ترغب بنشر مسار تعليمي؟ اضغط هنا

CO(J=6-5) Observations of the Quasar SDSS1044-0125 at z = 5.8

372   0   0.0 ( 0 )
 نشر من قبل Iwata Ikuru
 تاريخ النشر 2001
  مجال البحث فيزياء
والبحث باللغة English
 تأليف I. Iwata




اسأل ChatGPT حول البحث

We present a result of the quasar CO(J=6-5) observations of SDSSp J104433.04-012502.2 at z = 5.8. Ten-days observations with the Nobeyama Millimeter Array yielded an rms noise level of ~ 2.1 mJy/beam in a frequency range from 101.28 GHz to 101.99 GHz at a velocity resolution of 120 km/s. No significant clear emission line was detected in the observed field and frequency range. Three sigma upper limit on the CO(J=6-5) luminosity of the object is 2.8 x 10^10 K km/s pc^2, corresponding to a molecular gas mass of 1.2 x 10^11 Solar Mass, if a conversion factor of 4.5 Solar Mass /(K km/s pc^2) is adopted. The obtained upper limit on CO luminosity is slightly smaller than those observed in quasars at z=4-5 toward which CO emissions are detected.



قيم البحث

اقرأ أيضاً

93 - C. Qi 2005
We present the first images of the 691.473 GHz CO J=6-5 line in a protoplanetary disk, obtained along with the 690 GHz dust continuum, toward the classical T Tauri star TW Hya using the Submillimeter Array. Imaging in the CO J=6-5 line reveals a rota ting disk, consistent with previous observations of CO J=3-2 and 2-1 lines. Using an irradiated accretion disk model and 2D Monte Carlo radiative transfer, we find that additional surface heating is needed to fit simultaneously the absolute and relative intensities of the CO J=6-5, 3-2 and 2-1 lines. In particular, the vertical gas temperature gradient in the disk must be steeper than that of the dust, mostly likely because the CO emission lines probe nearer to the surface of the disk. We have used an idealized X-ray heating model to fit the line profiles of CO J=2-1 and 3-2 with Chi-square analysis, and the prediction of this model yields CO J=6-5 emission consistent with the observations.
Observations of higher-excited transitions of abundant molecules such as CO are important for determining where energy in the form of shocks is fed back into the parental envelope of forming stars. The nearby prototypical and protobinary low-mass hot core, IRAS16293-2422 (I16293) is ideal for such a study. The source was targeted with ALMA for science verification purposes in band 9, which includes CO J=6-5 (E_up/k_B ~ 116 K), at an unprecedented spatial resolution (~0.2, 25 AU). I16293 itself is composed of two sources, A and B, with a projected distance of 5. CO J=6-5 emission is detected throughout the region, particularly in small, arcsecond-sized hotspots, where the outflow interacts with the envelope. The observations only recover a fraction of the emission in the line wings when compared to data from single-dish telescopes, with a higher fraction of emission recovered at higher velocities. The very high angular resolution of these new data reveal that a bow shock from source A coincides, in the plane of the sky, with the position of source B. Source B, on the other hand, does not show current outflow activity. In this region, outflow entrainment takes place over large spatial scales, >~ 100 AU, and in small discrete knots. This unique dataset shows that the combination of a high-temperature tracer (e.g., CO J=6-5) and very high angular resolution observations is crucial for interpreting the structure of the warm inner environment of low-mass protostars.
