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Category of the project

II

Project Title: Brief introduction and scope of the project

Using 3 years of Fermi-LAT data we have analyzed the region of HESS J1857, a PWN detected at TeV energy by HESS, MAGIC and Veritas.

The corresponding pulsar PSR J1856+0245, found in Arecibo PALFA survey, remains undetected in Fermi-data. 

An excess of emission was observed (TS~38) in Fermi data consistent with a point source at the position of HESS J1857+026. Its spectrum is well fitted by a hard power law (gamma~1.5) and the SED obtained using Fermi data is consistent with those of HESS and MAGIC.

We are aiming for a A&A letter with a first draft before the end of the week.


    (lightbulb) =Task completed
    (grey lightbulb) = To do

    Required Tasks

    Status

    SG.Coord Approval

    Internal Referee/s Approval

    Pub. Board Approval

    First presentation to the group

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    Paper category

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    External Authors

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    LAT Internal Technical review*

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    Final Draft to internal referee

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    Revised draft and sign-up (2 weeks)

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    Walkthrough/Runtrough

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    Draft with author list/ack.

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    Request to submit

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    Request to submit on ArXiv

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    Request to resubmit after Journal referee comments

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    *Presentation of the LAT data analysis to the group.

    LAT Contact Authors:

    Name

    contribution to this project

    Romain Rousseau

    Analysis of Fermi data

    Marie-Hélène Grondin

    Search for pulsed emission

    Adam Van Etten

    Broad-Band modelling

    Marianne Lemoine-Goumard

     

    Other LAT Contributors:

    Name

    contribution to this project

     

     

    External Authors (Requirements: SG Coord Approval,Pub-board Approval)

    Name

    contribution to this project

     

    Ben Stappers


     

    Providing Jodrell's ephemerid for PSR J1856+026 not covered by the MoU

    Andrew Lyne

    Providing Jodrell's ephemerid for PSR J1856+026 not covered by the MoU

    Cristobal Espinoza

    Providing Jodrell's ephemerid for PSR J1856+026 not covered by the MoU

    Agenda of the day

    General Information (this is just an example, please update it)

    Source list (if applicable)

    NAME

    1/2FGL NAME

    RA

    DEC

    Notes

     

     

     

     

     

    Data Set

    Pass 7

    Event class

    Source (evclsmin/max = 2)

    Energy range

    100 MeV - 300 GeV

    Time interval

    UTC_Start -UTC_stop (MET 239557417 - )

    ROI size

    10°

    Zenith angle (applied also to gtltcube?)

    < 100°

    Time cuts filter

    DATA_QUAL==1 && LAT_CONFIG==1 && ABS(ROCK_ANGLE)<52

    Science Tools version

    v9r21p0

    IRFs P7_V6_Source

    Diffuse emission

    ring_2years_P76_v0.fits, isotrop_2year_P76_source_v0.txt and limb_2year_P76_source_v0_smooth.txt

    Optimizer and tolerance

    Minuit (1e-3 ABS)

    Catalog/s

    Preliminary 2-year (gll_psc24month_v2.fits)

    Spatial and Spectral Analysis

    The whole analysis is summarized here https://confluence.slac.stanford.edu/pages/viewpage.action?pageId=100515585.

    HESS data has shown an emission located at RA=284.3°, DEC=2.68°. It remained unidentified untill the detection of PSR J1856+026 in Arecibo PALFA survey (Hessels et al 2008).

    Here we tested the source for extension using pointlike then gtlike and found no significant extension.

    Fig. 1 Residual TS map obtained between 10GeV and 300GeV. Here HESS J1857 is not included in the model.

    The green contours are those obtained using HESS data (Aharonian et al.,2008).

    The SED shown a hard spectrum consistent with those of HESS and MAGIC. The best fit between 300MeV and 300GeV yields to the following parameters :

    Int Flux(100MeV-100GeV) =  (5.79 ± 0:75 ± 3.11) X 10^{-9} MeV/cm^2/s

    Gamma = 1.52 ± 0.16 ± 0.55

    With a TS of 38.7.

    Systematic Errors Analysis

    The systematics were estimated using the bracketting IRFS, fitting the source galactic background level at +/- 6% of the value of the best fit and the systematics on the shape of the source were computed using a template consistent with the extension derived using HESS data.

    Broad-Band modelling

    Other Analysis

    HESS 1857 is powered by a young and energetic pulsar, with a gamma-ray efficiency of 3.7% consistent with those observed using HESS data (3.1%) and consistent with the other values observed for the PWNe detected by Fermi.

    An upper limit on the DC emission pulsar yield to a luminosity < 8.27 X 10^

    Unknown macro: {35}

    erg/s.

    Draft link

    version

    Pub. Board link

    Figures

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    Tables

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    link

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    Internal referee report 1 (name)

    Authors response to referee 1

    internal referee report 2 (name)

    Authors response to referee 2

    Journal referee report

    Authors response to the referee

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