spatially Resolved Spectroscopy and Chemical History of Star-forming Galaxies in the Hercules Cluster: The Effects of the Environment

    NASA Astrophysics Data System (ADS)

    Petropoulou, V.; Vílchez, J.; Iglesias-Páramo, J.; Papaderos, P.; Magrini, L.; Cedrés, B.; Reverte, D.

    2011-06-01

    Spatially resolved spectroscopy has been obtained for a sample of 27 star-forming (SF) galaxies selected from our deep Hα survey of the Hercules cluster. We have applied spectral synthesis models to all emission-line spectra of this sample using the population synthesis code STARLIGHT and have obtained fundamental parameters of stellar components such as mean metallicity and age. The emission-line spectra were corrected for underlying stellar absorption using these spectral synthesis models. Line fluxes were measured and O/H and N/O gas chemical abundances were obtained using the latest empirical calibrations. We have derived the masses and total luminosities of the galaxies using available Sloan Digital Sky Survey broadband photometry. The effects of cluster environment on the chemical evolution of galaxies and on their mass-metallicity (MZ) and luminosity-metallicity (LZ) relations were studied by combining the derived gas metallicities, the mean stellar metallicities and ages, the masses and luminosities of the galaxies, and their existing H I data. Our Hercules SF galaxies are divided into three main subgroups: (1) chemically evolved spirals with truncated ionized-gas disks and nearly flat oxygen gradients, demonstrating the effect of ram-pressure stripping; (2) chemically evolved dwarfs/irregulars populating the highest local densities, possible products of tidal interactions in preprocessing events; and (3) less metallic dwarf galaxies that appear to be "newcomers" to the cluster and are experiencing pressure-triggered star formation. Most Hercules SF galaxies follow well-defined MZ and LZ sequences (for both O/H and N/O), though the dwarf/irregular galaxies located at the densest regions appear to be outliers to these global relations, suggesting a physical reason for the dispersion in these fundamental relations. The Hercules cluster appears to be currently assembling via the merger of smaller substructures, providing an ideal laboratory where the local

  9. The Relation between [O III]/Hβ and Specific Star Formation Rate in Galaxies at z ∼ 2

    NASA Astrophysics Data System (ADS)

    Mackay Dickey, Claire; van Dokkum, Pieter G.; Oesch, Pascal A.; Whitaker, Katherine E.; Momcheva, Ivelina G.; Nelson, Erica J.; Leja, Joel; Brammer, Gabriel B.; Franx, Marijn; Skelton, Rosalind E.

    2016-09-01

    Recent surveys have identified a seemingly ubiquitous population of galaxies with elevated [O iii]/Hβ emission line ratios at z > 1, although the nature of this phenomenon continues to be debated. The [O iii]/Hβ line ratio is of interest because it is a main component of the standard diagnostic tools used to differentiate between active galactic nuclei and star-forming galaxies as well as the gas-phase metallicity indicators O 23 and R 23. Here, we investigate the primary driver of increased [O iii]/Hβ ratios by median-stacking rest-frame optical spectra for a sample of star-forming galaxies in the 3D-HST survey in the redshift range z ∼ 1.4–2.2. Using N = 4220 star-forming galaxies, we stack the data in bins of mass and specific star formation rates (sSFRs), respectively. After accounting for stellar Balmer absorption, we measure [O iii]λ5007 Å/Hβ down to M ∼ 109.2 M ⊙ and sSFR ∼ 10‑9.6 yr‑1, greater than an order of magnitude lower than previous work at similar redshifts. We find an offset of 0.59 ± 0.05 dex between the median ratios at z ∼ 2 and z ∼ 0 at fixed stellar mass, in agreement with existing studies. However, with respect to sSFR, the z ∼ 2 stacks all lie within 1σ of the median SDSS ratios, with an average offset of only ‑0.06 ± 0.05. We find that the excitation properties of galaxies are tightly correlated with their sSFR at both z ∼ 2 and z ∼ 0, with a relation that appears to be roughly constant over the last 10 Gyr of cosmic time.

  10. Relation between Starlight and Nebular Emission Lines of Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Lu, Hong-Lin; Zhou, Hong-Yan; Wang, Ting-Gui; Zhuang, Zhen-Quan; Dong, Xiao-Bo; Wang, Jun-Xian; Li, Cheng

    2005-06-01

    We present an exercise that intends to establish a relationship between the strength of nebular emission lines and optical stellar features in the spectrum of a galaxy. After accurately subtracting the stellar continuum and the underlying stellar absorption, we made reliable measurements of the emission lines of all the galaxies in the Sloan Digital Sky Survey Data Release 2 (SDSS DR2). More than 4000 star-forming galaxies with high S/N ratio of both the stellar spectrum and the emission lines are selected. These galaxy spectra are fitted with the 10 PCs of Yip et al., after all the emission line regions have been filtered out. We find that the flux of hydrogen Balmer emission lines, Hα and Hβ can be well recovered from the PCs, while the metal lines are not well reproduced. The fluxes of Hα and Hβ measured from the PC-reconstructed spectra and from the observed spectra agree well with an rms scatter of only ~0.1 dex. This result suggests that, with moderate spectral resolution and S/N ratio, the optical stellar spectrum of a galaxy can serve as an indicator of star formation rate.