Examinando por Autor "Rigopoulou, D."

Mostrando 1 - 9 de 9

Acceso Abierto
A Complete 16 μm Selected Galaxy Sample at z ∼ 1: Mid-infrared Spectral Energy Distributions
(IOP Science Publishing, 2021-05-28) Huang, J. S.; Dai, Y. S.; Willner, S. P.; Faber, S. M.; Cheng, C.; Xu, H.; Yan, H.; Wu, S.; Shao, X.; Hao, C.; Xia, X.; Rigopoulou, D.; Pereira Santaella, M.; Magdis, Georgios E.; Cortzen, I.; Fazio, G. G.; Assmann, P.; Fan, L.; Musin, M.; Zang, Z.; Xu, K. C.; He, C.; Jin, G.; Esamdin, A.; National Natural Science Foundation of China (NSFC); Chinese Academy of Sciences (CAS); Danish National Research Foundation (DNRF); Science and Technology Facilities Council (STFC); South America Center for Astronomy (CASSACA); Huang, J. S. [0000-0001-6511-8745]; Dai, Y. S. [0000-0002-7928-416X]; Willner, S. P. [0000-0002-9895-5758]; Faber, S. M. [0000-0003-4996-214X]; Cheng, C. [0000-0003-0202-0534]; Yan, H. [0000-0001-7592-7714]; Rigopoulou, D. [0000-0001-6854-7545]; Pereira Santaella, M. [0000-0002-4005-9619]; Magdis, G. [0000-0002-4872-2294]; Cortzen, I. [0000-0001-9197-7623]; Fazio, G. G. [0000-0002-0670-0708]; Fan, L. [0000-0003-4200-4432]; Jin, G. [0000-0003-3087-318X]; Esamdin, A. [0000-0003-1845-4900]
We describe a complete, flux-density-limited sample of galaxies at redshift 0.8 < z < 1.3 selected at 16 μm. At the selection wavelength near 8 μm rest, the observed emission comes from both dust heated by intense star formation and active galactic nuclei (AGNs). Fitting the spectral energy distributions (SEDs) of the sample galaxies to local-galaxy templates reveals that more than half the galaxies have SEDs dominated by star formation. About one-sixth of the galaxy SEDs are dominated by an AGN, and nearly all of the rest of the SEDs are composite. Comparison with X-ray and far-infrared observations shows that combinations of luminosities at rest-frame 4.5 and 8 μm give good measures of both AGN luminosity and star formation rate. The sample galaxies mostly follow the established star-forming main sequence for z = 1 galaxies, but of the galaxies more than 0.5 dex above that main sequence, more than half have AGN-type SEDs. Similarly, the most luminous AGNs tend to have higher star formation rates than the main-sequence value. Galaxies with stellar masses >1011 M⊙ are unlikely to host an AGN. About 1% of the sample galaxies show an SED with dust emission typical of neither star formation nor an AGN.
Acceso Abierto
Cold molecular gas and PAH emission in the nuclear and circumnuclear regions of Seyfert galaxies
(EDP Sciences, 2020-07-07) Alonso Herrero, A.; Pereira Santaella, M.; Rigopoulou, D.; García Bernete, I.; García Burillo, S.; Domínguez Fernández, A. J.; Combes, F.; Davies, R. I.; Díaz Santos, T.; Esparza Borges, E.; González Martín, O.; Hernán Caballero, A.; Hicks, E. K. S.; Hönig, S. F.; Levenson, N. A.; Ramos Almeida, C.; Roche, P. F.; Rosario, D.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Science and Technology Facilities Council (STFC); Universidad Nacional Autónoma de México (UNAM); European Research Council (ERC); National Aeronautics and Space Administration (NASA); 0000-0001-8353-649X; 0000-0003-0699-6083; 0000-0002-0001-3587; 0000-0002-8524-8413; 0000-0003-4949-7217; 0000-0002-6353-1111
We investigate the relation between the detection of the 11.3 mu m polycyclic aromatic hydrocarbon (PAH) feature in the nuclear (similar to 24-230 pc) regions of 22 nearby Seyfert galaxies and the properties of the cold molecular gas. For the former we use ground-based (0.3-0.6 '' resolution) mid-infrared (mid-IR) spectroscopy. The cold molecular gas is traced by ALMA and NOEMA high (0.2-1.1 '') angular resolution observations of the CO(2-1) transition. Galaxies with a nuclear detection of the 11.3 mu m PAH feature contain more cold molecular gas (median 1.6x10(7) M-circle dot) and have higher column densities (N(H-2) = 2x10(23) cm(-2)) over the regions sampled by the mid-IR slits than those without a