scholarly journals COMBO-17+4: An Optical-NIR Survey for Galaxies out to z=2

2006 ◽  
Vol 2 (S235) ◽  
pp. 419-419
Author(s):  
M-H. Nicol ◽  
K. Meisenheimer ◽  
C. Tapken ◽  
C. Wolf
Keyword(s):  
Galaxy Evolution ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Optical Data ◽  
Spectral Energy ◽  
Data Set ◽  
Infrared Observation ◽  
Redshift Range ◽  
Red Sequence

AbstractClassifying Object by Medium-Band Observations in 17 filters (COMBO-17) has already produced a very accurate picture of galaxy evolution since z~1 based on 25000 galaxies in 17 medium optical bands. We now extend the range of reliable multi-color redshifts with COMBO-17+4, a deep optical-NIR survey which will combine the existing optical data set of COMBO-17 with near infrared observation in three medium bands: Y(λ/Δλ = 1040/80nm), J1(1190/130nm) and J2(1320/130nm) and one broad band H(1650/300nm). The NIR bands extend the photometric redshift range to z~2.1. COMBO 17+4 will provide the first large sample of galaxies (>5000) at 1<z<2 with a redshifts accuracy of Δz<0.03(1+z). Three fields are observed: Abell 901, Abell 226 and the COMBO 11h-field, for a total coverage of 0.77□2 of the sky. Each COMBO 17+4 field measures 31 × 30 sqarcmin. The NIR bands are observed with the Omega2000 camera at Calar Alto Observatory in Spain.The scientific goals for this study are multiple. COMBO-17+4 will enable us to establish the luminosity function for the red sequence and blue galaxies in the redshift range 1<z<2. Also it will be possible to determine the formation history at z=2 by analyzing the width of the red sequence galaxies. Moreover this survey will provide several thousand of individual galaxy masses (with an accuracy <30%) obtained with Spectral Energy Distribution (SED) template fitting. Once the masses are obtained the mass function will provide a useful tool to test the hierarchical model of evolution of galaxies by checking whether the massive red sequence galaxies (logM>10.5) are already in place at z>1.5 (9Gyr).We present first results from the full 21 bands photometry in half of the Abell 901 field. It allows us to study not only z>1 galaxies but also the stellar content of several hundred cluster galaxies.

scholarly journals Orbital and atmospheric characterization of the planet within the gap of the PDS 70 transition disk

2018 ◽  
Vol 617 ◽  
pp. L2 ◽  
Author(s):  
A. Müller ◽  
M. Keppler ◽  
Th. Henning ◽  
M. Samland ◽  
G. Chauvin ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Direct Detection ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Infrared Range ◽  
Data Set ◽  
Cloud Properties ◽  
Spectrophotometric Data ◽  
First Time

Context. The observation of planets in their formation stage is a crucial but very challenging step in understanding when, how, and where planets form. PDS 70 is a young pre-main sequence star surrounded by a transition disk, in the gap of which a planetary-mass companion has recently been discovered. This discovery represents the first robust direct detection of such a young planet, possibly still at the stage of formation. Aims. We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT. Methods. We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 yr, which allowed us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96–3.8 μm). We use different atmospheric models covering a large parameter space in temperature, log g, chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b. Results. PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at ~22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range 1000–1600 K and log g no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 RJ with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr. Conclusions. This study provides a comprehensive data set on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical of young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planetflux.

scholarly journals The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy PKS J1222+0413

2019 ◽  
Vol 487 (1) ◽  
pp. 181-197 ◽  
Author(s):  
Daniel Kynoch ◽  
Hermine Landt ◽  
Martin J Ward ◽  
Chris Done ◽  
Catherine Boisson ◽  
...  
Keyword(s):  
Near Infrared ◽  
Uv Spectroscopy ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Physical Models ◽  
Spectral Energy ◽  
Narrow Line ◽  
Relativistic Jet ◽  
Γ Ray ◽  
Apply Physical

