Browsing by Author "Bizyaev, D."

Now showing 1 - 7 of 7
  • No Thumbnail Available
    Item
    A Perspective on the Milky Way Bulge Bar as Seen from the Neutron-capture Elements Cerium and Neodymium with APOGEE
    (2024) Sales-Silva, J. V.; Cunha, K.; Smith, V. V.; Daflon, S.; Souto, D.; Guerco, R.; Queiroz, A.; Chiappini, C.; Hayes, C. R.; Masseron, T.; Hasselquist, Sten; Horta, D.; Prantzos, N.; Zoccali, M.; Allende Prieto, C.; Barbuy, B.; Beaton, R.; Bizyaev, D.; Fernandez-Trincado, J. G.; Frinchaboy, P. M.; Holtzman, J. A.; Johnson, J. A.; Joensson, Henrik; Majewski, S. R.; Minniti, D.; Nidever, D. L.; Schiavon, R. P.; Schultheis, M.; Sobeck, J.; Stringfellow, G. S.; Zasowski, G.
    This study probes the chemical abundances of the neutron-capture elements cerium and neodymium in the inner Milky Way from an analysis of a sample of similar to 2000 stars in the Galactic bulge bar spatially contained within divided by X-Gal divided by < 5 kpc, divided by Y-Gal divided by < 3.5 kpc, and divided by Z(Gal)divided by < 1 kpc, and spanning metallicities between -2.0 less than or similar to [Fe/H] less than or similar to +0.5. We classify the sample stars into low- or high-[Mg/Fe] populations and find that, in general, values of [Ce/Fe] and [Nd/Fe] increase as the metallicity decreases for the low- and high-[Mg/Fe] populations. Ce abundances show a more complex variation across the metallicity range of our bulge-bar sample when compared to Nd, with the r-process dominating the production of neutron-capture elements in the high-[Mg/Fe] population ([Ce/Nd] < 0.0). We find a spatial chemical dependence of Ce and Nd abundances for our sample of bulge-bar stars, with low- and high-[Mg/Fe] populations displaying a distinct abundance distribution. In the region close to the center of the MW, the low-[Mg/Fe] population is dominated by stars with low [Ce/Fe], [Ce/Mg], [Nd/Mg], [Nd/Fe], and [Ce/Nd] ratios. The low [Ce/Nd] ratio indicates a significant contribution in this central region from r-process yields for the low-[Mg/Fe] population. The chemical pattern of the most metal-poor stars in our sample suggests an early chemical enrichment of the bulge dominated by yields from core-collapse supernovae and r-process astrophysical sites, such as magnetorotational supernovae.
  • Thumbnail Image
    Item
    Atypical Mg-poor Milky Way Field Stars with Globular Cluster Second-generation-like Chemical Patterns
    (2017) Fernández Trincado J.; Zamora, O.; García Hernández, D.; Souto, D.; Dell'Agli, F.; Schiavon, R.; Geisler, D.; Tang, B.; Villanova, S.; Chanamé, Julio; Hasselquist, S.; Mennickent, R.; Cunha, K.; Shetrone, M.; Prieto, C.; Vieira, K.; Zasowski, G.; Sobeck, J.; Hayes, C.; Majewski, S.; Placco, V.; Beers, T.; Schleicher, D.; Robin, A.; Mészáros, S.; Masseron, T.; Pérez, A.; Anders, F.; Meza, A.; Alves-Brito A.; Carrera, R.; Minniti, D.; Lane, R.; Fernández-Alvar E.; Moreno, E.; Pichardo, B.; Pérez-Villegas, A.; Schultheis, M.; Roman-Lopes, A.; Fuentes, C.; Nitschelm, C.; Harding, P.; Bizyaev, D.; Pan, K.; Oravetz, D.; Simmons, A.; Ivans, I.; Blanco-Cuaresma, S.; Hernández J.; Alonso-García, J.; Valenzuela, O.