Quasar proximity zones at $z>5.5$ correspond to over-dense and over-ionized environments. Galaxies found inside proximity zones can therefore display features which would otherwise be masked by absorption in the IGM. We demonstrate the utility of thi s quasar-galaxy synergy by reporting the discovery of the first three `proximate Lyman-$alpha$ emitters (LAEs) within the proximity zone of quasar J0836 at $z=5.802$ (textit{Aerith A, B} and textit{C}). textit{Aerith A}, located behind the quasar with an impact parameter $D_perp = 278$ pkpc, provides the first detection of a Lyman-$alpha$ transverse proximity effect. We model the transmission and show it constrains the onset of J0836s quasar phase to $0.2 text{Myr}<t<20text{Myr}$ in the past. The second object, textit{Aerith B} at a distance $D=750$ pkpc from the quasar, displays a bright, broad double-peaked lal emission line. Based on relations calibrated at $zleq3$, the peak separation implies a low ionizing $f_{text{esc}} lesssim 1%$, the most direct such constraint on a reionization-era galaxy. We fit the Ly-$alpha$ line with an outflowing shell model, finding a completely typical central density $text{log N}_{text{HI}}/text{cm}^{-2} = 19.3_{-0.2}^{+0.8}$, outflow velocity $v=16_{-11}^{+4}$ km s$^{-1}$, and gas temperature $text{log} T/text{K} = 3.8_{-0.7}^{+0.8}$ compared to $2<z<3$ analogue LAEs. Finally, we detect an emission line at $lambda=8177$ AA in object textit{Aerith C} which, if it is lal at $z=5.726$, would correspond closely with the end of the quasars proximity zone ($Delta z<0.02$ from the boundary) and suggests the quasar influences the IGM up to $sim85$ cMpc away, making it the largest quasar proximity zone. Via the analyses conducted here, we illustrate how proximate LAEs offer unique insight into the ionizing properties of both quasars and galaxies during the epoch of reionization.
We carry out a series of deep Karl G. Jansky Very Large Array (VLA) S-band observations of a sample of 21 quasars at $zsim6$. The new observations expand the searches of radio continuum emission to the optically faint quasar population at the highest redshift with rest-frame $4400 rm AA$ luminosities down to $3 times10^{11} L_{odot}$. We report the detections of two new radio-loud quasars: CFHQS J2242+0334 (hereafter J2242+0334) at $z=5.88$ and CFHQS J0227$-$0605 (hereafter J0227$-$0605) at $z=6.20$, detected with 3 GHz flux densities of $87.0 pm 6.3 mu rm Jy$ and $55.4 pm 6.7 mu rm Jy$, respectively. Their radio replaced{loudness}{loudnesses} are estimated to be $54.9 pm 4.7$ and $16.5 pm 3.2$, respectively. To better constrain the radio-loud fraction (RLF), we combine the new measurements with the archival VLA L-band data as well as available data from the literature, considering the upper limits for non-detections and deleted{and} possible selection effects. The final derived RLF is $9.4 pm 5.7%$ for the optically selected quasars at $zsim6$. We also compare the RLF to that of the quasar samples at low redshift and check the RLF in different quasar luminosity bins. The RLF for the optically faint objects is still poorly constrained due to the limited sample size. Our replaced{result}{results} show no evidence of significant quasar RLF evolution with redshift. There is also no clear trend of RLF evolution with quasar UV/optical luminosity due to the limited sample size of optically faint objects with deep radio observations.
We present high angular resolution imaging ($23.9 times 11.3$ mas, $138.6 times 65.5$ pc) of the radio-loud quasar PSO~J352.4034$-$15.3373 at $z=5.84$ with the Very Long Baseline Array (VLBA) at 1.54 GHz. This quasar has the highest radio-to-optical flux density ratio at such a redshift, making it the radio-loudest source known to date at $z sim 6$. The VLBA observations presented here resolve this quasar into multiple components with an overall linear extent of 1.62 kpc ($0rlap{.}{}28$) and with a total flux density of $6.57 pm 0.38$ mJy, which is about half of the emission measured at a much lower angular resolution. The morphology of the source is comparable with either a radio core with a one-sided jet, or a compact or a medium-size Symmetric Object (CSO/MSO). If the source is a CSO/MSO, and assuming an advance speed of $0.2c$, then the estimated kinematic age is $sim 10^4$ yr.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا