scholarly journals The stellar metallicity distribution in intermediate-latitude fields

2012 ◽  
Vol 8 (S295) ◽  
pp. 319-319
Author(s):  
Xiyan Peng ◽  
Cuihua Du ◽  
Zhenyu Wu
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Galactic Centre ◽  
Fitting Method ◽  
The Galaxy ◽  
The Mean ◽  
Metallicity Distribution

AbstractBased on BATC and SDSS photometric data, we adopt the spectral energy distribution (SED) fitting method to evaluate stellar metallicities in the Galaxy. We find that the mean metallicity shifts from metal-rich to metal-poor with the increase of distance from the Galactic Centre.

scholarly journals Timing the earliest quenching events with a robust sample of massive quiescent galaxies at 2 < z < 5

2020 ◽  
Vol 496 (1) ◽  
pp. 695-707 ◽  
Author(s):  
A C Carnall ◽  
S Walker ◽  
R J McLure ◽  
J S Dunlop ◽  
D J McLeod ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Selection Criteria ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Photometric Redshift ◽  
The Times ◽  
Lower Redshift

ABSTRACT We present a sample of 151 massive (M* &gt; 1010 M⊙) quiescent galaxies at 2 &lt; z &lt; 5, based on a sophisticated Bayesian spectral energy distribution fitting analysis of the CANDELS UDS and GOODS-South fields. Our sample includes a robust sub-sample of 61 objects for which we confidently exclude low-redshift and star-forming solutions. We identify 10 robust objects at z &gt; 3, of which 2 are at z &gt; 4. We report formation redshifts, demonstrating that the oldest objects formed at z &gt; 6; however, individual ages from our photometric data have significant uncertainties, typically ∼0.5 Gyr. We demonstrate that the UVJ colours of the quiescent population evolve with redshift at z &gt; 3, becoming bluer and more similar to post-starburst galaxies at lower redshift. Based upon this, we construct a model for the time evolution of quiescent galaxy UVJ colours, concluding that the oldest objects are consistent with forming the bulk of their stellar mass at z ∼ 6–7 and quenching at z ∼ 5. We report spectroscopic redshifts for two of our objects at z = 3.440 and 3.396, which exhibit extremely weak Ly α emission in ultra-deep VANDELS spectra. We calculate star formation rates based on these line fluxes, finding that these galaxies are consistent with our quiescent selection criteria, provided their Ly α escape fractions are &gt;3 and &gt;10 per cent, respectively. We finally report that our highest redshift robust object exhibits a continuum break at λ ∼ 7000 Å in a spectrum from VUDS, consistent with our photometric redshift of $z_\mathrm{phot}=4.72^{+0.06}_{-0.04}$. If confirmed as quiescent, this object would be the highest redshift known quiescent galaxy. To obtain stronger constraints on the times of the earliest quenching events, high-SNR spectroscopy must be extended to z ≳ 3 quiescent objects.

Stellar Population Models of Distant Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 588-590
Author(s):  
D. Villani ◽  
S. Di Serego Alighieri
Keyword(s):  
Energy Distribution ◽  
Galaxy Formation ◽  
Stellar Population ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Stellar Populations ◽  
Radio Galaxies ◽  
Initial Mass Function ◽  
Spectral Energy ◽  
The Galaxy

Stellar populations of high redshift radio galaxies (HzRG) (z up to 4.2) are the oldest stellar systems known, that is the ones formed at the earliest cosmological epochs. Therefore they are the best objects for providing us with information about the epoch of galaxy formation. The information on the stellar populations in HzRG are obtained from the study of their Integrated Spectral Energy Distribution (ISED) which are gathered both from spectra and integrated magnitudes. The most common approach for the interpretation of colors and spectral features of the energy distribution of galaxies is the Evolutionary Population Synthesis (EPS), which has been introduced for the first time by Tinsley in 1972. EPS models have often been used in the past to interpret the ISED of HzRG (Chambers & Charlot 1990; Lilly & Longair 1984; di Serego Alighieri et al. 1994) in order to draw conclusions on the age of the stellar populations and therefore on the epoch of galaxy formation. The results are sometimes conflicting and a number of very recent EPS models have become available (Bressan et al. 1995; Bruzual & Charlot 1993; Buzzoni 1989; Guiderdoni & Rocca-Volmerange 1987): we are therefore analysing the differences between the various EPS models with the aim of assessing their suitability to study the stellar population at early epochs. The EPS models assume for stars a given Initial Mass Function(IMF) as well as a Star Formation Rate (SFR). Then one can compute the number of stars with given mass present in the galaxy as a function of time. The position of each star in the HR diagram is determined by means of the isochrones, which are calculated from stellar evolutionary models. The ISED of a galaxy is obtained from the superposition of the spectra of single stars obtained from a stellar spectral library. Thus these models describe the galaxy ISED as a function of the time, giving a complete evolutionary picture.