  • Thumbnail Image
    Item
    Baade's window and APOGEE Metallicities, ages, and chemical abundances
    (2017) Schultheis, M.; Rojas Arriagada, Alvaro; Pérez, A. E. García; Jönsson, H.; Hayden, M.; Nandakumar, G.; Cunha, K.; Prieto, C. Allende; Holtzman, J. A.; Beers, T. C.; Bizyaev, D.; Brinkmann, J.; Carrera, R.; Cohen, R. E.; Geisler, D.; Hearty, F. R.; Fernández-Trincado, J. G.; Maraston, C.; Minniti, D.; Nitschelm, C.; Roman-Lopes, A.; Schneider, D. P.; Tang, B.; Villanova, S.; Zasowski, G.; Majewski, S. R.
  • No Thumbnail Available
    Item
    From the bulge to the outer disc: monospace StarHorse monospace stellar parameters, distances, and extinctions for stars in APOGEE DR16 and other spectroscopic surveys
    (2020) Queiroz, A. B. A.; Anders, F.; Chiappini, C.; Khalatyan, A.; Santiago, B. X.; Steinmetz, M.; Valentini, M.; Miglio, A.; Bossini, D.; Barbuy, B.; Minchev, I; Minniti, D.; Garcia Hernandez, D. A.; Schultheis, M.; Beaton, R. L.; Beers, T. C.; Bizyaev, D.; Brownstein, J. R.; Cunha, K.; Fernandez-Trincado, J. G.; Frinchaboy, P. M.; Lane, R. R.; Majewski, S. R.; Nataf, D.; Nitschelm, C.; Pan, K.; Roman-Lopes, A.; Sobeck, J. S.; Stringfellow, G.; Zamora, O.
    We combine high-resolution spectroscopic data from APOGEE-2 survey Data Release 16 (DR16) with broad-band photometric data from several sources as well as parallaxes from Gaia Data Release 2 (DR2). Using the Bayesian isochrone-fitting code StarHorse, we derived the distances, extinctions, and astrophysical parameters for around 388 815 APOGEE stars. We achieve typical distance uncertainties of similar to 6% for APOGEE giants, similar to 2% for APOGEE dwarfs, and extinction uncertainties of similar to 0.07 mag, when all photometric information is available, and similar to 0.17 mag if optical photometry is missing. StarHorse uncertainties vary with the input spectroscopic catalogue, available photometry, and parallax uncertainties. To illustrate the impact of our results, we show that thanks to Gaia DR2 and the now larger sky coverage of APOGEE-2 (including APOGEE-South), we obtain an extended map of the Galactic plane. We thereby provide an unprecedented coverage of the disc close to the Galactic mid-plane (|Z(Gal)| < 1 kpc) from the Galactic centre out to R-Gal20 kpc. The improvements in statistics as well as distance and extinction uncertainties unveil the presence of the bar in stellar density and the striking chemical duality in the innermost regions of the disc, which now clearly extend to the inner bulge. We complement this paper with distances and extinctions for stars in other public released spectroscopic surveys: 324 999 in GALAH DR2, 4 928 715 in LAMOST DR5, 408 894 in RAVE DR6, and 6095 in GES DR3.
