Chandra and FUSE Detections of the WHIM: locally and at z > 0

Overview

The Local Group WHIM (Nicastro et al., 2002, ApJ, 573, 157; Nicastro et al., 2003, Nature, 421, 719)

The “Truly” Intervening WHIM

Mkn 421 (Nicastro et al., 2003, in preparation)

Future prospects (Pharos)

Chandra and FUSE Spectra of PKS 2155-304

Equivalent Width Ratios Diagnostics

All absorption Lines fall in the linear branch of the Curves of Growth (CoG)

è EW µ Ion Column Density:

EW ratios µ Ionization Balance:

WHIM Solution

Assuming a transverse size of 1´[H/O]_0.3 Mpc

OVI Velocity Distribution in the LSR

Local Group WHIM: Summary

HV-OVI Absorbers are at rest in the LGSR

logT = 5.8; d = 20-30

[Ne/O] = 2.5 [Ne/O]_€

Total Mass =

(0.6-2)´10¹² [H/O]_0.3M_€

Not in Milky Way Halo

Fits Predictions for Warm-Hot IGM

Dusty IGM?

Can Bind the Local Group

WHIM Detections at z > 0

Detecting z > 0 WHIM filaments is harder because of random orientation: lines of sight to background sources cross only a portion of the filament.

Until very recently, only 3 tentative detections have been claimed, along 2 different lines of sight (Fang et al., 2002, Mathur et al., 2002).

Exceptionally high quality X-ray spectra of background AGN are needed, implying exposures of Ms on the brightest blazars in their normal state.

Our Strategy

Mkn 421: Dispersed Image

Mkn 421: Chandra 1^st Order Dispersed Spectrum

The OVII Forest

Summary

Chandra and Newton-XMM detection of the Local Group WHIM Filament

Kinematics of the HV-OVI unambiguously locates them in the Local Group

Chandra ToO of Mkn 421 probes unprecedented N_OVII and detects 1-2 trees in the “X-ray Forest”.

Based on that detection: dN_OVII/dz = 75 (cf. dNOVI/dz = 20, Tripp & Savage, 2000): the majority of baryons at z < 2.

WHIM: Future Prospects

Next 2-4 years: collect data from 12 sightlines towards blazars in outburst: up to z = 0.5: è dN_WHIM/dz, W_b, T_WHIM(z<0.5), dT_WHIM/dz, dZ/dz

Long Term: mapping the WHIM up to z=2: needs high throughput and spextral resolution in X-ray: Constellation-X (R > 1000, A = 2000 cm²), and XEUS (R > 400, A = 30 m²)

Pharos: (Elvis, Fiore & the CWE team, 2002 SPIE, astro-ph/0303444), Midex concept (CfA, Obs. Rome, JHU): R > 5000, A = 1000 cm², Coverage: 12-150 Å. Slew on source in < 2-3 min.: about 20 Soft-GRB per year with F = 10^-5 erg cm^-2 (> 10 Ms on the brightest QSOs at z = 1-2).


	The Local Group WHIM (Nicastro et al., 2002, ApJ, 573, 157; Nicastro et al., 2003, Nature, 421, 719)
	The “Truly” Intervening WHIM
		Mkn 421 (Nicastro et al., 2003, in preparation)
		Future prospects (Pharos)


	All absorption Lines fall in the linear branch of the Curves of Growth (CoG)
	è EW µ Ion Column Density:

	EW ratios µ Ionization Balance:


	HV-OVI Absorbers are at rest in the LGSR

	logT = 5.8; d = 20-30

	[Ne/O] = 2.5 [Ne/O]_€

	Total Mass =
	(0.6-2)´10¹² [H/O]_0.3M_€
	Not in Milky Way Halo


	Fits Predictions for Warm-Hot IGM
	Dusty IGM?

	Can Bind the Local Group


	Detecting z > 0 WHIM filaments is harder because of random orientation: lines of sight to background sources cross only a portion of the filament.
	Until very recently, only 3 tentative detections have been claimed, along 2 different lines of sight (Fang et al., 2002, Mathur et al., 2002).
	Exceptionally high quality X-ray spectra of background AGN are needed, implying exposures of Ms on the brightest blazars in their normal state.


	Chandra and Newton-XMM detection of the Local Group WHIM Filament
	Kinematics of the HV-OVI unambiguously locates them in the Local Group
	Chandra ToO of Mkn 421 probes unprecedented N_OVII and detects 1-2 trees in the “X-ray Forest”.
	Based on that detection: dN_OVII/dz = 75 (cf. dNOVI/dz = 20, Tripp & Savage, 2000): the majority of baryons at z < 2.


	Next 2-4 years: collect data from 12 sightlines towards blazars in outburst: up to z = 0.5: è dN_WHIM/dz, W_b, T_WHIM(z<0.5), dT_WHIM/dz, dZ/dz

	Long Term: mapping the WHIM up to z=2: needs high throughput and spextral resolution in X-ray: Constellation-X (R > 1000, A = 2000 cm²), and XEUS (R > 400, A = 30 m²)

	Pharos: (Elvis, Fiore & the CWE team, 2002 SPIE, astro-ph/0303444), Midex concept (CfA, Obs. Rome, JHU): R > 5000, A = 1000 cm², Coverage: 12-150 Å. Slew on source in < 2-3 min.: about 20 Soft-GRB per year with F = 10^-5 erg cm^-2 (> 10 Ms on the brightest QSOs at z = 1-2).