detection. This suggests that molecular gas plays a role in shielding the PAH molecules in the harsh environments of Seyfert nuclei. Choosing the PAH molecule naphthalene as an illustration, we compute its half-life in the nuclear regions of our sample when exposed to 2.5 keV hard X-ray photons. We estimate shorter half-lives for naphthalene in nuclei without a 11.3 mu m PAH detection than in those with a detection. The Spitzer/IRS PAH ratios on circumnuclear scales (similar to 4 ''similar to 0.25-1.3 kpc) are in between model predictions for neutral and partly ionized PAHs. However, Seyfert galaxies in our sample with the highest nuclear H-2 column densities are not generally closer to the neutral PAH tracks. This is because in the majority of our sample galaxies, the CO(2-1) emission in the inner similar to 4 '' is not centrally peaked and in some galaxies traces circumnuclear sites of strong star formation activity. Spatially resolved observations with the MIRI medium-resolution spectrograph on the James Webb Space Telescope will be able to distinguish the effects of an active galactic nucleus (AGN) and star formation on the PAH emission in nearby AGN.
Acceso Abierto
Excitation and acceleration of molecular outflows in LIRGs: The extended ESO 320-G030 outflow on 200-pc scales
(EDP Sciences, 2020-11-06) Pereira Santaella, M.; Colina, L.; García Burillo, S.; González Alfonso, E.; Alonso Herrero, A.; Arribas, S.; Cazzoli, S.; Piqueras López, J.; Rigopoulou, D.; Usero, A.; Comunidad de Madrid; Agencia Estatal de Investigación (AEI); Usero, A. [0000-0003-1242-505X]; Pereira Santaella, M. [0000-0002-4005-9619]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We used high-spatial resolution (70 pc; 03) CO multi-transition (J = 1–0, 2–1, 4–3, and 6–5) ALMA data to study the physical conditions and kinematics of the cold molecular outflow in the local luminous infrared galaxy (LIRG) ESO 320-G030 (d = 48 Mpc, LIR/L⊙ = 1011.3). ESO 320-G030 is a double-barred isolated spiral, but its compact and obscured nuclear starburst (SFR ∼ 15 M⊙ yr−1; AV ∼ 40 mag) resembles those of ultra-luminous infrared galaxies (LIR/L⊙ > 1012). In the outflow, the CO(1–0)/CO(2–1) ratio is enhanced with respect to the rest of the galaxy and the CO(4–3) transition is undetected. This indicates that the outflowing molecular gas is less excited than the molecular gas in the nuclear starburst (i.e., outflow launching site) and in the galaxy disk. Non-local thermodynamic equilibrium radiative transfer modeling reveals that the properties of the molecular clouds in the outflow differ from those of the nuclear and disk clouds: The kinetic temperature is lower (Tkin ∼ 9 K) in the outflow, and the outflowing clouds have lower column densities. Assuming a 10−4 CO abundance, the large internal velocity gradients, 60−45+250 km s−1 pc−1, imply that the outflowing molecular clouds are not bound by self-gravity. All this suggests that the life-cycle (formation, collapse, dissipation) of the galaxy disk molecular clouds might differ from that of the outflowing molecular clouds which might not be able to form stars. The low kinetic temperature of the molecular outflow remains constant at radial distances between 0.3 and 1.7 kpc. This indicates that the heating by the hotter ionized outflow phase is not efficient and may favor the survival of the molecular gas phase in the outflow. The spatially resolved velocity structure of the outflow shows a 0.8 km s−1 pc−1 velocity gradient between 190 pc and 560 pc and then a constant maximum outflow velocity of about 700–800 km s−1 up to 1.7 kpc. This could be compatible with a pure gravitational evolution of the outflow, which would require coupled variations of the mass outflow rate and the outflow launching velocity distribution. Alternatively, a combination of ram pressure acceleration and cloud evaporation could explain the observed kinematics and the total size of the cold molecular phase of the outflow.
