اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدHigh Excitation Emission Line Nebula associated with an Ultra Luminous X-ray Source at $z=$ 0.027 in the textit{AKARI} North Ecliptic Pole Deep Field
117
0
0.0
(
0
)
تأليف
J. Diaz Tello
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Aims. We report our finding of a high excitation emission line nebula associated with an Ultra Luminous X-ray source (ULX) at $z=$ 0.027, which we found in our Chandra observation of the AKARI North Ecliptic Pole (NEP) Deep Field. Methods. We present a Chandra X-ray and Gran Telescopio Canarias (GTC) optical spectral analysis of the ULX blob. We investigate the nature of the emission line nebula by using line ratio diagnostic diagrams, and its physical properties estimated from Spectral Energy Distribution (SED) fitting. Results. The optical spectrum of this ULX blob shows emission line ratios that are located on the borderlines between star-formation and Seyfert regimes in [OIII]/H$beta$-[OI]/H$alpha$, [OIII]/H$beta$-[SII]/H$alpha$ and [OIII]/H$beta$-[OIII]/[OII] diagnostic diagrams. These are in contrast with those of a nearby blob observed with the same slit, which occupy the HII regimes. This result suggests that the ionization of the emission line nebula associated with the ULX is significantly contributed by energy input from the accretion power of the ULX, in addition to the star formation activity in the blob, suggesting the existence of an accretion disk in the ULX emitting UV radiation, or exerting shock waves.
قيم البحث
اقرأ أيضاً
(Abridged) We aim to study the evolution of dust attenuation in galaxies selected in the IR in the redshift range in which they are known to dominate the star formation activity in the universe. The comparison with other measurements of dust attenuat
ion in samples selected using different criteria will give us a global picture of the attenuation at work in star-forming galaxies and its evolution with redshift. Using multiple filters of IRC instrument, we selected more than 4000 galaxies from their rest-frame emission at 8 microns, from z~0.2 to 2$. We built SEDs from the rest-frame UV to the far-IR by adding data in the optical-NIR and from GALEX and Herschel surveys. We fit SEDs with the physically-motivated code CIGALE. We test different templates for AGNs and recipes for dust attenuation and estimate stellar masses, SFRs, amount of dust attenuation, and AGN contribution to the total IR luminosity. The AGN contribution to the total IR luminosity is found to be on average approximately 10% with a slight increase with redshift. Dust attenuation in galaxies dominating the IR luminosity function is found to increase from z=0 to z=1 and to remain almost constant from z=1 to z=1.5. Conversely, when galaxies are selected at a fixed IR luminosity, their dust attenuation slightly decreases as redshift increases but with a large dispersion. The attenuation in our mid-IR selected sample is found ~ 2 mag higher than that found globally in the universe or in UV and Halpha line selections in the same redshift range. This difference is well explained by an increase of dust attenuation with the stellar mass, in global agreement with other recent studies. Starbursting galaxies do not systematically exhibit a high attenuation
The $AKARI$ infrared (IR) space telescope conducted two surveys (Deep and Wide) in the North Ecliptic Pole (NEP) field to find more than 100,000 IR sources using its Infrared Camera (IRC). IRCs 9 filters, which cover wavebands from 2 to 24 $mu$m cont
inuously, make $AKARI$ unique in comparison with other IR observatories such as $Spitzer$ or $WISE$. However, studies of the $AKARI$ NEP-Wide field sources had been limited due to the lack of follow-up observations in the ultraviolet (UV) and optical. In this work, we present the Canada-France-Hawaii Telescope (CFHT) MegaPrime/MegaCam $u$-band source catalogue of the $AKARI$ NEP-Wide field. The observations were taken in 7 nights in 2015 and 2016, resulting in 82 observed frames covering 3.6 deg$^2$. The data reduction, image processing and source extraction were performed in a standard procedure using the textsc{Elixir} pipeline and the textsc{AstrOmatic} software, and eventually 351,635 sources have been extracted. The data quality is discussed in two regions (shallow and deep) separately, due to the difference in the total integration time (4,520 and 13,910 seconds). The 5$sigma$ limiting magnitude, seeing FWHM, and the magnitude at 50 per cent completeness are 25.38 mag (25.79 mag in the deep region), 0.82 arcsec (0.94 arcsec) and 25.06 mag (25.45 mag), respectively. The u-band data provide us with critical improvements to photometric redshifts and UV estimates of the precious infrared sources from the $AKARI$ space telescope.
