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In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\gamma$ ray spectra with EGRET…

Astrophysics · Physics 2008-11-26 Xiao-Jun Bi , Juan Zhang , Qiang Yuan

We present a new dust extinction technique with which we are able to retrieve parsec-scale gas surface density maps for entire nearby galaxies. The method measures the dust attenuation in optical bands on a pixel-by-pixel basis against a…

With current and upcoming experiments such as WFIRST, Euclid and LSST, we can observe up to billions of galaxies. While such surveys cannot obtain spectra for all observed galaxies, they produce galaxy magnitudes in color filters. This data…

Astrophysics of Galaxies · Physics 2022-10-19 Melanie Simet , Nima Chartab , Yu Lu , Bahram Mobasher

We report on the identification of the old stellar population galaxy candidates at z > 5. We developed a new infrared color selection scheme to isolate galaxies with the strong Balmer breaks at z > 5, and applied it to the ultra-deep and…

Astrophysics of Galaxies · Physics 2016-05-04 Ken Mawatari , Toru Yamada , Giovanni Fazio , Jiasheng Huang , Matthew Ashby

We describe a new method to identify young, late-type stars within ~150 pc of the Earth that employs visual or near-infrared data and the GALEX GR4/5 database. For spectral types later than K5, we demonstrate that the ratio of GALEX…

Solar and Stellar Astrophysics · Physics 2011-02-02 David R. Rodriguez , M. S. Bessell , B. Zuckerman , Joel H. Kastner

Velocity dispersion measurements are presented for luminous GCs in NGC 5128 derived from high-res. UVES spectra. The measurements are made with the pPXF code that parametrically recovers line-of-sight velocity dispersions. Combining the…

We present results of age and metallicity gradient analysis inferred from both optical and near-infrared surface photometry. The analysis is based on a sample of 36 nearby early-type galaxies, obtained from the Early Data Release of the…

Astrophysics · Physics 2008-11-26 Hong Wu , Zhengyi Shao , H. J. Mo , Xiaoyang Xia , Zugan Deng

In modern astrophysics, the machine learning has increasingly gained more popularity with its incredibly powerful ability to make predictions or calculated suggestions for large amounts of data. We describe an application of the supervised…

Astrophysics of Galaxies · Physics 2018-12-26 Yu Bai , JiFeng Liu , Song Wang , Fan Yang

The study of ages, helium mass fraction (Y) and chemical composition of globular clusters in dwarf galaxies is important for understanding the physical conditions at the main evolutionary stages of the host galaxies and for constraining the…

Astrophysics of Galaxies · Physics 2020-03-18 M. E. Sharina , V. V. Shimansky

Context. Extragalactic Planetary Nebulae (PNe) are useful distance indicators and are often used to trace the dark-matter content in external galaxies. At the same time, PNe can also be used as probes of their host galaxy stellar…

I introduce some improvements to the pPXF method, which measures the stellar and gas kinematics, star formation history (SFH) and chemical composition of galaxies. I describe the new optimization algorithm that pPXF uses and the changes I…

Astrophysics of Galaxies · Physics 2023-09-08 Michele Cappellari

Upcoming surveys will produce billions of galaxy images but comparatively few spectra, motivating models that learn cross-modal representations. We build a dataset of 134,533 galaxy images (HSC-PDR2) and spectra (DESI-DR1) and adapt a…

Instrumentation and Methods for Astrophysics · Physics 2025-10-28 Morgan Himes , Samiksha Krishnamurthy , Andrew Lizarraga , Srinath Saikrishnan , Vikram Seenivasan , Jonathan Soriano , Ying Nian Wu , Tuan Do

We use the combined GALFORM semi-analytical model of galaxy formation and GRASIL spectrophotometric code to investigate the properties of galaxies selected via their sub-mm emission. Our fiducial model has previously been shown to fit the…

[Abridged] We present an integrated photometric spectral energy distribution (SED) of the Magellanic-type galaxy NGC 4449 from the far-ultraviolet (UV) to the submillimetre, including new observations acquired by the Herschel Space…

Mass loss is a key property to understand stellar evolution and in particular for low-metallicity environments. Our knowledge has improved dramatically over the last decades both for single and binary evolutionary models. However, episodic…

We demonstrate a new multi-wavelength technique for two-dimensional parametric modelling of galaxy surface-brightness profiles, which we have incorporated into the widely used software GALFIT. Our new method, named GALFITM, extends…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Marina Vika , Steven P. Bamford , Boris Haeussler , Alex L. Rojas , Andrea Borch , Robert C. Nichol

We present the first version release of SESAMME, a public, Python-based full spectrum fitting tool for Simultaneous Estimates of Star-cluster Age, Metallicity, Mass, and Extinction. SESAMME compares an input spectrum of a star cluster to a…

Astrophysics of Galaxies · Physics 2023-10-17 Logan H. Jones , Svea Hernandez , Linda J. Smith , Bethan L. James , Alessandra Aloisi , Søren Larsen

Identification of metal-poor stars among field stars is extremely useful for studying the structure and evolution of the Galaxy and of external galaxies. We search for metal-poor stars using the artificial neural network (ANN) and extend…

Solar and Stellar Astrophysics · Physics 2015-06-16 Sunetra Giridhar , Aruna Goswami , Andrea Kunder , S. Muneer , G. Selvakumar

Spectral synthesis is basically the decomposition of an observed spectrum in terms of the superposition of a base of simple stellar populations of various ages and metallicities, producing as output the star formation and chemical histories…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Jean Michel Gomes , Polychronis Papaderos

Perovskite solar cells (PSCs) have experienced a remarkable rise in power conversion efficiency (PCE) over the past 15 years, positioning them as a promising alternative or complement to silicon for large-scale photovoltaic deployment.…