Restringido
Extinction in the 11.2 mu m PAH band and the low L-11.2/L-IR in ULIRGs
(Oxford Academics: Blackwell Publishing, 2020-08-05) Hernández Caballero, A.; Spoon, H. W. W.; Alonso Herrero, A.; Hatziminaoglou, Evanthia; Magdis, Georgios E.; Pérez González, P. G.; Pereira Santaella, M.; Arribas, S.; Cortzen, I.; Labiano, Á.; Piqueras, J.; Rigopoulou, D.; National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); Villum Fonden; Danish National Research Foundation (DNRF); Comunidad de Madrid; 0000-0002-4872-2294; 0000-0001-9197-7623; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present a method for recovering the intrinsic (extinction-corrected) luminosity of the 11.2 mu m PAH band in galaxy spectra. Using 105 high S/N Spitzer/IRS spectra of star-forming galaxies, we show that the equivalent width ratio of the 12.7 and 11.2 mu m PAH bands is independent on the optical depth (tau), with small dispersion (similar to 5 percent) indicative of a nearly constant intrinsic flux ratio R-int = (f(12.7)/f(11.2))(int) = 0.377 +/- 0.020. Conversely, the observed flux ratio, R-obs = (f(12.7)/f(11.2))(obs), strongly correlates with the silicate strength (S-sil) confirming that differences in R-obs reflect variation in tau. The relation between R-obs and S-sil reproduces predictions for the Galactic Centre extinction law but disagrees with other laws. We calibrate the total extinction affecting the 11.2 mu m PAH from R-obs, which we apply to another sample of 215 galaxies with accurate measurements of the total infrared luminosity (L-IR) to investigate the impact of extinction on L-11.2/L-IR. Correlation between L-11.2/L-IR and R-obs independently on L-IR suggests that increased extinction explains the well-known decrease in the average L-11.2/L-IR at high L-IR. The extinction-corrected L-11.2 is proportional to L-IR in the range L-IR = 10(9)-10(13) L-circle dot. These results consolidate L-11.2 as a robust tracer of star formation in galaxies.
Acceso Abierto
Integral field spectroscopy of luminous infrared main-sequence galaxies at cosmic noon
(Oxford Academics: Oxford University Press, 2021-02-26) Hogan, L.; Rigopoulou, D.; Magdis, Georgios E.; Pereira Santaella, M.; García Bernete, I.; Thatte, N.; Grisdale, K.; Huang, J. S.; Science and Technology Facilities Council (STFC); Villum Fonden; Comunidad de Madrid; Magdis, G. E. [0000-0002-4872-2294]; Pereira Santaella, M. [0000-0002-4005-9619]; Grisdale, K. [0000-0003-0375-5997]
We present the results of an integral field spectroscopy survey of a sample of dusty (ultra) luminous infrared galaxies (U/LIRGs) at 2 < z < 2.5 using KMOS on the Very Large Telescope. The sample has been drawn from Herschel deep field surveys and benefits from ancillary multiwavelength data. Our goal is to investigate the physical characteristics, kinematics, and the drivers of star formation in the galaxies whose contribution dominates the peak of the cosmic star formation density. Two-thirds of the sample are main-sequence galaxies in contrast to the starburst nature of local U/LIRGs. Our kinematic study, unique in its focus on z ∼ 2 dusty star-forming galaxies, uses the H α emission line to find that ∼40 per cent appear to be isolated discs based on the ratio of rotational velocity to the velocity dispersion, suggesting steady-state mechanisms are sufficient to power the large star formation rates (SFRs). The ratio of obscured to unobscured star formation indicates the sample of galaxies experiences less dust obscuration compared to intermediate and local counterparts, while also hosting cooler dust than local U/LIRGs. In addition to H α we detect [N II] 6583 Å in our targets and show the gas-phase metallicities do not exhibit the metal deficiency of local U/LIRGs. These results indicate that, despite their extreme IR luminosity, the underlying mechanisms driving the massive SFRs found at cosmic noon are due to scaled up disc galaxies as opposed to mergers.
