Near-UV photolysis cross sections of CH_3OOH and HOCH_2OOH determined via action spectroscopy

Knowledge of molecular photolysis cross sections is important for determining atmospheric lifetimes and fates of many species. A method and laser apparatus for measurement of these cross sections in the near-ultraviolet (UV) region is described. The technique is based on action spectroscopy, where the yield of a photodissociation product (in this case OH) is measured as a function of excitation energy. For compounds yielding OH, this method can be used to measure near-UV photodissociation cross section as low as 10−23 cm2 molecule−1. The method is applied to determine the photodissociation cross sections for methyl hydroperoxide (CH3OOH; MHP) and hydroxymethyl hydroperoxide (HOCH2OOH; HMHP) in the 305–365 nm wavelength range. The measured cross sections are in good agreement with previous measurements of absorption cross sections

A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates

Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circumbinary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35,383 spectroscopically confirmed quasars in the photometric database of the Palomar Transient Factory (PTF). We analysed Lomb-Scargle periodograms and assessed the significance of our findings by modeling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PTF and the Catalina Real-Time Transient Survey (CRTS). Assuming that the observed periods correspond to the redshifted orbital periods of SMBHBs, we conclude that our findings are consistent with a population of unequal-mass SMBHBs, with a typical mass ratio as low as q = M2/M1 ~ 0.01.Comment: MNRAS (accepted), new section 4.

