Examinando por Autor "Koekemoer, A. M."

Mostrando 1 - 5 de 5

Acceso Abierto
A Duality in the Origin of Bulges and Spheroidal Galaxies
(IOP Science Publishing, 2021-06-02) Constantin, L.; Pérez González, P. G.; Méndez Abreu, J.; Huertas Company, M.; Dimauro, P.; Alcalde Pampliega, B.; Buitrago, F.; Ceverino, D.; Daddi, E.; Domínguez Sánchez, H.; Espino Briones, N.; Hernán Caballero, A.; Koekemoer, A. M.; Rodighiero, G.; Constantin, L. [0000-0001-6820-0015]; Pérez González, P. G. [0000-0003-4528-5639]; Méndez Abreu, J. [0000-0002-8766-2597]; Huertas Company, M. [0000-0002-1416-8483]; Dimauro, P. [0000-0001-7399-2854]; Alcalde Pampliega, B. [0000-0002-4140-0428]; Buitrago, F. [0000-0002-2861-9812]; Caverino, D. [0000-0002-8680-248X]; Daddi, E. [0000-0002-3331-9590]; Domínguez Sánchez, H. [0000-0002-9013-1316]; Espino Briones, N. [0000-0001-6426-3844]; Hernán Caballero, A. [0000-0002-4237-5500]; Koekemoer, A. M. [0000-0002-6610-2048]; Rodighiero, G. [0000-0002-9415-2296]
Studying the resolved stellar populations of the different structural components that build massive galaxies directly unveils their assembly history. We aim at characterizing the stellar population properties of a representative sample of bulges and pure spheroids in massive galaxies (M⋆ > 1010 M⊙) in the GOODS-N field. We take advantage of the spectral and spatial information provided by SHARDS and Hubble Space Telescope data to perform the multi-image spectrophotometric decoupling of the galaxy light. We derive the spectral energy distribution separately for bulges and disks in the redshift range 0.14 < z ≤ 1 with spectral resolution R ∼ 50. Analyzing these spectral energy distributions, we find evidence of a bimodal distribution of bulge formation redshifts. We find that 33% of them present old mass-weighted ages, implying a median formation redshift ${z}_{\mathrm{form}}={6.2}_{-1.7}^{+1.5}$. They are relics of the early universe embedded in disk galaxies. A second wave, dominant in number, accounts for bulges formed at median redshift ${z}_{\mathrm{form}}={1.3}_{-0.6}^{+0.6}$. The oldest (first-wave) bulges are more compact than the youngest. Virtually all pure spheroids (i.e., those without any disk) are coetaneous with the second-wave bulges, presenting a median redshift of formation ${z}_{\mathrm{form}}={1.1}_{-0.3}^{+0.3}$. The two waves of bulge formation are distinguishable not only in terms of stellar ages but also in star formation mode. All first-wave bulges formed fast at z ∼ 6, with typical timescales around 200 Myr. A significant fraction of the second-wave bulges assembled more slowly, with star formation timescales as long as 1 Gyr. The results of this work suggest that the centers of massive disk-like galaxies actually harbor the oldest spheroids formed in the universe.
Acceso Abierto
Implications of Increased Central Mass Surface Densities for the Quenching of Low-mass Galaxies
(IOP Science Publishing, 2021-06-08) Guo, Y.; Carleton, T.; Bell, E. F.; Chen, Z.; Dekel, A.; Faber, S. M.; Giavalisco, M.; Kocevski, D. D.; Koekemoer, A. M.; Koo, D. C.; Kurczynski, P.; Lee, S. K.; Liu, F. S.; Papovich, C.; Pérez González, G.; National Science Foundation (NSF); National Aeronautics and Space Administration (NASA); National Research Foundation of Korea (NRF); Guo, Y. [0000-0003-2775-2002]; Carleton, T. [0000-0001-6650-2853]; Bell, E. F. [0000-0002-5564-9873]; Chen, Z. [0000-0002-2326-0476]; Dekel, A. [0000-0003-4174-0374]; Fabel, S. M. [0000-0003-4996-214X]; Giavalisco, M. [0000-0002-7831-8751]; Kocevski, D. D. [0000-0002-8360-3880]; Koekemoer, A. M. [0000-0002-6610-2048]; Koo, D. C. [0000-0003-3385-6799]; Kurczynski, P. [0000-0002-8816-5146]; Lee, S. K. [0000-0001-5342-8906]; Liu, F. S. [0000-0002-1064-1544]; Papovich, C. [0000-0001-7503-8482]; Pérez González, P. G. [0000-0003-4528-5639]