  • No Thumbnail Available
    Item
    SDSS-IV MaNGA: A Star Formation-Baryonic Mass Relation at Kiloparsec Scales
    (2021) Barrera-Ballesteros, J. K.; Heckman, T.; Sanchez, S. F.; Drory, N.; Cruz-Gonzalez, I.; Carigi, L.; Riffel, R. A.; Boquien, M.; Tissera, P.; Bizyaev, D.; Rong, Y.; Boardman, N. F.; Hurtado, P. Alvarez
    Star formation rate density, sigma(SFR), has shown a remarkable correlation with both components of the baryonic mass kiloparsec scales (i.e., the stellar mass density and molecular gas mass density, sigma(*) and sigma(mol), respectively) for galaxies in the nearby universe. In this study, we propose an empirical relation between sigma(SFR) and the baryonic mass surface density (sigma(b) = sigma(mol,Av) + sigma(*), where sigma(mol,Av) is the molecular gas derived from the optical extinction, A(V)) at kiloparsec scales using the spatially resolved properties of the MaNGA survey, the largest sample of galaxies observed via integral field spectroscopy (similar to 8400 objects). We find that sigma(SFR) tightly correlates with sigma(b). Furthermore, we derive an empirical relation between sigma(SFR) and a second-degree polynomial of sigma(b), yielding a one-to-one relation between these two observables. Both sigma(b) and its polynomial form show a stronger correlation and smaller scatter with respect to sigma(SFR) than the relations derived using the individual components of sigma(b). Our results suggest that these three parameters are indeed physically correlated, suggesting a scenario in which the two components of the baryonic mass regulate the star formation activity at kiloparsec scales.
  • Thumbnail Image
    Item
    SDSS-IV MaNGA: spatially resolved star formation histories in galaxies as a function of galaxy mass and type
    (OXFORD UNIV PRESS, 2017) Goddard, D.; Thomas, D.; Maraston, C.; Westfall, K.; Etherington, J.; Riffel, R.; Mallmann, N. D.; Zheng, Z.; Argudo Fernandez, M.; Lian, J.; Bershady, M.; Bundy, K.; Drory, N.; Law, D.; Yan, R.; Wake, D.; Weijmans, A.; Bizyaev, D.; Brownstein, J.; Lane, R. R.; Maiolino, R.; Masters, K.; Merrifield, M.; Nitschelm, C.; Pan, K.; Roman Lopes, A.; Storchi Bergmann, T.; Schneider, D. P.
    We study the internal gradients of stellar population propertieswithin 1.5 R-e for a representative sample of 721 galaxies, with stellar masses ranging between 10(9)M circle dot and 10(11.5)M circle dot from the SDSS-IV MaNGA Integral-Field-Unit survey. Through the use of our full spectral fitting code FIREFLY, we derive light-and mass-weighted stellar population properties and their radial gradients, as well as full star formation and metal enrichment histories. We also quantify the impact that different stellar population models and full spectral fitting routines have on the derived stellar population properties and the radial gradient measurements. In our analysis, we find that age gradients tend to be shallow for both early-type and late-type galaxies. Mass-weighted age gradients of early-types arepositive (similar to 0.09 dex/Re) pointing to ` outsidein' progression of star formation, while late-type galaxies have negative light-weighted age gradients (similar to-0.11 dex/R-e), suggesting an ` inside-out' formation of discs. We detect negative metallicity gradients in both early-and late-type galaxies, but these are significantly steeper in late-types, suggesting that the radial dependence of chemical enrichment processes and the effect of gas inflow and metal transport are far more pronounced in discs. Metallicity gradients of both morphological classes correlate with galaxy mass, with negative metallicity gradients becoming steeper with increasing galaxy mass. The correlation with mass is stronger for late-type galaxies, with a slope of d(del[Z/H])/d(logM) similar to -0.2 +/- 0.05, compared to d(del[Z/H])/d(logM) similar to -0.05 +/- 0.05 for early-types. This result suggests that the merger history plays a relatively small role in shaping metallicity gradients of galaxies.
  • Thumbnail Image
    Item
    SPIDERS : overview of the X-ray galaxy cluster follow-up and the final spectroscopic data release
    (2020) Clerc, N.; Kirkpatrick, C. C.; Finoguenov, A.; Capasso, R.; Comparat, J.; Damsted, S.; Furnell, K.; Kukkola, A. E.; Chitham, J. I.; Padilla, Nelson; Merloni, A.; Salvato, M.; Gueguen, A.; Dwelly, T.; Collins, C.; Saro, A.; Erfanianfar, G.; Schneider, D. P.; Brownstein, J.; Mamon, G. A.; Jullo, E.; Bizyaev, D.