ABSTRACT We present a multifrequency study of PKS J1222+0413 (4C +04.42), currently the highest redshift γ-ray emitting narrow-line Seyfert 1 (γ-NLS1). We assemble a broad spectral energy distribution (SED) including previously unpublished datasets: X-ray data obtained with the NuSTAR and Neil Gehrels Swift observatories; near-infrared, optical, and UV spectroscopy obtained with VLT X-shooter; and multiband radio data from the Effelsberg telescope. These new observations are supplemented by archival data from the literature. We apply physical models to the broad-band SED, parametrizing the accretion flow and jet emission to investigate the disc–jet connection. PKS J1222+0413 has a much greater black hole mass than most other NLS1s, MBH ≈ 2 × 108 M$\odot$, similar to those found in flat spectrum radio quasars (FSRQs). Therefore this source provides insight into how the jets of γ-NLS1s relate to those of FSRQs.

scholarly journals Surrogate modelling the Baryonic Universe – I. The colour of star formation

2020 ◽  
Vol 495 (2) ◽  
pp. 2088-2104
Author(s):  
Jonás Chaves-Montero ◽  
Andrew Hearin
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Principal Component ◽  
Major Axis ◽  
Sloan Digital Sky Survey ◽  
Star Formation History ◽  
Spectral Energy ◽  
Colour Space

ABSTRACT The spectral energy distribution of a galaxy emerges from the complex interplay of many physical ingredients, including its star formation history (SFH), metallicity evolution, and dust properties. Using galaxpy, a new galaxy spectral prediction tool, and SFHs predicted by the empirical model universemachine and the cosmological hydrodynamical simulation IllustrisTNG, we isolate the influence of SFH on optical and near-infrared colours from 320 to 1080 Å at z = 0. By carrying out a principal component analysis, we show that physically motivated SFH variations modify galaxy colours along a single direction in colour space: the SFH-direction. We find that the projection of a galaxy’s present-day colours on to the SFH-direction is almost completely regulated by the fraction of stellar mass that the galaxy formed over the last billion years. Together with cosmic downsizing, this results in galaxies becoming redder as their host halo mass increases. We additionally study the change in galaxy colours due to variations in metallicity, dust attenuation, and nebular emission lines, finding that these properties vary broad-band colours along distinct directions in colour space relative to the SFH-direction. Finally, we show that the colours of low-redshift Sloan Digital Sky Survey galaxies span an ellipsoid with significant extent along two independent dimensions, and that the SFH-direction is well-aligned with the major axis of this ellipsoid. Our analysis supports the conclusion that variations in SFH are the dominant influence on present-day galaxy colours, and that the nature of this influence is strikingly simple.

scholarly journals The polarized spectral energy distribution of NGC 4151

2020 ◽  
Vol 496 (1) ◽  
pp. 215-222
Author(s):  
F Marin ◽  
J Le Cam ◽  
E Lopez-Rodriguez ◽  
M Kolehmainen ◽  
B L Babler ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Far Infrared ◽  
Seyfert Galaxies ◽  
Mie Scattering ◽  
Polarization Measurement ◽  
Spectral Energy ◽  
Ngc 4151 ◽  
Near Ir

ABSTRACT NGC 4151 is among the most well-studied Seyfert galaxies that does not suffer from strong obscuration along the observer’s line of sight. This allows to probe the central active galactic nucleus (AGN) engine with photometry, spectroscopy, reverberation mapping, or interferometry. Yet, the broad-band polarization from NGC 4151 has been poorly examined in the past despite the fact that polarimetry gives us a much cleaner view of the AGN physics than photometry or spectroscopy alone. In this paper, we compile the 0.15–89.0 μm total and polarized fluxes of NGC 4151 from archival and new data in order to examine the physical processes at work in the heart of this AGN. We demonstrate that, from the optical to the near-infrared (IR) band, the polarized spectrum of NGC 4151 shows a much bluer power-law spectral index than that of the total flux, corroborating the presence of an optically thick, locally heated accretion flow, at least in its near-IR emitting radii. Specific signatures from the atmosphere of the accretion structure are tentatively found at the shortest ultraviolet (UV) wavelengths, before the onset of absorption opacity. Otherwise, dust scattering appears to be the dominant contributor from the near-UV to near-IR polarized spectrum, superimposed on to a weaker electron component. We also identify a change in the polarization processes from the near-IR to the mid-IR, most likely associated with the transition from Mie scattering to dichroic absorption from aligned dust grains in the dusty torus or narrow-line region. Finally, we present and discuss the very first far-infrared polarization measurement of NGC 4151 at 89 μm.