Kajian Persebaran Lalu Lintas Akibat Pembongkaran Jembatan Soekarno Hatta

Dengan memperhatikan kinerja jaringan jalan satu arah pada lingkar Universitas Brawijaya yang meliputi Jl. Soekarno Hatta, Jl. Mayjen Panjaitan, Jl. Bogor, Jl. Veteran, Jl. Sumbersari-Gajayana, Jl. MT Haryono, Jl. Bunga Coklat-Pisang Kipas, Jl. MT Haryono XIII (sebelah Polsek), Jl. Bunga Cengkeh, Jl. Dewandaru, Jl. Kumis Kucing, dan Jl. Cendanadi Kota Malang yang semakin ramai saat akhir pekan, maka diperlukannya upaya untuk menganalisis dan mencari solusi yang diperlukan agar dampak yang terjadi dapat diminimalisir. Skripsi ini bertujuan untuk mengetahui distribusi perjalanan pada lingkar Universitas Brawijaya pada saat keadaan arus lalu lintas satu arah dan membuat skenario pengaturan lalu lintas akibat pembongkaran jembatan rangka Soekarno Hatta dan masa pembangunan jembatan yang baru. Kajian yang dilakukan berupa distribusi kendaraan,analisa kinerja ruas, simpang dan jalinan serta membuat skenario pengaturan lalu lintas agar dapat memberi solusi dan mengurangi terjadinya kemacetan pada saat pembongkaran jembatan rangka Soekarno Hatta danmasa pembangunan jembatan yang baru. Data penelitian didapat dengan melakukan survei distribusi kendaraan dan survei traffic counting pada hari Jumat pukul 06.00-08.00 WIB dan 15.00-17.00 WIB dengan lokasi jaringan jalan satuarahpada lingkar Universitas Brawijaya. Analisis kinerja simpang dan ruas mengacu pada MKJI 1997, sedangkan untuk skenario pengaturan lalu lintas mengacu referensi terkait yaitu mengenai optimasi waktu siklus dan geometri. Sehingga diperoleh tingkat pelayanan pada masing-masing jaringan jalan di sekitar kawasan tersebut, kemudian diambil 2 skenario yang direkomendasikan karena memiliki tingkat kinerja jalan yang lebih baikdan memiliki tingkat pengaturan lalu lintas yang relatif lebih mudah dibanding skenario yang lain. Skenario yang direkomendasikan yaitu skenario 1 dan skenario 2. Hasil yang diperoleh dari skenario 1 yaitu ruas Soekarno Hatta (arah ke Universitas Brawijaya) dengan tingkat pelayanan A dengan DS sebesar 0,34;ruas Soekarno Hatta (arah ke Blimbing) dengan tingkat pelayanan C dengan DS sebesar 0,72; ruas Soekarno Hatta (ruas pada jembatan beton) dengan tingkat pelayanan D dengan DS sebesar 0,91; ruas Bunga Cengkeh dengan tingkat pelayanan B dengan DS sebesar 0,36; ruas Dewandaru dengan tingkat pelayanan A dengan DS sebesar 0,32; ruas Cendana dengan tingkat pelayanan A dengan DS sebesar 0,06; ruas Bunga Coklat-Pisang Kipas dengan tingkat pelayanan F dengan DS sebesar 1,23; ruas MT Haryono XIII (sebelahPolsek) dengan tingkat pelayanan F dengan DS sebesar 1,23; simpang Soekarno Hatta-Bunga Coklat dengan tingkat pelayanan F dengan tundaan sebesar 339,02 detik, simpang MT Haryono-Soekarno Hatta dengan tingkat pelayanan F dengan tundaan sebesar 711,98 detik; simpang Dewandaru dengan tingkat pelayanan B dengan tundaan sebesar 13,31 detik, simpang Kumis Kucing dengan tingkat pelayanan B dengan tundaan sebesar 6,53 detik, simpang Cendana dengan tingkat pelayanan A dengan tundaan sebesar 5,00 detik. Sedangkan hasil yang diperoleh dari skenario 2 yaitu dengan hasil ruas Soekarno Hatta (arah ke Universitas Brawijaya) dengan tingkat pelayanan A dengan DS sebesar 0,34; ruas Soekarno Hatta (arah ke Blimbing) dengan tingkat pelayanan C dengan DS sebesar 0,72; ruas Soekarno Hatta (ruas pada jembatan beton) dengan tingkat pelayanan D dengan DS sebesar 0,91; ruas Bunga Cengkeh dengan tingkat pelayanan C dengan DS sebesar 0,68; ruas Dewandaru dengan tingkat pelayanan F dengan DS sebesar 1,55; ruas Cendana dengan tingkat pelayanan F dengan DS sebesar 1,67; ruas Bunga Coklat-Pisang Kipas dengan tingkat pelayanan B dengan DS sebesar 0,42; ruas MT Haryono XIII (sebelah Polsek) dengan tingkat pelayanan A dengan DS sebesar 0,09; simpang Soekarno Hatta-Bunga Coklat dengan tingkat pelayanan F dengan tundaan sebesar 394,86 detik, simpang MT Haryono-Soekarno Hatta dengan tingkat pelayanan F dengan tundaan sebesar 647,86 detik, simpang Dewandaru dengan tingkat pelayanan F dengan tundaan sebesar 829,39 detik, simpang Kumis Kucing dengan tingkat pelayanan B dengan tundaan sebesar 7,90 detik, simpang Cendana dengan tingkat pelayanan B dengan tundaan sebesar 14,40 detik

Strategies for the Follow-up of Gravitational Wave Transients at Very High-Energy Gamma Rays with the Cherenkov Telescope Array

With the observation of the first electromagnetic counterpart of Gravitational Wave (GW) transient GW170817, the potential of multimessenger astronomy has been clearly demonstrated. In its full configuration, the Cherenkov Telescope Array (CTA) observatory will be capable of rapidly covering the regions localized by future GW observations with sufficient sensitivity at very high-energy gamma rays. In view of the forthcoming deployment of its first telescopes, we identify some general strategies for GW follow-up that will improve the CTA contribution to multimessenger discoveries