We use the Cosmic Assembly Deep Near-infrared Extragalactic Legacy Survey data to study the relationship between quenching and the stellar mass surface density within the central radius of 1 kpc (Σ1) of low-mass galaxies (stellar mass M* ≲ 109.5 M⊙) at 0.5 ≤ z < 1.5. Our sample is mass complete down to ∼109 M⊙ at 0.5 ≤ z < 1.0. We compare the mean Σ1 of star-forming galaxies (SFGs) and quenched galaxies (QGs) at the same redshift and M*. We find that low-mass QGs have a higher Σ1 than low-mass SFGs, similar to galaxies above 1010 M⊙. The difference of Σ1 between QGs and SFGs increases slightly with M* at M* ≲ 1010 M⊙ and decreases with M* at M* ≳ 1010 M⊙. The turnover mass is consistent with the mass where quenching mechanisms transition from internal to environmental quenching. At 0.5 ≤ z < 1.0, we find that Σ1 of galaxies increases by about 0.25 dex in the green valley (i.e., the transition region from star forming to fully quenched), regardless of their M*. Using the observed specific star formation rate gradient in the literature as a constraint, we estimate that the quenching timescale (i.e., time spent in the transition) of low-mass galaxies is a few (∼4) Gyr at 0.5 ≤ z < 1.0. The mechanisms responsible for quenching need to gradually quench star formation in an outside-in way, i.e., preferentially ceasing star formation in outskirts of galaxies while maintaining their central star formation to increase Σ1. An interesting and intriguing result is the similarity of the growth of Σ1 in the green valley between low-mass and massive galaxies, which suggests that the role of internal processes in quenching low-mass galaxies is a question worthy of further investigation.
Acceso Abierto
JWST/MIRI Simulated Imaging: Insights into Obscured Star Formation and AGNs for Distant Galaxies in Deep Surveys
(IOP Science Publishing, 2021-02-19) Yang, C.; Papovich, C.; Bagley, M. B.; Buat, V.; Burgarella, D.; Dickinson, M.; Elbaz, D.; Finkelstein, S.; Fontana, A.; Grogin, N. A.; Jung, I.; Kartaltepe, J. S.; Kirkpatrick, A.; Koekemoer, A. M.; Pérez González, P. G.; Pirzkal, N.; Yung, L. Y. A.; Yang, C. [0000-0001-8835-7722]; Papovich, C. [0000-0001-7503-8482]; Bagley, M. B. [0000-0002-9921-9218]; Buat, V. [0000-0003-3441-903X]; Burgarella, D. [0000-0002-4193-2539]; Dickinson, M. [0000-0001-5414-5131]; Finkelstein, S. L. [0000-0001-8519-1130]; Fontana, A. [0000-0003-3820-2823]; Grogin, N. A. [0000-0001-9440-8872]; Jung, I. [0000-0003-1187-4240]; Kartaltepe, J. S. [0000-0001-9187-3605]; Kirkpatrick, A. [0000-0002-1306-1545]; Koekemoer, A. M. [0000-0002-6610-2048]; Pérez González, P. G. [0000-0003-4528-5639]; Yung, L. Y. A. [0000-0003-3466-035X]
The James Webb Space Telescope MIRI instrument will revolutionize extragalactic astronomy with unprecedented sensitivity and angular resolution in mid-IR. Here we assess the potential of MIRI photometry to constrain galaxy properties in the Cosmic Evolution Early Release Science (CEERS) survey. We derive estimated MIRI fluxes from the spectral energy distributions (SEDs) of real sources that fall in a planned MIRI pointing. We also obtain MIRI fluxes for hypothetical active galactic nucleus (AGN)–galaxy mixed models varying the AGN fractional contribution to the total IR luminosity (fracAGN). Based on these model fluxes, we simulate CEERS imaging (3.6 hr exposure) in six bands from F770W to F2100W using mirisim and reduce these data using jwst pipeline. We perform point-spread-function-matched photometry with tphot and fit the source SEDs with x-cigale, simultaneously modeling photometric redshift and other physical properties. Adding the MIRI data, the accuracy of both redshift and fracAGN is generally improved by factors of ≳2 for all sources at z ≲ 3. Notably, for pure-galaxy inputs (fracAGN = 0), the accuracy of fracAGN is improved by ∼100 times thanks to MIRI. The simulated CEERS MIRI data are slightly more sensitive to AGN detections than the deepest X-ray survey, based on the empirical LX–L6 μm relation. Like X-ray observations, MIRI can also be used to constrain the AGN accretion power (accuracy ≈0.3 dex). Our work demonstrates that MIRI will be able to place strong constraints on the mid-IR luminosities from star formation and AGNs and thereby facilitate studies of the galaxy/AGN coevolution.
