Finger, M. H.

Jenke, P.

Wilson-Hodge, Colleen

NASA Technical Reports Server

Monitoring Accreting Pulsars 
with 
Fermi GBM
Colleen A. Wilson-Hodge (NASA/MSFC), 
M.H. Finger (USRA), P.Jenke (UAH)
https://ntrs.nasa.gov/search.jsp?R=20150023121 2019-08-31T04:58:35+00:00Z
Outline
• Introduction
– Fermi GBM
– Techniques
• Sources
– XTE J1946+274
– EXO 2030+375
– V0332+53
• Summary and Conclusions
GBM BGO
Detectors (2)
150keV – 40 MeV
GBM NaI
Detectors (12)
8 keV – 1 MeV
LAT
Fermi Gamma Ray Burst Monitor (GBM)
GBM Pulse Searches
• Daily Blind Search 
• 24 source directions equally spaced on the galactic plane. 
• Each direction - FFT based search from 1 mHz to 2 Hz.
• Source Specific Searches.
• Small ranges of frequency and frequency derivative
• Phase shifting and summing pulse profiles from short 
intervals of data
• Barycentered and possibly orbitally corrected times. 
• Typical exposure times are ~40 ks/day.
• Detections:
• 8 of 8 monitored persistent sources
• 26 of 29 monitored transients
Blind Pulse Search
Blind pulse search in 20-50 keV band, for 2010 January 8.
XTE J1946+274 –New Orbital Solution
Marcu-Cheatham, D. et al. 2015,  ApJ in press, arXiv:1510.05032v1
Parmeter Disk Wind
axsini [lt-s] 471.2+2.6-4.3 471.1
+2.7
-2.8
Porb [d] 172.7±0.6 171.4±0.4
τ [d] 55514.8+0.8-1.1 555515.5
+0.8
-0.7
eccentricity 0.246±0.009 0.266±0.007
ω (°) -87.4+1.5-1.7 -87.1
+1.2
-1.0
• Discovered with RXTE in 1998
• 15.8 s pulsations with BATSE
• Active 1998-2001, 2010-11 
• GBM (red) – spin periods, 
RXTE (green), Swift/BAT 
(grey) – fluxes
• 2-3 outbursts per orbit
• GBM data crucial to orbit 
determination
EXO 2030+375 Long  Term Behavior
V0332+53
Summary and Conclusions
The full sky coverage of GBM enables long term monitoring of 
the brighter accreting pulsars allowing:
• Precise measurements of spin frequencies and orbital 
parameters (e.g. XTE J1946+274)
• Study of spin-up or spin-down rates and hence the flow 
of angular momentum
• Detection and study of new transient sources or new 
outbursts of known transients.
• Tracking of QPOs throughout giant outbursts
• Observations of unexpected outburst behaviors
GBM Pulsar Project 
http://gammaray.nsstc.nasa.gov/gbm/science/pulsars/
GBM Earth Occultation Project
http://heastro.phys.lsu.edu/gbm
Many Thanks to the 
GBM Pulsar Team!
– C.A. Wilson-Hodge (PI), Mark H. Finger, E. Beklen, 
P.N. Bhat, D. Buckley, A. Camero-Arranz, M.J. Coe, 
V. Connaughton, P. Jenke, G. Kanbach, I. 
Negueruela, W.S. Paciesas
http://gammaray.nsstc.nasa.gov/gbm/science/pulsars
TextText
Background Subtraction
The rates in each 
channel of the 12 NaI
detectors are fit with a 
model with the following 
components:
•Models for bright 
sources.
•A stiff empirical model 
that contains the low-
frequency component of 
the remaining rates.  
The fits are made 
independently for each 
channel and subtracted 
from the rates.


Monitoring Accretion Pulsars with Fermi GBM

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server