Implication of pulsar timing array experiments on cosmological gravitational wave detection

Gravitational waves provide a new probe of the Universe which can reveal a number of cosmological and astrophysical phenomena that cannot be observed by electromagnetic waves. Different frequencies of gravitational waves are detected by different means. Among them, precision measurements of pulsar timing provides a natural detector for gravitational waves with light-year scale wavelengths. In this review, first a basic framework to detect a stochastic gravitational wave background using pulsar timing array is introduced, and then possible interpretations of the latest observational result of 12.5-year NANOGrav data are described.

Lightning Detection and Imaging Based on VHF Radar Interferometry

In this study, detection and three-dimensional (3D) imaging of lightning plasma channels are presented using radar interferometry. Experiments were carried out in Leshan, China with a 48.2 MHz VHF radar configured with an interferometric antenna array. The typical characteristics of lightning echoes are studied in the form of amplitude, phase, and doppler spectra derived from the raw in-phase/quadrature (I/Q) data. In addition, the 3D structure of lightning channels is reconstructed using the interferometry technique. The localization results of lightning are verified with the locating results of lightning detection networks operating at VLF ranges, which indicate the feasibility of using VHF radar for lightning mapping. The interpretation of the observational results is complicated by the dendric structure of lightning channel and the overlap between passive electromagnetic radiations and return echoes. Nevertheless, some parts of the characteristics of lightning are still evident. The observational result of return echoes shows good consistency with the overdense assumption of lightning channels. The transition from the overdense channel to the underdense channel in the form of amplitude and phase is clearly observed. This technique is very promising to reveal the typical characteristics of lightning return echoes and structure of lightning propagation processes.

l-galaxies 2020: The evolution of radial metallicity profiles and global metallicities in disc galaxies

We present a modified version of the L-Galaxies 2020 semi-analytic model of galaxy evolution, which includes significantly increased direct metal enrichment of the circumgalactic medium (CGM) by supernovae (SNe). These more metal-rich outflows do not require increased mass-loading factors, in contrast to some other galaxy evolution models. This modified L-Galaxies 2020 model is able to simultaneously reproduce the gas-phase metallicity (Zg) and stellar metallicity (Z*) radial profiles observed in nearby disc galaxies by MaNGA and MUSE, as well as the observed mass – metallicity relations for gas and stars at z = 0 and their evolution back to z ∼ 2 − 3. A direct CGM enrichment fraction of ∼90 per cent for SNe-II is preferred. We find that massive disc galaxies have slightly flatter Zg profiles than their lower-mass counterparts in L-Galaxies 2020, due to more efficient enrichment of their outskirts via inside-out growth and metal-rich accretion. Such a weak, positive correlation between stellar mass and Zg profile slope is also seen in our MaNGA-DR15 sample of 571 star-forming disc galaxies, although below ${\rm log}_{10}{(M_{*}/{\rm M_\odot} )}{}\sim {}10.0$ this observational result is strongly dependent on the metallicity diagnostic and morphological selection chosen. In addition, a lowered maximum SN-II progenitor mass of 25 M⊙, reflecting recent theoretical and observational estimates, can also provide a good match to observed Zg and Z* profiles at z = 0 in L-Galaxies 2020. However, this model version fails to reproduce an evolution in Zg at fixed mass over cosmic time, or the magnesium abundances observed in the intracluster medium (ICM).

Peningkatan Kemampuan Motorik Kasar Melalui Permainan Sirkuit Terowongan Geometri pada Anak Kelompok A di TK Kartika Bojonegoro