We study the behaviour of polycyclic aromatic hydrocarbon emission in galaxies at z=0.3-1.4 using 1868 samples from the revised catalogue of AKARI North Ecliptic Pole Deep survey. The continuous filter coverage at 2-24um makes it possible to measure
8um luminosity, which is dominated by polycyclic aromatic hydrocarbon emission for galaxies at up to z=2. We compare the IR8 (= LIR/L(8)) and 8um to 4.5um luminosity ratio (L(8)/L(4.5)) with the starburstiness, Rsb, defined as excess of specific star -formation rate over that of main-sequence galaxy. All AGN candidates were excluded from our sample using an SED fitting. We found L(8)/L(4.5) increases with starburstiness at log Rsb < 0.5 and stays constant at higher starburstiness. On the other hand, IR8 is constant at log Rsb < 0, while it increases with starburstiness at log Rsb > 0. This behaviour is seen in all redshift range of our study. These results indicate that starburst galaxies have deficient polycyclic aromatic hydrocarbon emission compared with main-sequence galaxies. We also find that galaxies with extremely high L(8)/L(4.5) ratio have only moderate starburstiness. These results suggest that starburst galaxies have compact star-forming regions with intense radiation, which destroys PAHs and/or have dusty HII regions resulting in a lack of ionising photons.
We present herein galaxy number counts of the nine bands in the 2-24 micron range on the basis of the AKARI North Ecliptic Pole (NEP) surveys. The number counts are derived from NEP-deep and NEP-wide surveys, which cover areas of 0.5 and 5.8 deg2, re
spectively. To produce reliable number counts, the sources were extracted from recently updated images. Completeness and difference between observed and intrinsic magnitudes were corrected by Monte Carlo simulation. Stellar counts were subtracted by using the stellar fraction estimated from optical data. The resultant source counts are given down to the 80% completeness limit; 0.18, 0.16, 0.10, 0.05, 0.06, 0.10, 0.15, 0.16, and 0.44 mJy in the 2.4, 3.2, 4.1, 7, 9, 11, 15, 18 and 24 um bands, respectively. On the bright side of all bands, the count distribution is flat, consistent with the Euclidean Universe, while on the faint side, the counts deviate, suggesting that the galaxy population of the distant universe is evolving. These results are generally consistent with previous galaxy counts in similar wavebands. We also compare our counts with evolutionary models and find them in good agreements. By integrating the models down to the 80% completeness limits, we calculate that the AKARI NEP-survey revolves 20%-50% of the cosmic infrared background, depending on the wavebands.
We present data products from the 300 ks Chandra survey in the AKARI North Ecliptic Pole (NEP) deep field. This field has a unique set of 9-band infrared photometry covering 2-24 micron from the AKARI Infrared Camera, including mid-infrared (MIR) ban
ds not covered by Spitzer. The survey is one of the deepest ever achieved at ~15 micron, and is by far the widest among those with similar depths in the MIR. This makes this field unique for the MIR-selection of AGN at z~1. We design a source detection procedure, which performs joint Maximum Likelihood PSF fits on all of our 15 mosaicked Chandra pointings covering an area of 0.34 square degree. The procedure has been highly optimized and tested by simulations. We provide a point source catalog with photometry and Bayesian-based 90 per cent confidence upper limits in the 0.5-7, 0.5-2, 2-7, 2-4, and 4-7 keV bands. The catalog contains 457 X-ray sources and the spurious fraction is estimated to be ~1.7 per cent. Sensitivity and 90 per cent confidence upper flux limits maps in all bands are provided as well. We search for optical MIR counterparts in the central 0.25 square degree, where deep Subaru Suprime-Cam multiband images exist. Among the 377 X-ray sources detected there, ~80 per cent have optical counterparts and ~60 per cent also have AKARI mid-IR counterparts. We cross-match our X-ray sources with MIR-selected AGN from Hanami et al. (2012). Around 30 per cent of all AGN that have MID-IR SEDs purely explainable by AGN activity are strong Compton-thick AGN candidates.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