Acceso Abierto
The host galaxies of luminous type 2 AGNs at z ∼ 0.3–0.4
(Oxford Academics: Oxford University Press, 2019-02-28) Urbano Mayorgas, J. J.; Villar Martín, M.; Buitrago, F.; Piqueras López, J.; Rodríguez del Pino, B.; Koekemoer, A. M.; Huertas Company, M.; Domínguez Tenreiro, R.; Carrera, F. J.; Tadhunter, C.; Fundação para a Ciência e a Tecnologia (FCT); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Buitrago, F. [0000-0002-2861-9812]; Koekemoer, A. M. [0000-0002-6610-2048]
We study the morphological and structural properties of the host galaxies associated with 57 optically selected luminous type 2 active galactic nuclei (AGNs) at z ∼ 0.3–0.4: 16 high-luminosity Seyfert 2 [HLSy2, 8.0 ≤ log(⁠L[OIII]/L⊙)< 8.3] and 41 obscured [QSO2, log(⁠L[OIII]/L⊙)≥ 8.3] quasars. With this work, the total number of QSO2s at z < 1 with parametrized galaxies increases from ∼35 to 76. Our analysis is based on Hubble Space Telescope WFPC2 and ACS images that we fit with GALFIT. HLSy2s and QSO2s show a wide diversity of galaxy hosts. The main difference lies in the higher incidence of highly disturbed systems among QSO2s. This is consistent with a scenario in which galaxy interactions are the dominant mechanism triggering nuclear activity at the highest AGN power. There is a strong dependence of galaxy properties with AGN power (assuming L[OIII] is an adequate proxy). The relative contribution of the spheroidal component to the total galaxy light (B/T) increases with L[OIII]⁠. While systems dominated by the spheroidal component spread across the total range of L[OIII]⁠, most disc-dominated galaxies concentrate at log(⁠L[OIII]/L⊙)<8.6. This is expected if more powerful AGNs are powered by more massive black holes which are hosted by more massive bulges or spheroids. The average galaxy sizes (〈re〉) are 5.0 ± 1.5 kpc for HLSy2s and 3.9 ± 0.6 kpc for HLSy2s and QSO2s, respectively. These are significantly smaller than those found for QSO1s and narrow-line radio galaxies at similar z⁠. We put the results of our work in the context of related studies of AGNs with quasar-like luminosities.
Restringido
The structural properties of classical bulges and discs from z ∼ 2
(Oxford Academics: Oxford University Press, 2019-09-02) Dimauro, P.; Huertas Company, M.; Daddi, E.; Pérez González, P. G.; Bernardi, M.; Caro, F.; Cattaneo, A.; Häubler, B.; Kuchner, U.; Shankar, F.; Barro, G.; Buitrago, F.; Faber, S. M.; Kocevski, D. D.; Koekemoer, A. M.; Koo, D. C.; Mei, S.; Peletier, R.; Primack, J.; Rodríguez Puebla, A.; Salvato, M.; Tuccillo, D.; Ministerio de Economía y Competitividad (MINECO); Salvato, M. [https://orcid.org/0000-0001-7116-9303]; Buitrago, F. [https://orcid.org/0000-0002-2861-9812]; Daddi, E. [https://orcid.org/0000-0002-3331-9590]; Peletier, R. [https://orcid.org/0000-0001-7621-947X]; Huertas Company, M. [https://orcid.org/0000-0002-1416-8483]
We study the rest-frame optical mass–size relation of bulges and discs from z ∼ 2 to z ∼ 0 for a complete sample of massive galaxies in the CANDELS fields using two-component Sérsic models. Discs and star-forming galaxies follow similar mass–size relations. The mass–size relation of bulges is less steep than the one of quiescent galaxies (best-fitting slope of 0.7 for quiescent galaxies against 0.4 for bulges). We find little dependence of the structural properties of massive bulges and discs with the global morphology of galaxies (disc versus bulge dominated) and the star formation activity (star-forming versus quiescent). This result suggests similar bulge formation mechanisms for most massive galaxies and also that the formation of the bulge component does not significantly affect the disc structure. Our results pose a challenge to current cosmological models that predict distinct structural properties for stellar bulges arising from mergers and disc instabilities.