This research aims to (1) implement geometry tunnel circuit games on improving rough motoric skills in children group A at TK Kartika Bojonegoro, (2) improving rough motoric skills in children group A at TK Kartika Bojonegoro through geometry tunnel circuit games. This research used classroom action research with a research model from Kemis and MC Taggart. Each cycle consists of planning, acting and observing, reflecting, and revise plans. This research results showed that through geometry tunnel circuit games, the children group A rough motoric skills at TK Kartika Bojonegoro was increased. This was proved from the pre-action observational result which reached an average 60,83 percent with percentage 38,33 percent. In the cycle I reached an average 67,91 percent with percentage 58,33 percent. While in cycle II reached an average 83,47 percent with percentage 86,11 percent. The children's rough motoric skills in cycle II had increased well and it fulfilled the standard of achievement which was decided from the researcher, that was a minimum of 70 percent. Abstrak: Tujuan penelitian ini adalah (1) menerapkan permainan sirkuit terowongan geometri untuk meningkatkan kemampuan motorik kasar anak kelompok A TK Kartika Bojonegoro (2) meningkatkan kemampuan motorik kasar anak kelompok A TK Kartika Bojonegoro melalui permainan sirkuit terowongan geometri. Rancangan penelitian ini berupa Penelitian Tindakan Kelas (PTK) dengan menggunakan model siklus Kemmis & Mc Tanggart yang terdiri dari, tahap perencanaan, pelaksanaan dan pengamatan, refleksi, dan perbaikan rencana. Hasil penelitian menunjukkan bahwa melalui penerapan permainan sirkuit terowongan geometri dapat meningkatkan kemampuan motorik kasar anak kelompok A di TK Kartika Bojonegoro. Terbukti pada penelitian pra tindakan mencapai rata-rata 60,83 dengan persentase 38,33 persen, pada siklus I meningkat mencapai rata-rata 67,91 dengan persentase 58,33 persen, sedangkan pada siklus II mencapai rata-rata 83,47 dengan persentase 86,11 persen. Kemampuan motorik kasar anak pada siklus II sudah berkembang sangat baik dan sudah memenuhi standar ketercapaian yang ditetapkan oleh peneliti yaitu minimal 70 persen.

Massive black hole binary systems and the NANOGrav 12.5 yr results

ABSTRACT The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) recently reported evidence for the presence of a common stochastic signal across their array of pulsars. The origin of this signal is still unclear. One possibility is that it is due to a stochastic gravitational-wave background (SGWB) in the ∼1–10 nHz frequency region. Taking the NANOGrav observational result at face value, we show that this signal would be fully consistent with an SGWB produced by an unresolved population of in-spiralling massive black hole binaries (MBHBs) predicted by current theoretical models. Considering an astrophysically agnostic model, the MBHB merger rate is loosely constrained. Including additional constraints from galaxy pairing fraction and MBH–bulge scaling relations, we find that the MBHB merger rate is ${1.2\times 10^{-5}}{\rm -}{4.5\times 10^{-4}}\, \mathrm{Mpc}^{-3}\, \mathrm{Gyr}^{-1}$ , the MBHB merger time-scale is $\le 2.7\, \mathrm{Gyr}$, and the norm of the MBH−Mbulge relation is $\ge 1.2\times 10^{8}\, {\rm M}_\odot$ (all quoted at 90 per cent credible intervals). Regardless of the astrophysical details of MBHB assembly, the NANOGrav result would imply that a sufficiently large population of massive black holes pair up, form binaries and merge within a Hubble time.

Peran Dinas Tenaga Kerja Dan Transmigrasi Kepulauan Riau Dalam Melakukan Pengawasan Keselamatan Dan Kesehatan Kerja (K3).

After out Undang-Undang Nomor 1 Tahun 1970 tentang Keselamatan Kerja then in it after set inside done supervision to safety work. Many still run other connect with safety work but supervision match with rule out Republic Of Indonesia Minister Of Manpower regulation Number: Per. 04 / Men / 1987 about safety Builder Committees And Penujukan's job and Procedure health An Old Hand At working safety, therefore about observation to K3 more assisted be. Mark sense this order is made that belonging of citizen can be accomplished, as to get work and subsistence that reasonably accords Section mandate 27 sentences (2) UUD 1945. That Besides to the effect marks sense this observation that a company places fires an employee to work gets to give rights belonging of that employ. According is aiming even appointed research this in writing which is: First, What that as evoked disease causal factor effect job. Both of, How forms observation that did by on duty Labour And Resettlement in do observation to the firm at archipelagic Riau. The observational method that is utilized in writing is an empirical judicial formality, by use of kualitatif's research type. The observational result is First, a factor that regards job effect disease for example a. Physical factor, b. Chemical factor, c. Biological factor, d. Ergonomics factor / Physiology, e. Psychology factor. Both of, Observation that did by the archipelagic Province Government Riau on duty Labour and Resettlement which is observation performing did by PPNS by sees, assess and another to the firm. Setelah keluarnya Undang-Undang Nomor 1 Tahun 1970 tentang Keselamatan Kerja kemudian di dalamnya setelah di atur dalam pengawasan terhadap keselamatan kerja. Sebenarnya masih banyak aturan lain yang berhubungan dengan keselamatan kerja tetapi berjalannya pengawasan sesuai dengan aturan Peraturan Menteri Tenaga Kerja Republik Indonesia Nomor: Per.04/Men/1987 tentang Panitia Pembina Keselamatan Dan Kesehatan Kerja Serta Tata Cara Penujukan Ahli Keselamatan Kerja, maka mengenai pengawasan terhadap K3 lebih terbantu lagi. Adanya aturan ini dibuat agar hak dari warga negara dapat terpenuhi, seperti mendapatkan pekerjaan dan penghidupan yang layak sesuai amanat Pasal 27 ayat (2) UUD 1945. Selain itu, tujuan adanya pengawasan ini agar prusahaan tempat karyawan bekerja dapat memberikan hak-hak dari pekerja tersebut. Berdasarkan tujuan penelitian yang diangkat dalam tulisan ini yaitu: Pertama, Apakah yang menjadi faktor-faktor penyebab penyakit yang timbul akibat kerja. Kedua, Bagaimana bentuk pengawasan yang dilakukan oleh Dinas Tenaga Kerja Dan Transmigrasi dalam melakukan pengawasan terhadap perusahaan di Kepulauan Riau. Metode penelitian yang digunakan dalam tulisan ini adalah yuridis empiris, dengan menggunakan jenis penelitian kualitatif. Hasil penelitian adalah Pertama, faktor-faktor yang mempengaruhi penyakit akibat kerja antara lain: a. Faktor fisik, b. Faktor Kimia, c. Faktor Biologi, d. Faktor Ergonomi/Fisiologi, e. Faktor Psikologi. Kedua, Pengawasan yang dilakukan oleh Pemerintah Provinsi Kepulauan Riau Dinas Tenaga Kerja dan Transmigrasi yaitu pelaksanaan pengawasan dilakukan oleh PPNS dengan cara melihat, menilai dan lainnya ke perusahaan.

