Sharpening up Galactic all-sky maps with complementary data - A machine learning approach

Galactic all-sky maps at very disparate frequencies, like in the radio and $\gamma$-ray regime, show similar morphological structures. This mutual information reflects the imprint of the various physical components of the interstellar medium. We want to use multifrequency all-sky observations to test resolution improvement and restoration of unobserved areas for maps in certain frequency ranges. For this we aim to reconstruct or predict from sets of other maps all-sky maps that, in their original form, lack a high resolution compared to other available all-sky surveys or are incomplete in their spatial coverage. Additionally, we want to investigate the commonalities and differences that the ISM components exhibit over the electromagnetic spectrum. We build an $n$-dimensional representation of the joint pixel-brightness distribution of $n$ maps using a Gaussian mixture model and see how predictive it is: How well can one map be reproduced based on subsets of other maps? Tests with mock data show that reconstructing the map of a certain frequency from other frequency regimes works astonishingly well, predicting reliably small-scale details well below the spatial resolution of the initially learned map. Applied to the observed multifrequency data sets of the Milky Way this technique is able to improve the resolution of, e.g., the low-resolution Fermi LAT maps as well as to recover the sky from artifact-contaminated data like the ROSAT 0.855 keV map. The predicted maps generally show less imaging artifacts compared to the original ones. A comparison of predicted and original maps highlights surprising structures, imaging artifacts (fortunately not reproduced in the prediction), and features genuine to the respective frequency range that are not present at other frequency bands. We discuss limitations of this machine learning approach and ideas how to overcome them

2MASS J06422218-0226285 - a new Outburst Source

We discovered the outburst of 2MASS J06422218--0226285. Between end 2012 and early 2014, this object brightened by 3 mag in r and i, and by 3.7 mag in J. Since then, it has stayed at high brightness of about 16 mag in r and 15 mag in i. Possible explanations for this kind of light curve might be a Catalysmic Variable, a Symbiotic Binary or a FUor or EXor type Young Stellar Object. The color properties favor an outbursting Young Stellar Object

Toward Understanding the Origin of Turbulence in Molecular Clouds: Small Scale Structures as Units of Dynamical Multi-Phase Interstellar Medium

In order to investigate the origin of the interstellar turbulence, detailed observations in the CO J=1--0 and 3--2 lines have been carried out in an interacting region of a molecular cloud with an HII region. As a result, several 1,000 to 10,000 AU scale cloudlets with small velocity dispersion are detected, whose systemic velocities have a relatively large scatter of a few km/s. It is suggested that the cloud is composed of small-scale dense and cold structures and their overlapping effect makes it appear to be a turbulent entity as a whole. This picture strongly supports the two-phase model of turbulent medium driven by thermal instability proposed previously. On the surface of the present cloud, the turbulence is likely to be driven by thermal instability following ionization shock compression and UV irradiation. Those small scale structures with line width of ~ 0.6 km/s have a relatively high CO line ratio of J=3--2 to 1--0, 1 < R(3-2/1-0) < 2. The large velocity gradient analysis implies that the 0.6 km/s width component cloudlets have an average density of 10^{3-4} cm^{-3}, which is relatively high at cloud edges, but their masses are only < 0.05 M_{sun}.Comment: 12 pages, 9 figures. To be published in the Astrophysical Journa

The Bochum Galactic Disk Survey

Diese Arbeit präsentiert den Bochum Galactic Disk Survey (GDS). Der GDS ist ein fortlaufendes Projekt, dessen Ziel die kontinuierliche photometrische Durchmusterung der Galaktischen Scheibe und die Variabilitätsanalyse der darin enthaltenen Sterne ist. Der GDS umfasst photometrische Informationen für 15.888.583 Quellen in $\it U$, $\it B$, $\it V$, $\it r’$, $\it i’$ und $\it z’$, von denen 64.151 Variable gleichzeitig in $\it r’$ und $\it i’$ beobachtet und identifiziert wurden, wovon 56.761 Quellen zuvor nicht als variabel bekannt waren. Die Ergebnisse umfassen Kataloge der variablen Sterne, mittlerer Helligkeiten aller Quellen in sechs Filtern sowie die Lichtkurven der Variablen. Zusätzlich wurde der FU-Orionis-Stern V960 Mon mittels GDS-Lichtkurven in sechs Filtern vor, während und nach dessen Ausbruch detailliert untersucht. Es zeigt sich ein Helligkeitsabfall nach dem Ausbruch sowie eine gleichzeitige sinusförmige Helligkeitsschwankung mit kleiner Amplitude, die auf einen Doppelstern mit exzentrischem Orbit hinweist

Search for narrow resonances using the dijet mass spectrum in pp collisions at s√=8 TeV

Results are presented of a search for the production of new particles decaying to pairs of partons (quarks, antiquarks, or gluons), in the dijet mass spectrum in proton-proton collisions at s√=8  TeV. The data sample corresponds to an integrated luminosity of 4.0  fb−1, collected with the CMS detector at the LHC in 2012. No significant evidence for narrow resonance production is observed. Upper limits are set at the 95% confidence level on the production cross section of hypothetical new particles decaying to quark-quark, quark-gluon, or gluon-gluon final states. These limits are then translated into lower limits on the masses of new resonances in specific scenarios of physics beyond the standard model. The limits reach up to 4.8 TeV, depending on the model, and extend previous exclusions from similar searches performed at lower collision energies. For the first time mass limits are set for the Randall–Sundrum graviton model in the dijet channel