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79 Publications visible to you, out of a total of 79
Radio Galaxy Zoo: host galaxies and radio morphologies derived from visual inspection

Abstract

Not specified

Authors: A. R. López-Sánchez, W. P. Maksym, K. L. Polsterer, K. Borden, R. P. Hollow, L. Whyte

Date Published: 25th Sep 2015

Publication Type: Journal

Automatic Galaxy Classification via Machine Learning Techniques: Parallelized Rotation/Flipping INvariant Kohonen Maps (PINK)

Abstract

Not specified

Authors: K. L. Polsterer, F. Gieseke, C. Igel

Date Published: 1st Sep 2015

Publication Type: InProceedings

Analyzing Complex and Structured Data via Unsupervised Learning Techniques

Abstract

Not specified

Authors: K. L. Polsterer, F. Gieseke, N. Gianniotis, S. D. Kuegler

Date Published: 1st Aug 2015

Publication Type: Journal

Featureless classification of light curves

Abstract

Not specified

Authors: S. D. Kügler, N. Gianniotis, K. L. Polsterer

Date Published: 25th Jun 2015

Publication Type: Journal

Autoencoding Time Series for Visualisation

Abstract

Not specified

Authors: N. Gianniotis, S. D. Kügler, P. Tino, K. L. Polsterer, R. Misra

Date Published: 1st May 2015

Publication Type: InProceedings

Determining spectroscopic redshifts by using k nearest neighbor regression. I. Description of method and analysis

Abstract

Not specified

Authors: S. D. Kügler, K. Polsterer, M. Hoecker

Date Published: 1st Apr 2015

Publication Type: Journal

Properties of optically selected BL Lacertae candidates from the SDSS

Abstract (Expand)

Context. Deep optical surveys open the avenue for finding large numbers of BL Lac objects that are hard to identify because they lack the unique properties classifying them as such. While radio or X-ray …ay surveys typically reveal dozens of sources, recent compilations based on optical criteria alone have increased the number of BL Lac candidates considerably. However, these compilations are subject to biases and may contain a substantial number of contaminating sources. Aims. In this paper we extend our analysis of 182 optically selected BL Lac object candidates from the SDSS with respect to an earlier study. The main goal is to determine the number of bona fide BL Lac objects in this sample. Methods. We examine their variability characteristics, determine their broad-band radio-UV spectral energy distributions (SEDs), and search for the presence of a host galaxy. In addition we present new optical spectra for 27 targets with improved signal-to-noise ratio with respect to the SDSS spectra. Results. At least 59% of our targets have shown variability between SDSS DR2 and our observations by more than 0.1–0.27 mag depending on the telescope used. A host galaxy was detected in 36% of our targets. The host galaxy type and luminosities are consistent with earlier studies of BL Lac host galaxies. Simple fits to broad-band SEDs for 104 targets of our sample derived synchrotron peak frequencies between 13.5 ≤ log 10(νpeak) ≤ 16 with a peak at log 10 ~ 14.5. Our new optical spectra do not reveal any new redshift for any of our objects. Thus the sample contains a large number of bona fide BL Lac objects and seems to contain a substantial fraction of intermediate-frequency peaked BL Lacs.

Authors: S. D. Kügler, K. Nilsson, J. Heidt, J. Esser, T. Schultz

Date Published: 1st Sep 2014

Publication Type: Journal

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