Bianchi Type- I Bulk Viscosity with a DE Cosmological Model

The finding article presents Bianchi type- I universe in the presence of bulk viscous and DE fluid nature of a cosmological model. The solutions of field equations were obtained by assuming hybrid expansion law. The physical significance of the obtained findings illustrates the dominance of bulk viscosity in early and dominance of dark energy fluid emergences in late. This leads to indicate the presence of bulk viscosity nature more effective in early time rather than late times, and also, it shows the dominance of dark energy in late times which grants the current observational result of the universe. Certain physical and geometrical properties of the model are also discussed.

Multiple populations of Hβ emission line stars in the Large Magellanic Cloud cluster NGC 1971

We revisited the young Large Magellanic Cloud star cluster NGC 1971 with the aim of providing additional clues to our understanding of its observed extended main-sequence turnoff (eMSTO), a feature commonly seen in young star clusters that has recently been argued to be caused by a real age spread similar to the cluster age (∼160 Myr). We combined accurate Washington and Strömgren photometry of stars with high membership probability to explore the nature of this eMSTO. From different ad hoc defined pseudo-colors, we found that bluer and redder stars distributed throughout the eMSTO do not show any inhomogeneities of light- and heavy-element abundances. These blue and red stars are split into two clearly different groups only when the Washington M magnitudes are employed, which delimites the number of spectral features that cause the appearance of the eMSTO. We speculate that Be stars populate the eMSTO of NGC 1971 because (i) Hβ contributes to the M passband, (ii) Hβ emissions are common features of Be stars, and (iii) the Washington M and T1 magnitudes are tightly correlated; the latter measuring the observed contribution of Hα emission line in Be stars, which is in turn correlated with Hβ emissions. This is the first observational result to our knowledge that indicates that Hβ emissions are the origin of eMSTOs observed in young star clusters. Our results certainly open new possibilities of studying eMSTO from photometric systems with passbands centered at features commonly seen in Be stars.

Meteor pairs and groups in Geminid meteor shower

<p>The existence of the pairs and larger groups of the meteors was already investigated in several papers. Recent statistical analyses of radar or optical data on several meteor showers provided rather negative results. Nevertheless, some level of groupings is possible, especially among young streams.</p> <p>When digitalizing older videotapes obtained during the 2006 Geminid campaign, we found a relatively higher number of meteors that appear in pairs. Therefore we investigated this observational result in more detail.</p> <p>Statistically, when observing Geminid meteor shower, we could expect 1.4 randomly paired meteors per 1 hour assuming ZHR = 100 and the maximum gap between meteors of 1 second. There were recorded 9 pairs during 3.5 hours of observation. Therefore at least some of them cannot be statistically random pairs. Moreover, a triplet of meteors detected within 1 second is well above the statistical threshold for random appearance.</p> <p>In this talk, we will provide more detailed analyses of all the cases as well as some possible scenarios of their origin.</p>