Proyecto de Investigación: ESP2015-65597-C4-1-R
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ESP2015-65597-C4-1-R
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GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre II. First data release of the catalogue and the most detailed CMDs of the GC
(EDP Sciences, 2019-10-15) Nogueras Lara, F.; Schödel, R.; Gallego Calvente, A. T.; Dong, H.; Gallego Cano, E.; Shahzamanian, B.; Girard, J. H. V.; Nishiyama, S.; Najarro, F.; Neumayer, N.; European Commission (EC); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Deutsche Forschungsgemeinschaft (DFG); Nogueras Lara, F. [0000-0002-6379-7593]; Schöedel, R. [0000-0001-5404-797X]; Gallego Calvente, A. T. [0000-0002-6428-8045]; Gallego Cano, E. [0000-0002-7452-1496]; Shahzamanian, B. [0000-0001-6437-6806]; Najarro, F. [0000-0002-9124-0039]; Neumayer, N. [0000-0002-6922-2598]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Context. The high extinction and extreme source crowding of the central regions of the Milky Way are serious obstacles to the study of the structure and stellar population of the Galactic centre (GC). Existing surveys that cover the GC region (2MASS, UKIDSS, VVV, SIRIUS) do not have the necessary high angular resolution. Therefore, a high-angular-resolution survey in the near infrared is crucial to improve the state of the art.
Aims. Here, we present the GALACTICNUCLEUS catalogue, a near infrared JHKs high-angular-resolution (0.2″) survey of the nuclear bulge of the Milky Way.
Methods. We explain in detail the data reduction, data analysis, calibration, and uncertainty estimation of the GALACTICNUCLEUS survey. We assess the data quality comparing our results with previous surveys.
Results. We obtained accurate JHKs photometry for ∼3.3 × 106 stars in the GC detecting around 20% in J, 65% in H, and 90% in Ks. The survey covers a total area of ∼0.3 deg2, which corresponds to ∼6000 pc2. The GALACTICNUCLEUS survey reaches 5σ detections for J ∼ 22 mag, H ∼ 21 mag, and Ks ∼ 21 mag. The uncertainties are below 0.05 mag at J ∼ 21 mag, H ∼ 19 mag, and Ks ∼ 18 mag. The zero point systematic uncertainty is ≲0.04 mag in all three bands. We present colour–magnitude diagrams for the different regions covered by the survey.
Early formation and recent starburst activity in the nuclear disk of the Milky Way.
(Nature Research Journals, 2020-04-01) Nogueras Lara, F.; Schödel, R.; Gallego Calvente, A. T.; Gallego Cano, E.; Shahzamanian, B.; Dong, H.; Neumayer, N.; Hilker, M.; Najarro, F.; Nishiyama, S.; Feldmeier Krause, A.; Girard, J. H. V.; Cassisi, S.; European Commission (EC); Ministerio de Educación, Cultura y Deporte (MECD); Agencia Estatal de Investigación (AEI); 0000-0001-5870-3735; 0000-0002-2363-5522; 0000-0002-7452-1496; 0000-0002-6922-2598; 0000-0002-6379-7593; 0000-0001-6437-6806; 0000-0002-0160-7221; 0000-0001-8627-0404; 0000-0002-6428-8045; 0000-0002-9440-7172; 0000-0001-5404-797X; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The nuclear disk is a dense stellar structure at the centre of the Milky Way, with a radius of ~150 pc (ref. (1)). It has been a place of intense star formation in the past several tens of millions of years(1-3), but its overall formation history has remained unknown(2). Here, we report that the bulk of its stars formed at least 8 Gyr ago. After a long period of quiescence, a starburst event followed about 1 Gyr ago that formed roughly 5% of its mass within ~100 Myr, in what may arguably have been one of the most energetic events in the history of the Milky Way. Star formation continued subsequently on a lower level, creating a few per cent of the stellar mass in the past ~500 Myr, with an increased rate up to ~30 Myr ago. Our findings contradict the previously accepted paradigm of quasi-continuous star formation at the Galactic Centre(4). The long quiescent phase agrees with the overall quiescent history of the Milky Way(2,5) and suggests that our Galaxy's bar may not have existed until recently, or that gas transport through the bar was extremely inefficient during a long stretch of the Milky Way's life. Consequently, the central black hole may have acquired most of its mass already in the early days of the Milky Way.
A global view of the inner accretion and ejection flow around super massive black holes Radiation-driven accretion disk winds in a physical context
(EDP Sciences, 2019-09-26) Giustini, M.; Proga, D.; Ministerio de Economía y Competitividad (MINECO); National Aeronautics and Space Administration (NASA); Giustini, M. [0000-0002-1329-658X]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Understanding the physics and geometry of accretion and ejection around super massive black holes (SMBHs) is important to understand the evolution of active galactic nuclei (AGN) and therefore of the large scale structures of the Universe.
Aims. We aim at providing a simple, coherent, and global view of the sub-parsec accretion and ejection flow in AGN with varying Eddington ratio, ṁ, and black hole mass, MBH.
Methods. We made use of theoretical insights, results of numerical simulations, as well as UV and X-ray observations to review the inner regions of AGN by including different accretion and ejection modes, with special emphasis on the role of radiation in driving powerful accretion disk winds from the inner regions around the central SMBH.