scholarly journals Spectroscopy with the JWST Advanced Deep Extragalactic Survey (JADES) - the NIRSpec/NIRCAM GTO galaxy evolution project

2019 ◽  
Vol 15 (S352) ◽  
pp. 342-346
Author(s):  
Andrew J. Bunker
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Rest Frame ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Spectral Energy ◽  
Balmer Line ◽  
Chemical Abundances ◽  
Star Forming

AbstractI present an overview of the JWST Advanced Deep Extragalactic Survey (JADES), a joint program of the JWST/NIRCam and NIRSpec Guaranteed Time Observations (GTO) teams involving 950 hours of observation. We will target two well-studied fields with excellent supporting data (e.g., from HST-CANDELS): GOODS-North and South, including the Ultra Deep Field. The science goal of JADES is to chart galaxy evolution at z > 2, and potentially out to z > 10, using the rest-frame optical and near-IR though observations from ≍ 1–5μm. Multi-colour NIRCam imaging with 9 filters will enable photometric redshifts and the application of the Lyman break technique out to unprecedented distances. NIRSpec spectroscopy (with spectral resolving powers of R = 100, 1000 & 2700) will measure secure spectroscopic redshifts of the photometrically-selected population, as well as stellar continuum slopes in the UV rest-frame, and hence study the role of dust, stellar population age, and other effects. Measuring emission lines can constrain the dust extinction, star formation rates, metallicity, chemical abundances, ionization and excitation mechanism in high redshift galaxies. Coupling NIRCam and NIRSpec observations will determine stellar populations (age, star formation histories, abundances) of galaxies and provide the information to correct their broad-band spectral energy distribution for likely line contamination. Potentially we can search for signatures of Population III stars such as HeII. We can address the contribution of star-forming galaxies at z > 7 to reionization by determining the faint end slope of the luminosity function and investigating the escape fraction of ionizing photons by comparing the UV stellar continuum with the Balmer-line fluxes.

scholarly journals Substructure and Signs of Planet Formation in the Disk of HD 169142

2013 ◽  
Vol 8 (S299) ◽  
pp. 145-148
Author(s):  
M. Osorio ◽  
G. Anglada ◽  
C. Carrasco-González ◽  
J. M. Torrelles ◽  
P. D'Alessio ◽  
...  
Keyword(s):  
Near Infrared ◽  
Planet Formation ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Dust Emission ◽  
Central Star ◽  
Physical Structure ◽  
Spectral Energy ◽  
High Angular Resolution ◽  
Compact Source

AbstractWe carried out 7 mm VLA observations at very high angular resolution that reveal substructure and evidence of planet formation in the disk of HD 169142. Our observations, along with near-infrared polarimetric imaging, show that this disk has a ring of enhanced, asymmetric emission at a radius of ~25 AU from the central star. This ring, whose inner region appears devoid of emission, is surrounded by an annular gap in surface density in the ~30-70 AU range of radii. Several mechanisms have been invoked in the literature to explain this kind of gaps and cavities. Among them, one of the most interesting is the possibility that one or more planets in formation are creating these cavities. Since our 7 mm observations show a compact source lying in the 30-70 AU gap, we speculate that this compact source could be tracing dust emission associated with a possible protoplanet. We model the broad-band spectral energy distribution of the disk and we infer its physical structure. From this modeling we infer the presence of a small (r ~ 0.7 AU) disk inside the central cavity, suggesting that the HD 169142 disk is in the pre-transitional disk phase.