Acceso Abierto
Multiphase feedback processes in the Sy2 galaxy NGC 5643
(EDP Sciences, 2021-01-12) García Bernete, I.; Alonso Herrero, A.; García Burillo, S.; Pereira Santaella, M.; García Lorenzo, B.; Carrera, F. J.; Rigopoulou, D.; Ramos Almeida, C.; Villar Martín, M.; González Martín, O.; Hicks, E. K. S.; Labiano, Á.; Ricci, C.; Mateos, S.; Ministerio de Economía y Competitividad (MINECO); Science and Technology Facilities Council (STFC); Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); García Lorenzo, M. B. [0000-0002-7228-7173]; Ramos Almeida, C. [0000-0001-8353-649X]; Carrero, F. J. [0000-0003-2135-9023]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Unidad de Excelencia Científica María de Maeztu AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS (CSIC), MDM-2017-0765
We study the multiphase feedback processes in the central ∼3 kpc of the barred Seyfert 2 galaxy NGC 5643. We used observations of the cold molecular gas (ALMA CO(2−1) transition) and ionized gas (MUSE IFU optical emission lines). We studied different regions along the outflow zone, which extends out to ∼2.3 kpc in the same direction (east-west) as the radio jet, as well as nuclear and circumnuclear regions in the host galaxy disk. The CO(2−1) line profiles of regions in the outflow and spiral arms show two or more different velocity components: one associated with the host galaxy rotation, and the others with out- or inflowing material. In the outflow region, the [O III]λ5007 Å emission lines have two or more components: the narrow component traces rotation of the gas in the disk, and the others are related to the ionized outflow. The deprojected outflowing velocities of the cold molecular gas (median Vcentral ∼ 189 km s−1) are generally lower than those of the outflowing ionized gas, which reach deprojected velocities of up to 750 km s−1 close to the active galactic nucleus (AGN), and their spatial profiles follow those of the ionized phase. This suggests that the outflowing molecular gas in the galaxy disk is being entrained by the AGN wind. We derive molecular and ionized outflow masses of ∼5.2 × 107 M⊙ (αCOGalactic) and 8.5 × 104 M⊙ and molecular and ionized outflow mass rates of ∼51 M⊙ yr−1 (αCOGalactic) and 0.14 M⊙ yr−1, respectively. This means that the molecular phase dominates the outflow mass and outflow mass rate, while the kinetic power and momentum of the outflow are similar in both phases. However, the wind momentum loads (Ṗout/ṖAGN) for the molecular and ionized outflow phases are ∼27−5 (αCOGalactic and αCOULIRGs) and < 1, which suggests that the molecular phase is not momentum conserving, but the ionized phase most certainly is. The molecular gas content (Meast ∼ 1.5 × 107 M⊙; αCOGalactic) of the eastern spiral arm is approximately 50−70% of the content of the western one. We interpret this as destruction or clearing of the molecular gas produced by the AGN wind impacting in the eastern side of the host galaxy (negative feedback process). The increase in molecular phase momentum implies that part of the kinetic energy from the AGN wind is transmitted to the molecular outflow. This suggests that in Seyfert-like AGN such as NGC 5643, the radiative or quasar and the kinetic or radio AGN feedback modes coexist and may shape the host galaxies even at kiloparsec scales through both positive and (mild) negative feedback.
Acceso Abierto
Searching for molecular gas inflows and outflows in the nuclear regions of five Seyfert galaxies.