scholarly journals Nature of the Dusty S-cluster Object (DSO/G2): Pre-main-sequence star with non-spherical dusty envelope

2016 ◽  
Vol 11 (S322) ◽  
pp. 231-232
Author(s):  
M. Zajaček ◽  
M. Valencia-S. ◽  
B. Shahzamanian ◽  
F. Peissker ◽  
A. Eckart ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Main Sequence ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Main Sequence Star ◽  
Continuum Emission ◽  
Spectral Energy ◽  
Galactic Centre ◽  
Infrared Excess ◽  
Sgr A

AbstractNear-infrared observations reveal several infrared-excess sources near the Galactic Centre with emission lines present in their spectra. One of these objects, DSO/G2, which moves around the supermassive black hole (Sgr A*) on a highly eccentric orbit, passed the pericentre at approximately 160 AU in 2014. It remained compact, which implies that at least in this case it is a star embedded in a dusty envelope. The spectral energy distribution and the detection of polarized continuum emission indicate that it is probably a pre-main-sequence star surrounded by a dense envelope with bipolar cavities. In addition, the star associated with DSO/G2 plausibly develops a bow shock due to its supersonic motion. The model of the star surrounded by the non-spherical dusty envelope can reproduce the main characteristics of the DSO/G2 source: 1. spectral energy distribution in near-infrared bands; 2. linear polarization in Ks band; and 3. the overall compact behaviour.

First galaxy SED: Contribution from pre-main-sequence stars

2019 ◽  
Vol 15 (S341) ◽  
pp. 287-288
Author(s):  
Hiroto Mitani ◽  
Naoki Yoshida ◽  
Kazuyuki Omukai ◽  
Takashi Hosokawa
Keyword(s):  
Energy Distribution ◽  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Mass Function ◽  
Initial Mass Function ◽  
Spectral Energy ◽  
Population Synthesis ◽  
Main Sequence Stars ◽  
The Galaxy ◽  
First Galaxies

AbstractWe calculate the spectral energy distribution of the first galaxies which contain pre-main-sequence stars by using the stellar evolution code Modules for Experiments in Stellar Astrophysics, the spectra model BT-Settl, and the stellar population synthesis code PEGASE. We calculate the galaxy spectral energy distribution for Salpeter Initial Mass Function. We find that very young first galaxies are bright also in mid-infrared, and the contribution of pre-main-sequence stars can be significant over 0.1 Myr after a star-formation episode.

scholarly journals The Kinematics of Globular Cluster NGC 288

2001 ◽  
Vol 183 ◽  
pp. 333-334
Author(s):  
Chan-Kao Chang ◽  
Alfred B. Chen ◽  
Wean-Shun Tsay ◽  
Wen-Ping Chen ◽  
Phillip K. Lu
Keyword(s):  
Energy Distribution ◽  
Globular Cluster ◽  
Effective Temperature ◽  
Proper Motion ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Galactic Rotation ◽  
Distribution Fitting ◽  
The Mean ◽  
Effective Temperatures

AbstractThe mean radial velocity of NGC 288 (accuracy 5.5 km/s) is determined to be −56.3 ± 20.1 km/s which, when combined with the mean proper motion (Guo, 1995), yields a peculiar velocity with respect to the LSR of (u,v,w) = (29.7 ± 18.1, −258.6 ± 18.3,62.3 ± 20.3) km/s. This implies that NGC 288 moves in a retrograde sense with the Galactic rotation. We also derived the effective temperatures for stars in our sample and, as a corroborative effort, compared with those estimated previously from the BATC data (Tsai 1998) by spectral energy distribution fitting. We demonstrate that the BATC/SED fitting is an appropriate and efficient way to estimate the effective temperature of a star.

scholarly journals Multiwavelength data for bright active galaxies

2011 ◽  
Vol 7 (S284) ◽  
pp. 237-239
Author(s):  
Areg M. Mickaelian ◽  
Hayk V. Abrahamyan ◽  
Gurgen M. Paronyan ◽  
Gohar S. Harutyunyan
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Active Galaxies ◽  
Photometric Data ◽  
Spectral Energy ◽  
X Rays ◽  
Large Area ◽  
X Ray ◽  
Space Objects ◽  
Cross Correlations

