Central Compact Objects: some of them could be spinning up?

Among confirmed central compact objects (CCOs), only three sources have measured period and period derivatives. We have investigated possible evolutionary paths of these three CCOs in the fallback disc model. The model can account for the individual X-ray luminosities and rotational properties of the sources consistently with their estimated supernova ages. For these sources, reasonable model curves can be obtained with dipole field strengths $\sim$ a few $\times 10^9$ G on the surface of the star. The model curves indicate that these CCOs were in the spin-up state in the early phase of evolution. The spin-down starts, while accretion is going on, at a time $t \sim 10^3 - 10^4$ yr depending on the current accretion rate, period and the magnetic dipole moment of the star. This implies that some of the CCOs with relatively long periods, weak dipole fields and high X-ray luminosities could be strong candidates to show spin-up behavior if they indeed evolve with fallback discs.Comment: 5 pages, 3 figures, accepted for publication in MNRA

On the Outbursts of Soft X-ray Transients

We suggest a new scenario to explain the outburst light curves of black hole soft X-ray transients together with the secondary maximum and the bump seen on their decay phases. Our explanations are based on the disk instability models considering the effect of X-ray irradiation. The scenario is consistent with the observed X-ray delays by a few days with respect to the optical rise for both the main outburst and the later maxima. We test our scenario by numerically solving the disk diffusion equation. The obtained model curve fits well to the observed X-ray outburst photon flux curve of the black hole soft X-ray transient GS/GRS 1124-68, a typical representative of the four BH SXTs with very similar light curves.Comment: 11 pages, 8 figures, accepted for publication in A&

X-ray outbursts of AXPs and SGRs

We show that the X‐ray enhancement light curves of transient AXP∕SGRs can be reproduced by the active fallback disk model. We solve the diffusion equation for the relaxation of a disk that has been pushed back by a soft gamma‐ray burst. Our preliminary results indicate that a critical temperature around 1500 K leads to a thermal‐viscous instability in the fallback disks of all AXP∕SGRs. The effect of the instability on the light curves are different for transient and persistent sources due to different pre‐burst disk conditions in these systems

On the enhanced X-ray emission from SGR 1900+14 after the August 27th giant flare

We show that the giant flares of soft gamma ray repeaters (E similar to 10(44) erg) can push the inner regions of a fall-back disk out to larger radii by radiation pressure, while matter remains bound to the system for plausible parameters. The subsequent relaxation of this pushed-back matter can account for the observed enhanced X-ray emission after the August 27(th) giant flare of SGR 1900+14

Bebek Camii

Taha Toros Arşivi, Dosya No: 45-Bebekİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

İstanbul'un tarihi ağaçları

Taha Toros Arşivi, Dosya No: 117-Parklarİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033)Vakvak ağacı, Bayezıt'taki dut ağacı, Yeniçeriler çınarı, Ve diğerler

Tramvayları boşuna mı idam ettik?

Taha Toros Arşivi, Dosya No: 125-Tramvayİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033)"Tercihli yoldan" dan "Hafif raylı sistem" e..

İstanbul'un mesireleri:2

Taha Toros Arşivi, Dosya No: 117-Parklarİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033)Yuşa Tepesi, Beykoz çayırı, Mesirelerde geçen olaylar, Kadınlara mesire yasağı, İstanbul'un diğer mesireleri, Büyükdere mesiresi, Emirgan mesiresi

Mısır Çarşısı

Taha Toros Arşivi, Dosya No: 2-Mısır Çarşısıİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Refah gemisi faciası

Taha Toros Arşivi, Dosya No: 60-Denizyolları. Not: Gazetenin "Tarihte Bu Hafta" köşesinde yayımlanmıştır.Unutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010