(EDP Sciences, 2020-11-13) Domínguez Fernández, A. J.; Alonso Herrero, A.; García Burillo, S.; Davies, R. I.; Usero, A.; Labiano, Á.; Levenson, N. A.; Pereira Santaella, M.; Imanishi, M.; Ramos Almeida, C.; Rigopoulou, D.; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Comunidad de Madrid; Science and Technology Facilities Council (STFC); Ramos Almeida, C. [https://orcid.org/0000-0001-8353-649X]; Davies, R. [https://orcid.org/0000-0003-4949-7217]; Alonso Herrero, A. [https://orcid.org/0000-0001-6794-2519]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Active galactic nucleus (AGN) driven outflows are believed to play an important role in regulating the growth of galaxies, mostly via negative feedback. However, their effects on their hosts are far from clear, especially for low- and moderate-luminosity Seyferts. To investigate this issue, we obtained cold molecular gas observations, traced by the CO(2-1) transition, using the NOEMA interferometer of five nearby (distances between 19 and 58 Mpc) Seyfert galaxies. The resolution of ∼0.3–0.8 (∼30–100 pc) and field of view of NOEMA allowed us to study the CO(2-1) morphology and kinematics in the nuclear regions (∼100 pc) and up to radial distances of ∼900 pc. We detected CO(2-1) emission in all five galaxies with disky or circumnuclear ring-like morphologies. We derived cold molecular gas masses on nuclear (∼100 pc) and circumnuclear (∼650 pc) scales in the range from 106 to 107 M⊙ and from 107 to 108 M⊙, respectively. In all of our galaxies, the bulk of this gas is rotating in the plane of the galaxy. However, noncircular motions are also present. In NGC 4253, NGC 4388, and NGC 7465, we can ascribe the streaming motions to the presence of a large-scale bar. In Mrk 1066 and NGC 4388, the noncircular motions in the nuclear regions are explained as outflowing material due to the interaction of the AGN wind with molecular gas in the galaxy disk. We conclude that for an unambiguous and precise interpretation of the kinematics of the cold molecular gas, we need detailed knowledge of the host galaxy (i.e., presence of bars, interactions, etc.), and also of the ionized gas kinematics and ionization cone geometry.
Restringido
Simulating gas kinematic studies of high-redshift galaxies with the HARMONI integral field spectrograph.
(Oxford Academics: Oxford University Press, 2020-09-07) Richardson, M. L. A.; Routledge, L.; Thatte, N.; Tecza, M.; Houghton, R. C. W.; Pereira Santaella, M.; Rigopoulou, D.; Science and Technology Facilities Council (STFC); Comunidad de Madrid
We present simulated observations of gas kinematics in a galaxy formed in a 10 pc resolution cosmological simulation with the hydrodynamical + N-body code RAMSES, using the new RAMSES2HSIM pipeline with the simulated observing pipeline (HSIM) for the Extremely Large Telescope High Angular Resolution Monolithic Optical and Near-infrared Integral field spectrograph (HARMONI IFS). We post-process the galaxy's gas kinematics and Hα line emission for each simulation cell, and integrate the emission to produce an extinction-corrected input cube. We then simulate observations of the input cube with HARMONI, for a range of exposure times, spatial sampling, and spectral resolution. We analyse the mock observations to recover galaxy properties such as its kinematics and compare with the known simulation values. We investigate the cause of biases between the ‘real’ and ‘observed’ kinematic values, demonstrating the sensitivity of the inferred rotation curve to knowledge of the instrument’s point spread function.
Restringido
The properties of polycyclic aromatic hydrocarbons in galaxies: constraints on PAH sizes, charge and radiation fields
(Oxford Academics: Oxford University Press, 2021-04-12) Rigopoulou, D.; Barale, M.; Clary, D. C.; Shan, X.; Alonso Herrero, A.; García Bernete, I.; Hunt, L.; Berkeni, B.; Pereira Santaella, M.; Roche, P. F.; Science and Technology Facilities Council (STFC); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Based on theoretical spectra computed using Density Functional Theory we study the properties of polycyclic aromatic hydrocarbons (PAH). In particular using bin-average spectra of PAH molecules with varying number of carbons we investigate how the intensity of the mid-infrared emission bands, 3.3, 6.2, 7.7, and 11.3 μm, respond to changes in the number of carbons, charge of the molecule, and the hardness of the radiation field that impinges the molecule. We confirm that the 6.2/7.7 band ratio is a good predictor for the size of the PAH molecule (based on the number of carbons present). We also investigate the efficacy of the 11.3/3.3 ratio to trace the size of PAH molecules and note the dependence of this ratio on the hardness of the radiation field. While the ratio can potentially also be used to trace PAH molecular size, a better understanding of the impact of the underlying radiation field on the 3.3 μm feature and the effect of the extinction on the ratio should be evaluated. The newly developed diagnostics are compared to band ratios measured in a variety of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. We demonstrate that the band ratios can be used to probe the conditions of the interstellar medium in galaxies and differentiate between environments encountered in normal star forming galaxies and active galactic nuclei. Our work highlights the immense potential that PAH observations with the James Webb Space Telescope will have on our understanding of the PAH emission itself and of the physical conditions in galaxies near and far.