AbstractThe spectral energy distribution (SED) gives a complete picture of the radiation of space objects and may result in correct classifications compared to those based only on optical (or other local) spectra. This is especially crucial for active galaxies, both AGN and Starbursts (SB). For this, multiwavelength (MW) data are needed taken from available surveys and catalogs. We have cross-correlated the Catalogue of quasars and active galaxies with all-sky or large-area MW catalogues, such as X-ray ROSAT (BSC and FSC), UV GALEX (MIS and AIS), optical APM, MAPS, USNO-B1.0, GSC 2.3.2, and SDSS DR8, NIR 2MASS, MIR/FIR WISE, IRAS (PSC and FSC) and AKARI (IRC and FIS), radio GB6, NVSS, FIRST, and WENSS. We have established accurate positions and photometry for a few thousands of objects that appeared in the catalog with poor data, as well as achieved the best astrometric and photometric data for all objects. This allowed correct cross-correlations and establishing correct MW data for these objects. As a result, we obtained 34 photometric points from X-rays to radio and using VO tools built SEDs for some 10,000 bright objects. Some data from other surveys were also used, such as Chandra, XMM, Spitzer, etc. All objects were grouped into several forms of SED and were compared to the known optical classes given in the catalog (QSO, BLL, Sy1, Sy1.2–1.9, Sy2, LINER, SB, and HII). This allowed reveal obscured AGN, as well as find previously misclassified objects. A homogeneous classification for these objects was established. The first part of this project is presented; establishment of accurate positions and photometry and cross-correlations with MW catalogs.

scholarly journals NEW SPECTRAL ANALYSIS RESULTS WITHIN THE SCOPE OF EXTENDED MATTER RESEARCH IN THE AR LACERTAE ACTIVE BINARY SYSTEM

2021 ◽  
Vol 57 (1) ◽  
pp. 167-179
Author(s):  
O. Karakuş ◽  
F. Ekmekçi
Keyword(s):  
Spectral Analysis ◽  
High Resolution ◽  
Binary System ◽  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Light Curves ◽  
Spectral Energy ◽  
Orbital Phase ◽  
Low Dispersion

Within the scope of extended matter research, we present new spectral analysis results of an active binary system, AR Lac. The low and high resolution spectra of this system, were taken during the period 2013-2016. The evaluation of low dispersion spectra together with the B, V, Rc, Ic and WISE photometric data showed that AR Lac has an excess radiation in the W2 band. In addition, the spectral energy distribution and the minima depth ratios of the light curves of this active binary system were studied to examine the flux contributions of the components of the system depending on wavelengths and on orbital phase. Furthermore, high resolution spectral analysis showed evidence of prominence-like structures and a possible extended matter around the cooler component of AR Lac.

scholarly journals A new model for the infrared emission of IRAS F10214+4724

2011 ◽  
Vol 7 (S284) ◽  
pp. 205-209
Author(s):  
Andreas Efstathiou ◽  
Natalie Christopher ◽  
Aprajita Verma ◽  
Ralf Siebenmorgen
Keyword(s):  
Energy Distribution ◽  
Gravitational Lensing ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Infrared Emission ◽  
Spectral Energy ◽  
New Model ◽  
Average Spectrum ◽  
Line Region ◽  
The Galaxy

AbstractWe present a new model for the infrared emission of the high redshift hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first demonstrate that the combination of the AGN tapered disc and starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of type 2 AGN measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the ν Sν distribution of the galaxy falls very steeply with increasing frequency (a characteristic of heavy absorption by dust) but shows a silicate feature in emission. We propose a model that assumes two components of emission: clouds that are associated with the narrow-line region and a highly obscured starburst. The emission from the clouds must suffer significantly stronger gravitational lensing compared to the emission from the torus to explain the observed spectral energy distribution.

scholarly journals Strong FeII emission in NLS1s: An unsolved mystery

2019 ◽  
Vol 15 (S341) ◽  
pp. 297-298
Author(s):  
Swayamtrupta Panda ◽  
Katarzyna Małek ◽  
Marzena Śniegowska ◽  
Bożena Czerny
Keyword(s):  
Energy Distribution ◽  
Accretion Disk ◽  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Spectral Fitting ◽  
Main Driver ◽  
Multi Band

AbstractIn Panda et al.2018a, we constructed a refined sample from the original Shen et al.(2011) QSO catalog. Based on our hypothesis — the main driver of the Quasar Main Sequence is the maximum of the accretion disk temperature (TBBB) defined by the Big Blue Bump on the Spectral Energy Distribution (Panda et al.2017; Panda et al.2018b). We select the four extreme sources that have RFeII ⩾ 4.0 and use {CIGALE (Boquien et al.2018) to fit their multi—band photometric data. We also perform detailed spectral fitting including the Fe II pseudo—continuum (based on Śniegowska et al.2018)) to estimate and compare the value of RFEII. We show the dependence of FeII strength on changing metallicity.

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