Commissioning of the tuned DC readout at GEO 600

Recent experimental results from GEO600 operating with a DC readout and a tuned signal recycling cavity are reported. Compared to the S5/Astrowatch setup, two major changes in the configuration have been implemented: the control readout to keep the interferometer on the dark fringe is changed from heterodyne to homodyne readout and the signal recycling cavity is shifted from a 550 Hz detuning to a 0 Hz detuning (also called tuned). As preliminary experiments showed, the tuned DC readout sensitivity is similar to the heterodyne one. To take advantage of the new DC readout detection scheme, an Output Mode Cleaner (OMC) has to be installed. The design, building and testing of the GEO OMC, which consists of a 4 mirrors monolithic ring cavity, will also be presented in this article.Science and Technology Facilities Council (STFC)BMBFMax Planck Society (MPG)State of Lower Saxony in GermanyEuropean Gravitational Observatory (EGO)DFG/SFB/Transregio

Control and automatic alignment of the output mode cleaner of GEO 600

The implementation of a mode cleaner at the output port of the GEO 600 gravitational wave detector will be part of the upcoming transition from GEO 600 to GEO-HF. Part of the transition will be the move from a heterodyne readout to a DC readout scheme. DC readout performance will be limited by higher order optical modes and control sidebands present at the output port. For optimum performance of DC readout an output mode cleaner (OMC) will clean the output beam of these contributions. Inclusion of an OMC will introduce new noise sources whose magnitudes needed to be estimated and for which new control systems will be needed. In this article we set requirements on the performance of these control systems and investigate the simulated performance of different designs.Science and Technology Facilities Council (STFC)BMBFMax Planck Society (MPG)State of Lower Saxony in GermanyEuropean Gravitational Observatory (EGO)DFG/SFB/Transregio

The stellar content of the young open cluster Trumpler 37

With an apparent cluster diameter of 1.5{\deg} and an age of ~4 Myr, Trumpler 37 is an ideal target for photometric monitoring of young stars as well as for the search of planetary transits, eclipsing binaries and other sources of variability. The YETI consortium has monitored Trumpler 37 throughout 2010 and 2011 to obtain a comprehensive view of variable phenomena in this region. In this first paper we present the cluster properties and membership determination as derived from an extensive investigation of the literature. We also compared the coordinate list to some YETI images. For 1872 stars we found literature data. Among them 774 have high probability of being member and 125 a medium probability. Based on infrared data we re-calculate a cluster extinction of 0.9-1.2 mag. We can confirm the age and distance to be 3-5 Myr and ~870 pc. Stellar masses are determined from theoretical models and the mass function is fitted with a power-law index of alpha=1.90 (0.1-0.4 M_sun) and alpha=1.12 (1-10 M_sun).Comment: 9 pages, 10 figures, 2 long tables, accepte

YETI observations of the young transiting planet candidate CVSO 30 b

CVSO 30 is a unique young low-mass system, because, for the first time, a close-in transiting and a wide directly imaged planet candidates are found around a common host star. The inner companion, CVSO 30 b, is the first possible young transiting planet orbiting a previously known weak-lined T-Tauri star. With five telescopes of the 'Young Exoplanet Transit Initiative' (YETI) located in Asia, Europe and South America we monitored CVSO 30 over three years in a total of 144 nights and detected 33 fading events. In two more seasons we carried out follow-up observations with three telescopes. We can confirm that there is a change in the shape of the fading event between different observations and that the fading event even disappears and reappears. A total of 38 fading event light curves were simultaneously modelled. We derived the planetary, stellar, and geometrical properties of the system and found them slightly smaller but in agreement with the values from the discovery paper. The period of the fading event was found to be 1.36 s shorter and 100 times more precise than the previous published value. If CVSO 30 b would be a giant planet on a precessing orbit, which we cannot confirm, yet, the precession period may be shorter than previously thought. But if confirmed as a planet it would be the youngest transiting planet ever detected and will provide important constraints on planet formation and migration time-scales.Comment: 14 pages (20 with appendix), 7 figures (16 with appendix), 6 tables (7 with appendix