Look For Counterparts Research Articles

Probing the infrared counterparts of diffuse far-ultraviolet sources in the Galaxy

Recent availability of high quality infrared (IR) data for diffuse regions in the Galaxy and external galaxies have added to our understanding of interstellar dust. A comparison of ultraviolet (UV) and IR observations may be used to estimate absorption, scattering and thermal emission from interstellar dust. In this paper, we report IR and UV observations for selective diffuse sources in the Galaxy. Using archival mid-infrared (MIR) and far-infrared (FIR) observations from Spitzer Space Telescope, we look for counterparts of diffuse far-ultraviolet (FUV) sources observed by the Voyager, Far Ultraviolet Spectroscopic Explorer (FUSE) and Galaxy Evolution Explorer (GALEX) telescopes in the Galaxy. IR emission features at 8µm are generally attributed to Polycyclic Aromatic Hydrocarbon (PAH) molecules, while emission at 24µm are attributed to Very Small Grains (VSGs). The data presented here is unique and our study tries to establish a relation between various dust populations. By studying the FUV-IR correlations separately at low and high latitude locations, we have identified the grain component responsible for the diffuse FUV emission.

A wide search of obscured Active Galactic Nuclei using XMM-Newton and WISE

AbstractWe use the WISE all sky survey observations to look for counterparts of hard X-ray selected sources from the XMM-Newton-SDSS survey. We then measure the 12 μm luminosity of the AGN by decomposing their optical to infrared SEDs with a host and an AGN component and compare it to the X-ray luminosity and their expected intrinsic relation. This way we select 20 X-ray under-luminous heavily obscured candidates and examine their X-ray and optical properties in more detail. We find evidence for a Compton-thick nucleus for six sources, a number lower than what expected from X-ray background synthesis models, which shows the limitations of our method.

Near‐Sun and near‐Earth manifestations of solar eruptions

We compare the near‐Sun and near‐Earth manifestations of solar eruptions that occurred during November 1994 to June 1998. We compared white‐light coronal mass ejections, metric type II radio bursts, and extreme ultraviolet wave transients (near the Sun) with interplanetary (IP) signatures such as decameter‐hectometric type II bursts, kilometric type II bursts, IP ejecta, and IP shocks. We did a two‐way correlation study to (1) look for counterparts of metric type II bursts that occurred close to the central meridian and (2) look for solar counterparts of IP shocks and IP ejecta. We used data from Wind and Solar and Heliospheric Observatory missions along with metric radio burst data from ground‐based solar observatories. Analysis shows that (1) most (93%) of the metric type II bursts did not have IP signatures, (2) most (80%) of the IP events (IP ejecta and shocks) did not have metric counterparts, and (3) a significant fraction (26%) of IP shocks were detected in situ without drivers. In all these cases the drivers (the coronal mass ejections) were ejected transverse to the Sun‐Earth line, suggesting that the shocks have a much larger extent than the drivers. Shocks originating from both limbs of the Sun arrived at Earth, contradicting earlier claims that shocks from the west limb do not reach Earth. These shocks also had good type II radio burst association. We provide an explanation for the observed relation between metric, decameter‐hectometric, and kilometric type II bursts based on the fast mode magnetosonic speed profile in the solar atmosphere.

A VLA survey of radio-emitting young stars in the Rho Ophiuchi dark cloud

An extensive radio-continuum survey of the Rho Ophiuchi molecular cloud was conducted with the Very Large Array to look for counterparts of several dozen pre-main-sequence stars found in X-ray, optical, and infrared surveys. The authors detect 93 radio sources, significantly more than in previous observations. Thirteen radio sources are found to be probably stellar. They include five variable X-ray stars, seven near- or far-infrared sources, five stars visible on the Palomar Sky Survey, and ten sources with flat or ascending radio spectra. No optical T Tauri star is detected. The remaining sources are extragalactic, in agreement with radio-source counts. The spatial distribution of the stellar radio sources is weakly clustered to the northeast of the core region of the cloud, like the moderately embedded infrared sources. 65 references.

Radio emission from young stellar objects in the Rho Ophiuchi cloud

Following an Einstein X-ray survey of the rho Oph molecular cloud, uncovering several dozen young stellar objects (YSO) (Montmerle et al. 1983), an extensive radio continuum VLA(C) survey was conducted in 1983 to look for counterparts to these sources at 1.4 and 5 GHz (André et al. 1986) To shed light on emission mechanisms, we performed follow-up VLA(A/B) observations of identified radio stars in March 1985 at 1.4, 5 and 15 GHz.