Results. We propose five ṁ regimes where the physics of the inner accretion and ejection flow around SMBHs is expected to change, and that correspond observationally to quiescent and inactive galaxies; low luminosity AGN (LLAGN); Seyferts and mini-broad absorption line quasars (mini-BAL QSOs); narrow line Seyfert 1 galaxies (NLS1s) and broad absorption line quasars (BAL QSOs); and super-Eddington sources. We include in this scenario radiation-driven disk winds, which are strong in the high ṁ, large MBH regime, and possibly present but likely weak in the moderate ṁ, small MBH regime.
Conclusions. A great diversity of the accretion/ejection flows in AGN can be explained to a good degree by varying just two fundamental properties: the Eddington ratio ṁ and the black hole mass MBH, and by the inclusion of accretion disk winds that can naturally be launched by the radiation emitted from luminous accretion disks.
Variability of the near-infrared extinction curve towards the Galactic centre
(EDP Sciences, 2019-09-23) Nogueras Lara, F.; Schödel, R.; Najarro, F.; Gallego Calvente, A. T.; Gallego Cano, E.; Shahzamanian, B.; Neumayer, N.; European Commission (EC); European Southern Observatory (ESO); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Nogueras Lara, F. [0000-0002-6379-7593]; Schöedel, R. [0000-0001-5404-797X]; Gallego Calvente, A. T. [0000-0002-6428-8045]; Shahzamanian, B. [0000-0001-6437-6806]; Neumayer, N. [0000-0002-6922-2598]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Context. Due to the extreme extinction towards the Galactic centre (AV ∼ 30 mag), its stellar population is mainly studied in the near-infrared (NIR) regime. Therefore, a proper analysis of the NIR extinction curve is necessary to fully characterise the stellar structure and population of the inner part of the galaxy.
Aims. We studied the dependence of the extinction index (αλ) in the NIR on the line of sight, wavelength, and extinction.
Methods. We used the GALACTICNUCLEUS imaging survey, a high angular resolution catalogue (0.2″) for the inner part of the Galaxy in JHKs, and studied the spatial variation in the extinction index. We also applied two independent methods based on red clump stars to compute the extinction index between different bands and its variation with wavelength.
Results. We did not detect any significant line-of-sight or extinction variation in α within the studied region in the nuclear stellar disc. The extinction index between JH and HKs differs by 0.19 ± 0.05. We obtained mean values for the extinction indices αJH = 2.43 ± 0.03 and αHKs = 2.23 ± 0.03. The dependence of the extinction index on the wavelength could explain the differences obtained for αλ in the literature since it was assumed constant for the NIR regime.
Chemical complexity in high-mass star formation An observational and modeling case study of the AFGL 2591 VLA 3 hot core
(EDP Sciences, 2019-11-08) Gieser, C.; Semenov, D.; Beuther, H.; Ahmadi, A.; Mottram, J. C.; Henning, T.; Beltrán, M. T.; Maud, L. T.; Bosco, F.; Leurini, S.; Peters, T.; Klaassen, P. D.; Kuiper, R.; Feng, S.; Urquhart, J. S.; Moscadelli, L.; Csengeri, T.; Lumsden, S.; Winters, J. M.; Suri, S.; Zhang, Q.; Pudritz, R.; Palau, A.; Menten, K. M.; Galván Madrid, R.; Wyrowski, F.; Schilke, P.; Sánchez Monge, A.; Linz, H.; Johnston, K. G.; Jiménez Serra, I.; Longmore, S.; Möller, T.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); European Research Council (ERC); Kuiper, R. [0000-0003-2309-8963]; Sánchez Monge, A. [0000-0002-3078-9482]; Galván Madrid, R. [0000-0003-1480-4643]; Leurini, S. [0000-0003-1014-3390]; Ahmadi, A. [0000-0003-4037-5248]; Semenov, D. [0000-0002-3913-7114]; Gieser, C. [0000-0002-8120-1765]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Aims. In order to understand the observed molecular diversity in high-mass star-forming regions, we have to determine the underlying physical and chemical structure of those regions at high angular resolution and over a range of evolutionary stages.
Methods. We present a detailed observational and modeling study of the hot core VLA 3 in the high-mass star-forming region AFGL 2591, which is a target region of the NOrthern Extended Millimeter Array (NOEMA) large program CORE. Using NOEMA observations at 1.37 mm with an angular resolution of ~0″. 42 (1400 au at 3.33 kpc), we derived the physical and chemical structure of the source. We modeled the observed molecular abundances with the chemical evolution code MUSCLE (MUlti Stage ChemicaL codE).
Results. With the kinetic temperature tracers CH3CN and H2CO we observe a temperature distribution with a power-law index of q = 0.41 ± 0.08. Using the visibilities of the continuum emission we derive a density structure with a power-law index of p = 1.7 ± 0.1. The hot core spectra reveal high molecular abundances and a rich diversity in complex molecules. The majority of the molecules have an asymmetric spatial distribution around the forming protostar(s), which indicates a complex physical structure on scales <1400 au. Using MUSCLE, we are able to explain the observed molecular abundance of 10 out of 14 modeled species at an estimated hot core chemical age of ~21 100 yr. In contrast to the observational analysis, our chemical modeling predicts a lower density power-law index of p < 1.4. Reasons for this discrepancy are discussed.
Conclusions. Combining high spatial resolution observations with detailed chemical modeling allows us to derive a concise picture of the physical and chemical structure of the famous AFGL 2591 hot core. The next steps are to conduct a similar analysis for the whole CORE sample, and then use this analysis to constrain the chemical diversity in high-mass star formation to a much greater depth.
