Fermi-GBM type I X-ray burst project:

An all-sky view of thermonuclear bursts.

M. Linares (MIT, Rubicon Fellow)

V. Connaughton (CSPAR/UAH), P. Jenke (ORAU), A. Camero-Arranz (FECYT), E. Beklen (METU), M. H. Finger (USRA), C. Wilson-Hodge, C. Kouveliotou (NASA/MSFC),

A. J. van der Horst (NASA/MSFC/ORAU), D. Chakrabarty (MIT), A. L. Watts (Amsterdam)

World English Dictionary monitor  — n 1. a person or piece of

equipment that warns, checks, controls, or keeps a continuous record

of something

Dictionary.com

monitor  — 6. an instrument for detecting dangerous gases, radiation,

etc.

Thermonuclear bursts from NS-LMXBshttp://w

ww

.gsfc.nasa.gov/topstory/2004/0220stardisk.html

• Field of view: all unocculted (75%) sky.• X-ray response: down to 8 keV.• Optimal instrument to detect rare & bright

thermonuclear bursts.

Fermi-GBM

GBM and X-ray bursts

Systematic X-ray burst search and processing at NSSTC & MIT.So far (March 2010 – November 2010): ~346 XRB candidates (~1.3/day)

GBM and X-ray bursts

Durations: 20-400 s; Av. net rates: 5-100 c/s (11-27 keV band)

GBM and thermonuclear bursts: 4U 0614+09

7 type I X-ray bursts from 4U 0614+09 between March and October, 2010.

51% observation duty cycle: Burst recurrence time = 16 +/- 6 d

GBM and thermonuclear bursts: 4U 0614+09

Kuulkers et al. (2009)

7 GBM bursts in ~8 months!

GBM and thermonuclear bursts: 4U 0614+09

GBM and thermonuclear bursts: 4U 0614+09

GBM and thermonuclear bursts: 4U 0614+09

Long (aka ‘intermediate duration’) type I burst from XTE J1701-407:XRT ~15x longer than BAT

GBM and thermonuclear bursts: 4U 0614+09Linares et al. (2009) Falanga et al. (2009)

Observations of bursts have been strongly biased towards bright (and therefore high Mdot ) states of LMXBs. Recurrence times of low-Mdot bursts have proven extremely difficult to measure.

A scenario has been proposed to explain short low-Mdot bursts that involves stable(unstable) hydrogen burning that builds up(ignites) a pure helium layer (Fujimoto et al. 1981; Bildsten 1998). On the other hand, sedimentation of heavy elements is thought to play an important role in the production of long low-Mdot bursts (Peng et al. 2007).

GBM is measuring their recurrence time to provide crucial missing info: how much mass is accreted to reach ignition?

GBM and thermonuclear bursts: 4U 0614+09

(see Cir X-1 poster for high Mdot bursts)

MAXI:-”Normal” type I bursts.-Well suited to superbursts (duration ~day).-Well sampled long-term accretion rate history.

MAXI and thermonuclear bursts

GBM: Also an X-ray burst monitor, building a valuable archive of several transient high-

energy phenomena.

GBM has opened new ways in the study of thermonuclear bursts, low-Mdot bursts in

particular.

4U 0614+09 bursts every ~16 days during 2010, while Mdot keeps close to 1%

Eddington.

Summary

Arigato for your attention.