scholarly journals CPz: Classification-aided photometric-redshift estimation

2018 ◽  
Vol 619 ◽  
pp. A14 ◽  
Author(s):  
S. Fotopoulou ◽  
S. Paltani
Keyword(s):  
Galaxy Evolution ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Ultra Violet ◽  
Cost Effective ◽  
Continuum Emission ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Optical Photometry ◽  
Photometric Redshift

Broadband photometry offers a time and cost effective method to reconstruct the continuum emission of celestial objects. Thus, photometric redshift estimation has supported the scientific exploitation of extragalactic multiwavelength surveys for more than twenty years. Deep fields have been the backbone of galaxy evolution studies and have brought forward a collection of various approaches in determining photometric redshifts. In the era of precision cosmology, with the upcoming Euclid and LSST surveys, very tight constraints are put on the expected performance of photometric redshift estimation using broadband photometry, thus new methods have to be developed in order to reach the required performance. We present a novel automatic method of optimizing photometric redshift performance, the classification-aided photometric redshift estimation (CPz). The main feature of CPz is the unified treatment of all classes of objects detected in extragalactic surveys: galaxies of any type (passive, starforming and starbursts), active galactic nuclei (AGN), quasi-stellar objects (QSO), stars and also includes the identification of potential photometric redshift catastrophic outliers. The method operates in three stages. First, the photometric catalog is confronted with star, galaxy and QSO model templates by means of spectral energy distribution fitting. Second, three machine-learning classifiers are used to identify 1) the probability of each source to be a star, 2) the optimal photometric redshift model library set-up for each source and 3) the probability to be a photometric redshift catastrophic outlier. Lastly, the final sample is assembled by identifying the probability thresholds to be applied on the outcome of each of the three classifiers. Hence, with the final stage we can create a sample appropriate for a given science case, for example favoring purity over completeness. We apply our method to the near-infrared VISTA public surveys, matched with optical photometry from CFHTLS, KIDS and SDSS, mid-infrared WISE photometry and ultra-violet photometry from the Galaxy Evolution Explorer (GALEX). We show that CPz offers improved photometric redshift performance for both normal galaxies and AGN without the need for extra X-ray information.

scholarly journals A new lepto-hadronic model applied to the first simultaneous multiwavelength data set for Cygnus X–1

2020 ◽  
Vol 500 (2) ◽  
pp. 2112-2126
Author(s):  
D Kantzas ◽  
S Markoff ◽  
T Beuchert ◽  
M Lucchini ◽  
A Chhotray ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Spectral Energy ◽  
Electromagnetic Spectrum ◽  
X Rays ◽  
Relativistic Jets ◽  
Data Set ◽  
Dynamical Properties

ABSTRACT Cygnus X–1 is the first Galactic source confirmed to host an accreting black hole. It has been detected across the entire electromagnetic spectrum from radio to GeV gamma-rays. The source’s radio through mid-infrared radiation is thought to originate from the relativistic jets. The observed high degree of linear polarization in the MeV X-rays suggests that the relativistic jets dominate in this regime as well, whereas a hot accretion flow dominates the soft X-ray band. The origin of the GeV non-thermal emission is still debated, with both leptonic and hadronic scenarios deemed to be viable. In this work, we present results from a new semi-analytical, multizone jet model applied to the broad-band spectral energy distribution of Cygnus X–1 for both leptonic and hadronic scenarios. We try to break this degeneracy by fitting the first-ever high-quality, simultaneous multiwavelength data set obtained from the CHOCBOX campaign (Cygnus X–1 Hard state Observations of a Complete Binary Orbit in X-rays). Our model parametrizes dynamical properties, such as the jet velocity profile, the magnetic field, and the energy density. Moreover, the model combines these dynamical properties with a self-consistent radiative transfer calculation including secondary cascades, both of leptonic and hadronic origin. We conclude that sensitive TeV gamma-ray telescopes like Cherenkov Telescope Array (CTA) will definitively answer the question of whether hadronic processes occur inside the relativistic jets of Cygnus X–1.

