Probing the Warm Inter-galactic Medium through Absorption against Gamma Ray Bursts X-ray Afterglows
نویسنده
چکیده
Gamma Ray Burst (GRB) afterglows close to their peak intensity are among the brightest X-ray sources in the sky. Despite their fast power-law like decay, when fluxes are integrated from minutes up to hours after the GRB event, the corresponding number counts (logN-logF relation) far exceeds that of any other high redshift (z> 0.5) source, the flux of which is integrated over the same time interval. We discuss how to use X–ray afterglows of GRBs as distant beacons to probe the warm (10K < T < 10K) intergalactic matter in filaments and outskirts of clusters of galaxies by means of absorption features, the “X-ray forest”. According to current cosmological scenarios this matter may comprise 30− 40% of the baryons in the Universe at z< 1. Present-generation X-ray spectrometers such as those on Chandra and XMM-Newton can detect it along most GRBs’ lines of sight, provided afterglows are observed fast enough (within hours) after the burst. A dedicated medium-sized X-ray telescope (effective area < ∼ 0.1 m) with pointing capabilities similar to that of Swift (minutes) and high spectral resolution (E/∆E > ∼ 300) would be very well suited to exploit the new diagnostic and study the physical conditions in the Universe at the critical moment when structure is being formed. Subject headings: gamma rays: bursts, cosmology: observations, large-scale structure of universe
منابع مشابه
Cosmic Dispersion Measure from Gamma-Ray Burst Afterglows: Probing the Reionization History and the Burst Environment
We show a possible way to measure the column density of free electrons along the light path, the so-called Dispersion Measure (DM), from the early [∼ 415(ν/1 GHz)−2(DM/105 pc cm−3) s] radio afterglows of the gamma-ray bursts. We find that the proposed Square Kilometer Array can detect bright radio afterglows around the time ∼ 10(ν/160 MHz)−2 s to measure the intergalactic DM (& 6000 pc cm−3 at ...
متن کاملStudying the Whim with Gamma Ray Bursts
We assess the possibility to detect and characterize the physical state of the missing baryons at low redshift by analyzing the X-ray absorption spectra of the Gamma Ray Burst [GRB] afterglows, measured by a micro calorimeters-based detector with 3 eV resolution and 1000 cm effective area and capable of fast repointing, similar to that on board of the recently proposed X-ray satellites EDGE and...
متن کاملX-Ray Afterglows from Gamma-Ray Bursts
We consider possible interpretations of the recently detected X-ray afterglow from the gamma-ray burst source GRB 970228. Cosmological and Galactic models of gamma-ray bursts predict different flux and spectral evolution of X-ray afterglows. We show that models based on adiabatic expansion of relativistic forward shocks require very efficient particle energization or post-burst re-acceleration ...
متن کاملEvidence for a Molecular Cloud Origin for Gamma-Ray Bursts: Implications for the Nature of Star Formation in the Universe
It appears that the majority of rapidly-, well-localized gamma-ray bursts with undetected, or dark, optical afterglows, or ‘dark bursts’ for short, occur in clouds of size R ∼> 10L 1/2 49 pc and mass M ∼> 3× 10 L49 M⊙, where L is the isotropic-equivalent peak luminosity of the optical flash. We show that clouds of this size and mass cannot be modeled as a gas that is bound by pressure equilibri...
متن کاملThe absorption properties of gamma-ray burst afterglows measured by BeppoSAX
We present an analysis of the X-ray absorption properties of 6 gamma-ray burst (GRB) afterglows measured with BeppoSAX. Between 8 hrs and 20 hrs after the initial GRB trigger, individual spectra can be described by a power-law with a photon index of ∼2 and absorption, NH, marginally consistent with the galactic value. Taken collectively, the data are inconsistent with zero NH at the >99.999% co...
متن کامل