Multiwavelength study of different flaring and low-activity states of blazar 4C+21.35

2020 ◽  
Vol 500 (1) ◽  
pp. 1127-1138
Author(s):  
Debbijoy Bhattacharya ◽  
Krishna Mohana A ◽  
Subir Bhattacharyya ◽  
Nilay Bhatt ◽  
C S Stalin
Keyword(s):  
Spectral Energy Distribution ◽  
Broad Band ◽  
Optical Data ◽  
Spectral Energy ◽  
Emission Region ◽  
Electromagnetic Spectrum ◽  
Large Area ◽  
Γ Ray ◽  
The One ◽  
Low Activity

ABSTRACT Blazars, a class of active galactic nuclei, emit over the entire accessible electromagnetic spectrum and modelling of their broad-band spectral energy distribution (SED) is the key to constrain the underlying emission mechanisms. Here we report the results on the one-zone leptonic emission modelling carried out on the blazar 4C+21.35 using multiwavelength data spanning over the period 2008–2018. Broad-band SED modelling using γ-ray data from Fermi-Large Area Telescope, X-ray data from Swift-XRT and AstroSat, and UV–optical data from Swift-UVOT, AstroSat, and Catalina Real-Time Transient Survey was carried out at seven different epochs, including three γ-ray flaring episodes and four quiescent periods (three long-term averaged ones and one during AstroSat observing period). Our SED modelling suggests that two compact emission regions originating at a different time outside the broad-line region and moving away from the core with variation primarily in the jet electron spectra can explain the emission from the high-, moderate-, and low-activity periods. The emissions from high- and first low-activity states are likely to have originated in the first region. The moderate- and second low-activity states are likely due to the second emission region with fresh particle acceleration/injection at a later time.

scholarly journals Towards studying hierarchical assembly in real time: a Milky Way progenitor galaxy at z = 2.36 under the microscope

2020 ◽  
Vol 493 (4) ◽  
pp. 5653-5661 ◽  
Author(s):  
Tom O Zick ◽  
Daniel R Weisz ◽  
Bruno Ribeiro ◽  
Mariska T Kriek ◽  
Benjamin D Johnson ◽  
...  
Keyword(s):  
Near Infrared ◽  
Milky Way ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Star Clusters ◽  
Star Formation History ◽  
Ex Situ ◽  
Spectral Energy ◽  
Space Telescope

ABSTRACT We use Hubble Space Telescope (HST) imaging and near-infrared spectroscopy from Keck/Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) to study the substructure around the progenitor of a Milky Way-mass galaxy in the Hubble Frontier Fields (HFF). Specifically, we study an $r_\mathrm{ e} = 40^{+70}_{-30}$ pc, $M_{\star } \sim 10^{8.2} \, \mathrm{M}_{\odot }$ rest-frame ultraviolet luminous ‘clump’ at a projected distance of ∼100 pc from a M⋆ ∼ 109.8 M⊙ galaxy at z = 2.36 with a magnification μ = 5.21. We measure the star formation history of the clump and galaxy by jointly modelling the broad-band spectral energy distribution from HST photometry and Hα from MOSFIRE spectroscopy. Given our inferred properties (e.g. mass, metallicity, dust) of the clump and galaxy, we explore scenarios in which the clump formed in situ (e.g. a star-forming complex) or ex situ (e.g. a dwarf galaxy being accreted). If it formed in situ, we conclude that the clump is likely a single entity as opposed to a aggregation of smaller star clusters, making it one of the most dense star clusters catalogued. If it formed ex situ, then we are witnessing an accretion event with a 1:40 stellar mass ratio. However, our data alone are not informative enough to distinguish between in situ and ex situ scenarios to a high level of significance. We posit that the addition of high-fidelity metallicity information, such as [O iii] 4363 Å, which can be detected at modest signal-to-noise ratio with only a few hours of James Webb Space Telescope(JWST)/Near-Infrared Spectrograph (NIRSpec) time, may be a powerful discriminant. We suggest that studying larger samples of moderately lensed substructures across cosmic time can provide unique insight into the hierarchical formation of galaxies like the Milky Way.

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